Application Of Electroluminescent Sensor Based On Transition Metal In Detection Of Disease Marker

Electrochemiluminescence?ECL?can cause electron transfer reactions on the surface of electrodes to produce luminescence.As a combination of electrochemical and photophysical methods,ECL possesses several advantages over chemiluminescence and photoluminescence.Therefore,ECL not only has the advantages of simplicity and stability of electrochemical methods,but also possesses the characteristics of high sensitivity and wide dynamic range of photoluminescence.The ECL method has great application potential.And,the transition metals are one of important nanomaterials due to the good thermal stability,anti-toxicity,high selectivity to oxidation reaction and long service life and so on.On this basis,the transition metal was used as luminophor,luminescent signal augmenting agent,luminescence signal quencher to construct sandwich ECL immunosensors.And the immunosensors were used for the high sensitive analysis of disease markers.The main researches are as follows:?1?A sensitive ECL immunosensor was constructed for detection of insulin.It is based on the quenching effect of octahedral cuprous oxide decorated with gold nanoparticles?Cu₂O@Au NPs?.A composite constructed from multiwalled carbon nanotubes/reduced graphene oxide nanoribbons provides a large specific surface that promotes electron transfer on the surface of electrodes.In parallel,CdS nanoclusters were loaded with europium???to get CdS:Eu NCs.The Eu???ions exert a large enhancement in ECL intensity of the CdS NCs.Cu₂O is biocompatible and high specific surface.It was used as a quencher for the ECL immunosensor.If Au NPs are loaded onto Cu₂O,the fluorescence of the CdS NCs?with emission peaks at 525 nm? is quenched.The Cu₂O@Au NPs also can be employed as a label for the secondary antibodies?Ab₂? to improve the sensitivity of the ECL immunosensor.When the working potential was from 0 V to-1.6 V,the immunoassay has a linear range of0.5 pg?mL^-1to 50 ng?mL^-1and a detection limit of 0.04 pg?mL^-1.?2?A sandwich quenching ECL immunosensor was constructed for insulin detection.In this work,the SnO₂/reduced graphene oxide/gold nanoparticles?SnO₂/rGO/Au NPs?nanocomposites combined with luminol?Lu?were utilized to construct the base of the immunosensor,and the SiO₂@Polydopamine?SiO₂@PDA? nanomaterials acted as efficient ECL signal quencher.SiO₂@PDA was firmly anchored secondary antibody?Ab₂? by covalent bonding due to the reactive quinones at the surface of PDA film.Au NPs which functionalized SnO₂/rGO were acted as the bridge to incubate with primary antibody?Ab₁? by Au-N bond and simultaneously enhanced the sensitivity of immunosensor.In addition,we used the luminol-O₂ system to obtain more stable ECL signal.Under the optimal experimental conditions,a reliable determination of insulin was realized within a linear range of 0.0001-50 ng/mL and with a detection limit of 26 fg/mL?S/N=3?.Therefore,the ECL immunosensor exhibited good sensitivity,acceptable selectivity and high repeatability.Meanwhile,the proposed sandwich quenching ECL immunosensor was also evaluated by detecting insulin in real samples,this immunosensor has potential application value in insulin detection.?3?A sandwich ECL immunosensor was constructed based on the CuO@GO nanocomposites for the detection of cardiac troponin i?cTnI?.The m-CNNS which had high luminescent properties was obtained via facile mechanical ground CN.CuO is widely used in analytical chemistry due to its narrow bandgap?1.2 eV?,excellent conductivity and low cost.On the surface of GO contains hydroxyl group,epoxy group,carbon-oxygen group and other oxygen groups,which has good hydrophilicity and high biocompatibility.Copper oxide@graphene oxide?CuO@GO? was synthesized and used as a lable to load insulin antibody.Therefore,the proposed immunosensor has good selectivity,stability and anti-interference.?4?In this study,a sandwich-type ECL immunosensor was constructed to detect cardiac troponin i?cTnI?.In this study,aminated multi-walled carbon nanotubes?MWCNTs-NH₂@N? were used as substrate to immobilize photoluminescent tripyridyl ruthenium(Ru?bpy?₃²⁺),spherical molybdenum carbide?Mo₂C@C?with good electrical conductivity was used to load the antibody of cTnI?Ab₂? and used as a signal amplifier.BNQDs have good biocompatibility and stability and have great potential in bioanalysis.On the one hand,the ECL efficiency of Ru?bpy?₃²⁺was improved by Mo₂C@C,on the other hand,the ECL intensity of Ru?bpy?₃²⁺ was increased by boron nitride quantum dot?BNQDs?.In addition,the constructed ECL immunosensor showed good stability,repeatability and anti-interference,and detected CTnI successfully.