Green Synthesis of Zinc Oxide Nanoparticles Characterization and Use for Formulation of Sunscreen Topical Creams

Many nanomaterial compounds are known to possess inherent sun protection properties as well as the ability to enhance the effectiveness of other sun-screening compounds. The current work aimed to biologically synthesize zinc oxide nanoparticles (ZONPs) from zinc acetate dihydrate using Vernonia amygdalina (V.amygdalina) leaf extract as the reducing agents and, thereafter usethe synthesized nanoparticles to formulate sunscreen creams. The extract, obtained by the Soxhlet technique was subjected to quantitative phytocomponent analysis while the nanoparticles were characterized for optical, morphological, size, and elemental composition analysis. The fusion method was used to prepare six cream formulations containing varying proportions of the nanoparticles and the creams were, thereafter evaluated for standard cream characteristics. The nanoparticles showed maximum ultraviolet light absorption at 350 nm and a mean particle size of 49.75 ± 0.46 nm. The major elemental components consisted of zincites, smithsonite, sphalerite and quartz. The nanoparticles consisted of both singlet and aggregate hexagonal components while Fourier’s transform infrared spectroscopy indicated surface attachment of some biomolecules of the V. amygdalina to the nanoparticles. The pH, viscosity, spreadability and sun protection factors of the creams were in the ranges of 5.98 ± 0.18 - 6.87 ± 0.47, 12.03 ± 0.02 - 13.70 ± 0.73, 18.54 ± 0.03 - 19.72 ± 0.89 and 11.35 ± 0.5 - 30.21 ± 0.2 respectively. The calculated sun protection factor of the optimized formulation was comparable to that of the positive control. The current procedure, therefore, represents a simple green-based approach for enhancing the sun-screening property of zinc oxide compounds.