Cascade enzymatic catalysis in poly(acrylic acid) brushes-nanospherical silica for glucose detection

• Colorimetric bioassay was designed for the ultrasensitive detection of glucose.
• Signal amplification was achieved using PAA-nano silica-bienzyme.
• Good performance was obtained with a detection limit of 0.04 μM.
• Favorable results were achieved for detecting glucose in complex biological samples.

The ultrasensitive monitoring of glucose with a fast and accurate method is significant in potential therapeutics and optimizes protein biosynthesis. Incorporation of enzyme into matrix is considered as promising candidates for constructing highly sensitive glucose-responsive systems. In this study, three-dimensional poly(acrylic acid) brushes-nanospherical silica (PAA-nano silica) with high amplification capability and stability were used to covalently immobilize bienzymes for cascade enzymatic catalysis. The major advantages of PAA-nano silica-bienzyme co-incorporation is that the enzymes are proximity distribution, and such close confinement both minimized the diffusion of intermediates among the enzymes in the consecutive reaction and improve the utilization efficiency of enzymes, thereby enhancing the overall reaction efficiency and specificity. Thus, this present bienzymatic biosensor shows robust signal amplification and ultrasensitivity of glucose-responsive properties with a detection limit of 0.04 μM.

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