title: Anodic-stripping voltammetric immunoassay for ultrasensitive detection of low-abundance proteins using quantum dot aggregated hollow microspheres.
abstract: A new anodic-stripping voltammetric immunoassay protocol for detection of IgG1, as a model protein, was designed by using CdS quantum dot (QD) layer-by-layer assembled hollow microspheres (QDHMS) as molecular tags. Initially, monoclonal anti-human IgG1 specific antibodies were anchored on amorphous magnetic beads preferably selective to capture F(ab) of IgG1 analyte from the sample. For detection, monoclonal anti-human IgG1 (F(c)-specific) antibodies were covalently coupled to the synthesized QDHMS. In a sandwich-type immunoassay format, subsequent anodic-stripping voltammetric detection of cadmium released under acidic conditions from the coupled QDs was conducted at an in situ prepared mercury film electrode. The immunoassay combines highly efficient magnetic separation with signal amplification by the multilayered QD labels. The dynamic concentration range spanned from 1.0 fg mL(-1) to 1.0 μg mL(-1) of IgG1 with a detection limit of 0.1 fg mL(-1). The electrochemical immunoassay showed good reproducibility, selectivity, and stability. The analysis of clinical serum specimens revealed good accordance with the results obtained by an enzyme-linked immunosorbent assay method. The new immunoassay is promising for enzyme-free, and cost-effective analysis of low-abundance biomarkers.
authors.affiliation: MOE Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
authors.forename: Irina Yu
authors.initials: IY
authors.lastname: Goryacheva
authors.forename: Reinhard
authors.initials: R
authors.lastname: Niessner
authors.forename: Dietmar
authors.initials: D
authors.lastname: Knopp
mesh_terms: D000906:Antibodies / Q000737:chemistry* / Q000276:immunology*; D015415:Biomarkers / Q000737:chemistry*; D002104:Cadmium / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007118:Immunoassay; D007074:Immunoglobulin G / Q000737:chemistry* / Q000276:immunology*; D057230:Limit of Detection; D008863:Microspheres; D045663:Quantum Dots
chemical_list: D000906:Antibodies; D015415:Biomarkers; D007074:Immunoglobulin G; D002104:Cadmium