Venenum Bufonis is prepared by drying the white serous secretion obtained from the postauricular and skin glands of Bufo bufo gargarizans or Duttaphrynus melanostictus. Its major bioactive constituents include the bufadienolides cinobufagin, bufalin and resibufogenin. The source material reports that these compounds have been investigated for activities including inducing apoptosis in tumor cells, inhibiting angiogenesis and affecting signaling pathways. The highly lipophilic bufadienolides contribute to Venenum Bufonis’s poor aqueous solubility and limited bioavailability, while the material can irritate blood vessels and the gastrointestinal tract. Rapid elimination and extensive tissue distribution may also contribute to a short biological half-life, and cardiotoxicity further narrows the range within which it might be used.

The study used zein, a major storage protein obtained as a by-product of corn-starch processing, as a carrier for the poorly water-soluble material. Zein contains relatively high proportions of proline, leucine, alanine and phenylalanine, giving it strong hydrophobic characteristics and self-assembly properties that can support encapsulation of hydrophobic compounds. The investigators dissolved 0.04 g of zein and different amounts of Venenum Bufonis in 20 mL of 60% aqueous ethanol, producing the four tested mass ratios. The mixtures were treated in an ultrasonic shaker at 35 ± 1 °C for 10 minutes, stirred at 4,000 rpm for two hours and freeze-dried. The resulting powders were stored in sealed bags at 4 °C and analyzed within 48 hours. This antisolvent-precipitation approach was selected for its comparatively mild preparation conditions and its suitability for hydrophobic compounds.

The complexes differed markedly in physical behavior. At a 5:1 ratio, the light-scattering hydrodynamic radius was 2,567 ± 55 nm, with a polydispersity index of 1.01 ± 0.02, indicating large, broadly distributed structures rather than conventional nanoparticles. Electron microscopy showed irregular particles averaging about 560 nm, with wrinkled surfaces and aggregation. The 10:1 formulation had a much smaller hydrodynamic radius of 721 ± 7 nm and a polydispersity index of 1.32 ± 0.01, while microscopy identified structures of approximately 40–107 nm. The 20:1 and 30:1 formulations had hydrodynamic radii of 1,041 ± 23 nm and 607 ± 3 nm, respectively, and contained aggregated or assembled particles in the tens to hundreds of nanometers. These measurements were made by different methods, so their numerical sizes are not directly interchangeable.

Surface charge also changed with composition and did not follow a simple progression. The 5:1 suspension had a pH of 5.60 ± 0.01 and a zeta potential of 1.900 ± 0.390 mV, whereas the 10:1 formulation had a pH of 5.32 ± 0.02 and a zeta potential of −2.747 ± 0.379 mV. The 20:1 complex had a pH of 5.15 ± 0.01 and was nearly neutral at 0.384 ± 0.219 mV, while the 30:1 complex had a pH of 5.01 ± 0.01 and a zeta potential of 9.087 ± 0.405 mV. The authors associated these differences with altered exposure of charged residues during zein assembly and binding, but the measurements do not by themselves establish the detailed molecular arrangement of the protein. Infrared spectroscopy showed shifts near characteristic hydroxyl and carbon–hydrogen stretching bands, while changes near the amide I region suggested modification of zein conformation. The researchers interpreted the combined spectral evidence as consistent with hydrogen bonding and hydrophobic interactions between zein and Venenum Bufonis.

Encapsulation efficiency did not rise with every increase in protein content. The 5:1 formulation encapsulated 96.54 ± 0.06% of the drug and had a loading capacity of 16.63 ± 0.14%, the highest loading measured. The 10:1 formulation reached the study’s highest encapsulation efficiency, 98.29 ± 0.06%, but its loading capacity was lower at 9.04 ± 0.09%. At 20:1, encapsulation fell to 58.29 ± 0.11% and loading to 4.74 ± 0.09%; at 30:1, the corresponding values were 40.27 ± 0.07% and 3.19 ± 0.09%. The proposed explanation is that excess zein self-associates through hydrophobic interactions and intermolecular disulfide bonding, competing with drug binding and reducing the amount of Venenum Bufonis that can be accommodated. The results therefore show a trade-off: adding more zein did not guarantee better encapsulation or larger particle size.

