A SERS aptasensor based on AuNPs functionalized PDMS film for selective and sensitive detection of Staphylococcus aureus.

In this study, a sensitive biosensor was developed based on aptamer functionalized polydimethylsiloxane (PDMS) film for the detection of Staphylococcus aureus (S. aureus) using surface-enhanced Raman scattering (SERS) technology. Initially, the surface of PDMS film was chemically modified by piranha solution and 3-Aminopropyltriethoxysilane (APTES), and then AuNPs-PDMS film was prepared by coating gold nanoparticles (AuNPs) through electrostatic interaction. Next, the aptamers were immobilized on the AuNPs-PDMS membrane via gold-sulfur bond to form the capture substrate. Meanwhile, gold-silver core-shell nanoflowers (Au@Ag NFs) modified with mercaptobenzoic acid (4-MBA) and aptamers were applied as a signal probe. In the presence of the target, the signal molecular probe and the capturing substrate specifically combined with the target and resulted in a sandwich structure "capture substrate-target-signal molecular probe". Under the optimized experimental condition, the signal of 4-MBA at 1085 cm-1 was linearly related to the S. aureus concentration in the range of 4.3 × 10 cfu mL-1-4.3 × 107 cfu mL-1 (y = 326.91x-117.62, R2 = 0.9932) with a detection limit of 13 cfu mL-1. The method was successfully applied to spiked actual samples and a 92.5-110% recovery rate was achieved.