title: Copper-doped titanium dioxide nanoparticles as dual-functional labels for fabrication of electrochemical immunosensors.
abstract: Constructions of versatile electroactive labels are key issues in the development of electrochemical immunosensors. In this study, copper-doped titanium dioxide nanoparticle (Cu@TiO2) was synthesized and used as labels for fabrication of sandwich-type electrochemical immunosensors on glassy carbon electrode (GCE). Due to the presence of copper ions, Cu@TiO2 shows a strong response current when coupled to an electrode. The prepared nanocomposite also shows high electrocatalytic activity towards reduction of hydrogen peroxide (H2O2). The dual functionality of Cu@TiO2 enables the fabrication of immunosensor using different detection modes, that is, square wave voltammetry (SWV) or chronoamperometry (CA). While Cu@TiO2 was used as labels of secondary antibodies (Ab2), carboxyl functionalized graphene oxide (CFGO) was used as electrode materials to immobilize primary antibodies (Ab1). Using human immunoglobulin G (IgG) as a model analyte, the immunosensor shows high sensitivity, acceptable stability and good reproducibility for both detection modes. Under optimal conditions, a linear range from 0.1 pg/mL to 100 ng/mL with a detection limit of 0.052 pg/mL was obtained for SWV analysis. For CA analysis, a wider linear range from 0.01 pg/mL to 100 ng/mL and a lower detection limit of 0.0043 pg/mL were obtained. The proposed metal ion-based enzyme-free and noble metal-free immunosensor may have promising applications in clinical diagnoses and many other fields.
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China; School of Resources and Environment, University of Jinan, Jinan 250022, PR China.
authors.forename: Sen
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Hongmin
authors.initials: H
authors.lastname: Ma
authors.affiliation: School of Resources and Environment, University of Jinan, Jinan 250022, PR China.
authors.forename: Liangguo
authors.initials: L
authors.lastname: Yan
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Cao
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yan
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China. Electronic address: sdjndxwq@163.com.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wei
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Bin
authors.initials: B
authors.lastname: Du
mesh_terms: D003300:Copper / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation; D007074:Immunoglobulin G / Q000032:analysis*; D057230:Limit of Detection; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D014025:Titanium / Q000737:chemistry*
chemical_list: D007074:Immunoglobulin G; C009495:titanium dioxide; D003300:Copper; D014025:Titanium
keywords: Chronoamperometry; Human immunoglobulin G; Metal ions-based immunosensor; Square wave voltammetry