title: Sequential pH-dependent adsorption of ionic amphiphilic diblock copolymer micelles and choline oxidase onto conductive substrates: toward the design of biosensors.
abstract: This work examines the fabrication regime and the properties of polymer-enzyme thin-films adsorbed onto conductive substrates (graphite or gold). The films are formed via two-steps, sequential adsorption of poly(n-butylmethacrylate)-block-poly(N,N-dimethylaminoethyl methacrylate) (PnBMA-b-PDMAEMA) diblock copolymer micelles (1st step of adsorption), followed by the enzyme choline oxidase (ChO) (2nd step of adsorption). The solution properties of both adsorbed components are studied and the pH-dependent step-by-step fabrication of polymer-enzyme biosensor coatings reveals rather drastic differences in their enzymatic activities in dependence on the pH of both adsorption steps. The resulting hybrid thin-films represent highly active biosensors for choline with a low detection limit of 30 nM and a good linearity in a range between 30 nM and 100 μM. The sensitivity is found to be 175 μA mM(-1) cm(-2) and the operational stability of the polymer-enzyme thin-films can be additionally improved via enzyme-to-enzyme crosslinking with glutaraldehyde.
authors.affiliation: Department of Chemistry, Lomonosov Moscow State University, 119991, Moscow, Russia. lsigolaeva@genebee.msu.ru.
authors.forename: Larisa V
authors.initials: LV
authors.lastname: Sigolaeva
authors.forename: Ulrike
authors.initials: U
authors.lastname: Günther
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Pergushov
authors.forename: Snezhana Yu
authors.initials: SY
authors.lastname: Gladyr
authors.forename: Ilya N
authors.initials: IN
authors.lastname: Kurochkin
authors.forename: Felix H
authors.initials: FH
authors.lastname: Schacher
mesh_terms: D000327:Adsorption; D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D015374:Biosensing Techniques / Q000295:instrumentation*; D004553:Electric Conductivity; D004867:Equipment Design; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008823:Micelles; D008970:Molecular Weight; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D011522:Protons; D012996:Solutions; D055672:Static Electricity
chemical_list: D007477:Ions; D008823:Micelles; D011108:Polymers; D011522:Protons; D012996:Solutions; D000429:Alcohol Oxidoreductases; C019888:choline oxidase
keywords: block copolymers; choline biosensors; choline oxidase; enzyme adsorption; polyelectrolytes; polymer films; surface modification