Energy level-engineered of PS@PANI/AuNPs core-shell nanoprobes for magazine-type quasi-solid-state ECL immunosensing...

Early cancer screening in resource-limited settings demands low-cost, high-performance sensors, where nanomaterial design is critical to breaking the limitations of traditional electrode-based platforms. Herein, we report a magazine-type quasi-solid-state electrochemiluminescence (ECL) immunosensor for sensitive detection of alpha-fetoprotein (AFP, a hepatocellular carcinoma marker), enabled by energy level-engineered PS@PANI/AuNPs core-shell nanoprobes and a 3D-printed continuous detection device. 350 nm polystyrene (PS) nanoparticles serve as templates to synthesize PS@PANI/AuNPs (with 12 nm AuNPs uniformly distributed on the PANI shell). Orthogonal experiments were employed to precisely regulate the oxidation state (phenylenediamine/quinonediimine ratio) and doping state (sulfosalicylic acid) of PANI, achieving matched HOMO/LUMO energy levels between PANI and the excited state of Ru(bpy)₃²⁺. The sensor uses agarose gel as a quasi-solid substrate: glutaraldehyde activation enables efficient immobilization of capture antibodies, providing a biocompatible, low-cost biointerface. Integration of the gel substrate with a 3D-printed magazine-type device enables sequential analysis of up to 20 samples per hour. Under optimal conditions, the sensor exhibits a linear range of 0.39-200 ng/mL, a limit of detection (LOD) of 0.28 ng/mL, and excellent stability (RSD = 2.87%). This work highlights the role of nanomaterial electronic structure regulation in advancing ECL sensors, offering a scalable, low-cost solution for early cancer screening in global health applications.