The research team, which included Gabriela Svartz, Elizabeth Acosta, María Jazmín Penelas and Emmanuel de la Fournière, ran three sets of 96-hour laboratory bioassays. In the first, tadpoles and plants were exposed individually to gold nanoparticles at concentrations of 1 and 10 milligrams per litre. In the second, larvae and plants were exposed simultaneously.

In the third, larvae were placed in clean water with plants that had already been contaminated, testing whether the metal could move through a simple plant-to-larvae route. Gold concentrations were quantified in both organisms, and accumulation factors were calculated. The simultaneous-exposure results were the most striking.

Accumulation factors in the larvae reached 6,666 ± 1,020 litres per kilogram at 1 milligram per litre and 10,089 ± 760 litres per kilogram at 10 milligrams per litre, markedly higher than in the individual-exposure trials. The authors interpret this pattern as evidence that the presence of aquatic vegetation enhances the availability of the nanoparticles to the amphibians. Trophic transfer also occurred, but less efficiently.

Tadpoles that encountered gold only by ingesting previously contaminated plants still accumulated the metal, although at lower levels than larvae exposed directly in the water. This indicates that a dietary route from plants can contribute to nanoparticle accumulation in tadpoles even when the surrounding medium is clean, but that direct aqueous exposure transfers the particles more effectively. Lemna minor took up gold under both isolated and simultaneous exposure conditions, confirming the authors' description of aquatic plants as nanoparticle reservoirs in aquatic systems.

The study was conducted in laboratory bioassays over a 96-hour window at two nanoparticle concentrations, so the findings reflect short-term uptake under controlled conditions rather than effects on survival, development or wild populations; the measured endpoints concern gold accumulation and transfer only, and no toxic outcomes are reported. Gold nanoparticles are increasingly used in industrial and biomedical applications, raising concerns about their release into aquatic environments and their potential effects on non-target organisms. Within that context, the results demonstrate that aquatic vegetation can significantly modulate nanoparticle transfer and availability in freshwater amphibians.

Subject of Research: Accumulation and trophic transfer of gold nanoparticles in amphibian larvae and the aquatic plant Lemna minor under direct and plant-mediated exposure scenarios

Article Title: Gold nanoparticle accumulation in amphibian larvae under direct and plant-mediated exposure scenarios

Article References: Svartz, G., Acosta, E., Penelas, M. J., & de la Fournière, E. (2026). Gold nanoparticle accumulation in amphibian larvae under direct and plant-mediated exposure scenarios. Ecotoxicology, 35(9), Article 195. https://doi.org/10.1007/s10646-026-03185-7

Image Credits: AI Generated

DOI: 10.1007/s10646-026-03185-7

Keywords: gold nanoparticles, Rhinella arenarum, Lemna minor, ecotoxicology, amphibian larvae, trophic transfer, freshwater, bioaccumulation, nanomaterials, aquatic plants, Gold, nanoparticle

The device belongs to a class of technologies known as non-enzymatic glucose sensors. Conventional glucose monitors rely on enzymes such as glucose oxidase, which are exquisitely selective but inherently unstable: they degrade with temperature and pH swings, lose activity during storage, and suffer mass-transfer bottlenecks once immobilized on an electrode. A non-enzymatic electrode instead catalyzes glucose oxidation directly at an active surface, eliminating the biological degradation problem, at the cost of needing careful engineering to keep other electroactive molecules from interfering.

Titanium dioxide nanotubes were chosen as the scaffold because their vertically ordered architecture offers a very large surface area for catalyst attachment, and their walls provide a direct electron pathway to the underlying substrate. Titanium dioxide is also chemically stable across a wide pH range, biocompatible, and far cheaper than noble metal electrodes. The team made the nanotubes by anodic oxidation of commercially pure titanium foil in an ethylene glycol electrolyte containing ammonium fluoride and water. In a two-step process — a first anodization at 60 volts for 45 minutes followed by ultrasonic removal of the initial layer, then a second anodization under identical conditions for 120 minutes — they grew well-ordered nanotubes roughly 100 nanometers in diameter and up to 15 micrometers long. Annealing in air at 400 degrees Celsius for three hours crystallized the amorphous material into the anatase phase.

Pristine titanium dioxide, however, makes a poor glucose sensor on its own. Its wide bandgap of about 3.2 electronvolts renders it electrically insulating in the dark, and its surface lacks the catalytic sites needed to oxidize glucose at useful rates. Decorating the nanotubes with gold nanoparticles solves both problems at once: the gold supplies catalytic active sites while the metal–semiconductor interface forms a Schottky barrier that assists electron transfer. Electrodeposition was the method of choice because, unlike chemical reduction, photodeposition or sputtering, it allows precise, real-time control over particle loading, size and dispersion simply by adjusting the deposition potential, time and number of voltammetric cycles.

The deposition itself was carried out in a three-electrode cell, with the nanotube electrode as the working electrode, a silver/silver chloride reference, and a platinum counter electrode. Cyclic voltammetry swept from −1.25 to −0.7 volts versus the reference at 50 millivolts per second in a potassium chloride solution containing tetrachloroauric acid. Scanning and transmission electron microscopy then revealed what happens as the cycles accumulate. Nucleation begins along the inner nanotube walls, but the elongated channels impose severe diffusion constraints on the gold precursor. Ions deposit preferentially near the nanotube entrances, where the diffusion path is shortest, so particle number and size grow with each additional cycle and eventually begin to choke the pore openings.

Particle statistics tracked the cycle count closely. Mean particle sizes were 27 nanometers at 10 cycles, 33 at 20, 39 at 40 and 33 at 60, with individual particles ranging from roughly 15 to 60 nanometers. Energy-dispersive X-ray analysis showed gold content peaking at 13.38 atomic percent at 40 cycles before easing back to 9.15 percent at 60 cycles, a dip the authors attribute to saturation or changes in deposition dynamics. By 60 cycles, transmission electron microscopy showed the nanotube surface covered with well-dispersed spherical particles inside and outside the tubes, and lateral coalescence had begun to stitch neighboring particles into an interconnected network about 33 nanometers across on average.

X-ray diffraction confirmed the anatase phase in every sample and revealed a subtle but meaningful structural story. Pure nanotubes had an average crystallite size of 9.13 nanometers. Early gold incorporation disrupted the lattice: at 10 cycles the crystallite size dropped to 7.86 nanometers while microstrain rose to 1.343 × 10−3 percent. As deposition continued, the structure recovered and then improved — at 60 cycles the crystallites grew to 12.42 nanometers, the largest in the series, while microstrain fell to its minimum of 0.85 × 10−3 percent and peak widths narrowed correspondingly. Prolonged deposition, in other words, does not just pile on gold; it refines the underlying crystal structure and reduces lattice defects that would otherwise impede charge transport.

Optically, the gold decoration transformed the material in a non-monotonic way. Pure nanotubes showed a bandgap of 3.36 electronvolts, consistent with anatase. After 10 cycles the bandgap narrowed to 3.21 electronvolts, and at 20 cycles it reached its deepest redshift at 2.94 electronvolts, which the authors attribute to new electronic states introduced by the gold, strong interfacial coupling at the metal–semiconductor junction, and near-field enhancement from localized surface plasmon resonance — the collective oscillation of conduction electrons in the nanoparticles. Then the trend reversed: at 40 cycles the bandgap widened to 3.47 electronvolts, above even the pristine value, apparently because the particles had coalesced into larger aggregates that damp the discrete plasmon resonance and reduce the interfacial area. At 60 cycles it fell again to 3.01 electronvolts, signaling the emergence of a percolated conductive network with different dominant absorption behavior. Photoluminescence measurements echoed this evolution: the 10-cycle sample showed the lowest emission intensity, consistent with a Schottky junction that ferries photogenerated electrons from the semiconductor into the metal and suppresses recombination, while the 60-cycle sample showed the highest intensity, consistent with a shift toward ohmic-like contact behavior as the particles agglomerate.

The electrochemical payoff came at 60 cycles. In cyclic voltammetry, a well-defined anodic peak near 334 millivolts, tied to the formation of an incipient hydrous gold oxide layer, grew steadily with deposition cycles and reached its maximum for the 60-cycle electrode. When glucose was added, the peak shifted to about 350 millivolts and its current rose linearly with glucose concentration from 0.1 to 4 millimolar, reflecting the catalytic oxidation of glucose to gluconic acid. In alkaline media the gold nanoparticles mediate this oxidation through active gold hydroxide species, while the nanotube scaffold conducts electrons along the tube walls and prevents particle aggregation. Calibration gave a sensitivity of 7.96 microamperes per millimolar per square centimeter for the 60-cycle electrode — the best among bare and decorated samples, which ranged from as low as 0.68 for the 10-cycle electrode up to 6.96 at 20 cycles — and a detection limit of 15.1 micromolar calculated by the 3-sigma method with a blank standard deviation of 0.04 microamperes per square centimeter.

