ИСТИНА

LBL technique has attracted considerable attention as an enzyme immobilization method for design, fabrication, and applications of biosensors. The amount of enzyme incorporated into such polymer films and strength of its binding to a polymer have the most important influence on basic characteristics of these bioanalytical surfaces, such as activity and stability. Micelle-forming polyampholytic (cationic/anionic/non-ionic hydrophobic) triblock terpolymers represent a novel type of polymeric components for LBL formed sensor coatings. The presence of domains differing in their polarity and chemical composition (hydrophobic core, interpolyelectrolyte complex shell, and ionic corona) may facilitate realization of binding of enzyme molecules via non-electrostatic interactions and provide for them more suitable microenvironment. The core-shell-corona micelles of polyampholytic triblock terpolymer, polybutadiene-block-poly(methacrylic acid)-block-poly(dimethylaminoethylmethacrylate) quaternized with methyl iodide, (B800MAA200Dq285, BMDq, number-average degrees of polymerization are indicated by the subscripts, aggregation number in water Nagg.= 2500) was used as a polycationic component to form the initial (first) polymeric layer in multilayered sensor coatings. Deposition of the micelles onto highly oriented pyrolytic graphite (HOPG) followed by the attachment of electrochemically active enzyme, tyrosinase (Tyr), provides HOPG/BMDq/Tyr films suitable for phenol detection at –150 mV. Adsorption of the micelles onto HOPG, modified by MnO2 nanoparticles followed by the attachment of another electrochemically active enzyme, choline oxidase (ChO), results in HOPG/MnO2/BMDq/ChO films applicable for choline assay at +350 mV. Each stage of the LBL film deposition was characterized by means of AFM, SEM, and ellipsometry. The electrochemical activity of the incorporated enzymes and the stability of selforganized polymer/enzyme films were studied amperometrically. It was found that micelles are able to adsorb onto freshly cleaved HOPG in nearly unchanged (unperturbed) state with the density of 13-14 micelles per square micron, which is close to theoretical jamming limit (55%) according to random sequential adsorption model. Alternatively, some change in micellar structure (spreading of spherical structures) was observed when micelles were adsorbed onto rather rough HOPG/MnO2 substrate. Nevertheless, uniformly distributed film of enzymes was observed in both cases upon deposition of Tyr and ChO onto HOPG/BMDq and HOPG/MnO2/BMDq films, respectively. It is expected that results obtained will considerably expand our knowledge on surface modification techniques applicable for biosensor design.