Grewia tenax bark extract mediated silver nanoparticles as an antibacterial, antibiofilm and antifungal agent

Abstract

Grewia tenax plant possesses many medicinal qualities that can be harnessed for bio-applications via nanotechnology in a cost-effective and environment-friendly manner. The synthesised silver nanoparticles (GTB-AgNPs) from Grewia tenax bark extract were first detected by observing the change in colour from yellowish brown to dark brown and confirmed by UV–vis spectroscopy. UV–vis spectral analysis recorded the surface plasmon resonance at 420 nm. In the current research, several process parameters (time, temperature, concentration of AgNO3 and the ratio of extract to AgNO3) were adjusted by using one variable at a time (OVAT) approach. Spectroscopy accompanied by dynamic light scattering (DLS), x-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive x-ray (EDX) determines the size, nature, morphological variations and chemical constituents of GTB-AgNPs. The size range was found within 35−45 nm and the image clearly showed that the GTB-AgNPs were spherical in shape and well dispersed in nature. Zeta potential and Fourier-transform infrared spectroscopy (FTIR) were done to analyse GTB-AgNPs stability, dispersion and the biomolecules in aqueous bark extract liable for the bioreduction of silver particles. These GTB-AgNPs showed excellent antibacterial action against Gram-positive (S. aureus and B. subtilis) and Gram-negative bacteria (P. aeruginosa and E. coli) which was observed by disc diffusion assay. Congo red agar plate (CRA) assay effectively unveiled the antibiofilm proficiency of the particles. These studies displayed a reduction in bacterial sustainability and the formation of exopolysaccharides. Disc diffusion assay confirmed the antifungal competency against A. niger and C. albicans. SEM was performed to elucidate the intracellular breakage and morphological transformations in cells of Gram-positive bacteria and fungi after treatment with GTB-AgNPs. The current study, therefore, enlightened applications of GTB-AgNPs as an efficient antimicrobial agent and applicable substitute in the pharmaceutical area.