Facile preparation of fluorescent Ag-clusters-chitosan-hybrid nanocomposites for bio-applications

Fluorescent silver nanoclusters (Ag NCs) are an important kind of luminescent nanomaterial with many practical applications. In this report, a facile route was designed for the preparation of fluorescent Ag NCs-chitosan hybrid nanocomposites based on the reduction of Ag+ with NaBH4. The hybrid nanocomposites had a spherical morphology with a size of 80 +/- 10 nm. Moreover, the as-prepared nanospheres displayed high fluorescence with the emission peak center at 562 nm due to the formation of Ag NCs. In addition, chitosan, a natural polymer, worked as a stabilizing agent, and made the nanocomposites biocompatible, biodegradable and have low-toxicity. These properties mean that the nanospheres are promising materials for bio-applications. The methyl thiazolyl tetrazolium assay confirmed that the fluorescent chitosan-Ag NCs hybrid nanospheres had almost negligible toxicity to normal cells of MC3T3-E1. The outstanding low virulence of the as-prepared fluorescent chitosan-Ag NCs hybrid nanospheres was tested and verified by MC3T3-E1 cells and CAL-27 cells for bio-imaging as well.