Dual-enhanced Electrochemiluminescence Probes And Construction Of Immune Sensors

Sandwich immunosensors are one of the efficient tools for biological analysis,but the preparation of label probes is complicated and expensive.The use of metal nanoclusters（NCs）as labeled probes can solve the difficult problems of antibody labeling,but it also has the defect of weak electrochemiluminescence（ECL）signal.In this study,double-enhanced ECL luminophore were constructed based on metal nanoclusters（NCs）and sandwich electrochemiluminescence immunosensors.The main contents and conclusions are as follows:1.Construction of dual-enhanced ECL luminophoreMetal nanoclusters（NCs）electrochemiluminescence（ECL）luminophore owing to surface functional group diversity,excellent optical properties,low toxicity,easy synthesis and tunable emission wavelength,have attracted considerable interest in biological analysis.However,most of them have too low luminescence efficiency due to the ligand rotation-induced energy dissipation and the self-quenching effect,which greatly limits their application in electrochemical luminescence analysis.First of all,using L-glutathione（L-GSH）as a protective agent and reducing agent,BNCs with good optical properties were prepared by the principle of element replacement.Because the ligand GSH of BNCs contains a large number of carboxyl groups,the co-coreactive DPEA is anchored to the surface of BNCs through amidation reaction,thus shortening the electron transfer distance between them（realizing intercluster electron transfer）and generating Self-Enhanced ECL signals.The results showed that the ECL efficiency of DBNCs formed after covalency was significantly higher than that of BNCs and DPEA mixed together.Then,the DBNCs was assembled into the metal-organic framework（ZIF-8）.Because DBNCs were uniformly distributed in the porous structure of ZIF-8,the aggregation induction（AIE）effect was obtained.The ECL efficiency of ZIF-8@DBNCs is significantly higher than that of DBNCs alone.Meanwhile,the maximum PL emission intensity of ZIF-8@DBNCs also changes compared with DBNCs,but the emission wavelength does not change,which proves to some extent that DBNCs is embedded in ZIF-8 and produces AIE effect.2.Construction of immune sensorsDue to the extremely low concentration of target in biological system,the accuracy of traditional detection methods such as enzyme-linked immunosorbent assay（ELISA）is not high,and the detection results are interfered by many factors.Immune sensors is a combination of electrochemical luminescence and immunoassay,which has the advantages of low detection limit,high sensitivity and wide linear range.In this study,ZIF-8@BNCs@Ab₂was used as ECL probes to construct sandwich immune sensors.Firstly,The amidation reaction was used to bind BNCs to（trapping antibody）Ab₂to obtain（BNCs@Ab₂）as probes.BNCs@Ab₂was embedded into ZIF-8 to form immune probes ZIF-8@BNCs@Ab₂with aggregation induction（AIE）mechanism.The using PSA as the model protein,sandwich-type immune sensors was constructed with ZIF-8@BNCs@Ab₂as composite immune probes.The results showed that the linear range of the immune sensors with aggregation induction（AIE）mechanism was 0.1 pg/m L～10 ng/m L,and the detection limit（LOD）was 0.053 pg/m L,showing good selectivity.Therefore,the sandwich immune sensors provides a new way to detect PSA antigen and other biomarkers.