Precise positioning of enzymes within hierarchical polymer nanostructures for switchable bioelectrocatalysis

The ability to reversibly switch bioelectrocatalytic sensors is attractive for the design of biomonitoring platforms displaying a complex environmental response, or for the protection of biosensors. However, the retention of reversible biocatalytic properties upon multiple environmental cycles, with broad detection range, low signal-to-noise and limit of detection remains challenging. In this report, we demonstrate the precise positioning of the enzyme glucose oxidase within block-copolymer brush nanostructures, via the re-initiation of N-isopropylacrylamide (NIPAM) polymerisation from enzyme-decorated poly(dimethylaminoethyl methacrylate) (PDMAEMA) blocks. We find that the precise design of polymer brush grafting density, thickness and crosslinking of the PNIPAM block enables the stable positioning of biocatalytic sites close to electrode surfaces. The control of the polymer brush nanostructure, its conformation and the distribution of biocatalytic sites is characterised via a combination of in situ ellipsometry, X-ray photoelectron spectroscopy, grazing angle FTIR and surface plasmon resonance. In turn, cyclic voltammetry and electrochemical impedance spectroscopy demonstrate that such control of the polymeric nanostructures confers a unique combination of low limit of detection (23.9 μM), a broad dynamic range of glucose sensing (0.05–12.8 mM) and true “OFF” state upon pH or thermal stimulation, whilst retaining excellent performance over repeated switching cycles of the sensor. Therefore, hierarchical biocatalytic polymer brushes display unique properties for the design of responsive biosensors and complex multi-functional gating platforms. ●PNIPAM brushes can be re-initiated from enzyme-modified PDMAEMA brushes to generate block-copolymer brush architectures with precisely positioned biocatalysts.●Block copolymer brush nanoarchitectures (grafting density, thickness and crosslinking) significantly impact the responsiveness of the interface and stable enzyme embedding.●Controlling the block copolymer nanoarchitecture modulates sensing of analytes such as glucose by precisely embedded biocatalytic sites.●Polymer brush nanoarchitectures with precisely positioned biocatalytic sites enable the development of stable switchable bioelectrocatalytic sensors whilst retaining excellent sensitivity, dynamic range and reversibility upon cyclic switching, a combination of features and properties that had not been achieved in previous switchable biosensors.