The plant at the heart of this study is no exotic botanical rarity. Pergularia daemia, a climbing shrub common across South Asia and Africa, has long been used in folk medicine to treat microbial infections, inflammation, oxidative stress, and reproductive disorders. What makes it scientifically interesting is its dense phytochemical arsenal: flavonoids, tannins, phenolics, alkaloids, glycosides, and terpenoids, all confirmed by phytochemical screening of the leaf extract used in the study. These molecules are not merely passive passengers. In nanoparticle synthesis, they act as natural reducing, capping, and stabilizing agents, replacing the toxic solvents and harsh conditions that plague conventional chemical methods.

The synthesis itself is elegantly simple. The researchers collected leaves from the Courtallam Hills near Tenkasi, dried them for ten days, ground them into powder, and stirred ten grams into 100 milliliters of distilled water at 50 degrees Celsius for two hours. The resulting extract was then combined with a titanium precursor, tetraisopropyl orthotitanate dissolved in ethanol, and left overnight at 40 degrees Celsius. The phytochemicals in the extract coordinated with the titanium alkoxide, catalyzed its hydrolysis into reactive titanium hydroxide species, and drove condensation reactions that forged titanium-oxygen-titanium bonds, ultimately nucleating into crystalline titanium dioxide nanocrystals. The plant molecules then wrapped themselves around the growing particles, preventing agglomeration and conferring colloidal stability.

Characterization revealed a mixed-phase material with intriguing properties. X-ray diffraction, refined using the Rietveld method, showed the nanoparticles comprised 58.65 weight percent rutile and 41.35 weight percent anatase, the two tetragonal polymorphs of titanium dioxide. Raman spectroscopy confirmed the presence of both phases, with the characteristic anatase Eg mode appearing near 143 wavenumbers. X-ray photoelectron spectroscopy verified that titanium existed predominantly in the tetravalent state, with no significant trivalent titanium signal, suggesting a stoichiometric composition with few oxygen vacancies. The mean crystallite size, calculated using the Debye-Scherrer equation, was 32 nanometers, while high-resolution transmission electron microscopy revealed individual particles averaging 30.80 nanometers with well-defined lattice fringes.

Dynamic light scattering told a different story, revealing a hydrodynamic diameter of 188.75 nanometers, larger than the primary particle size measured by electron microscopy. This discrepancy arises because DLS measures particles in suspension, including their hydration layers and any slight aggregation in aqueous media. The zeta potential of minus 44.68 millivolts indicated strong electrostatic repulsion between particles, a hallmark of good colloidal stability. Nitrogen adsorption studies confirmed a mesoporous structure with a Type IV isotherm and an H3 hysteresis loop, with a BET surface area of 29.4 square meters per gram and pore widths reaching up to 60 nanometers.

The biological results are where the study becomes genuinely compelling. Against nine bacterial strains, including Gram-positive species such as Bacillus subtilis, Staphylococcus aureus, and Streptococcus pyogenes, and Gram-negative organisms including Escherichia coli, Salmonella typhimurium, and Klebsiella pneumoniae, the nanoparticles produced zones of inhibition reaching 24.2 millimeters against multidrug-resistant E. coli at 200 micrograms per milliliter. Most strikingly, amikacin, a standard antibiotic, was completely ineffective against multidrug-resistant S. aureus, while the biosynthesized nanoparticles produced a 21.1-millimeter zone. Minimum inhibitory concentrations ranged from 25 to 50 micrograms per milliliter, far outperforming the crude plant extract, which required 100 micrograms per milliliter across all strains.

The antibiofilm activity was equally impressive. Using a crystal violet microtiter plate assay, the researchers found that the nanoparticles suppressed biofilm formation by roughly 80 to 95 percent at 200 micrograms per milliliter, depending on the strain. Biofilms, the slimy bacterial communities that coat medical devices and chronic wounds, are notoriously resistant to antibiotics because their extracellular polymeric matrix shields cells from penetration. The nanoparticles’ small size, large surface area, and negative surface charge allow them to infiltrate this matrix and generate reactive oxygen species, including hydroxyl radicals, superoxide anions, and hydrogen peroxide, which damage membrane lipids, proteins, and nucleic acids. The researchers caution that these mechanisms were proposed based on physicochemical properties and existing literature rather than directly measured in this study.

