Fabricating The ECL Biosensors Based On Functional Carbon Materials To Detect Tumor Markers

Combining the advantages of electrochemistry,chemiluminescence and immunoassay,electrochemiluminescence(ECL)immunoassay possesses features of high specificity,high sensitivity,as well as low background signal,which have been broadly used in early prognosis as well as clinical detection of diseases.But,it is difficult to achieve the trace detection of disease markers relying on the ECL suppression of targets.To meet this pursuit,the construction of a quenched ECL biosensor based on a high-efficiency quencher is the detection of low abundance of disease markers provides a new research direction.This thesis mainly uses carbon materials as ECL emitters.Luminescence materials(carbon materials),based on the energy transfer between ceria@polydopamine(CeO₂@PDA)composites,copper sulfide@cobalt disulfide double shelled nanoboxes(Cu S@CoS₂ DSNBs),and carboxyl cobalt disulfide nanoboxes(carboxyl CoS₂ NBs),design high-efficiency quenching sensing strategies,and explore the quenching mechanism.A series of ECL immunoassays are designed and used for sensitive analysis of disease markers.The main research contents of the thesis are as follows:(1)Based on the relationship between 1-pyrene butyric acid(Py-COOH,sodium salt)modified CNNS(m-CNNS)and CeO₂@PDA composites quenching constructs sandwich type electrochemiluminescence immunosensor.For the detection of brain natriuretic peptide(BNP),m-CNNS is used to connect the capture antibody.CeO₂@PDA is used as a label to connect the BNP detection antibody.After specific recognition between antigen and antibody,the ECL signal of m-CNNS can be quenched.Under the best experimental conditions,the immunosensor can achieve sensitive detection of BNP in the range of 0.5 pg/mL-100 ng/mL,with a detection limit of 0.1 pg/mL.This quenching construction strategy will have potential applications in the early detection of very low concentrations of disease markers.(2)A sandwich-type ECL immunosensor was prepared based on the quenching effect of Cu S@CoS₂ DSNBs on gold nanoparticles functionalized carbon nitride(Au@C₃N₄)composites electrochemiluminescence.The sensor was used for quantitative detection of?-amyloid_1-42 oligomers.The prepared Au@C₃N₄composites could could also worked as the substrate for fixing the primary antibody(Ab₁)through the Au-N Bond,in addition to supplying the excellent ECL signal sources.Using K₂S₂O₈ as the coreactant,electrochemiluminescence behaviour of Au@C₃N₄could be observed.Silver nanoparticle modified Cu S@CoS₂ double shelled nanoboxes(Cu S@CoS₂DSNBs@Ag NPs)as a secondary antibody marker immobilized the A?detection antibody.Based on the energy transfer between Au@C₃N₄(donor)and Cu S@CoS₂ DSNBs@Ag NPs(acceptor),we constructed a dual-quenching type ECL immunosensor and used to detect A?.Under optimal experimental conditions,the sensor detects A?in the range of 0.5 pg/mL-20 ng/mL and the detection limit was 0.0038 pg/mL.The sensor also provides important references for highly sensitive detection of other disease markers.(3)An immunosensor based on carboxyl CoS₂ NBs quenching graphitic carbon nitride coupled bismuth molybdenum oxide(g-C₃N₄/Bi₂Mo O₆)electrohemiluminescence was constructed,and then it was used for sensitive detection of alpha fetoprotein(AFP).Emloying K₂S₂O₈,ECL behaviour of g-C₃N₄/Bi₂Mo O₆ could be observed.So that,energy transfer between g-C₃N₄/Bi₂Mo O₆ and CoS₂ NBs can occur,triggering ECL quenching effects.Under optimal experimental conditions,the sensor detects AFP in the range of 0.5 pg/mL-20 ng/mL and the detection limit was 0.04 pg/mL.As emerging electrochemiluminescence(ECL)emitters,graphitic carbon nitride(g-C₃N₄)composites not just possess the advantages of pristine g-C₃N₄ with good biocompatibility,despite improve its dispersion as well as ECL efficiency.That's why,they have presently become a rising attention in ECL.We summarized the recent progress of various g-C₃N₄composites ECL systems as well as associated applications in biosensors.We highlight the enhanced ECL performances of different g-C₃N₄ composites,such as metal nanoparticles/g-C₃N₄ composites,metal nanoparticles/C₃N₄ composites,metal oxide/g-C₃N₄composites and other material/g-C₃N₄ composites.Lastly,this thesis ends through perspectives in searching novel and effective g-C₃N₄ composites/capable energy acceptors or C₃N₄ composites/capable energy acceptors ECL systems and in assembling sensitive ECL biosensors.