Double-layered polyion complex for application to biosensing electrodes

•Molecular sieve for polyion complex (PIC) is regulated by selecting polyions.•Double-layered PIC is applied for glucose biosensing electrode.•Enzyme-PIC electrode demonstrates high performance biosensing.

Polyion complex (PIC) layers are formed via self-assemble ion pairing by alternately placing polycation/polyanion solutions on platinum electrodes. Their molecular sieving behavior for electrochemically reactive species through the layers is examined by electrochemical methods. Different molecular-sieve sizes are achieved by the selection of polycations with different intramolecular distances of neighboring cationic groups. Amperometric glucose sensing electrodes are fabricated by immobilizing glucose oxidase in a PIC double-layer. The proper double-layer configuration is efficient to improve the glucose response, blocking interferents due to the molecular sieving effect.