Quantitative evaluation of trace ritonavir in serum by versatile SERS substrate based on silver-decorated hollow reduced graphene oxide/zinc oxide nanotubes

Because of its fascinating molecular fingerprint identification ability and high sensitivity, surface-enhanced Raman scattering (SERS) shows an attractive application prospect in the clinical monitoring of blood drug concentration and efficacy judgment. In this study, a quantitative SERS-based detection of ritonavir in serum sample was conducted by developing silver (Ag)-decorated zinc oxide (ZnO)@reduced graphene oxide (rGO) nanotubes. Taking advantage of the efficient light absorption and molecular enrichment capabilities of hollow rGO-modified ZnO nanotubes with high specific surface area, an extremely low limit of detection (LOD) value of 466.7 pg/mL was achieved for ritonavir owing to the synchronous electromagnetic and chemical enhancement after the participation of Ag islands. Such a detection was carried out in a recyclable mode based on the intrinsic photocatalytic activity of ZnO, which was ascribed to the Ag and rGO-mediated effective separation of photo-induced electron-hole pairs. A practical SERS-based monitoring of ritonavir was finally facilitated in serum, demonstrating high recovery rates varied from 82.1% to 89.7%. Such a novel metal-semiconductor SERS sensor with ideal biocompatibility and sensitivity is promising in drug diagnostics.