Phytosynthesis of zinc oxide nanoparticles using methanol extract of Senna alata leaf: Characterization, optimization, antimicrobial properties, and its application in cold cream formulation.

Background: Phyto-reduction using Senna alata methanol leaf extract for nanoparticle (NP) biosynthesis is of great importance for the production of value-added nanomaterial with antimicrobial potential.

Objectives: The aim of this study was to investigate the biosynthesis of zinc oxide nanoparticles (ZnONPs) using crude methanol leaf extract of S. alata (SaZnONPs), antimicrobial efficacy of this extract, optimization of its production parameters, and its application in cold cream formulation.

Material And Methods: Phytosynthesized SaZnONPs were characterized using UV-Vis absorption spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), dynamic light scattering (DLS), X-ray diffraction (XRD) analysis, and energy-dispersive X-ray (EDX) spectroscopy. The antimicrobial activity of SaZnONPs and the formulated cold cream was evaluated.

Results: The SaZnONPs surface plasmon resonance (SPR) was 400 nm. Functional groups such as alkenes, alkynes and alkyl aryl ether were present. The SEM image showed NPs 7.10 nm in size and with a needle-like shape. The TGA values show the formations of stable ZnONPs, while the DLS showed the particle diameter average of 89.7 nm and 855.4 nm with 0.595 polydispersity index. The EDX analysis confirmed the formation of pure ZnONPs, and the crystallinity was confirmed with XRD analysis. Twenty-four hours of incubation and production at pH13 was optimal for NPs synthesis. The SaZnONPs and the formulated cold cream have antimicrobial properties against some pathogenic bacteria and Pichia sp. (16.00 mm) and Trichophyton interdigitale (11.00 mm).

Conclusions: Senna alata was able to serve as a stabilizing and capping agent for SaZnONPs biosynthesis. The SaZnONPs had good antimicrobial potential and can be used in cold cream formulation.