Session: Colloidal Hybrid Materials Intended for Biological Applications:

Graphene oxide (GO) nanosheets and silver nanoparticles (AgNPs) have gained great attention in public health for bio-applications. AgNPs-grafted-GO nanosheets may lead enhancements of antiviral effects in combining the AgNPs functions and the GO large surface area, stability, and its nanosheet’s toxicity to live cells. In this research, GO nanosheets were produced by a green process through microwave irradiation; and citric acid, from the juice of citrus fruits, was used to replace many other reported reducing agents for the synthesis of AgNP-grafted GO nanosheets. Different types of AgNPs-grafted-GO nanosheets were obtained by reducing silver nitrate with citric acid on GO nanosheets at room temperature at different reaction times. Characterizations of all the AgNP-GO nanomaterials via UV-vis spectroscopy, Raman Spectroscopy, Dynamic Light Scattering (DLS), TEM and SEM Electron Microscopes, and X-ray Energy-Dispersive Spectroscopy (EDS) were intensively performed. UV-vis spectroscopy presents distinctive peaks for GO nanosheet absorption; an exciting discovery is its unique peak at 400nm to 420 nm that was detected for GO-based-AgNPs corresponds to the Surface Plasmon Resonance (SPR) of AgNPs; this feature peak shifts to the red-light direction as AgNP’s size increases. Raman spectroscopy proved the GO nanosheet’s D and G band vibrations, and the vibrations resulting from grafted-AgNPs on GO nanosheets with molecular bridges of O-Ag and O-Ag-COO chemical bonds. The TEM and SEM images present the spherical AgNPs-anchored on the GO nanosheet, and finally EDS verified the elemental components in the AgNPs-GO nanomaterials. All of the above characterizations confirmed the successful synthesis of AgNP-grafted-GO nanosheets with the citric acid green chemical method. Another new finding is that both DSL and image analysis by TEM and SEM show that the grafted-AgNPs particle sizes were confined within the GO nanosheets, which shows that when other reaction conditions are fixed, only a slight size increase as the reaction time lasts. An effective control for AgNP sizes and anti-aggregation is achieved with the GO nanosheets as the base, in comparison with regular sodium citrate processing. Our green synthesis has demonstrated that the GO nanosheet functions as a matrix to anchor AgNPs and to cap AgNPs when they form. This method may become a cost-effective and environmentally friendly synthesis to produce AgNPs-grafted-GO nanosheets for bio-applications.

Arthur McClelland

Appearances