Supporting Materials That Improve the Stability of Enzyme Membranes

Abstract

Long-term stability is a key property of enzyme membranes that can be used for biosensors, bioreactors, and bio-fuel cells. This review discusses factors that decrease the stability, and provides two examples of enzyme membranes, a polyion complex membrane and a cellulose membrane, with which stability loss can be avoided. By using these materials, long-term stability was improved. These supporting materials could be applied to construct biosensors, bioreactors, and bio-fuel cells.

Enzyme and Mediator-coadsorbed Carbon Felt Electrode for Electrochemical Detection of Glucose Covered with Polymer Layers Based on Layer-by-Layer Technique

“…To improve the stability of sensors, it is important to avoid fouling from sample components such as lipids and proteins. 33 If a sensor can measure lower concentrations, the sensor would be able to avoid the problem because the sample could be diluted. For example, the glucose concentration in normal sera is 70 -109 mg/dL (= 3.9 -6.1 mM), which is considerably higher in concentration to the measuring range of the present electrode; the sample would be diluted 100 -1000 times to measure glucose concentration in the present electrode.…”

How to Lengthen the Long-Term Stability of Enzyme Membranes: Trends and Strategies

“…To enhance the long-term stability of immobilized enzyme membranes, factors that decrease stability should be eliminated. The factors that affect the supporting materials can be classified into three groups [10]: (1) tight binding (or immobilization) to the materials; (2) fouling and contamination caused by proteins, lipids, and microorganisms in the samples; and (3) lifetime of supporting materials. Though these factors would complicatedly conform to the property of the stability in the actual case, solutions to each factor are shown below.…”

“…Another method to prevent enzyme loss to the substrates is by covering it with a density membrane (Figure 3). Nafion [77], chitosan [78], ionic polymers [79], polyion complex membranes [80][81][82][83], and cellulose [10,84,85] have been used to cover the enzyme layer. These methods are effective, but the resulting membranes can become thicker, i.e., penetration of substrates can worsen.…”

“…Immediately after placing the third solution, the mixed solution becomes turbid. After drying, the enzyme-immobilized polyion complex membrane is obtained [10].…”

“…In these developments, one demand is for the improvement of immobilized enzyme stability. Naturally, the lifespan of apparatuses such as biosensing systems, bioreactors and biofuel cells could be extended by improving immobilized enzyme stability [8][9][10], and, as a result, the cost would be reduced.…”