Storage experiments revealed that none of the formulations remained physically unchanged throughout 12 days in aqueous dispersion at room temperature. The 5:1 and 20:1 complexes initially aggregated, with their hydrodynamic radii increasing from 2,567 ± 55 to 4,403 ± 215 nm and from 1,041 ± 23 to 4,173 ± 357 nm, respectively, before falling to 1,173 and 20 nm by day 12. The 10:1 complex decreased continuously from 721 ± 7 nm to 199 ± 9 nm and then 32 ± 1 nm, while the 30:1 formulation fell from 607 ± 3 nm to 445 ± 30 nm and finally 23 ± 1 nm over the same period. The authors interpreted these patterns as structural rearrangement, dissociation, aggregation and, possibly, precipitation rather than simple storage stability. Exposure to pH 2.0 left few detectable complexes in suspension, whereas pH 12.0 produced smaller particles. Heating caused size changes that were interpreted as initial disruption followed by possible reassembly, with the 30:1 formulation remaining within the nanoscale range after one-hour treatments at 60, 80 and 100 °C.

Release profiles also depended on composition. All four formulations released Venenum Bufonis gradually in simulated gastric fluid and simulated intestinal fluid, but the 10:1 formulation showed somewhat faster release than the 5:1 complex. The 20:1 and 30:1 formulations released the drug more rapidly, consistent with weaker retention in those systems. The 10:1 preparation released 49.0% cumulatively under the simulated gastrointestinal conditions and was judged to offer the best balance among encapsulation, loading and controlled release. A first-order kinetic model described the release profile of the 5:1 formulation most closely, and the source reports that the other formulations could also be described by that model except for the 10:1 preparation, although fitting quality differed among formulations. The Higuchi, Hixson–Crowell, Korsmeyer–Peppas and Weibull models were tested. Because the experiments used simulated fluids, they cannot establish how quickly the drug would be released, absorbed or cleared in humans.

The results support further investigation of zein as a plant-protein carrier for Venenum Bufonis, but they do not demonstrate a therapeutic advantage. Encapsulation could reduce direct contact between free drug molecules and gastrointestinal surfaces, and the gradual release observed in vitro could theoretically reduce short-lived peaks in local exposure. The experiments used simulated gastric and intestinal fluids, with no animals or human participants, and therefore did not measure absorption, pharmacological efficacy, cardiotoxicity or gastrointestinal injury. The source also notes that the tested Venenum Bufonis concentration was maintained below approximately 400 μg mL−1, lower than the 6 mg mL−1 concentration reported for intravenous administration, but that concentration comparison does not establish safety or clinical advantage. In vivo pharmacokinetic studies, biological efficacy tests and formal toxicity assessments would still be required. The 10:1 formulation is therefore best described as the most promising laboratory formulation among those tested, rather than as a clinically validated delivery system.

Subject of Research: In vitro zein-based delivery of the poorly water-soluble medicine Venenum Bufonis

Article Title: Characterization and optimization of a zein-based mesoscopic complex system for Venenum Bufonis delivery

Article References: Mao, P., Chen, S., Niu, F., Lu, Z., & Pan, W. (2026). Characterization and optimization of a zein-based mesoscopic complex system for Venenum Bufonis delivery. Frontiers in Nutrition, 13, Article 1916662. https://doi.org/10.3389/fnut.2026.1916662

Image Credits: AI Generated

DOI: 10.3389/fnut.2026.1916662

Keywords: Venenum Bufonis, zein, drug delivery, mesoscopic complexes, encapsulation, gastrointestinal release, plant protein carrier, physicochemical characterization, in vitro digestion, bufadienolides, Characterization, optimization

The motivation is straightforward. Pork is one of the world’s most consumed meats, and projections cited by the Organization for Economic Co-operation and Development suggest global consumption will reach 129 million metric tons by 2032, accounting for roughly a third of projected growth in total meat consumption. Yet pork’s high lipid and protein content, stored in the humid microclimate of a sealed package, makes it an ideal substrate for microbial spoilage. Consumers still judge freshness by color and odor, subjective cues that vary from person to person, while conventional laboratory tests for spoilage are costly, slow, and require trained personnel and elaborate sample preparation.

Smart labels offer a way around that bottleneck. As meat spoils, microbes and enzymes release volatile compounds that raise the pH inside the package. Freshness indicators exploit this chemistry by embedding pH-sensitive pigments that visibly change color as the atmosphere shifts. Synthetic pigments work well but raise health and environmental concerns, so researchers have turned to natural dyes. Curcumin, the polyphenol that gives turmeric its golden hue, is yellow under acidic conditions and turns orange-red when alkaline. Alizarin, an anthraquinone from madder roots, goes from light yellow in acid to bluish-purple in base. Used alone, however, each pigment responds over a narrow pH window with limited color contrast.

