Facile synthesis of the dendritic structure of silver nanoparticles-chitosan and its application as an effective SERS substrate

The dendritic structure with high concentration of monodisperse silver nanoparticles into the chitosan matrix (D-AgNP@Chit) was prepared via a reduction process using sodium borohydride. The D-AgNP@Chit substrates were prepared by drop-drying AgNP@Chit colloidal solution on amine modified glass slides. The preparation conditions and SERS performance of the D-AgNP@Chit substrates were systematically investigated. Such a D-AgNP@Chit SERS substrate exhibits an enhancement factor of 2.1 x 10(6) and a detection limit of 10(-12) mol L-1 for 4-aminobenzenethiol (4-ABT) could be achieved. Moreover, the SERS spectra repeatability of 4-ABT without any interference, from the support background, could be maintained over the dendritic structures. The fast time of detection and repeatability of the SERS measurements qualify the D-AgNP@Chit substrate as an effective SERS sensor for molecular analysis.