Biosynthesis of gold nanoparticles (AuNPs) and the reducing agents in the process

Abstract

Metallic nanoparticles (NPs) are being used mainly because they have excellent physical, chemical and biological properties, intrinsic to their size, therefore there is a boom in the use of these nanoparticles in various fields and recently, due to the pandemic about coronavirus. Copper NPs began to be used for use in medical supplies such as face masks. NPs are normally obtained through inorganic synthesis, however, the methodologies used to obtain them are in general terms expensive and involve the use of hazardous chemicals, which has increased the development of sustainable and environmentally friendly alternatives, as one of the main objectives of nanotechnology. Considering that nanoparticle biosynthesis is of greatest importance since it allowed obtaining organic NPs through an environmentally friendly; quick and inexpensive.
 In this work, the synthesis and characterization of AuNPs of six different plant extracts that in traditional medicine are used for respiratory diseases care, were performed. These NPs can be used in different fields; even they represent a good option to be added to medical supplies. As the AuNPs obtained from chamomile extract that turned out to be spherical, 20 nm in diameter, and well dispersed, these could be applied orally, as nanocapsules that are easily eliminated from the human body, or by aerosol, as a possible treatment for the pneumonia and SARS-CoV-2, in addition later for other nosocomial diseases. And to answer the question of what or which reducing agents are involved in the process? We proposed that, for biological synthesis, malic acid may be acting as a reducing agent and the amino group as a stabilizing agent, so we performed a synthesis with malic acid and obtained stable NPs. However, we do not dismiss other metabolites enzymes and/or proteins that could be involved in the process.