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.