title: Carbon nanotubes functionalized by click chemistry as scaffolds for the preparation of electrochemical immunosensors. Application to the determination of TGF-beta 1 cytokine.
abstract: An electrochemical immunosensor for the determination of the multifunctional Transforming Growth Factor β1 (TGF-β1) cytokine has been prepared using multi-walled carbon nanotube (MWCNT)-modified screen-printed carbon electrodes. MWCNTs were functionalized by means of copper(i) catalyzed azide-alkyne cycloaddition ("click" chemistry) as an efficient strategy for the covalent immobilization of immunoreagents without altering their configurations and preserving their biological activity. Alkyne-functionalized IgGs were also prepared and used to assemble IgG-alkyne-azide-MWCNT conjugates used as scaffolds for the immunosensor preparation. After a blocking step with casein, anti-TGF was immobilized and the target cytokine was sandwiched with biotinylated anti-TGF labeled with poly-HRP-labeled streptavidin. The affinity reaction was monitored amperometrically at -0.20 V using the hydroquinone (HQ)/H2O2system. The calibration plot for TGF-β1 exhibited a range of linearity (r2= 0.995) extending between 5 and 200 pg mL-1which is suitable for the determination of the target cytokine in human serum. A limit of detection of 1.3 pg mL-1was achieved. The analytical performance of the immunosensor can be advantageously compared with that claimed for ELISA kits. The immunosensor was applied to the analysis of spiked human serum samples at different concentration levels with excellent recoveries.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040-Madrid, Spain. yseo@quim.ucm.es.
authors.forename: E
authors.initials: E
authors.lastname: Sánchez-Tirado
authors.forename: A
authors.initials: A
authors.lastname: González-Cortés
authors.forename: P
authors.initials: P
authors.lastname: Yáñez-Sedeño
authors.forename: J M
authors.initials: JM
authors.lastname: Pingarrón
mesh_terms: D055910:Antibodies, Immobilized; D015374:Biosensing Techniques; D057930:Click Chemistry; D055664:Electrochemical Techniques; D004566:Electrodes; D006801:Humans; D006861:Hydrogen Peroxide; D006873:Hydroquinones; D007118:Immunoassay; D007074:Immunoglobulin G; D058726:Nanoconjugates; D037742:Nanotubes, Carbon; D053773:Transforming Growth Factor beta1 / Q000032:analysis* / Q000097:blood
chemical_list: D055910:Antibodies, Immobilized; D006873:Hydroquinones; D007074:Immunoglobulin G; D058726:Nanoconjugates; D037742:Nanotubes, Carbon; C508960:TGFB1 protein, human; D053773:Transforming Growth Factor beta1; D006861:Hydrogen Peroxide; C031927:hydroquinone