The research team, led by Bingcan Liu, Siling Zhang, and Zeyu Wu of Hefei University of Technology, solved both the pigment problem and a materials problem at once. They blended curcumin and alizarin at six different mass ratios, from pure curcumin to pure alizarin, and electrospun each mixture into nanofibers made of polyvinyl alcohol (PVA) blended with zein, a hydrophobic corn protein. Electrospinning draws a charged polymer jet from a Taylor cone under a 16-kilovolt electric field; as the jet whips and stretches toward the collector, it dries into solid fibers with enormous surface area and porosity, ideal for gas sensing. Crucially, the process involves no high temperatures, so the delicate pigments survive intact.

The polymer blend was the key to durability. Pure PVA films dissolve in humid conditions because of their abundant hydroxyl groups, which would be fatal for a label inside a moist meat package. By mixing in zein, rich in nonpolar amino acids, the researchers produced fibers averaging roughly 76 to 120 nanometers in diameter, far finer than the 347-nanometer fibers of pure PVA. Scanning electron microscopy showed smooth, continuous, well-fused fibers, evidence of good compatibility between the two polymers. Fourier transform infrared spectroscopy confirmed hydrogen bonding across the network, with characteristic zein amide bands appearing alongside PVA’s hydroxyl and carbon-oxygen stretches.

Water resistance improved dramatically. Pure PVA films showed 100 percent water solubility and a 100 percent swelling index, meaning they disintegrated completely in water. With zein and pigments added, water solubility fell to between 31 and 35 percent, moisture content dropped from 7.58 percent to as low as 4.5 percent, and the swelling index fell by about 35 percent. The hydrophobic protein shields PVA’s polar groups from water, while hydrogen bonds between the pigments and the matrix occupy binding sites that water molecules would otherwise attack. The films also held their color during ten days of storage at both 4 and 25 degrees Celsius, with total color differences remaining below 3, well under the threshold of 5 that untrained observers can perceive.

Sensitivity testing sealed squares of each film in a chamber with controlled vapors of ammonia, dimethylamine, and trimethylamine, the signature gases of meat decay, at concentrations from 1 to 40 parts per million. The mixed-pigment films outperformed single-pigment versions on both ends of the spectrum. Films containing both dyes detected ammonia and dimethylamine at just 1 part per million, five times more sensitive than the alizarin-only film, while mixed formulations responded to trimethylamine at 10 parts per million, better than curcumin alone. The three intermediate blends, with curcumin-to-alizarin ratios of 4:1, 3:2, and 2:3, showed the most pronounced and varied color changes, because the paired pigments broaden the pH response range and multiply the distinguishable hues.

The decisive test came with real pork. The team affixed a circular array of six indicator films inside the lids of glass containers holding about 60 grams each of chilled pork tenderloin, then refrigerated the samples at 4 degrees Celsius for six days. Daily measurements of total volatile basic nitrogen, the regulatory benchmark for meat spoilage, tracked the meat’s decline: below 10 milligrams per 100 grams on day one, between 10 and 15 on days two and three, and 15.54 on day four, crossing the Chinese national limit of 15. Lipid oxidation, measured by the thiobarbituric acid assay, rose from 0.16 to 0.52 milligrams per kilogram, and pH climbed from 5.96 to 6.58 as protein-degrading bacteria took over from glycogen fermenters.

The array’s color output mirrored this trajectory almost perfectly. The films drifted from light yellow through reddish-brown to purple as spoilage progressed, and a composite chromatic parameter calculated from all six films jumped sharply on day four, exactly when the meat crossed into the spoiled category. Pearson correlation coefficients between the color parameter and the three chemical spoilage markers were strikingly high: 0.98 for total volatile basic nitrogen, 0.98 for lipid oxidation, and 0.95 for pH. Single-pigment labels, by contrast, often lagged or produced changes too subtle to notice, which is precisely why the array design matters. By reading several films together, the system converts a fuzzy qualitative signal into a reliable three-tier grading of fresh, less fresh, and spoiled.

