Dual-function nanostructured platform for isolation of nasopharyngeal carcinoma circulating tumor cells and EBV DNA detection

Circulating tumor cells (CTCs) and plasma levels of Epstein-Barr virus (EBV) DNA are sensitive prognostic tools for monitoring disease status in nasopharyngeal carcinoma (NPC) patients. Herein, we introduce a novel and low-cost platform for capturing CTCs, the Si nanowires/microscale pyramids (NWs/MPs) hierarchical substrate, which could capture NPC cells in vitro and also detect EBV DNA at very low concentrations. In this study, Si NWs/MPs hierarchical substrates with varying wire length were fabricated using a metal-assisted chemical etching method. Anti-EpCAM antibodies were further conjugated on the substrate for capturing NPC CTCs in vitro. Capture efficiency was evaluated using immunofluorescence and scanning electronic microscopy (SEM) was utilized to understand cell morphology. The Si NWs/MPs substrate was also transformed into a Surface enhanced Raman scattering (SERS) substrate by coating with Ag nanoparticles (AgNPs) for detection of EBV DNA by Raman spectroscopy. The results demonstrated that Si NWs/MPs with 20 min of etch time had the best capturing performance. Additionally, SEM observations revealed good contact of CTCs with Si NWs/MPs substrates. Moreover, the AgNPs-coated NWs/MPs substrate was shown to be a sensitive EBV DNA detector, by which the DNA detection limit can reach up to 10(-13)M. In conclusion, the Si NWs/MPs platform not only exhibits superior cell capturing ability, but also can sensitively detect EBV DNA at very low concentrations. This platform has great potential to become a promising diagnostic tool for monitoring disease status and prognostication of NPC patients.