Novel Benzopyran-Coumarin Derivative-Sensitized BiOI Nanoarray-Driven Photoelectrochemical/Fluorescence Dual-Mode Microfluidic Biosensor for Sensitive Detection of Golgi Protein 73

Rapid and accurate detection of biomarkers is essential for the early diagnosis and prevention of cancer, yet single-mode biosensors remain inadequate to meet the demands for both high-precision and high-throughput detection. To address this challenge, we designed a dual-mode photoelectrochemical (PEC) and fluorescence (FL) microfluidic biosensing platform for the ultrasensitive detection of Golgi protein 73 (GP73), a liver cancer marker. A novel Bzp-C/BiOI composite material was successfully synthesized by sensitizing BiOI nanoarrays with benzopyran-coumarin derivatives (Bzp-C), serving as the dual-signal sensing matrix. This composite material enhances visible-light absorption and promotes electron-hole separation efficiency, which not only obtains high PEC photocurrent signals but also maintains intrinsic fluorescence properties. To further increase sensitivity, Pt nanoparticle functionalized CeO₂ nanospheres (Pt@CeO₂) were engineered as a label for amplifying the signal to enhance the sensitivity of the biosensor. In PEC mode, Pt@CeO₂ could quench the photocurrent intensity because part of the photogenerated electrons (e^-) of Bzp-C/BiOI is quickly transferred to the more positive conduction band of CeO₂ through Pt nanoparticles to achieve signal amplification. For FL detection, Pt@CeO₂ exhibits peroxidase-like activity, catalyzing the formation of H₂O₂ to generate hydroxyl radicals (^•OH) via Ce³⁺/Ce⁴⁺ cycling. These radicals trigger electrophilic reactions with oxonium groups on Bzp-C, producing π-conjugated fluorophores to amplify FL signal. In addition, by integrating a PEC-FL dual-mode biosensor into a microfluidic chip, both the PEC and FL biosensors achieved highly sensitive and portable detection of GP73 in the linear range of 10 fg/mL-100 ng/mL (PEC, LOD = 3.4 fg/mL) and 1 fg/mL-100 ng/mL (FL, LOD = 0.38 fg/mL). Furthermore, the proposed biosensor exhibits exceptional stability and high selectivity, enabled by the synergistic PEC-FL self-verification mechanism. This work establishes a paradigm for developing automated, cost-effective biosensors with high-throughput capabilities, offering significant potential for clinical biomarker diagnostics.