Biomineralization-mimetic preparation of robust metal-organic frameworks biocomposites film with high enzyme load for electrochemical biosensing

Inspired by biomineralization, we propose robust enzyme-metal-organic-frameworks (MOFs) biocomposites to fabricate ultra-stable modified-electrode for electrochemical biosensing. Glucose oxidase (GOx) and zeolitic imidazolate framework-8 (ZIF-8) were adopted as model enzyme and MOFs to illustrate and examine the proposed concept. The biocomposites could be readily prepared by mixing GOx and precursors of MOFs. The biomineralization-assisted in-situ entrapment method facilitated the formation of the biocomposites and endowed the biocomposites with high load of enzyme of 89%. The biocomposite film on the Au electrode also benefited the mass transfer efficiency due to its superior porosity. Accordingly, the modified electrodes worked well both at the first and second generation biosensing modes for the detection of glucose, exhibited satisfactory sensitivity, as well as detection limit down to micromolar level, which is comparable with or better than analogues. More specially, taking advantages of the biomineralization-mimetic effect, the in-situ encapsulation method, and the rigid frameworks of MOFs, the biocomposite film-modified electrode presented superior stability towards repeated electrochemical scanning (200 cycles), high temperature of 90 °C, organic solvents (acetone), and storage (almost no response lost for >50 days). The biosensor also presented satisfactory selectivity and feasibility for detection in red wine. The proposed modified-electrode might be promising as robust detection tool in different conditions, and the proposed biomineralization-inspired method should contribute to the development of multi-functional composite materials.