Safety profiling was comprehensive and largely reassuring. Hemolysis assays using human blood showed that even at 1000 micrograms per milliliter, the nanoparticles lysed less than 2 percent of red blood cells, well below the 5 percent threshold set by the ASTM F756-17 standard. Microscopic examination confirmed that erythrocytes retained their intact biconcave structure with no membrane damage or aggregation. A chromosomal aberration assay in human peripheral blood lymphocytes found no structural abnormalities, chromosomal fragments, breaks, exchanges, or gaps at any tested concentration, with mitotic indices remaining comparable to negative controls. Acute toxicity in brine shrimp larvae showed mortality below 10 percent even at the highest concentrations, and zebrafish embryo exposure from 4 to 72 hours post-fertilization revealed no developmental abnormalities, deformities, or hatching delays at concentrations up to 1000 micrograms per milliliter.

Perhaps the most unexpected finding came from the chorioallantoic membrane assay in chicken embryos. Rather than inhibiting blood vessel formation, the nanoparticles promoted angiogenesis, increasing vascular density, branching points, and total vessel length. Quantitative analysis using Fiji software showed that the treated membranes developed vascular areas of 76 to 81 square millimeters by day five, compared with 19 square millimeters in untreated controls. No bleeding, clotting, or inflammation was observed, suggesting remarkable vascular compatibility. This pro-angiogenic effect, particularly pronounced at lower concentrations, hints at potential wound-healing applications, where stimulating new blood vessel growth is essential for tissue repair.

The antioxidant capacity of the nanoparticles was also quantifiable. In the DPPH radical scavenging assay, the nanoparticles achieved an IC50 value of 51.62 micrograms per milliliter, while the ABTS assay yielded 42.66 micrograms per milliliter. The ferric reducing antioxidant power assay showed concentration-dependent activity, with ferrous sulfate equivalent values rising from 63.63 to 148.48 micrograms per milliliter across the tested range. These values place the biosynthesized nanoparticles within the documented range for green-synthesized titanium dioxide nanomaterials, though below the potency of the crude plant extract and ascorbic acid standards. The researchers attribute the antioxidant activity primarily to the phytochemical capping agents on the nanoparticle surface, with the titanium dioxide core serving as a support matrix that facilitates electron transport.

The authors are careful to frame their findings as preliminary. The biological activities were assessed through in vitro and in ovo screening experiments, and the researchers explicitly state that these results do not yet substantiate direct claims of biomedical applicability. They call for extensive in vivo research to validate wound-healing potential in animal models, comprehensive pharmacokinetic and biodistribution studies, and chronic toxicity profiling before any therapeutic or diagnostic applications can be considered. Batch-to-batch consistency, influenced by fluctuations in the phytochemical composition of plant extracts, remains an acknowledged limitation of green synthesis approaches.

Nevertheless, the study represents a meaningful advance in the holistic evaluation of a single nanomaterial system. Previous investigations of biosynthesized titanium dioxide nanoparticles often provided incomplete physicochemical characterization or evaluated only single biological properties. By simultaneously assessing antibacterial, antifungal, antioxidant, angiogenic, cytotoxic, and genotoxic properties, the Bharathiar University team has established a more complete structure-activity relationship than most prior work. The choice of Pergularia daemia as the reducing and capping agent, unexplored for titanium dioxide synthesis until now, adds a novel dimension to the growing catalogue of plant-mediated nanomaterials.

As antibiotic resistance continues to escalate globally, with multidrug-resistant pathogens rendering once-reliable treatments obsolete, the search for alternative antimicrobial strategies has become urgent. Nanomaterials that operate through multiple complementary mechanisms, rather than a single molecular target, reduce the probability that microorganisms will develop resistance. The multifaceted antibacterial pathways of titanium dioxide nanoparticles, involving reactive oxygen species generation, membrane disruption, and intracellular component leakage, exemplify this approach. If future in vivo studies confirm the safety and efficacy suggested by these preliminary findings, nanoparticles synthesized from common medicinal weeds could eventually find their way into antimicrobial coatings, wound dressings, and biosensing platforms, transforming a plant once valued only in folk medicine into a cornerstone of sustainable nanotechnology.

Subject of Research: Green synthesis of titanium dioxide nanoparticles using Pergularia daemia leaf extract and their biomedical applications

Article Title: Biogenic synthesis of titanium dioxide nanoparticles using Pergularia daemia leaf extract: Characterization and biomedical applications

Article References: Biogenic synthesis of titanium dioxide nanoparticles using Pergularia daemia leaf extract: Characterization and biomedical applications. (n.d.). https://doi.org/10.1016/j.rechem.2026.103947

Image Credits: AI Generated

DOI: 10.1016/j.rechem.2026.103947

Keywords: green synthesis, titanium dioxide nanoparticles, Pergularia daemia, antimicrobial resistance, antibiofilm, angiogenesis, nanomedicine, phytochemistry, Biogenic, synthesis, titanium, dioxide