Oxygen Vacancy-Enhanced Electrochemiluminescence Sensing Strategy Using Luminol Thermally Encapsulated in Apoferritin as a Transducer for Biomarker Immunoassay
Yu Du, Jingwei Xue, Xu Sun, Dan Wu, Xuejing Liu, Huangxian Ju, Lei Yang, Qin Wei
Abstract
Oxygen vacancies (OVs) enhanced electrochemiluminescence (ECL) biosensing strategy using luminol thermally encapsulated in apoferritin (Lum@apoFt) as an efficient transducer was investigated for ultrasensitive biomarker detection. By applying the oxygen-defect engineering (ODE) strategy, the OVs enriched cobalt–iron oxide (r-CoFe2O4) was fabricated as the sensing substrate to boost the electron mobility and catalyze the generation of superoxide anion radical (O2•–) for signal amplification. It should be noted that r-CoFe2O4 with higher OVs density dramatically accelerated the ECL reaction between O2•– and luminol anionic radicals, achieving 6.5-fold stronger ECL output than CoFe2O4 with no or low OVs density. Moreover, facile encapsulation of approximate 412 luminol molecules in a single apoFt cavity was first realized by an efficient thermal-induction method. The obtained Lum@apoFt complexes exhibited well-maintained ECL efficiency and excellent biocompatibility for biological modifications. On this basis, a biosensor was developed for early diagnostics of squamous cell carcinomas by detecting its representative biomarker named cytokeratin 19 fragment 21-1 (CYFRA 21-1), from which excellent linearity was achieved in 0.5 pg/mL to 50 ng/mL with a detection limit of 0.14 pg/mL. This work not only put forward a novel idea of creating OVs enriched sensing interface with excellent signal-amplification function but also proposes a facile and robust methodology to design apoFt-based transducers for developing more practical nanoscale biosensors in early diagnostics of diseases.