Functionalized SERS substrate based on silicon nanowires for rapid detection of prostate specific antigen

Abstract Owing to its high sensitivity, surface-enhanced Raman spectroscopy (SERS) is widely used in biosensing as an efficient optical transduction technique. In this work, we report the elaboration of a novel SERS-powered aptasensing substrate for the ultra-sensitive and selective detection of prostate specific antigen (PSA). The transducing SERS substrate is formed by vertically aligned silicon nanowires (SiNWs) decorated with silver nanoparticules (AgNPs). The silver nanoparticles have two purposes : a) aptamer immobilization via thiol chemistry and b) Raman signal enhancement. The presence of PSA induces the appearance of amide bond vibration modes only if the aptamer is present on the surface of SiNWs. The platform is highly sensitive, selective and specific to PSA in a wide range of concentrations from 0.1 to 20 μg.L−1 with a detection limit of 0.1 μg.L−1, which encompasses the blood serum range of healthy subjects and ill patients. This optical biosensor shows a great stability and it is successfully validated in human blood serum samples showing very good results.