Dielectrophoresis-Assisted PVDF/DES/Au NP-Based Microfluidic ECL Biosensor for In Situ Detection of Extracellular Vesicles.

Herein, a regenerable dielectrophoresis (DEP)-assisted microfluidic electrochemiluminescence (ECL) biosensor was developed for in situ detection of extracellular vesicles (EVs) in gastric cancer ascites. In the integrated microfluidic ECL sensor, a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/deep eutectic solvent (DES)/Au NP (PDES/Au NPs) self-supporting electrode was developed. The DES treatment increased the polar β-phase proportion in PVDF-HFP and improved its conductivity. Meanwhile, Au NPs deposited on the electrode surface amplified the ECL signal of Ru(bpy)32+/TPrA@SiO2 nanobeads through the localized surface plasmon resonance (LSPR) effect and generated an inhomogeneous electric field distribution for EV capture. Due to the DEP effect, the polarized EVs migrated and enriched on the PDES/Au NP electrode surface. As a result, the isolation time of EVs was reduced from 120 to 30 min. Consequently, the sensing platform effectively captured and detected EVs in gastric cancer ascites. The detection range was 1.0 × 101.6-1.0 × 105.3 particles μL-1, and the limit of detection was 9 particles μL-1. Moreover, a regenerative strategy was designed by controllably cleaving Au-S bonds on the self-supporting electrode. This developed microfluidic ECL biosensor achieved real-time quantification of low-concentration EVs in ascites, which established a promising analytical tool for gastric cancer diagnosis as well as the discrimination of peritoneal metastatic lesions.