Dual-recognition immune-co-chemical ECL-sensor based on Ti,Mg@N-CDs-induced and novel signal-sensing units Poly(DVB-co-PBA)-reported for alpha-fetoprotein detection

• A label-free Immune-co-Chemical ECL-sensor based on poly(DVB-Co-PBA) and high luminous-efficiency Ti,Mg@N-CDs was developed. • The Ti,Mg@N-CDs-based ECL-reagent enhanced biosensor signal and provide binding sites of antibody for capturing target. • The dual-recognition Immune-co-Chemical ternary-system exhibits good selectivity and sensitivity towards AFP. • By changing AFP recognition unit, this method can be extended to determination of other disease biomarkers. In this paper, a high-efficiency electrochemiluminescence (ECL) ternary immune-system was firstly constructed for ultrasensitive assay of alpha-fetoprotein (AFP) based on the Ti, N/Mg co-doped carbon dots (Ti,Mg@N-CDs) as brand-new nanocomposite emitter, Poly(DVB-Co-PBA) as novel AFP-signal reporter and coreaction accelerator. A fluorescent microspheres Poly(DVB-Co-PBA), synthesizing based on 4-vinylphenylboronic acid (4-MPBA) and divinylbenzene (DVB), was used as a signal indicator-probe via the specific carbohydrate-AFP interaction to fabricate a dual-recognition label-free immune-co-chemical biosensor. The as-prepared Ti,Mg@N-CDs exhibited high ECL emission of 3.7-folds compared with CDs. Moreover, the large surface area, promising biocompatibility and nitrogen-rich functional group bearing on the nanohybrid was helpful for the antibody adsorption immobilization of Anti AFP /Ti,Mg@N-CDs/GCE. The successful synthesis and enhancement mechanism of the nanomaterials were also characterized through a serious of techniques including HR-TEM, SEM, EDS, FT-IR, UV–vis, PL and CV. With an immune-co-chemical ECL-assay format, target and signal reporter-probe (Poly(DVB-Co-PBA)) were introduced in sequence via specific reaction. Based on multiple signal amplification and dual recognition strategy, a largely linear detection ranges from 2.25 × 10 −6 to 2250 ng mL -1 with a low detection limit (1.55 × 10 -7 ng mL -1 ) were obtained via the resultant ECL ternary (Poly(DVB-Co-PBA)-AFP/Anti AFP /Ti,Mg@N-CDs/GCE) system. This proposed new method was applied to detect human serum samples with satisfactory results and acceptable recovery (96.04 % ∼ 111.22 %), indicating a potential application in clinical monitoring of disease biomarkers.