Green biosynthesis of gold nanoparticles by onion peel extract: Synthesis, characterization and biological activities

- A novel approach to utilization of food waste in gold NP synthesis was developed.
- AuNPs were characterized by microscopic and spectroscopic analyses.
- AuNPs exhibited promising synergistic antibacterial potential.
- AuNPs exhibited promising synergistic anticandidal activity.
- AuNPs showed antioxidant activity and proteasome inhibitory potential.

Nanoparticles of various noble metals have been studied owing to their eminent outstanding physical and chemical properties, viz. controllable size, surface morphology and surface chemistry. Herein, utilization of the food waste material (aqueous extract of dried onion peels (OP)) to synthesize gold nanoparticles (OP-AuNPs) was investigated along with study of its biological potentials. The synthesized OP-AuNPs were characterized by UV-vis spectroscopy, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) analysis, X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and differential thermo gravimetric analysis (DT-TGA) analysis. Surface plasmon resonance spectra were obtained at 535 nm with an average particle size of 45.42 nm. The results of FT-IR confirmed the involvement of various water soluble phenolic compounds and cysteine derivatives in the reduction and stabilization of OP-AuNPs. OP-AuNPs displayed strong synergistic antibacterial and anticandidal activity along with antioxidant and strong proteasome inhibitory potential. The results of the present study will facilitate easy green synthesis of gold nanoparticles using food waste materials and their effective applications in biomedical fields as antibacterial dressings, antibacterial and anticandidal drugs, cancer treatments, proteasome inhibitors, cosmetic industries as sunscreen lotion and anti-aging creams, food sector as antibacterial coatings, and pharmaceutical sectors as medicines and drug formulations.

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