title: Layer-by-layer assembly of multilayer films composed of avidin and biotin-labeled antibody for immunosensing.
abstract: Protein multilayers composed of avidin and biotin-labeled antibody (bio-Ab) were prepared on gold surface by layer-by-layer assembly technology using the high specific binding constant (K(a): approximately 10(15) M(-1)) between avidin and biotin. The assembly process of the multilayer films was monitored by using real-time BIA technique based on surface plasmon resonance (SPR). The multilayer films were also characterized by electrochemical impedance spectroscopy (EIS) and reflection absorption Fourier transform infrared spectroscopy (FTIR). The results indicate that the growth of the multilayer is uniform. From response of SPR for each layer, the stoichiometry S for the interaction between avidin and bio-Ab is calculated to be 0.37 in the multilayer whereas 0.82 in the first layer. The protein mass concentration for each layer was also obtained. The schematic figure for the multilayer assembly was proposed according to the layer mass concentration and S value. The utility of the mutilayer films for immunosensing has been investigated via their subsequent interaction with hIgG. The binding ability of the multilayer increased for one to three layers of antibody, and then reach saturation after the fourth layer. These layer-by-layer constructed antibody multilayers enhance the binding ability than covalently immobilized monolayer antibody. This technology can be also used for construction of other thin films for immunosensing and biosensor.
authors.affiliation: State Key Laboratory of Electroanalytical Chemistry and National Analytical Research Center of Electrochemistry and Spectroscopy, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, People's Republic of China.
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Cui
authors.forename: Renjun
authors.initials: R
authors.lastname: Pei
authors.forename: Zhenxin
authors.initials: Z
authors.lastname: Wang
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.forename: Ying
authors.initials: Y
authors.lastname: Ma
authors.forename: Shaojun
authors.initials: S
authors.lastname: Dong
authors.forename: Xiurong
authors.initials: X
authors.lastname: Yang
mesh_terms: D000818:Animals; D000906:Antibodies; D001360:Avidin; D015374:Biosensing Techniques; D001710:Biotin; D006046:Gold; D007118:Immunoassay / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared; D020349:Surface Plasmon Resonance
chemical_list: D000906:Antibodies; D001360:Avidin; D001710:Biotin; D006046:Gold