A dual mode biosensor based on self-enhanced polyfluorene nanomaterial for fluorescence and electrochemiluminescence detection of Tau protein.

Dual mode detection can overcome the poor anti-interference ability of single-mode detection, and greatly improve the detection accuracy. Fluorescence/electrochemiluminescence (FL/ECL) dual mode detection combines the advantages of FL and ECL, and has a promising application in bioanalysis. Common FL/ECL dual mode detection used different signal probes. Multiple signal probes inevitably have complex operation and uncontrollable differences between the two modes. In this work, poly [9,9-dioctylfluorenyl-2,7-diyl]-End-capped with 2,5-diphenyl-1,2,4-oxadiazole (PFO) was functionalized by sodium dodecyl sulfate (SDS) and polyethylenimine (PEI), and the resulting PFO-SDS-PEI nanoparticles (PSP NPs) exhibited excellent FL and ECL performance at the same time, so were creatively developed as mono-luminophore-based signal probe for FL/ECL dual-mode detection. The functional reagent SDS can significantly improve the water dispersion of luminophores, and PEI can not only provide amino functional groups for assembling biomolecules, but also significantly enhance the FL and ECL signals of the luminophores. Self-enhanced PSP NPs coupled strand displacement reaction (SDR) mediated by exonuclease Ⅲ (Exo Ⅲ) to achieve FL/ECL dual-mode detection of Tau protein, a biomarker of Alzheimer's disease (AD). The linear ranges for FL and ECL detection were 0.001-500 pg/mL and 0.00001-1.0 pg/mL and the limit of detections were 549.16 ag/mL and 5.45 ag/mL, respectively, showing good application potential. Self-enhanced PSP NPs provided an ideal mono-luminophore-based signal probe for FL/ECL dual-mode detection, and built a new method for detecting AD biomarker.