title: Graphene/quantum dot bionanoconjugates as signal amplifiers in stripping voltammetric detection of EpCAM biomarkers.
abstract: A sensitive electrochemical immunosensor for the detection of epithelial cell adhesion molecule (EpCAM) antigen, a common marker for tumors of epithelial origin, employing bionanoconjugates as signal-transduction labels has been developed. The bionanoconjugates were fabricated by carboxylation of the two-dimensional graphene oxide nanosheets (GRs) and immobilizing streptavidin and amine-functionalized CdSe quantum dots (QDs) on carboxylated GRs via carbodiimide coupling chemistry, followed by the immunoreaction with the biotinylated secondary antibodies. Since carboxylated GRs have a higher density of active sites, it allows a large number of CdSe QDs to be immobilized onto the surface of the bionanoconjugates, and hence, enhance the sensitivity of the immunosensor. The method enabled detection limits of 100 fg/mL and 1 pg/mL (based on the S/N=3) in PBS buffer and serum samples, respectively, using anodic stripping voltammetric readout. The immunosensor showed a good selectivity, reproducibility, and long-storage stability, and may become a promising technique for the early detection of tumor biomarker in clinical/biological samples.
authors.affiliation: Australian Institute for Bioengineering & Nanotechnology (AIBN), Centre for Biomarker Research and Development, The University of Queensland, QLD 4072, Australia. Electronic address: m.shiddiky@uq.edu.au.
authors.forename: Muhammad J A
authors.initials: MJA
authors.lastname: Shiddiky
authors.affiliation: Australian Institute for Bioengineering & Nanotechnology (AIBN), Centre for Biomarker Research and Development, The University of Queensland, QLD 4072, Australia.
authors.forename: Sakandar
authors.initials: S
authors.lastname: Rauf
authors.affiliation: Australian Institute for Bioengineering & Nanotechnology (AIBN), Centre for Biomarker Research and Development, The University of Queensland, QLD 4072, Australia.
authors.forename: Prakash H
authors.initials: PH
authors.lastname: Kithva
authors.affiliation: Australian Institute for Bioengineering & Nanotechnology (AIBN), Centre for Biomarker Research and Development, The University of Queensland, QLD 4072, Australia; Australian Institute for Bioengineering & Nanotechnology (AIBN), School of Chemistry & Molecular Biosciences, Centre for Biomarker Research and Development, The University of Queensland, QLD 4072, Australia. Electronic address: m.trau@uq.edu.au.
authors.forename: Matt
authors.initials: M
authors.lastname: Trau
mesh_terms: D055910:Antibodies, Immobilized; D000951:Antigens, Neoplasm / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D015374:Biosensing Techniques / Q000379:methods* / Q000706:statistics & numerical data; D019187:Cadmium Compounds; D015815:Cell Adhesion Molecules / Q000032:analysis*; D058266:Dielectric Spectroscopy; D055664:Electrochemical Techniques; D000071858:Epithelial Cell Adhesion Molecule; D006108:Graphite; D006801:Humans; D057230:Limit of Detection; D018613:Microscopy, Confocal; D058726:Nanoconjugates; D045663:Quantum Dots; D018036:Selenium Compounds
chemical_list: D055910:Antibodies, Immobilized; D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D019187:Cadmium Compounds; D015815:Cell Adhesion Molecules; C499379:EPCAM protein, human; D000071858:Epithelial Cell Adhesion Molecule; D058726:Nanoconjugates; D018036:Selenium Compounds; D006108:Graphite; C058667:cadmium selenide