Two further results explain why the best performance arrived at the very loading where the nanotubes are most clogged. First, selectivity: against dopamine, ascorbic acid, lactose and fructose, the selectivity coefficients all stayed at or below 0.055, corresponding to less than 6 percent cross-reactivity, and the glucose signal recovered to roughly 62 percent of its original 81.2-microampere value after an interferent cocktail, indicating robust anti-fouling behavior. Second, and more intriguingly, the partial pore choking at 60 cycles turns out to be offset by a mechanistic transition. Although the roughly 95-nanometer surface clusters restrict diffusion into the deep channels, their lateral coalescence creates a continuous, highly conductive metallic network across the electrode interface, cutting charge-transfer resistance and enabling rapid electron extraction. The team describes this as a shift from porous, diffusion-limited kinetics to electronic percolation-dominated charge collection — the interconnected gold topology simply wins out over the lost pore accessibility.

The authors are careful to frame the limits of the claim. The reported electrochemical measurements were performed in concentrated alkaline media rather than under physiological conditions, and they note that further testing in such conditions would be required to confirm clinical potential. Still, the low detection limit falls within the 10-to-200-micromolar glucose range found in biofluids such as tears and sweat, and the sensor retained reproducible operation over 40 operational cycles. Beyond glucose monitoring, the same deposition-controlled tuning of bandgap, crystallite quality and metal–semiconductor interface bears directly on photocatalysis, anticorrosion coatings and photoelectrochemical energy conversion, where the gold–titanium dioxide junction is already under active study. What the work adds is a demonstration that a single fabrication dial — the number of voltammetric cycles — can steer the optical, structural and electrochemical character of the whole system, and that the sweet spot for sensing may lie precisely where discrete nanoparticles stop being isolated islands and start becoming a wire.

Subject of Research: Non-enzymatic electrochemical glucose detection using gold nanoparticle-decorated TiO2 nanotube electrodes

Article Title: Insight on gold nanoparticle-decorated TiO2 nanotube electrochemical sensor for non-enzymatic glucose detection

Article References: Benghanoum, H., Sassi, S., Zaghouani, R. B., Bouich, A., Arbaoui, A., El Hawary, M., Dhiflaoui, H., Khezami, L., Karrech, A., Soucase, B. M., & Hajjaji, A. (2026). Insight on gold nanoparticle-decorated TiO2 nanotube electrochemical sensor for non-enzymatic glucose detection. Frontiers in Materials, 13, Article 1938438. https://doi.org/10.3389/fmats.2026.1938438

Image Credits: AI Generated

DOI: 10.3389/fmats.2026.1938438

Keywords: gold nanoparticles, TiO2 nanotubes, non-enzymatic glucose sensor, electrodeposition, electrochemical biosensor, localized surface plasmon resonance, Schottky junction, anodization, detection limit, sensitivity, selectivity, bandgap tuning

The study was designed as a proof-of-concept for decentralized dengue screening. Its central idea is to carry a small diagnostic strip to a location that can be reached by drone, perform the test near the collection point and transmit the result through a digital workflow. The platform used a DJI Mini 3 Pro weighing less than 249 grams, with dimensions of 251 by 362 by 70 millimetres, an intelligent-flight battery capacity of 2,453 milliampere-hours and a stated top speed of 16 metres per second in S mode under sea-level, no-wind conditions. The lateral-flow strip was attached to the drone with a double-sided adhesive and enclosed in translucent Plexiglas to protect it during flight. A QR code placed on the aircraft opened a reporting webpage through which a user could transmit results to laboratory personnel.

At the biochemical core of the system is a 34-base DNA aptamer designed to recognize polyvalent dengue antigen. Researchers synthesized gold nanoparticles by reducing chloroauric acid with trisodium citrate, then mixed 24 microlitres of aptamer with 500 microlitres of the nanoparticle suspension at a pH of 9.2 to 9.6. After incubation, bovine serum albumin was added as a blocking agent, and the conjugate was washed, resuspended in phosphate-buffered saline and stored at 4 degrees Celsius. Zeta-potential analysis gave the unmodified particles a mean surface charge of minus 37.56 millivolts, consistent with strong electrostatic repulsion and colloidal stability. Dynamic light scattering measured an average hydrodynamic diameter of 11.59 nanometres, while transmission electron microscopy gave a particle diameter of 12.43 plus or minus 0.20 nanometres. The particles were well dispersed and spherical.

Aptamer attachment altered the nanoparticles in ways that were consistent with successful functionalization. Their surface-plasmon-resonance band shifted from 521 to 526 nanometres after conjugation, accompanied by a decrease in absorbance, indicating a change in the local environment around the gold surface. Dynamic light scattering also recorded an increase in hydrodynamic diameter to 17.11 nanometres, which the authors attributed to the aptamer coating rather than aggregation. The investigators characterized the interaction between the aptamer and dengue antigen through molecular docking and an electrophoretic mobility shift assay. Docking produced a score of minus 326.89, which the authors interpreted as strong predicted binding affinity, although a ligand root-mean-square deviation of 66.33 angstroms indicated considerable conformational flexibility or imperfect structural alignment after docking. In the mobility assay, the conjugate shifted relative to the free aptamer, as did the aptamer–antigen complex, supporting the formation of the intended molecular complexes.

The lateral-flow sensor used a sample pad, conjugate pad, nitrocellulose membrane and absorbent pad mounted in a plastic cassette. A 70-microlitre sample was applied to the pad and moved by capillary action. When dengue antigen was present, it bound the aptamer and promoted release of the gold nanoparticles from the complex. The free nanoparticles then reached a test line containing immobilized lysozyme and formed a visible red signal. In the absence of dengue antigen, the gold–aptamer complex remained associated and did not produce the test-line band. During a separate verification using 80-microlitre samples, dengue antigen and phosphate-buffered saline controls were run at room temperature for 30 seconds. Of three tested stages—free nanoparticles, gold–aptamer conjugate and gold–aptamer–dengue antigen complex—only the complete three-component stage generated a signal. Scanning electron microscopy showed the porous and fibrous structures of the strip components and the deposition of biomaterial on the test line.

The researchers optimized the pH and aptamer loading before evaluating analytical performance. The gold nanoparticles performed well at pH 7, while increasing the amount of aptamer initially strengthened the test-line signal before reaching a plateau or modest decline at higher loadings. The investigators attributed that downturn to steric hindrance or excessive surface capping, which could impede the release of nanoparticles required by the competitive assay format. Strips were then tested across dengue-antigen concentrations from 1 to 100 micrograms per milliliter. Test-band intensity rose with concentration, and ultraviolet-visible spectroscopy was used to examine the associated changes in nanoparticle dispersion. Densitometric analysis with ImageJ produced a calibration coefficient of determination of 0.994 within the working range, allowing the authors to describe the assay as suitable for semiquantitative antigen measurement. Each concentration was tested in seven replicates for the intensity analysis.

The reported limit of detection was calculated as three times the standard deviation of the response divided by the slope of the calibration curve, using seven observations. It was 0.91 micrograms per milliliter, and the study’s highlights state that a visible result could be obtained within five seconds. Recovery tests produced values of 92.79% and 105.96%, with relative standard deviations of 1.61% and 2.33%. Student’s t-values of 0.850 and 0.442 were below the critical value of 2.447 for six degrees of freedom at a two-tailed 0.05 significance level. In separate repeatability measurements, the reported intra-day mean was 112.41% plus or minus 1.18%, with an RSD of 1.05%, while the inter-day mean was 113.32% plus or minus 1.45%, with an RSD of 1.28%. These are analytical assay results rather than measurements of accuracy against a broad clinical population.

Selectivity experiments tested chikungunya virus and hepatitis C virus at 1 microgram per milliliter, the lowest dengue-antigen concentration used in the reported comparison. Neither produced a test-line signal, supporting specificity for the intended target under the conditions tested. The researchers also evaluated three independently collected human-serum samples, each tested in triplicate, and observed dengue signals in spiked serum. A commercial gold-standard lateral-flow kit was used for comparison, although the supplied article does not provide a detailed clinical agreement table. The human-serum work was approved by the Jamia Hamdard Institutional Ethics Committee, and participants provided written informed consent. The study nevertheless involved a small set of specimens, so the serum results support feasibility rather than establishing performance across diverse patients or a validated clinical diagnosis.

