Multilayer fluorescent thin films based on keratin-stabilized silver nanoparticles

Two kinds of nanocomposite ultrathin films, i.e., (Ag@keratin/PDDA)n and (keratin/PDDA)n + Ag(0) nanoparticles (NP), have been fabricated by layer-by-layer (LbL) deposition and in situ deoxidization method, respectively. The assembling process was monitored by means of UV–vis spectroscopy. Scanning electron microscope (SEM) was used to observe the surface morphology and thickness of the multilayer films. The distribution of silver NP within the two LbL films were evaluated by transmission electron microscope (TEM) measurement. It was found that (Ag@keratin/PDDA)n films present superior fluorescent properties that that of (keratin/PDDA)n + Ag(0) NP. TEM results suggest that the fusion of the small silver clusters (which is fluorescent) is hindered in the direct LbL assembly, while larger Ag NP are formed by the in situ preparation. The corrosion-resistance of the Ag@keratin/PDDA multilayer films against the acid and basic etching solution is also tested.