The researchers describe the platform as eco-friendly, low-cost, and scalable, and the ingredients support that claim: biodegradable PVA, an abundant food-grade corn protein, and non-toxic dyes already common in the food supply. Because the label works inside ordinary packaging and needs no instrument beyond the human eye, it could plausibly move from the laboratory to supermarket shelves and home refrigerators. The work also points toward broader applications, since the same dual-pigment, dual-polymer strategy could be tuned for fish, shrimp, beef, or any protein-rich food whose spoilage chemistry raises the local pH. For a food system that loses enormous value to spoilage and foodborne illness alike, a label that quietly turns from yellow to purple may prove one of the simplest and most consequential safety tools yet devised.

Subject of Research: A pH-sensitive curcumin-alizarin electrospun nanofiber array for colorimetric monitoring of pork freshness

Article Title: Synergistic PVA/zein electrospun nanofiber array with curcumin-alizarin: a water-resistant, sensitive colorimetric platform for graded pork freshness monitoring

Article References: Liu, B., Zhang, S., Geng, H., Hu, C., Zhou, A., & Wu, Z. (2026). Synergistic PVA/zein electrospun nanofiber array with curcumin-alizarin: a water-resistant, sensitive colorimetric platform for graded pork freshness monitoring. Food Chemistry: X, Article 104591. https://doi.org/10.1016/j.fochx.2026.104591

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104591

Keywords: electrospinning, nanofibers, curcumin, alizarin, smart packaging, pork freshness, food safety, pH indicator, volatile amines, zein, polyvinyl alcohol, colorimetric sensor

The research addresses a persistent challenge in modern food supply chains. Even with advances in processing and logistics, food products remain vulnerable to spoilage through oxidation and the proliferation of pathogenic microorganisms, leading to quality deterioration, shortened shelf life, and potential safety risks. Packaging materials that can actively scavenge destructive free radicals and suppress bacterial growth have therefore become a major focus of food science. Electrospun nanofiber membranes are particularly attractive candidates because their high surface-to-volume ratio, breathability, and capacity for controlled release of active substances make them ideal platforms for functional additives.

The choice of materials reflects a deliberate balancing act. Zein is abundant, renewable, and biodegradable, with excellent film-forming ability and biocompatibility, but films made from it alone are brittle and mechanically weak. PVDF, by contrast, is a semi-crystalline fluoropolymer offering excellent barrier properties, thermal stability, and mechanical strength, and it improves the chain entanglement of spinning solutions, making electrospinning easier. Combining the two polymers mitigates the brittleness of protein-based films while retaining a substantial bio-based component. The missing ingredient was a functional filler that could add antioxidant and antibacterial activity without compromising the composite structure, and that is where the coffee grounds came in.

To make the carbon dots, the researchers dried waste coffee residue from a franchise café, dispersed two grams of the powder in water, and sealed it in an autoclave at 200 degrees Celsius for six hours in a hydrothermal reaction. The resulting dark brown dispersion was filtered through microporous membranes, dialyzed for 24 hours to remove low-molecular-weight impurities, and freeze-dried into a solid powder. Transmission electron microscopy revealed quasi-spherical particles ranging from 0.91 to 3.00 nanometers in diameter, with an average of 1.88 nanometers, well dispersed without aggregation. Lattice fringes with an interplanar spacing of about 0.21 nanometers indicated locally ordered carbon domains embedded in a largely disordered framework, a structure typical of carbon dots.

Spectroscopic analysis painted a detailed picture of the nanoparticles’ chemistry. X-ray photoelectron spectroscopy showed the dots were composed of roughly 70 percent carbon, 6 percent nitrogen, and 24 percent oxygen, with the carbon core containing sp2 and sp3 hybridization and the surface decorated with hydroxyl, carbonyl, and carboxyl groups. Nitrogen was present in pyridinic, pyrrolic, and graphitic forms, making these nitrogen-doped carbon dots with good water solubility. Optically, the dots absorbed strongly in the ultraviolet and emitted blue fluorescence at 430 nanometers when excited at 350 nanometers, with emission that shifted depending on the excitation wavelength, a hallmark of carbon dots with multiple surface defect states serving as emissive sites.

The functional performance of the dots proved impressive. In radical-scavenging assays, the DPPH inhibition rate climbed from less than 1 percent to 93.41 percent as the concentration rose to 128 micrograms per milliliter, accompanied by a visible color change from dark purple to yellow. Similar concentration-dependent activity was recorded against ABTS radicals. The mechanism, the authors suggest, involves hydrogen atom transfer, electron transfer, or both, driven by the abundant surface functional groups. More striking was the antibacterial behavior: under illumination from a full-spectrum LED lamp, the dots inhibited Staphylococcus aureus and Escherichia coli in a concentration-dependent manner, while activity in the dark remained limited. Electron spin resonance spectroscopy confirmed that light exposure triggered the generation of superoxide and hydroxyl radicals, but no detectable singlet oxygen, pointing to a Type I radical-mediated photodynamic pathway rather than the singlet-oxygen-dominated Type II route.