Automated image analysis was added to reduce dependence on subjective visual interpretation. The YOLOv5 small model was used first to locate the predefined result window, not to diagnose patients. On a 47-image working set, the region-of-interest localization achieved a mean average precision at an intersection-over-union threshold of 0.5 of about 0.995 and a value across thresholds from 0.5 to 0.95 of about 0.945. A separate linear support-vector-machine classifier assessed positive or negative strips. Its 25-image test set contained 18 positive and seven negative images, producing six true negatives, one false positive, no false negatives and 18 true positives. Reported accuracy was 96.00%, sensitivity 100.00%, specificity 85.71%, precision 94.74% and F1 score 97.30%, with a reported ROC-AUC and average precision of 1.000. The authors cautioned that the reconstructed image dataset was small and that historical independence of the training and test sets could not be guaranteed, making these results preliminary model-development performance rather than independent clinical validation.

The reporting layer, called the Delhi Against Dengue platform, links a QR code to a mobile webpage showing the result, a unique barcode for an electronic prescription and summary counts of positive and negative reports. It also presents dengue information and graphs of reported trends from 2020 to 2024. This digital element is designed to support communication with clinicians and laboratory authorities, but the platform’s surveillance value was not established through a prospective outbreak trial. The authors identify several constraints to operational use: drone flight endurance of roughly 20 to 30 minutes, payload limits, adverse-weather sensitivity, communication range and bandwidth, crash risk, and aviation, privacy and security requirements in populated or sensitive areas. Large multicenter clinical studies, environmental robustness tests, field trials, regulatory clearance and optimized hardware would be needed before deployment. The demonstrated result is therefore a technically characterized drone-integrated diagnostic prototype, while autonomous outbreak surveillance, real-time epidemiological mapping and large-scale remote deployment remain future objectives.

Subject of Research: Proof-of-concept drone-integrated lateral-flow biosensor for dengue antigen detection

Article Title: Intelligent drone-based biosensor for the detection of dengue virus antigen towards smart unmanned aerial-vehicle platform-based virus diagnosis

Article References: Hasan, M. R., Khan, S., Naithani, D., Sharma, P., Mehta, Y., Ansari, S., kumar, S., Naikoo, U. M., Baliyan, A., Abbas, M., Parayangat, M., Kalathil, S., & Narang, J. (2026). Intelligent drone-based biosensor for the detection of dengue virus antigen towards smart unmanned aerial-vehicle platform-based virus diagnosis. Frontiers in Bioengineering and Biotechnology, 14, Article 1907197. https://doi.org/10.3389/fbioe.2026.1907197

Image Credits: AI Generated

DOI: 10.3389/fbioe.2026.1907197

Keywords: dengue virus, biosensor, lateral-flow assay, gold nanoparticles, DNA aptamer, unmanned aerial vehicle, YOLOv5, point-of-need testing, digital reporting, Intelligent, drone-based, detection

Localized surface plasmon resonance arises when light drives the conduction electrons in a metal nanoparticle into collective oscillation. The resulting electric field is strongest near sharp corners, elongated tips and narrow gaps between neighboring particles, creating the “hot spots” exploited by surface-enhanced Raman spectroscopy. Symmetrical gold particles generally support one resonance, whereas rods, bipyramids and stars support transverse and longitudinal modes that can be separated and tuned. Rods with greater aspect ratios shift their longitudinal resonance toward the near-infrared and can concentrate more energy at their ends, making minute changes in geometry directly consequential for optical and chemical performance.

The authors argue that reliable synthesis requires a mechanistic understanding rather than blind adherence to a recipe. Face-centered-cubic gold and palladium naturally favor compact forms, so elongated or sharply faceted particles are generally out-of-equilibrium structures that must be stabilized during growth. Ligands, halides, silver ions and seed architecture can lower the energy of selected crystal facets, block atomic deposition or create twins and stacking faults. At the same time, the rate of precursor reduction must be balanced against surface diffusion: rapid deposition can freeze in anisotropy, whereas slow delivery allows atoms to rearrange toward a more rounded form.

Halides provide several overlapping levers. Chloride, bromide and iodide can bind selectively to particular facets, complex metal precursors and etch unstable particles. Iodide is especially influential in gold nanoplates because it binds strongly to the basal {111} faces, confining growth to the edges. Bromide can favor palladium cubes by stabilizing {100} facets, while silver underpotential deposition can arrest growth on high-index gold surfaces. These mechanisms rarely act alone, and published recipes can fail when the commercial CTAB used as a surfactant contains a different amount of iodide than the original laboratory encountered.

Gold nanorods demonstrate how narrow the operating window can become. In seed-mediated synthesis, silver nitrate content primarily controls aspect ratio, while hydroquinone can deliver higher yields and near-infrared tuning than ascorbic acid at the cost of longer reactions. Mini-nanorods have been produced with widths below 10 nanometres, aspect ratios above 10 and optical resonances beyond 1,300 nanometres. Yet changing the volume of gold precursor by roughly one-third can shift the longitudinal plasmon peak from about 560 to nearly 800 nanometres, and a modest change in silver addition can move it by more than 100 nanometres. Above a threshold, the growth mechanism itself can switch from rod formation to spheres.

Other gold shapes emerge from similarly tight chemical windows. Bromide-directed growth can yield ordinary cubes, while a chloride environment combined with silver can stabilize the stepped faces of concave cubes. Surfactant-free gold stars require quick, simultaneous addition of silver and reductant: slow reduction favors spheres, early silver addition can cause unwanted precipitation, and delayed addition allows isotropic particles to form before branching begins. Their sharp tips also evolve over time, making prompt stabilization essential because even modest changes in tip geometry can broaden the plasmon band and alter field enhancement. For plates, slow oxidative etching can remove high-energy tips and convert irregular particles into more uniform disks.

Palladium offers a distinct but related set of opportunities. Its plasmonic response is more strongly damped than that of gold, so measurable near-infrared resonances generally require particular shapes and environments. Nevertheless, palladium’s catalytic activity, thermal stability and sensitivity to refractive-index changes make tailored structures attractive for catalysis and thermo-plasmonics. Five-fold-twinned palladium rods are produced with iodide, bromide, silver and ascorbic acid, but silver appears to act mainly during nucleation by creating transient template nuclei rather than by passivating the finished rods. Palladium cubes instead rely on single-crystalline seeds and bromide-selected {100} facets, with no silver additive required.

Carbon monoxide produces one of the most dramatic palladium structures: freestanding hexagonal nanosheets only 1.8 nanometres thick. Carbon monoxide caps the broad {111} basal faces, bromide regulates the side edges and PVP prevents aggregation. Delivery rate is critical, because slow release creates a low flux of palladium atoms that favors twinned, plate-forming nuclei, whereas fast delivery floods the solution with atoms and promotes tetrahedral crystals. The synthesis also depends on confined nucleation at a bromide-bearing interface, illustrating that a shape-directing ligand cannot compensate for unsuitable reaction architecture.

The review’s central message is that reproducibility depends on documenting the entire reaction environment, including reagent provenance, water quality, pH, addition order, mixing, seed concentration and illumination. Seed stocks should be characterized directly rather than inferred from nominal dilutions, and optical spectra or microscopy should be used to verify intermediate and final products. Scale-up adds heat-transfer and mixing gradients, while washing can alter surface ligands and dispersibility. Future progress may come from liquid-cell electron microscopy, synchrotron scattering, high-throughput experiments and machine-learning-assisted optimization, but none can replace explicit control of variables that conventional methods sections often omit.

