S-dots@CTAB micelle/PVDF-HFP/MB-OEt electrode-based microfluidic ECL biosensor for miR-483-5p detection in urinary extracellular vesicles.

In this study, a novel microfluidic electrochemiluminescence (ECL) biosensor with PVDF-HFP/MB-OEt (PHMBO) self-supporting flexible electrode was developed. Ethoxy groups were covalently grafted onto the surface of MoB MBene, which strengthened the interaction between PVDF-HFP and MoB MBene. As a result, the β/α phase ratio in PVDF-HFP was increased, which improved the electrical conductivity of the PHMBO flexible electrode. Furthermore, S-dots@cetyltrimethylammonium bromide (S-dots@CTAB) micelle was synthesized as the ECL nanoprobe. The hydrophobic core provided by CTAB micelle suppressed the aggregation of S-dots. In addition, the positively charged hydrophilic shell electrostatically enriched the coreactant S2O82-, thus shortening the interfacial reaction distance and enhancing the ECL efficiency. Finally, the microfluidic ECL sensing system achieved highly sensitive detection of microRNA-483-5p (miR-483-5p) in urinary extracellular vesicles (EVs) with a linear range from 1 fM to 100 nM and a low detection limit of 0.21 fM. The biosensor successfully distinguished between samples from immunoglobulin A nephropathy (IgAN) patients and normal people, which offered a new strategy for the clinical diagnosis of IgAN.