Green Synthesis of Silver Nanoparticles Using Aspergillus niger and Its Efficacy Against Human Pathogens

Antibiotic resistance is one of the world’s most pressing public healthcare problems. People who become infected with drug-resistant microorganisms usually spend more time in the hospital and require a form of treatment that uses two or three different antibiotics and is less effective, more toxic, and more expensive. Silver nanoparticles (AgNPs) are attractive option because they are non-toxic to the human body at low concentrations and have broadspectrum antibacterial actions. The biosynthesis of nanoparticles has received increasing attention due to the growing need to develop safe, cost-effective and environmentally friendly technologies for nano-materials synthesis. In this report, silver nanoparticles (AgNPs) were synthesized using a reduction of aqueous Ag+ ion with the culture supernatants of Aspergillus niger. The reaction occurred at ambient temperature and in a few hours. The bioreduction of AgNPs was monitored by ultraviolet-visible spectroscopy, and the AgNPs obtained were characterized by transmission electron microscopy and X-ray diffraction. The synthesized AgNPs were polydispersed spherical particles ranging in size from 1 to 20 nm and stabilized in the solution. Furthermore, the antimicrobial potential of AgNPs was systematically evaluated. The synthesized AgNPs could efficiently inhibit various pathogenic organisms, including bacteria and fungi. The current research opens a new avenue for the green synthesis of nano-materials and AgNPs have the potential to serve as an alternative to antibiotics and to control microbial infections such as those caused by multidrug- resistant pathogens.