Subject of Research: Reproducible synthesis of shape-controlled gold and palladium plasmonic nanocrystals

Article Title: Synthesis of shape-controlled gold and palladium plasmonic nanocrystals: reliable methods and good practices

Article References: Rozenberg, M., Perez, D., & Zitoun, D. (2026). Synthesis of shape-controlled gold and palladium plasmonic nanocrystals: reliable methods and good practices. Journal of Nanoparticle Research, 28(11), Article 272. https://doi.org/10.1007/s11051-026-06778-9

Image Credits: AI Generated

DOI: 10.1007/s11051-026-06778-9

Keywords: plasmonic nanocrystals, gold nanoparticles, palladium nanoparticles, shape control, colloidal synthesis, localized surface plasmon resonance, halide passivation, seed-mediated growth, nanoparticle reproducibility, surface-enhanced Raman spectroscopy, Synthesis, shape-controlled

The new material, described in the Journal of Materials Science, is a core–shell–satellite nanocomposite with the tongue-twisting formula Fe3O4@Au@Ag. Each component of that structure does a specific job. At the center sits a magnetite (Fe3O4) core, made by a standard hydrothermal synthesis, which provides the magnetic handle that makes the whole catalyst recyclable. Wrapped around that core is a shell of gold, grown through a seeded-growth process so that the precious metal coats the magnetic particle uniformly. Finally, the surface is decorated with small silver nanoparticles, deposited in amounts that the researchers can tune by adjusting the dosage of silver nitrate during synthesis.

The reason this three-layer architecture works so well lies in a phenomenon called localized surface plasmon resonance, or LSPR. When light strikes a metallic nanoparticle much smaller than the wavelength of that light, the conduction electrons in the metal oscillate collectively at a characteristic frequency. At that resonant frequency, the nanoparticle becomes an extraordinarily efficient absorber and scatterer of light, and the electromagnetic field near its surface is amplified by orders of magnitude. Gold nanoparticles resonate in the visible range, but the exact wavelength depends on the particle’s size, shape, and chemical environment. By adding silver satellites to a gold shell, the team could tune the resonance and dramatically broaden and strengthen the material’s absorption of visible light, which is the energy source that drives the catalytic destruction of pollutants.

But the silver decoration does something even more important than simply tuning the color of the particles. When a moderate amount of silver sits on the gold surface, the plasmons of the two metals couple together, producing electromagnetic hot spots in the nanoscale gaps between them where the local electric field becomes intensely concentrated. These hot spots accelerate the photocatalytic reactions that break down organic molecules, and they also promote efficient separation of the charge carriers, the energized electrons and holes that do the actual chemical work of shredding pollutant molecules into harmless fragments. The researchers confirmed this picture using finite-difference time-domain simulations, a computational electrodynamics technique that models how electromagnetic fields propagate through complex nanostructures, and the simulated field enhancements matched the experimentally observed catalytic behavior.

To measure performance, the team used the photodegradation of methyl orange, a common azo dye that serves as a standard test compound in photocatalysis research. The best-performing composite destroyed more than 95 percent of the dye within four minutes of irradiation. Just as importantly for any real-world application, the material did not quit after one use. After six cycles of degradation, recovery, and reuse, the catalyst still retained efficiency above 80 percent, a durability figure that many photocatalysts struggle to approach and that speaks to the robustness of the layered structure.

The kinetics of the reaction also revealed a subtle and instructive dependence on how much silver was deposited. The researchers tracked two parameters: the characteristic induction time, denoted t0, which is the delay before degradation reaches full speed, and the apparent reaction constant, which measures how quickly the dye molecules are destroyed once the reaction is running. As the silver nitrate dosage increased during synthesis, the induction time first declined and then rose again, while the reaction constant followed exactly the opposite trajectory, rising and then falling. The sweet spot corresponded to a moderate silver loading, where Au–Ag plasmonic coupling is strongest.

The explanation for this non-monotonic behavior is elegantly physical. A moderate amount of silver creates strong plasmonic coupling between the silver satellites and the gold shell, generating the intense hot spots and charge-separation efficiency that supercharge the catalysis. But when too much silver is deposited, the silver particles grow and merge until they fully encapsulate the gold surface, burying it under an inert metallic blanket. With the gold no longer exposed, the interfacial electromagnetic interactions between the two metals weaken, the hot spots fade, and catalytic performance declines. More is not better; there is a precise structural optimum, and the ability to tune silver loading via the silver nitrate dosage gives chemists direct control over where on that curve their catalyst lands.

The magnetic core is not a minor convenience feature; it addresses one of the biggest practical obstacles to deploying nanoparticles in water treatment. Nanoparticle catalysts offer enormous surface area, but recovering them from treated water is difficult and expensive, and catalyst particles that escape into the environment become pollutants themselves. The Fe3O4 core solves this problem: the composite exhibited a saturation magnetization of 71.6 emu/g, a figure high enough that a simple external magnet pulls the particles out of suspension rapidly and completely. The catalyst can be collected, rinsed, and redeployed, turning a single-use nanomaterial into a genuinely recyclable one and keeping the nanomaterial out of the discharge stream.

The work also highlights a broader trend in materials chemistry: the deliberate engineering of multi-component nanostructures in which each element plays a distinct role, and where the interactions between components, rather than any single component alone, produce the desired property. Previous studies have explored magnetic plasmonic systems in various forms, including Fe3O4@TiO2@Au composites for visible-light degradation and Schottky-type Fe3O4–Au heterostructures, and silver has long been known to enhance the performance of gold in electrocatalysis. The Hangzhou Dianzi team’s contribution is the systematic demonstration that the degree of Ag coverage on a Au shell acts as a tuning knob for plasmonic coupling, and the direct computational corroboration that coupling-induced field enhancement underlies the catalytic gains.

The research was led by Weiwei Que and Song Fu of the College of Materials and Environmental Engineering, together with Jie Liu and Tian-Song Deng of the School of Electronics and Information Engineering, with support from the Zhejiang Provincial Natural Science Foundation and the National Natural Science Foundation of China. The authors suggest that the structural modulation strategy, growing a magnetic core, a plasmonic shell, and a tunable satellite layer, offers a general recipe for building recyclable, high-performance plasmonic photocatalysts. If the approach extends beyond methyl orange to the full zoo of industrial dyes and organic contaminants, and if it can be scaled from beakers to treatment tanks, magnetic plasmonic nanocomposites of this kind could give wastewater engineers something they rarely get: a catalyst that works in minutes, survives repeated use, and comes home when called.

Subject of Research: Recyclable plasmonic Fe3O4@Au@Ag magnetic nanocomposites for photocatalytic degradation of organic dye pollutants in wastewater

Article Title: Enhanced photocatalytic degradation of organic pollutants by plasmonic Au/Ag-decorated magnetic nanocomposites

Article References: Que, W., Fu, S., Liu, J., & Deng, T.-S. (2026). Enhanced photocatalytic degradation of organic pollutants by plasmonic Au/Ag-decorated magnetic nanocomposites. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13949-5

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13949-5

Keywords: photocatalysis, plasmonics, nanocomposites, Fe3O4, gold nanoparticles, silver nanoparticles, methyl orange, wastewater treatment, LSPR, magnetic recovery, hot spots, FDTD simulation

CA 15-3 is a circulating fragment of MUC1, a large transmembrane glycoprotein that is heavily overexpressed and abnormally glycosylated in breast tumors. Healthy serum levels sit below 30 units per milliliter, but 30 to 50 percent of breast cancer patients show concentrations above 100 units per milliliter, making the marker valuable for tracking disease severity, recurrence, and metastasis. Conventional clinical assays such as ELISA and ECLIA detect the protein through antibody binding, but they demand labeling steps, long processing times, and costly reagents. The South African team, led by Nastaran Ghaffari and Priscilla Baker of the SensorLab research group, asked whether the protein’s own chemistry could do the work of a receptor.

The answer lies in cysteine. MUC1 contains multiple cysteine residues, many of which are locked in disulfide bonds, but partial unfolding or interfacial contact can expose sulfur-containing groups capable of binding gold. When the protein meets a nanostructured gold surface, accessible thiols undergo dissociative chemisorption, forming covalent-like gold-sulfur bonds with strengths of roughly 40 to 50 kilocalories per mole. Each bound molecule partially insulates the electrode, blocking electroactive gold sites and suppressing the characteristic gold oxidation peak near 1.2 volts. The more CA 15-3 in the sample, the more the peak fades, providing a built-in, label-free readout that requires no secondary reagents.

To maximize this effect, the researchers turned to an unlikely substrate: pencil lead. Pentel HB pencil graphite rods, 0.5 millimeters in diameter, were cleaned in nitric acid, electrochemically conditioned in acetate buffer, and then coated with gold nanoparticles electrodeposited from a 5 millimolar chloroauric acid solution. Deposition began with a fixed potential of minus 0.6 volts for three minutes, followed by twenty cyclic voltammetry sweeps between minus 1.0 and plus 1.0 volts under constant magnetic stirring. A custom multi-compartment cell machined from polyethylene terephthalate lids allowed eight electrodes to be coated simultaneously, a fabrication strategy that proved critical for reproducibility.

