Silver nanoparticles prepared using mushroom (Lenzites betulina) aqueous extract: Green synthesis, characterization, antioxidant property on stable radical, and catalytic activity on dye reduction

• Main Author: Sytu, Marion Ryan C.
• Format: text
• Language: English
• Published: Animo Repository 2016
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/5246
• Institution: De La Salle University

Silver nanoparticles (AgNPs) find wide use in microelectronics, medicine and in drug delivery systems due to their small size and large surface area. Green synthesis, using aqueous extracts of natural products, offers a cheap and eco-friendly alternative to the traditional synthesis of silver nanoparticles, where the metabolites in the extract are capable to reduce silver ions and stabilize AgNPs. This study explored the synthesis of silver nanoparticles using the aqueous extract of Lenzites betulina, a macrofungus with antioxidant properties. An optimized method for the synthesis of silver nanoparticles from L.betulina (L.betu-AgNPs) has been developed where the L.betu-AgNPs exhibited a surface plasmon resonance (SPR) peak at 420 nm in the UV-Vis spectrum. SEM and TEM showed that the L.betu-AgNPs are mostly spherical. FT-IR spectra for both L.betulina aqueous extract and L.betu-AgNPs showed similar stretching frequencies, confirming the role of organic compounds in L.betulina as capping molecules in the synthesized L.betu-AgNPs. EDS analysis also reveals the presence of elements Ag, C, N, and O. The presence of -C=O stretch and -N-H bend from the FT-IR as well as C, N and O components from EDS suggests that the capping molecules are proteinaceous. DLS reported average hydrodynamic diameter of L.betu- AgNPs as 270.8 nm, while TEM reported the AgNP diameter in the size range 14-50 nm. L.betu-AgNPs were found to be relatively stable with a zeta potential of -26.7 mV. XRD analysis showed characteristic 2q angles of face centered cubic silver and face centered cubic silver oxide, also revealing the presence of crystalline organic phases accompanying the AgNPs. DPPH assays showed that the L.betu-AgNPs displayed antioxidant activity, significantly higher than that of the L.betulina aqueous extract. The presence of L.betu-AgNPs, in the solution of methyl orange and sodium borohydride increases the reduction and degradation rates of the dye, demonstrating its catalytic activity. Further characterization of the metabolites of L.betulina as well as the capping molecules on the synthesize AgNPs can be explored. Other degradation processes of toxic compounds can also be explored. The recovery, stability and recyclability of the AgNP catalysts have yet to be studied.