Advanced Dual-Mode\nMicrofluidic Sensing Platform Based\non Amphiphilic Polymer-Capped Perovskite Nanozymes Induced Photoelectrochemical\nSignal Amplification and Fluorescence Emission

A novel dual-mode microfluidic sensing platform integrating\nphotoelectrochemical\n(PEC) and fluorescence (FL) sensors was developed for the sensitive\nmonitoring of heart fatty acid binding protein (h-FABP). First, BiVO<sub>4</sub>/AgInS<sub>2</sub> (BVAIS) composites with excellent photoelectric\nactivity were synthesized as sensing matrices. The BVAIS heterojunction\nwith a well-matched internal energy level structure provided a stable\nphotocurrent. Second, an innovative signal amplification strategy\nbased on octylamine-modified poly(acrylic acid) (OPA)-capped CsPbBr<sub>3</sub> (OPCB) nanocrystals (NCs) with excellent catalytic activity\nand fluorescence property was proposed. On the OPCB nanozyme possessing\nascorbate oxidase-like catalytic activity could catalyze the oxidation\nof ascorbic acid, which achieved quenching of the photocurrent signals\nby competitively consuming the electron donor. On the other hand,\nthe OPCB NCs that overcame the water stability defect processed good\nluminescence performance and were able to produce obvious FL signals.\nMutually verified dual-response signals effectively enhance the precision\nof test outcomes and avoid false-positive or false-negative results.\nFinally, the constructed microfluidic sensing platform realized sensitive\ndetection of h-FABP in the linear range of 0.0001–150 ng/mL\n(PEC mode) and 0.001–150 ng/mL (FL mode), with detection limits\nof 36 fg/mL and 0.32 pg/mL, respectively. The present work provided\na new perspective for designing an efficient dual-mode sensing strategy\nto achieve sensitive detection of disease markers.