Facile Aptasensor with enhanced electrochemiluminescence by nanozyme in nanoporous silica film for highly sensitive detection of carbohydrate antigen 15–3

Establishing sensitive detection method for carbohydrate antigen 15–3 (CA15–3) is of great significance for the early diagnosis and therapeutic monitoring of breast cancer. Herein, an electrochemiluminescence (ECL) sensor was fabricated by growing Co 3 O 4 nanoparticles in-situ within nanochannels and employing a signal gating strategy, achieving highly sensitive detection of CA15–3. Using simple Stöber method, a silica nanochannel film (SNF) was deposited onto an indium tin oxide (ITO) glass electrode. This two-dimensional (2D) nanoporous silica film provided a confined space, within which Co 3 O 4 nanozymes were synthesized in situ. Co 3 O 4 served as a peroxidase (POD)-mimic nanozyme, enabling the catalytic conversion of hydrogen peroxide (H 2 O 2 ) into reactive oxygen species (ROS). Functioning as a nanocatalyst, Co 3 O 4 remarkedly enhanced the electrochemical oxidation of luminol, thereby boosting the ECL signal. This dual enhancement mechanism enabled the sensor to achieve high luminol-based ECL signal. The bio-recognition interface was constructed by functionalizing the outer surface of SNF with silane coupling agents and immobilizing aptamers. A measurable decrease in the ECL signal was generated due to the hindered diffusion of the emitter and co-reactant and increased interfacial resistance, which occurred when the aptamer-CA15–3 complex formed on the electrode surface. This response allowed for the quantification of CA15–3. Under optimal conditions, the developed aptasensor can detect CA15–3 in the range of 0.1 to 10,000 mU/mL, with a limit of detection of 26 μU/mL. Owing to its merits of simple fabrication, rapid analysis, high sensitivity, good reproducibility, and excellent selectivity, the developed immunosensor holds great potential for clinical diagnostics of tumor biomarkers.