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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 × 106 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.