Dual-quenching electrochemiluminescence resonance energy transfer system from CoPd nanoparticles enhanced porous g-C3N4 to FeMOFs-sCuO for neuron-specific enolase immunosensing

Abstract

For the diagnosis and therapy of small cell lung cancer (SCLC), the accurate and sensitive determination of neuron-specific enolase (NSE) content is crucial. This work outlines a dual-quenching electrochemiluminescence resonance energy transfer (ECL-RET) immunosensor based on the double quenching effects of iron base metal organic frameworks (FeMOFs) loaded with small sized CuO nanoparticles (FeMOFs-sCuO) towards CoPd nanoparticles (CoPdNPs) enhanced porous g-C3N4 (P–C3N4-CoPdNPs). To be specific, we prepared a porous g-C3N4 (P–C3N4) which has a rich porous structure, and significantly increased the specific surface area and the number of reaction sites of P–C3N4. Meanwhile, the CoPdNPs were loaded onto P–C3N4 to improve the ECL luminescence property of P–C3N4/K2S2O8 system through acting as a coreaction accelerator. In addition, the ultraviolet–visible (UV–vis) absorption spectra of FeMOFs and small sized CuO nanoparticles (sCuO) showed considerable overlap with the ECL emission spectra of P–C3N4 appropriately. Therefore, FeMOFs with high specific surface area were prepared and well combined with sCuO to effectively dual-quenching the ECL emission of P–C3N4 based on resonance energy transfer. Hence, a new type ECL-RET couple made up of P–C3N4-CoPdNPs (donor) and FeMOFs-sCuO (acceptor) were developed for the first time. A certain amount of P–C3N4-CoPdNPs, Ab1, BSA, NSE were modified layer by layer onto the electrode surface. Then FeMOFs-sCuO-Ab2 bioconjugates was incubated through the immune recognition binding. As a result, a sandwich-type ECL biosensor was manufactured successfully for NSE immunoassay. Under optimal experimental conditions, the limit of detection (LOD) and the limit of quantitation (LOQ) of the prepared ECL sensor for NSE analysis was 20.4 fg mL−1 and 7.99 fg mL−1, respectively, with the relative standard deviation (RSD) of 1.68%. The linear detection range was 0.0000500–100 ng mL−1. The studied immunosensor had satisfactory sensitivity, specificity and reproducibility, manifesting the suggested sensing strategy might offer a good technical means and theoretical basis for the sensitivity analysis of NSE and has a potential application in clinical diagnosis analysis.