Characterization confirmed the transformation. Scanning electron microscopy with energy-dispersive X-ray spectroscopy showed uniformly distributed, round gold nanoparticles across the graphite surface, while atomic force microscopy revealed predominantly spherical particles smaller than 100 nanometers covering both the machining grooves and the flatter regions of the pencil lead. Electrochemical impedance spectroscopy in a ferricyanide-ferrocyanide probe showed that charge-transfer resistance, measured at 508.3 ohms on the bare graphite, was effectively eliminated after gold modification. Cyclic voltammetry told a similar story: the electroactive surface area jumped from 1.10 to 4.21 square centimeters, the roughness factor rose from 5.8 to 22.3, and the peak-to-peak separation shrank from 0.85 volts to 0.116 volts, indicating fast, nearly reversible electron transfer.

The analytical performance was striking. After a 25-minute incubation with CA 15-3 and a brief chronoamperometric conditioning step at minus 0.5 volts, linear sweep voltammetry recorded the gold oxidation peak at approximately 1.2 volts. Across CA 15-3 concentrations from 1 to 6 parts per billion, the peak current fell in a strong inverse linear relationship with a correlation coefficient of 0.98. The calculated limit of detection, using the standard three-sigma-over-slope method, was 0.12 parts per billion, equivalent to 1.2 times ten to the minus four units per milliliter, orders of magnitude below normal serum levels and far beneath the concentrations seen in most breast cancer patients.

Reproducibility numbers were equally impressive. A single modified electrode held its baseline gold oxidation current within a relative standard deviation of 0.4 percent over five consecutive measurements in buffer. When eight electrodes were coated simultaneously with the multi-electrode technique, the batch-to-batch variation was just 0.5 percent, compared with 2.7 percent when electrodes were prepared one at a time. The platform can therefore operate either as a single-use disposable sensor or be reused at least five times without performance loss, eliminating the cleaning and maintenance burden of conventional gold electrodes.

Selectivity tests probed the mechanism directly. Urea, glucose, and lactate, common plasma components that lack accessible thiol groups, produced negligible changes in the sensor response even at twice the CA 15-3 concentration. Cysteine and human serum albumin, which carries a well-known free cysteine residue at position 34, both caused pronounced additional signal suppression, consistent with gold-sulfur bond formation. The results confirm that the sensor is chemically selective for thiol-bearing species rather than immunochemically specific for CA 15-3, a distinction the authors acknowledge as a limitation of the receptor-free design.

Real-sample testing in diluted human serum plasma demonstrated practical feasibility. Using the standard addition method with samples spiked at 2 parts per billion, the sensor achieved recoveries between 97.5 and 104 percent with relative standard deviations between 1.74 and 2.77 percent across triplicate measurements. The correlation coefficient in the plasma matrix reached 0.999. Thiol-containing plasma proteins create a stable background of surface passivation, but incremental CA 15-3 additions produced measurable additional suppression of the gold oxidation peak on top of that baseline, allowing quantitative determination in a complex biological matrix.

The approach joins a growing family of pencil graphite electrochemical sensors that have recently been applied to epigenetic biomarkers in urine, paracetamol, drug-DNA interactions, and pharmaceutical analysis. Its appeal is obvious: the sensing element costs pennies, fabrication takes minutes, and each measurement can use a freshly prepared electrode. The authors note that mechanical fragility of pencil graphite remains a challenge and suggest future routes such as reconstituting crushed graphite into pellet electrodes with potassium bromide binders or blending pencil graphite with gold nanoparticles into carbon paste formulations for screen-printed electrodes. While clinical deployment will require validation in more complex biological environments and careful management of cross-reactivity with other thiol-containing proteins, the study establishes a chemically driven sensing framework that turns gold surface chemistry itself into the analytical signal, offering a simplified and cost-effective path toward label-free cancer biomarker detection.

Subject of Research: Label-free electrochemical detection of the breast cancer biomarker CA 15-3 using gold nanoparticle-modified pencil graphite electrodes

Article Title: Thiol-mediated electrochemical sensor for the breast cancer biomarker CA 15-3

Article References: Ghaffari, N., & Baker, P. (2026). Thiol-mediated electrochemical sensor for the breast cancer biomarker CA 15-3. Frontiers in Sensors, 7, Article 1807434. https://doi.org/10.3389/fsens.2026.1807434

Image Credits: AI Generated

DOI: 10.3389/fsens.2026.1807434

Keywords: breast cancer, CA 15-3, electrochemical sensor, gold nanoparticles, pencil graphite electrode, label-free detection, biosensors, MUC1, Thiol-mediated, electrochemical, sensor, breast

Natural chiral materials, however, generally exhibit limited optical responses and cannot meet the diverse functional demands of practical applications. Artificial chiral materials have consequently become an important research direction, but existing routes each carry shortcomings. Chemical synthesis can produce a rich variety of organic chiral materials, yet these often cannot withstand prolonged exposure to high temperatures, intense light, or other demanding operating conditions. Precision nanofabrication techniques, such as focused ion beam processing, can sculpt intricate structures, but they are costly and usually confine those structures to material surfaces. Inorganic optical crystals, by contrast, combine excellent mechanical strength, thermal stability, and optical performance. Encapsulating chiral structures within such crystals could yield three-dimensional optical materials that unite these advantages. Yet a crystal lattice is not a blank sheet on which arbitrary patterns can be drawn, and the controlled construction of embedded chiral nanostructures inside a crystal has remained a formidable challenge.

Metal nanoparticles offer a promising way to address this challenge. When driven by a light field, the free electrons in these particles oscillate collectively, a phenomenon known as localized surface plasmon resonance that confines optical energy to nanoscale regions. This effect magnifies subtle changes in particle shape, orientation, or arrangement into measurable differences in optical response. Metal nanoparticles buried in advance inside a crystal can therefore serve as structures that may be deliberately reconfigured after embedding. Femtosecond lasers are well suited to this task. Their pulses last on the order of one quadrillionth of a second, and their energy can be confined to an extremely small focal region. They can penetrate transparent materials and finely modify internal nanostructures while leaving the surrounding lattice largely undisturbed. As the technology has advanced, femtosecond lasers have evolved from tools for simply changing material properties into instruments capable of directing the evolution of nanoparticles inside glasses and crystals.

In a study published online in Opto-Electronic Science on September 7, 2026, a joint team from Shandong University in China, the Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences, Swinburne University of Technology in Australia, and Helmholtz-Zentrum Dresden-Rossendorf in Germany proposed a top-down two-step strategy for the controllable synthesis of chiral nanostructures inside optical crystals. The researchers first encapsulated gold nanoparticles in yttrium aluminum garnet crystals, then used a femtosecond laser with a continuously varying polarization direction to manipulate them. The concentrated, ultrashort laser energy reshaped and rearranged the originally near-spherical particles into gold nanorods with varying orientations. Differences in nanorod orientation and depth broke the crystal’s original mirror symmetry, giving the material a chiroptical response capable of distinguishing left- from right-circularly polarized light.

Experimental measurements and numerical simulations jointly confirmed that reversing the direction in which the laser polarization rotated produced nanostructures of opposite handedness. Adjusting the laser-processing parameters also tuned the chiroptical response across the visible to near-infrared range. The team subsequently incorporated these chiral structures into optical waveguides, causing circularly polarized light of opposite handedness to emerge with different output intensities after transmission. This result not only established that the material possessed measurable chirality but also demonstrated its potential for integration into photonic devices, tracing a complete path from chiral-structure design to polarization-selective light transmission.

Unlike conventional precision machining of solid materials, the team’s approach uses ultrafast laser pulses to actively trigger the reorganization of nanoscale structures already inside the crystal, thereby endowing the material with tunable optical functions. One of the study’s most important features is that the chiral nanostructures are constructed in situ within an optical crystal at room temperature and atmospheric pressure. Conventional chiral nanostructures are commonly fabricated on material surfaces, where they are vulnerable to wear, contamination, and environmental changes. By contrast, the gold nanostructures in this work are enclosed in three dimensions by the crystal and closely integrated with the surrounding lattice, potentially giving them greater long-term durability. Femtosecond laser direct writing also offers high spatial selectivity, adjustable processing parameters, and flexible design. Without assembling nanoparticles one by one, it can reshape and organize them according to predetermined requirements, opening a possible route to large-area, low-cost, and customized manufacturing.

