Surface Defect-Involved And Single-Waveband Electrochemiluminescence Of Unary Gold Nanoclusters And Silver Nanoclusters For Immunosensing

Electrochemiluminescence(ECL)refers to the radiative charge transfer and recombination between some electrochemically generated radicals by electrochemical means.ECL biochemical analysis has been extensively utilized in biomolecular detection,imaging technology,clinical diagnosis,environmental monitoring and other fields because of its merits of a high signal/noise ratio,simple equipment,a wide dynamic range and so on.The two types of ECL of nanoparticles are bandgap-enigineered ECL and surface defect-involved ECL,respectively.The single-waveband ECL is normally achieved via suppressing surface defects.In this paper,the surface defect-involved ECL of unary gold nanoclusters and silver nanoclusters are studied,and single-waveband ECL and immunosensing are achieved focusing on the surface defect-involved ECL of nanoparticle luminophores.The specific research contents are as follows:(1)A series of unary gold nanoclusters(Thiol-AuNCs)are synthesized using linear mcrcaptoalkanoic acids as thiol-capping agents.The surface defect-involved and singlewaveband ECL of water-soluble Thiol-AuNCs are achieved in the red light region.The effects of carbon chain length of the capping agent on the optical and electrochemical responses of Thiol-AuNCs are systematically studied.Immunoassay is performed with the assistance of 11mercaptoundecanoic acid capped AuNCs(MUA-AuNCs)/hydrazine(N2H4).ThiolAuNCs/N2H4 are constructed by utilizing the as-prepared Thiol-AuNCs capped with linear mercaptoalkanoic acid with a long-carbon chain length as ECL luminophores and N2H4 as coreactant.The monodispersed Thiol-AuNCs exhibit similar ECL spectra and ECL intensitypotential profiles,indicating that the carbon chain lengths of thiol-capping agents significantly affect the ECL intensity of Thiol-AuNCs instead of the ECL excited state of Thiol-AuNCs.ECL spectrum show that the maximum emission wavelength of Thiol-AuNCs is at 713 nm.ThiolAuNCs capped with linear mercaptoalkanoic acids only exhibit surface defect-involved and single-waveband ECL.In addition,ECL immunosensor is constructed to achieve the detection of CA125 using MUA-AuNCs as ECL luminophores and N2H4 as coreactant.The constructed sandwiched ECL immunosensor successfully exhibits a linear range of 0.5 mU/mL to 1 U/mL with a limit of detection of 0.1 mU/mL.The immunosensor performs an excellent selectivity.(2)Unary silver nanoclusters(LPA-AgNCs)are synthesized using L-penicillamine as capping agent.The surface defect-involved and single-waveband ECL of water-soluble LPAAgNCs is achieved in the near infrared region using N2H4 as coreactant.Immunoassay is performed with the assistance of LPA-AgNCs/N2H4.The surface defect-involved and singlewaveband ECL system of LPA-AgNCs/N2H4 is independently developed with the maximum emission wavelength of 870 nm by utilizing LPA-AgNCs as ECL luminophore and N2H4 as coreactant,and the oxidative-reductive ECL of LPA-AgNCs/N2H4 exbibits a narrow potential width with the maximum emission potential of+1.27 V.The surface defect-involved ECL mechanism for LPA-AgNCs is independently developed.The holes are injected into the monodispersed LPA-AgNCs via electrochemical oxidation.N2H4 and its producing chemical and radicals inject electrons into the oxidized LPA-AgNCs.The recombination of electrons and holes achieve surface defect-involved ECL.In addition,the effects of coreactants,buffer solution and pH of buffer solution on the ECL behavior of LPA-AgNCs are systematically searched.It is found that ECL system exhibits the best ECL intensity using N2H4 as coreactant and phosphate buffer solution with pH 8.0 as buffer solution.ECL immunosensor is constructed to achieve the detection of CEA using LPA-AgNCs as ECL luminophores and N2H4 as coreactant.The constructed sandwiched ECL immunosensor successfully exhibits a linear range of 0.5 pg/mL to 1 ng/mL with a limit of detection of 0.1 pg/mL.The immunosensor exhibits an excellent selectivity.