title: Electrochemical immunosensor for casein based on gold nanoparticles and poly(L-Arginine)/multi-walled carbon nanotubes composite film functionalized interface.
abstract: In this paper, a novel electrochemical immunosensor for the determination of casein based on gold nanoparticles and poly(L-Arginine)/multi-walled carbon nanotubes (P-L-Arg/MWCNTs) composite film was proposed. The P-L-Arg/MWCNTs composite film was used to modify glassy carbon electrode (GCE) to fabricate P-L-Arg/MWCNTs/GCE through electropolymerization of L-Arginine on MWCNTs/GCE. Gold nanoparticles were adsorbed on the modified electrode to immobilize the casein antibody and to construct the immunosensor. The stepwise assembly process of the immunosensor was characterized by cyclic voltammetry and differential pulse voltammetry. Results demonstrated that the peak currents of [Fe(CN)(6)](3-/4-) redox pair decreased due to the formation of antibody-antigen complex on the modified electrode. The optimization of the adsorption time of gold nanoparticles, the pH of supporting electrolyte and the incubation time were investigated in details. Under optimal conditions, the peak currents obtained by DPV decreased linearly with the increasing casein concentrations in the range from 1 × 10(-7) to 1 × 10(-5) g mL(-1) with a linear coefficiency of 0.993. This electrochemical immunoassay has a low detection limit of 5 × 10(-8) g mL(-1) and was successfully applied to the determination of casein in cheese samples.
authors.affiliation: College of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, 19A YuQuan Road, Beijing 100049, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Cao
authors.forename: Hong
authors.initials: H
authors.lastname: Zhao
authors.forename: Yimin
authors.initials: Y
authors.lastname: Yang
authors.forename: Yujian
authors.initials: Y
authors.lastname: He
authors.forename: Nan
authors.initials: N
authors.lastname: Ding
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Zhijiao
authors.initials: Z
authors.lastname: Wu
authors.forename: Kaixiang
authors.initials: K
authors.lastname: Xiang
authors.forename: Guangwei
authors.initials: G
authors.lastname: Wang
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002364:Caseins / Q000032:analysis*; D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007118:Immunoassay / Q000379:methods*; D053768:Metal Nanoparticles / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002364:Caseins; D037742:Nanotubes, Carbon; D010455:Peptides; C015462:polyarginine; D006046:Gold