Renjun Pei | PubMed Health

PubMed2006

Behavior of polycatalytic assemblies in a substrate-displaying matrix.

We describe polycatalytic assemblies, comprising one or two streptavidin molecules and two to six attached nucleic acid catalysts (deoxyribozymes), with phosphodiesterase activity. When exposed to a matrix covered at high densities with oligonucleotide substrates, these molecules diffuse through the matrix continuously cleaving the substrate at rates comparable to those of individual catalysts in solution. Rates of diffusion (movement), processivity, and resident times of assemblies can be controlled through the number of catalytic units and the length of substrate/product recognition regions. The assemblies were characterized at the ensemble level using surface plasmon resonance.

Catalysis↗

PubMed2003

Layer-by-layer assembly of multilayer films composed of avidin and biotin-labeled antibody for immunosensing.

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.

Animals↗