Photoluminescence immunoassay based on grapefruit peel-extracted carbon quantum dots encapsulated into silica nanospheres for p53 protein

We herein designed a simple and feasible photoluminescence (PL) immunoassay for sensitive detection of p53 protein in biological fluid by using grapefruit peel-extracted carbon quantum dots (CQDs) as the signal-generation tags. CQDs were first synthesized on the basis of grapefruit peel as the carbon source via a typical hydrothermal method. Thereafter, the synthesized CQDs were encapsulated into silica nanoparticles (CQD-SiNP) for the signal enhancement. In the presence of p53, a sandwich-type immunoreaction was fulfilled on monoclonal anti-p53 capture antibody-coated microplate by using CQD-SiNP-labeled polyclonal anti-p53 secondary antibody. Relative to CQD-labeled strategy, use of CQD-SiNP could amplify the photoluminescence signal toward the same-concentration target p53. Under the optimum conditions, the photoluminescence intensity via the CQD-SiNP-labeled strategy exhibited high sensitivity, and allowed the detection of target p53 as low as a concentration of 2.7 pg mL−1. No interfering signals were acquired toward non-target analytes including biomarkers or enzymes in human serum. Below 15% of relative standard deviations (RSDs) were obtained for detection of p53 analyte in all cases. Additionally, CQD-SiNP-based photoluminescence immunoassays were utilized for the evaluation of real human serum samples, and received well-matched results with commercial enzyme-linked immunosorbent assay (ELISA) kit.