'Green' synthesis and optical properties of silver-chitosan complexes and nanocomposites

Silver nanoparticles were synthesized in a chitosan biopolymer by an in situ 'green' chemical procedure, using d-glucose as the reducing agent. The reaction intermediates (silver-chitosan complexes) as well as the obtained nanocomposites were investigated using transmission electron microscopy, UV-vis, FTIR and photoluminescence spectroscopy. The theoretical analysis of the UV-vis absorption of the Ag-chitosan complexes suggested that the significant contribution to the complex spectrum arises from clusters of silver containing 4-9 atoms. The absorption spectrum of the nanocomposite exhibited a strong surface plasmon resonance band at 406 nm. The photoluminescence behavior of the pure chitosan, the silver-chitosan complexes and the nanocomposites were discussed in terms of morphology and silver weight content.