With the dots characterized, the team electrospun composite membranes containing 0, 1, 3, 5, and 7 percent CG-CDs by weight relative to the total polymer mass, using a solution of 15 percent total polymer at a 1:1 zein-to-PVDF ratio in a dimethylformamide and acetone solvent mixture. Scanning electron microscopy showed smooth, continuous, bead-free fibers at all loadings, though average fiber diameter increased gradually with higher dot content. The researchers attribute this to molecular associations between the dots’ surface groups and the polymer matrix, which raised solution viscosity and chain entanglement while charge shielding effects weakened the electric-field stretching of the jet, allowing fibers to solidify before they could be drawn thinner.

The structural and physical consequences of doping were systematic and, in places, surprising. Fourier transform infrared spectroscopy confirmed that the primary chemical structures of both polymers were preserved, while X-ray diffraction showed that the characteristic alpha-phase crystal structure of PVDF remained intact at all loadings, with crystalline ordering actually sharpening up to 5 percent before broadening at 7 percent, likely due to local aggregation of the dots. Thermogravimetric analysis revealed slightly improved thermal stability at moderate loadings, as interfacial interactions restricted polymer segment mobility. Water contact angles fell from about 118 degrees for the undoped membrane to roughly 85 degrees at 7 percent, shifting the surface from hydrophobic to hydrophilic thanks to the dots’ oxygen-containing groups. Mechanical testing exposed a clear trade-off: tensile strength dropped from about 12 megapascals to 6, while elongation at break rose from roughly 45 percent to 72 percent, meaning the membranes became more flexible and extensible at the cost of strength, possibly because thicker fibers slip more easily within the network during deformation.

The functional payoff was substantial. DPPH scavenging by the membranes rose from negligible levels to more than 90 percent at the highest loading, and ABTS radical reduction followed the same trend, confirming that the antioxidant capacity of the dots survived the electrospinning process. Under light irradiation, the composite membranes showed substantially enhanced antibacterial activity against both bacterial strains compared with dark conditions, consistent with the ROS-generating capability confirmed by electron spin resonance. Gram-positive S. aureus proved more susceptible than Gram-negative E. coli, likely because the outer membrane of E. coli provides an additional protective barrier against oxidative attack. Notably, Caco-2 intestinal cell viability exceeded 90 percent when exposed to extracts of even the highest-loaded membrane, offering preliminary evidence that the materials are cytocompatible and plausible candidates for food-contact use.

The study’s broader significance lies in its demonstration of a circular-economy pathway for active packaging: a waste product that cafés discard daily becomes the functional heart of a multifunctional material. By systematically mapping how loading level controls fiber diameter, crystallinity, wettability, thermal behavior, mechanics, and light-responsive antibacterial performance, the researchers have provided a design framework for tuning such membranes to specific applications. The authors caution that practical packaging performance and food-contact safety still require further evaluation, and a possible photothermal contribution to the antibacterial effect remains to be investigated. But the core result stands: coffee grounds, carbon dots, and electrospun proteins can be combined into smart packaging that fights oxidation and bacteria with nothing more than light.

Subject of Research: Coffee ground-derived carbon dots incorporated into zein/PVDF electrospun nanofiber membranes for antioxidant and photodynamic antibacterial food packaging

Article Title: Coffee ground-derived carbon dots reinforced zein/PVDF electrospun nanofiber membranes with antioxidant and photodynamic antibacterial activities

Article References: Yao, F., Niu, K., Dong, Y., Jin, C., Li, Z., Liu, C., & Chen, F. (2026). Coffee ground-derived carbon dots reinforced zein/PVDF electrospun nanofiber membranes with antioxidant and photodynamic antibacterial activities. Food Chemistry: X, 39, Article 104414. https://doi.org/10.1016/j.fochx.2026.104414

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104414

Keywords: carbon dots, coffee grounds, electrospinning, zein, PVDF, nanofibers, antioxidant, photodynamic antibacterial, food packaging, biomass waste, reactive oxygen species, food safety