The study connects nanoscale material control with optical-device construction and demonstrates how the interior of a transparent crystal can be transformed into a functional optical medium. As the technology matures, it could enable more accessible nanofabrication, smaller optical components, and more highly integrated optical communication systems. The ability to write handedness directly into a crystal lattice, rather than assembling it layer by layer on a surface, represents a conceptual shift in how chiral photonic materials might be produced, moving from surface-bound patterning toward genuinely three-dimensional, embedded optical functionality.

Several challenges remain before this proof of principle can become a practical device. Researchers need to strengthen the material’s ability to distinguish the two circular polarizations, reduce intrinsic propagation losses in the waveguide, and improve the uniformity and reproducibility of nanostructures across large processing areas so that the method can meet the performance requirements of specific optical applications. More precise quantitative relationships must also be established between the power, scanning speed, and polarization changes of the laser and the morphology and optical properties of the nanoparticles. This would shift structural design from empirical adjustment toward predictable, programmable manufacturing, a transition that will be essential if the technique is to compete with established nanofabrication platforms.

Future studies could extend the approach to other metal nanoparticles and optical crystal systems, explore more complex three-dimensional arrangements and broader operating wavelength ranges, and increase fabrication throughput through parallel direct writing. As these challenges are addressed, the interior of a crystal could become an on-demand, three-dimensional optical space capable of generating, guiding, filtering, sensing, and processing light on a single material platform. For photonic integrated circuits and quantum optics, where the ability to differentiate between spin states of light underpins both generation and detection, a method for embedding tunable chirality deep within robust inorganic crystals could prove a decisive step toward compact, durable, and polarization-selective optical technologies.

Subject of Research: Femtosecond laser writing of embedded chiral nanostructures in optical crystals

Article Title: New laser-writing method enables controlled construction of embedded chirality

Article References: New laser-writing method enables controlled construction of embedded chirality. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: chirality, femtosecond laser, gold nanoparticles, yttrium aluminum garnet, chiroptical response, photonic integrated circuits, quantum optics, circular polarization, optical waveguides, nanofabrication, localized surface plasmon resonance, Opto-Electronic Science

TMV has long been a favorite of structural biologists and nanotechnologists alike. The virus consists of 2,130 identical copies of a 17.5-kilodalton coat protein wound helically around a 6.4-kilobase RNA genome, forming a rigid rod roughly 300 nanometers long and 18 nanometers wide, with a hollow central channel about 4 nanometers across. Because the particle self-assembles with stoichiometric precision and presents a highly repetitive, accessible surface, researchers have used it as a scaffold for dyes, peptides, and therapeutic cargos. Crucially, TMV assembly can be nucleated by a specific RNA element known as the origin of assembly sequence (OAS), which means heterologous RNAs bearing this packaging signal can be selectively encapsidated.

Conventional surface modification of TMV, however, has relied on chemically coupling molecules to naturally occurring reactive residues such as lysines or cysteines scattered across the coat protein. That approach often yields heterogeneous products with poorly controlled ligand orientation, a serious drawback when displaying biologically active proteins, antibodies, or receptor-binding ligands whose function depends on correct presentation. The UCLA team, led by William M. Gelbart and Charles M. Knobler, instead genetically encoded a short peptide motif, LPETG, at the C-terminus of every coat protein. LPETG is the recognition sequence for Sortase A (SrtA), a transpeptidase from Staphylococcus aureus that swaps the motif for any molecule bearing an N-terminal polyglycine tag, forming a covalent bond in a site-specific and directional manner.

A key constraint shaped the choice of production host. Assembly-competent TMV coat protein requires eukaryotic post-translational processing: the initiator methionine must be removed and the exposed N-terminal serine acetylated. Bacteria generally cannot do this, so the researchers turned to Komagataella phaffii, the methylotrophic yeast formerly known as Pichia pastoris, which grows rapidly, scales well, and performs the necessary maturation. Previous studies had shown that TMV-like particles can self-assemble in yeast, but the new work adds two crucial elements: a sortase-addressable surface and a self-amplifying RNA cargo.

For the cargo, the team borrowed from Nodamura virus, an insect alphanodavirus whose RNA1 replicon can replicate autonomously in yeast. They designed a replicon encoding the NoV RNA-dependent RNA polymerase and a luciferase reporter, flanked by the NoV untranslated regions needed for replication, and carrying the TMV OAS. A hepatitis delta virus ribozyme at the 3′ end generates a defined RNA terminus, while a Thosea asigna virus 2A sequence lets the polymerase and luciferase be produced as separate proteins. Once the initial positive-sense transcript is translated, the polymerase amplifies the RNA, and a subgenomic promoter on the negative-sense intermediate directs synthesis of a shorter, roughly 1,800-nucleotide RNA. The idea is that replicating RNA bearing the OAS will be preferentially packaged by the coat protein inside the cell, eliminating the need to produce and purify RNA and protein separately for in vitro assembly.

The evidence that this worked came from several directions. Transmission electron microscopy of particles purified from yeast lysates by sucrose cushion and cesium chloride gradient centrifugation revealed rods with wild-type TMV morphology. Length analysis of 200 particles showed a bimodal distribution centered near 100 and 200 nanometers. Because TMV rod length is dictated by the encapsidated RNA at a ratio of about 4.7 nanometers per 100 nucleotides, the longer population matches the predicted 211-nanometer length for the full 4,563-nucleotide replicon transcript, while the shorter population is consistent with the 1,825-nucleotide subgenomic RNA, which can only exist if replication occurred inside the yeast cells. The authors note that fragmentation during purification cannot be excluded, but the correspondence between observed and predicted lengths strongly suggests the intended RNA was incorporated.

RT-PCR on RNA extracted from the purified particles confirmed the presence of sequences from the NoV-RdRp-Luc-OAS construct, yielding amplicons of the expected 4.5-kilobase and 1.8-kilobase sizes that matched the anticipated regions by sequencing. Before extraction, the team treated particles with RNase A and washed away unprotected RNA, so the recovered sequences represent RNA genuinely shielded inside the capsid rather than contaminating debris. The researchers are careful to point out that the 1.8-kilobase product alone cannot prove replication, since that region also exists within the full-length transcript, but the bimodal particle lengths provide independent corroboration.

The functionalization experiments delivered the most striking results. Incubating intact nanorods with Sortase A and an N-terminal polyglycine Alexa Fluor 488 probe produced a fluorescent band at the expected conjugated molecular weight on SDS-PAGE, visible only when all three reaction components were present. At higher dye-to-coat-protein ratios the team achieved conjugation levels up to 80 percent, though they kept the reaction deliberately modest in the published gels to keep bands distinct. Even more impressive was the conjugation of a polyglycine-tagged affibody, a small 7.9-kilodalton engineered binding protein based on the Z domain of protein A. Here the conjugated band, at roughly 27.9 kilodaltons, dominated the gel, indicating around 80 percent modification efficiency while the rod morphology remained intact under the electron microscope.

To prove that the displayed affibody was not just attached but accessible, the researchers exploited an exposed cysteine on the affibody to couple 5-nanometer maleimide-activated gold nanoparticles via thiol-maleimide chemistry. Because such small gold labels are hard to see directly, they enlarged them with a silver-gold enhancement reagent before imaging. Transmission electron microscopy then showed multiple gold particles studding the surfaces of individual nanorods, direct structural evidence that the conjugated ligands project outward from the assembled particles and remain chemically addressable.

The broader significance lies in manufacturing. In vitro assembly of TMV particles offers fine control but requires independent production and purification of coat protein and RNA cargo followed by controlled assembly reactions, a multistep workflow that complicates scale-up. Producing conjugatable, RNA-loaded nanorods directly in yeast collapses those steps into a single biological system, and K. phaffii is already a workhorse of industrial biotechnology. The authors envision the platform extending to antibodies, enzymes, imaging agents, and other targeting ligands, with future work aimed at improving RNA packaging specificity, characterizing the encapsidated RNA species more thoroughly, and testing how different surface ligands affect cellular uptake and in vivo biological activity. If those efforts succeed, the humble tobacco mosaic virus, once a footnote in plant pathology, may become a modular chassis for precision nanomedicine.

