Iodine-Vacancy BiOI Nanosheets-Embedded on Bi2O3 Electrospun Heterojunction for Label-Free Interleukin-6 Photoelectrochemical Aptasensor with High Signal-to-Noise Ratio
Lower-background photoelectrochemical (PEC) bioanalysis is crucial for high-sensitivity biomolecule detection and early clinical disease screening by effectively eliminating matrix interference and reducing the background photocurrent noise. In this work, a novel, simple, label-free split-type PEC aptasensor was successfully constructed for interleukin-6 (IL-6) analysis based on electrospun Bi2O3 nanofibers (NFs) coupled with in situ grown iodine vacancy (IV) BiOI nanosheets (IV-BiOI/Bi2O3 NFs). The introduction of heterojunction interfaces and IV in BiOI/Bi2O3 NFs can synergistically regulate light absorption capacity, optimize electronic band structure, efficiently promote the separation and migration of photogenerated electron–hole pairs, and inhibit charge recombination, thus greatly enhancing PEC photocurrent response. Aptamer-capped mesoporous silica nanospheres encapsulate ascorbic acid to specifically recognize IL-6 (10.0 ng/mL), triggering large amounts of AA release. This boost-on photocurrent response yields a 30.9-fold enhancement versus the control group. By separating biorecognition reactions from photocurrent readout, the split-type strategy avoids electrode surface biomodification interference and achieves an ultralow background. The sensor presents a wide linear range, low detection limit (0.6 pg/mL), favorable selectivity, and stability and achieves reliable detection in real serum and sweat samples. This work provides a new paradigm for defective heterojunction-based PEC biosensing with label-free operation, simple fabrication, and a high signal-to-noise ratio.