Green Synthesis Of Ag Nanoparticles And Its Functionalities Research

Silver nanoparticles have wide-ranging applications in the fields of photonics, catalysis, microelectronics, biosensing and antimicrobial functionalities for its excellent diathermancy, conductivity, surfaceactivity, catalysis. In the past decades, many efforts have been developed for the synthesis of Ag nanoparticles. However, the environmental and biological risks are usually caused due to the use of noxious reducing and/or stabilizing agents in the synthesis procedures and the process have been complicated because of the introduction of dispersant. For overcoming shortage above-mentioned, we use natural biomarcomolecules, which have wide-ranging implications in the fields of food and biomaterials, as both reducing agent and dispersant to prepare silver nanoparticles in a convenient, inexpensive and green way.Firstly, we use silk sericin (SS) with rich Aspartate and Glutamate, as both the reductant and dispersant to systhesis Ag nanoparticles. The homogeneous and mono-dispersed Ag nanoparticles were obtained. Fathermore, making use of results above, we use sericin degumming solution to prepare silver nanoparticles and its antimicrobial functionalities were check with MIC value. For obtaining other shape of silver nanoparticles such as nanoplates which have special capability compare to the shape of sphere with SS, we use another natural polymer Hyaluronan (HA), one of natural polydisaccharide, to prepare silver nanoplates, which have excellent capability of surface enhanced Raman scattering (SERS) by a micro-Raman spectroscopy. The effect of reaction conditions such as pH value, temperature and molar ratio of SS/HA to AgNO3 on the Ag nanoparticle formation were investigated using UV-vis spectrophotometer (UV-vis), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM).The results showed silver nanoparticles with average diameter of around 5 nm were prepared with the assistant of SS at 70°C with the pH=11and the molar ratio of SS to AgNO3 0.025/1 after two hours. The obtained sol was stable even after two months at room temperature. The Sericin degumming solution contain 1% SS completely reacted with 12.5 mM Ag~+ solution. The average diameter of obtained silver nanoparticles was around 16.3 nm, and MIC were 25 ppm to coliform and 55 ppm to Staphylococcus aureus, which implied excellent antimicrobial functionalities of these particles. The Ag nanoplates could be fabricated with a low molar ratio of HA to AgNO3 by aging seed, which were prepared at 70°C with the pH=11 and the molar ratio of HA to AgNO3 0.05/1 after two hours. The obtained nanoplates showed excellent capability of SERS.So, we offered a green, simple and one-pot method for the synthesis of silver nanospheres with SS and nanoplates with HA as both reducing agent and dispersant. A new way to reuse sericin degumming solution has been developed on the basis of the results of SS. Moreover, the antimicrobial properties and the capability of SERS with obtained nanoplates were demonsrated. This work supply new way for preparation of silver nanoparticles and their functional application.