Green Synthesis of Silver Nanoparticles (AgNPs) from Lenzites betulina and the Potential Synergistic Effect of AgNP and Capping Biomolecules in Enhancing Antioxidant Activity

摘要

Properties of silver nanoparticles (AgNPs) are influenced by interactions and molecular structure of capping agents that stabilize them. Green synthesis of AgNPs using Lenzites betulina, a macrofungus with antioxidant properties, should be possible allowing the active metabolites or biomolecules to be incorporated in AgNP as capping molecules. Using surface plasmon resonance (SPR), the synthesis of AgNP using the aqueous extract of L. betulina was optimized. The purified L.betulina-capped AgNPs were then characterized and its antioxidant activity was compared with the raw L. betulina extract. The L. betulina-capped AgNPs exhibited SPR peak characteristic of AgNPs. Morphological analyses showed non-uniform spherical AgNP with visible intertwining capping agents engulfing the nanomaterial. FT-IR spectra revealed amide, carboxylate, and hydroxyl absorptions, confirming the role of some organic compounds as capping molecules. Extraction and complexation of the capping agent with SDS showed characteristic electronic excitation of phenylalanine along with tryptophan and tyrosine residues, suggesting the proteinaceous or polypeptide nature of the capping agent. The L. betulina-capped AgNPs were relatively stable (zeta potential -26.7 mV), and the antioxidant activity was significantly enhanced compared to the raw extract. This is the first demonstration of L. betulina mushrooms in synthesizing AgNPs, the investigation of the proteinaceous capping biomolecules, and the enhanced effect of L. betulina-capped AgNPs in promoting stable radical reduction.