Synthesis and characterization of gold–chitosan nanocomposite and application of resultant nanocomposite in sensors

Chitosan gold nanocomposite (CGNC) was synthesized in a single step process and the pH dependent properties of the composite were investigated. The structure of the polymer was pH dependent and gelation of the polymer observed at pH 4–5. Transmission electron microscopy (TEM) analysis showed that the distribution of gold nanoparticles within unit area varied with the gelation of the polymer, without affecting the size of the nanoparticles. The resulting CGNC system was explored for its use as a sensor for the detection of lead. It was found that lead could be detected at a concentration of 1 μM by absorption spectroscopy. The CGNC was electrodeposited on a gold electrode and the deposited film was used for the detection of lead using cyclic voltammetry. Lead could be detected with a detection limit of 10 μM. The fabrication reproducibility for four sensor electrodes showed a relative standard deviation (RSD) of 2.09% for the determination of 1 mM lead nitrate. The developed sensor system showed high reproducibility, stability and satisfactory selectivity.