Subject of Research: Enzyme-mediated site-specific functionalization of RNA-containing Tobacco mosaic virus-like nanorods produced in yeast

Article Title: Enzyme-mediated site-specific functionalization of mRNA-containing TMV nanorods produced in yeast

Article References: Tisnado, J., Duran Meza, A. L., Moreno Gutierrez, D. S., Harpell, N. M., Cruz, A., Knobler, C. M., & Gelbart, W. M. (2026). Enzyme-mediated site-specific functionalization of mRNA-containing TMV nanorods produced in yeast. Frontiers in Virology, 6, Article 1955107. https://doi.org/10.3389/fviro.2026.1955107

Image Credits: AI Generated

DOI: 10.3389/fviro.2026.1955107

Keywords: Tobacco mosaic virus, virus-like particles, Sortase A, Komagataella phaffii, nanorods, RNA packaging, origin of assembly sequence, affibody, gold nanoparticles, Nodamura virus replicon, surface functionalization, nanobiotechnology

The concept at the heart of the review is theranostics, the fusion of therapy and diagnostics into a single nanoscale platform. Nanomaterials offer an unusual combination of properties: enormous surface-to-volume ratios, tunable surface chemistry, distinctive optical and magnetic behaviors, and the ability to be functionalized with drugs, antigens, or targeting ligands. The authors survey six major material families—metal nanoparticles, metal oxides, carbon-based structures, polymers, lipids, and hybrid composites—and find that each brings a different capability to the malaria fight. Gold nanoparticles, for example, exploit a phenomenon called localized surface plasmon resonance, in which collective oscillations of conduction electrons produce intense color changes when the particles encounter their molecular targets. That property has been turned into a remarkably simple diagnostic: researchers functionalized gold nanoparticles with oligonucleotides specific to the Plasmodium vivax MSP10 gene and used them to detect parasite DNA in urine, producing a visible color shift without any laboratory instrumentation. The assay achieved 84 percent sensitivity and 97 percent specificity, and because it uses urine rather than blood, it avoids the risks and discomfort of venipuncture in field settings.

Gold nanoparticles are also proving useful as drug carriers and vaccine vehicles. Ultra-small glucose-coated gold nanoclusters of roughly two nanometers selectively target cysteine-rich proteins expressed by P. falciparum across all intraerythrocytic stages, from ring forms to schizonts. When the antibiotic ciprofloxacin was conjugated to these clusters, its solubility, cellular uptake, and antiparasitic efficacy all improved compared with the free drug, while hemolytic toxicity toward red blood cells remained negligible. Separately, nanoparticles synthesized using extracts of the medicinal plant Senna auriculata showed potent activity against P. falciparum with an inhibitory concentration around 20 micrograms per milliliter and a selectivity index exceeding 400 micrograms per milliliter against normal human cells, suggesting that phytochemical-mediated synthesis can deliver both efficacy and biocompatibility. On the vaccination front, conjugating the transmission-blocking antigen Pfs25 to gold nanoparticles of varying shapes and sizes produced strong antibody responses in mice, outperforming soluble antigen formulations by promoting better uptake and processing by antigen-presenting cells.

Silver nanoparticles occupy a different niche: broad-spectrum biocidal action against both the parasite and its mosquito vector at comparatively low production cost. Their mechanism is multipronged. Released silver ions bind to parasite and larval cell membranes, disrupting integrity and letting essential metabolites leak out. Simultaneously, exposure raises intracellular reactive oxygen species by depleting antioxidant defenses such as glutathione, triggering apoptosis-like cell death involving caspase-3 and calpain activation and shifts in the Bax/Bcl-2 ratio. Silver ions also bind thiol and phosphate groups in proteins and nucleic acids, inactivating enzymes and fragmenting parasite DNA, with identified targets including the P. falciparum enzymes M18 aspartyl aminopeptidase and Pf12p. The potency can be striking: green-synthesized particles from Terminalia bellirica leaf extract inhibited P. falciparum 3D7 at an IC50 of 94.70 nanograms per milliliter, while Artemisia abrotanum-derived particles halted parasite maturation at the ring stage with an IC50 of just 0.05 micrograms per milliliter. The review’s authors, however, issue a pointed caution: several widely cited reports of silver nanoparticle larvicidal activity against Anopheles stephensi have been formally retracted, underscoring the need for independent validation before efficacy claims are accepted.

Iron oxide nanoparticles, principally magnetite and maghemite, may be the most clinically mature of the metal platforms, since some formulations are already approved as MRI contrast agents and iron replacement therapies. Their superparamagnetism allows external magnetic fields to steer drug-loaded particles toward infection sites without residual magnetization, and it enables a diagnostically elegant trick: the malaria parasite converts toxic heme from hemoglobin digestion into crystalline hemozoin, which is paramagnetic. Infected erythrocytes can therefore be pulled out of blood by high-gradient magnetic separation, a label-free enrichment method that sharpens detection when parasitemia falls below 50 to 100 parasites per microliter. Iron oxide platforms also potentiate artemisinin chemistry. In acidic conditions the particles release ferrous ions that catalyze cleavage of the drug’s endoperoxide bridge through Fenton-like reactions, generating parasite-killing radicals. One multifunctional system, heparin-coated magnetic hollow mesoporous ferrite nanoparticles loaded with artemisinin, accumulated selectively around infected red blood cells through interactions with paramagnetic hemozoin, sustained drug release, and simultaneously blocked merozoite invasion of healthy cells via multivalent binding, sharply lowering the effective dose of both drug and heparin.

Zinc oxide nanoparticles add a third metal-oxide option with the advantage of Generally Recognized as Safe status from the US Food and Drug Administration. Their wide bandgap drives photocatalytic generation of reactive oxygen species, while slow zinc ion release interferes with metabolic enzymes and appears to hinder hemozoin formation, causing toxic free heme to accumulate inside parasitized cells. Green-synthesized particles from plants such as Lagenaria siceraria and Rhazya stricta outperformed raw plant extracts against P. falciparum, and related formulations showed strong larvicidal effects against mosquito larvae by degrading midgut microvilli and disrupting epithelial integrity. A recent acorn-fruit-derived synthesis, confirmed by UV-Vis spectroscopy, FTIR, XRD, and electron microscopy, achieved larvicidal LC50 values of 13.6 parts per million against Culex quinquefasciatus, hinting at eco-friendly vector control tools that could ease the mounting crisis of insecticide resistance.

Carbon-based nanomaterials contribute extraordinary electronic and optical properties. Graphene oxide nanosheets physically adsorb merozoites and deplete nutrients from culture media, inhibiting P. falciparum invasion and delaying development from ring to trophozoite stages, while dry graphene layers have been shown to act as mechanical and molecular barriers that prevent mosquitoes from sensing skin chemicals and biting. In diagnostics, a graphene-enhanced surface plasmon resonance biosensor boosted malaria DNA detection sensitivity roughly 100-fold over conventional optical platforms, and carbon nanotube-based sensors have pushed limits further still. A flexible multi-walled carbon nanotube–zinc oxide nanofiber chemiresistive biosensor detected the malaria biomarker histidine-rich protein II across a range from 10 femtograms to 10 nanograms per milliliter, while carbon nanofiber immunosensors reached detection limits of 0.01 nanograms per milliliter with response times near one minute. Carbon dots, fluorescent quasi-spherical particles under ten nanometers, pair with DNA aptamers to detect parasite glutamate dehydrogenase down to 0.48 nanomolar, and nitrogen-doped variants selectively enter infected erythrocytes through malaria-induced permeability pathways, enabling high-contrast live-cell imaging with minimal uptake by healthy cells.

Polymeric and lipid nanocarriers tackle a persistent pharmacological problem: many antimalarials are poorly soluble, rapidly metabolized, and toxic at high doses. Biodegradable matrices made of PLGA, polylactic acid, chitosan, or gelatin protect cargo, extend circulation time, and release drugs gradually. Ingenious designs go beyond simple delivery. Single-chain polymer nanoparticles selectively attacked the ookinete stage of P. berghei inside the mosquito midgut, blocking transmission, while methoxybenzenesulfonate-functionalized biopolymer nanoparticles prevented cytoadherence of infected red blood cells, reducing the microvascular sequestration and inflammation that make severe malaria lethal. A quinine-loaded chitosan-polycaprolactone core-shell system cut the IC50 in chloroquine-resistant strains from 130 to 33 nanograms per milliliter, and microarray patches delivering primaquine and chloroquine transdermally boosted chloroquine exposure 4.4-fold by bypassing first-pass hepatic metabolism. On the lipid side, liposomes encapsulating the insoluble drug decoquinate achieved better than 95 percent entrapment efficiency and complete parasitemia clearance in mice, while nanostructured lipid carriers, which blend solid and liquid lipids into an amorphous matrix, improved oral bioavailability of artemether-lumefantrine nearly fourfold over conventional formulations.

