Layer-by-layer (LBL) self-assembly efficient immobilization of glucose oxidase onto PDMS microfluidic chip towards glucose biosensing

Enzyme immobilization in the microfluidic chip channel to improve enzyme activity and stability has become a powerful strategy to enhance biocatalysis and biomass conversion. Here, a miniaturized glucose biosensor in which glucose oxidase (GOx) was efficiently immobilized in the PDMS chip microchannel by layer-by-layer self-assembly was developed and used successfully for amperometric determination of glucose. After the surface of PDMS microfluidic chip was treated with 365 nm ultraviolet light, the methacrylic acid monomer was grafted onto it using poly dimethyl diallyl ammonium chloride as linker, then GOx was electrostatically adsorbed on the inner wall of the PDMS chip microchannel to construct multilayer GOx. According to the results of confocal laser scanning microscopy, immobilized enzyme activity, and GOx loading, the maximum quantity of enzyme immobilized on 4 layers of GOx was observed within the PDMS microchannels. The amperometric response of glucose with the biosensor under the optimal conditions exhibited linear relationship in the range of 0.4 to 2.0 mM with correlation coefficient 0.9973, and the limit of detection was 84 μM. In addition, the microfluidic system greatly reduced the consumption of samples during tests and showed excellent accuracy, stability and reproducibility.