Synthesis of ZnO Nanoparticles From Pergularia daemia Fibre: Potential for Caries Prevention and Infection Control
Raja Thandavamoorthy, Yuvarajan Devarajan, Kulmani Mehar
Abstract
Antimicrobial resistance and biofilm-associated infections present major challenges in oral healthcare, necessitating sustainable nanomaterials with multifunctional efficacy. This study reports the green synthesis of zinc oxide nanoparticles (ZnO NPs) from Pergularia daemia ( P. daemia ) fibre (PDF) extracts and evaluates their structural, thermal, and biological properties for dental and biomedical applications. ZnO NPs were synthesised using aqueous PDF extracts as natural reducing and stabilising agents. Structural crystallinity was examined by X-ray diffraction (XRD), functional groups by Fourier-transform infrared spectroscopy (FTIR), morphology by scanning electron microscopy (SEM), and thermal stability by thermogravimetric analysis (TGA). Antibacterial performance against Klebsiella pneumoniae and Streptococcus mutans was assessed via agar well diffusion, while antibiofilm efficacy was evaluated using confocal laser scanning microscopy (CLSM). XRD confirmed a semi-crystalline ZnO phase with a crystallite size of 28.6 nm and a crystallinity index of 21%. FTIR revealed hydroxyl, carbonyl, and carboxylate groups contributing to nanoparticle stabilisation. SEM micrographs showed irregular, porous, and agglomerated morphologies spanning nanometre to submicron scales. TGA indicated multi-step degradation with a stable residual fraction of ∼14% at 670 °C. Antibacterial assays demonstrated strong inhibition zones (27 mm, 32 mm at 75 µg; 31 mm, 41 mm at 100 µg), comparable to streptomycin (34 mm and 43 mm). CLSM confirmed significant antibiofilm activity through membrane disruption and reduced bacterial viability. The enhanced antibacterial and antibiofilm performance of PDF-derived ZnO NPs arises from synergistic effects of nanoparticle cores, reactive oxygen species generation, and phytochemical surface functionalization. Their stability and bioactivity underscore their promise as sustainable nanomaterials. PDF-mediated ZnO NPs show potential for dental applications, including caries prevention, root canal disinfection, and biofilm-resistant coatings for restorative and implant materials. Their multifunctional profile further supports broader biomedical use in antimicrobial therapy, drug delivery, and composite engineering. • Green synthesis of zinc oxide (ZnO) nanoparticles using Pergularia daemia ( P. daemia ) stem fibres as a sustainable bio-resource. • Phytochemical-assisted reduction and stabilisation achieved without toxic chemicals. • Formation of semi-crystalline ZnO nanoparticles confirmed by X-ray diffraction with JCPDS comparison. • Porous and irregular nanoparticle morphology revealed by scanning electron microscopy, enhancing surface activity. • Strong antibacterial and antibiofilm efficacy against Klebsiella pneumoniae and Streptococcus mutans was demonstrated. • Potential application of biosynthesised ZnO nanoparticles in caries prevention and oral infection control.