(397bp) Green-One Step Synthesis of Silver Nanoparticles in PVA Polymer Solution

In recent years the synthesis of silver nanoparticles (AgnP’s) has been subject of focusing research due to their unique optical, electrical, and thermal properties coupled with their wide potential applications including molecular diagnostics and photonic devices. Different routes for AgnP’s synthesis have been reported including ultraviolet irradiation, lithography, laser ablation and thermal decomposition to name just a few. However, the development of efficient green chemistry methods for synthesis of metal nanoparticles has become a very important issue to find an eco-friendly technique for their production. Some metal nanoparticles green syntheses have been reported. The green synthesis techniques are generally synthetic routes that utilize relatively non-toxic chemicals to synthesize nanomaterials, and use non-toxic solvents such as water or plant extracts for reduction. Even though biological processes are eco-friendly, they usually are elaborate processes that involve multiple steps from the collection of the plant to silver nanoparticles synthesis which in turns translates into time and money.  The chemical reduction of metal ions is still the most widely applied technique. Different reducing agents could be used; however, sodium borohydride (NABH₄) and sodium citrate (Na₃C₆H₅O₇) are the most commonly used. This method also could differ in the use of different sources to drive the reduction (i.e. microwave, ultraviolet, gamma, thermal decomposition or thermal radiation). Although chemical reduction is the most commonly used method for metal nanoparticles synthesis, it is considered hazardous to environment because it employs many chemical agents.

On the other hand, the chemical reduction synthesis of metal nanoparticles in polymer solutions is a practical technique since polymers can act as stabilizing agents, and polymer/metal nanoparticles composites can be simultaneously produced.  Polyvinyl alcohol (PVA)/ AgnP’s is a very attractive combination for composites production, since PVA is a biocompatible, biodegradable, non-toxic and water soluble polymer for potential biomedical applications and combined with AgnP’s could produce an organic/inorganic hybrid material with antibacterial activity, which is highly desired in applications where hygiene is a key factor; especially in biomedicine. There are several works on PVA/AgnP’s composite synthesis via chemical reduction, and two green synthesis without the use of any reducing agent and using different stirring times at high temperature (90°C and 70°C) have also been reported. However, as it can be seen, artificial energy to rise temperature and uphold stirring to drive the reduction is still used. This paper reports a green-one step silver nanoparticles synthesis method in PVA polymer solution without using any reducing agent, using water as the solvent and with no artificial energy to drive chemical reduction, providing a facile, economic, quick, efficient and more eco-friendly method for the synthesis of metal nanoparticles that results in the production of a PVA/AgnP’s composite were PVA acts simultaneously as reducing and stabilizing agent.