Fabrication of chitosan/silver nanocomposite films and their fluorescence sensing of aluminum ions

A simple and efficient method for the fabrication of highly fluorescent chitosan/silver (CS/Ag) films is reported in this paper. The synthesis method uses NaBH4 as a reductant and involves less time and extremely mild experimental conditions. The structure, surface and fluorescence properties of the nano-sized CS/Ag films were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy. Aluminium ion sensing was determined by and fluorescence intensity measurement. Fluorescence measurement by emission spectroscopy indicated that the emission wavelength of CS/Ag was 368 nm. Experimental results indicated that the fluorescence emission of the nanocomposite films was sensitive to the presence of aluminium ions, and a micro-amount of aluminium ions significantly increases the emissions. Under the optimum conditions, the fluorescence intensity of the films was linearly proportional to aluminium ion concentrations between 0 and 1·8 × 10−4 mol L−1. The films may be developed into sensors for aluminium ions.