Novel silver nanoparticles modified by -cyclodextrin and TiO₂ as a SERS substrate for ultrasensitive detection of sisomicin

The silver nanoparticles coated with beta-cyclodextrin and TiO2 (beta-CD/TiO2@AgNPs) were synthesized as SERS substrate to detect sisomicin. Compared to conventional AgNPs, beta-CD/TiO2@AgNPs exhibited superior stability and sensitivity in enhancing the Raman signal of sisomicin, and the enhancement factor (EF) was calculated as 1.48 x 10(6) (at the maximum peak at 577 cm(- 1)). The performances of beta-CD/TiO2@AgNPs were characterized by UV-vis, XRD, TEM and TGA. The interaction of the substrate with sisomicin was also investigated through multispectral techniques. The surface enhancement mechanism of sisomicin and silver nanosubstrate was discussed in detail. The optimization of experimental conditions was achieved through a combination of single factor experiment and response surface model. The effects of some interferences on the detection were investigated. Based on these findings, a standard curve I-SERS = 31.64 c + 59,716.22 (c: nmol L-1) with good linearity for the detection of sisomicin within the concentration range of 20.00-666.67 nmol L-1 was established. The method had much higher sensitivity with LOD 3.91 nmol L-1. The recoveries of sisomicin in serum samples were 97.43-102.77 %.