The review is candid about the distance between laboratory promise and bedside reality. The same reactivity that kills parasites can damage mammalian cells at higher concentrations; silver and zinc oxide particles carry dose-dependent cytotoxic and ecotoxic risks, especially for aquatic organisms; nanoparticles aggregate in biological fluids and degrade in tropical heat and humidity; and the protein corona that forms in plasma can mask targeting ligands and accelerate clearance. Manufacturing consistency, scalable synthesis, standardized characterization, and regulatory frameworks are all lacking, and most evidence remains confined to in vitro experiments and mouse models. The authors see artificial intelligence as a force multiplier, with convolutional neural networks already improving microscopy-based diagnosis and machine learning poised to optimize formulation design and personalize therapy. Their prescription for the field is hybridization: multifunctional, stimuli-responsive nanocomposites that merge the sensing power of gold and carbon materials, the magnetic control of iron oxide, and the delivery finesse of lipids and polymers, all validated in clinically relevant models. If that integration succeeds, the humble nanoparticle could become the platform on which malaria’s diagnosis, treatment, and prevention finally converge.

Subject of Research: Nanotheranostic nanomaterials for malaria diagnosis, drug delivery, vaccination, and vector control

Article Title: Advanced nanomaterials for malaria theranostics

Article References: Thangudu, S., Nuthalapati, K., Patra, C., Kamble, G., Korupalli, C., & Gollavelli, G. (2026). Advanced nanomaterials for malaria theranostics. Frontiers in Malaria, 4, Article 1925644. https://doi.org/10.3389/fmala.2026.1925644

Image Credits: AI Generated

DOI: 10.3389/fmala.2026.1925644

Keywords: malaria, nanotechnology, theranostics, gold nanoparticles, silver nanoparticles, iron oxide nanoparticles, zinc oxide, graphene, carbon dots, liposomes, drug delivery, artificial intelligence

The team, led by Claudia Lago Durán, M. Andrea Molina Torres, Valeria Pfaffen, and Natalia L. Pacioni, worked within the Instituto de Investigaciones en Fisicoquímica de Córdoba (INFIQC-CONICET) and the university’s Faculty of Chemical Sciences. Their starting point was a known but under-exploited chemistry: the formation of gold nanoparticles from gold(III) ions in alkaline aqueous medium, where hydroxide ions rather than an added chemical reductant drive the transformation. By systematically mapping how the key reaction variables interact, they arrived at a recipe that delivers concentrated, predominantly spherical particles of roughly 19 nanometers with remarkably tight reproducibility between batches.

To understand why this matters, it helps to recall how gold nanoparticles are usually made. The dominant approach for more than seventy years has been the Turkevich method, first published in 1951, in which citrate reduces chloroauric acid in boiling water while simultaneously acting as a capping agent that stabilizes the growing particles. It is elegant and simple, but it embeds a tension: the same molecule both reduces and stabilizes, and subtle shifts in pH, citrate protonation, temperature, and mixing can swing the outcome from a clean monodisperse colloid to a polydisperse mixture of spheres, plates, and aggregates. Studies as recent as 2018 have shown that even slight pH fluctuations during citrate synthesis measurably alter the performance of the resulting particles in sensing applications.

For applications that demand a clean surface, researchers have long sought so-called naked nanoparticles, particles free of citrate or other stabilizing ligands, whose surfaces can be functionalized precisely with the chemistry of choice. Photochemical routes and other reductant-free strategies have been explored, but they often trade cleanliness for complexity, requiring specialized equipment or yielding dilute, poorly controlled colloids. The Córdoba group’s approach is deliberately minimalist: gold(III) precursor, sodium hydroxide, water, heat, and stirring, nothing else. The alkaline medium converts gold(III) into hydroxo species that appear to undergo self-reduction and growth under the reaction conditions, producing particles whose surfaces carry no foreign capping molecules.

The real innovation, however, lies not in the chemistry itself but in how the team optimized it. Rather than adjusting one variable at a time, the traditional and inefficient approach, they employed a Box–Behnken design, a response surface methodology from the design of experiments (DoE) toolkit. This statistical framework allows researchers to explore a multidimensional parameter space efficiently, fitting a mathematical model that captures not only the main effects of each variable but also the interactions between them. The team investigated four factors: the concentration of Au(III), the concentration of sodium hydroxide, the stirring rate, and the temperature, monitoring the outcome through ultraviolet-visible absorbance and the plasmon-related response parameter Ψ.

The model revealed something that one-variable-at-a-time experimentation would almost certainly have missed: the significant drivers of nanoparticle formation were not just the individual concentrations of gold and hydroxide, but the interactions of NaOH concentration with both stirring rate and temperature. In other words, the effect of hydroxide depends on how fast the solution is mixed and how hot it is, a coupling that reflects the delicate balance between nucleation, growth, and stabilization in the forming colloid. Complementary control experiments reinforced the picture, confirming that the alkaline medium is essential for particle formation and that temperature governs the rate at which the nanoparticles appear.

Armed with the fitted model, the researchers applied a desirability function, a standard DoE technique that combines multiple response goals into a single optimization target. Here the goals were twofold: maximize the concentration of nanoparticles produced while minimizing polydispersity, the spread of particle sizes that degrades performance in sensing and imaging. The optimization converged on a precise set of conditions: 200 micromolar Au(III), 4.75 millimolar NaOH, a temperature of 130 degrees Celsius, and a stirring rate of 350 revolutions per minute. When the team ran the synthesis under these conditions, the resulting colloid showed excellent reproducibility from batch to batch, the central goal of the entire exercise.

Characterization confirmed the quality of the product. Transmission electron microscopy showed predominantly spherical particles with a mean diameter of 18.66 nanometers and a standard deviation of 4.78 nanometers, indicating a reasonably narrow size distribution. Dynamic light scattering, which measures the particles in solution rather than dried on a grid, gave a hydrodynamic diameter of 19.8 plus or minus 0.9 nanometers with a polydispersity index of 0.208, values consistent with a stable, well-defined colloid. The close agreement between the dry and hydrodynamic sizes suggests the particles carry minimal surface decoration, exactly what one expects from naked nanoparticles stabilized only by the ionic environment of the alkaline medium.

The broader significance of the work extends beyond gold. The same group had previously demonstrated that an experimental design approach could improve batch-to-batch reproducibility in silver nanoparticle synthesis, and the new study extends that philosophy to a reductant-free gold system. As a 2022 review noted, design of experiments remains a surprisingly underused strategy in inorganic materials synthesis, where tradition and intuition often dictate protocol development. By treating synthesis as a quantifiable, modelable process rather than an art, the Córdoba team offers a template that other laboratories can adapt to their own nanomaterial systems, potentially accelerating the path from bench-scale curiosity to manufacturable product.

For the growing community working on gold nanoparticle biosensors, therapeutics, and catalysis, the message is compelling. A clean, ligand-free particle of controlled size, produced by a statistically validated protocol that any competent lab can reproduce, removes two of the biggest obstacles to translating nanogold research into real-world devices: surface contamination that complicates functionalization, and irreproducibility that undermines comparisons between studies. The work was supported by grants from Argentina’s National Agency for the Promotion of Science and Technology (ANPCyT) and the university’s Secretariat of Science and Technology, with fellowship support from CONICET. As nanomedicine and nanosensing mature, methods like this one, humble in their chemistry but rigorous in their statistics, may prove to be the quiet foundation on which reliable nanotechnology is built.

Subject of Research: Reducing-agent-free synthesis of gold nanoparticles optimized by design of experiments for batch-to-batch reproducibility

Article Title: Efficient production of gold nanoparticles without reducing agents: a strategy optimized using the design of experiments

Article References: Durán, C. L., Torres, M. A. M., Pfaffen, V., & Pacioni, N. L. (2026). Efficient production of gold nanoparticles without reducing agents: a strategy optimized using the design of experiments. Journal of Nanoparticle Research, 28(10), Article 267. https://doi.org/10.1007/s11051-026-06790-z

Image Credits: AI Generated

DOI: 10.1007/s11051-026-06790-z

Keywords: gold nanoparticles, nanoparticle synthesis, design of experiments, Box-Behnken design, chemometric optimization, reducing-agent-free synthesis, batch-to-batch reproducibility, alkaline aqueous medium, naked nanoparticles, transmission electron microscopy, dynamic light scattering, polydispersity