Green synthesis of Ag nanoparticles using elm pod polysaccharide for catalysis and bacteriostasis.

The green synthesis of silver nanoparticles (Ag NPs) for catalysis and biological applications has gained great interest. Natural elm pods are a type of food that possesses anti-inflammatory and pain-relieving effects. In this study, elm pod polysaccharide (EPP) was extracted from elm pods using hot water extraction for the first time. Biocompatible EPP-stabilized silver nanoparticles (EPP-Ag NPs) were prepared by using a green synthesis method. The EPP-Ag NPs had a hydrodynamic size of 40.9 nm and a highly negative surface charge of -27.4 mV. Furthermore, EPP-Ag NPs exhibited high catalytic activity for the reduction of 4-nitrophenol, and the catalytic reaction followed a pseudo-first order kinetic equation. More importantly, the inhibition rate of EPP-Ag NPs on Escherichia coli was 71 % when samples were treated with an 808 nm laser. Besides, EPP-Ag NPs effectively inhibited the proliferation of tumor cells irradiated by an 808 nm laser. The improved performance of EPP-Ag NPs was due to the good stability of EPP. Taken together, EPP-Ag NPs had good stability, catalytic activity, antibacterial and antitumor ability under laser irradiation. EPP is a good stabilizer for many nanoparticles which have broad applications in the field of catalysis and biomedicine in the future.