A Rapid Dual-Mode Sers/Fl Cytosensor Assisted Via DNA Walker-Based Plasmonic Nanostructures

Abstract

Various surface–enhanced Raman scattering (SERS) biosensors offer powerful tools for the ultrasensitive detection of CTCs and tumor diagnosis. Despite their efficacy, the swift and precise preparation of SERS plasmonic nanostructures poses an ongoing challenge. In this study, we introduce DNA–assisted plasmonic nanostructures capable of producing dual signals and facilitating DNA Walker signal amplification, resulting in the development of a SERS/Fluorescent (FL) dual–mode cytosensor for CTCs detection. Firstly, Au@Ag nanoparticle multimers (Au@AgNMs) featuring interparticle nano–gaps were synthesized through DNA self–assembly and in–situ deposition, which provided excellent SERS performance. Hence, the nano–gap distance was meticulously regulated after optimization to achieve both SERS enhancement and fluorescence quenching. Subsequently, the aptamer (Apt) recognized CTCs specifically for strand displacement reaction (SDR) and further triggered the DNA Walker reaction for signal amplification. The limit of detection (LOD) of proposed cytosensor can be obtained as low as 5 cells/mL in SERS mode and 21 cells/mL in FL mode. This innovative strategy of dual–mode cytosensor could offer a reliable, flexible and ultrasensitive detection method for CTCs.

Keywords: Dual-mode cytosensor, Plasmonic nanostructures, DNA Walker reaction, CTCs