Abstract
The green synthesis of gold nanoparticles (AuNPs) using Mangifera indica (mango) fruit peel and its subsequent application to imbue color and antibacterial properties to cotton thread is explored in this study. Mango peels were dried, ground, and extracted with methanol and was added to gold ion solutions at 55 °C to synthesize AuNP. AuNPs were synthesized at different concentrations, producing various colors, and were successfully used to dye cotton threads via a heating method. The structural and optical properties of AuNPs were investigated by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), ultraviolet-visible spectrophotometer (UV-Vis) and dynamic light scattering (DLS). The bioactive compounds of mango peel extract were determined using Nuclear magnetic resonance spectroscopy (NMR). The antibacterial potential of AuNP-dyed cotton threads was examined by disc diffusion method against E. coli and S. aureus based on the zone of inhibition. Change in color of the reaction mixture to red indicated the formation of AuNPs. The presence of UV characteristic peak around 530 nm confirmed the presence of spherical AuNPs. NMR spectrum further confirmed the presence of bioactive functional groups involved in the reduction of HAuCl(4) to AuNPs. TEM analysis displayed the shape of AuNPs with mean size of 16.90 nm whereas the hydrodynamic diameters range from 41 to 78 nm. The AuNP-dyed cotton threads showed antimicrobial activity against E. coli and S. aureus suggesting that this can be an excellent strategy to develop versatile and eco-friendly fabric-based biomedical products. The AuNP-dyed cotton threads demonstrated excellent color fastness and resistance to fading when subjected to various harsh conditions.