A BIOSENSOR STABILIZED BY POLYETHYLENE-GLYCOL FOR THE MONITORING OF HYDROGEN-PEROXIDE IN ORGANIC-SOLVENT MEDIA

Since many chemical/biochemical reactions containing hydrogen peroxide are performed in organic solvent media, the development of a stabiliz ed biosensor in organic solvent media is very crucial. A stable hydrog en peroxide sensor with a wide measurement range and a long life in or ganic solvent as well as aqueous solution was developed. To maintain t he stability of the sensor in the organic solvent system, catalase was mixed with polyethylene glycol (PEG). The treatment could apparently enhance the stability of the enzyme activity. The induction of hydroge n bonding between enzyme and PEG was assumed to be the possible reason for the stabilization, and was also confirmed by infrared spectrophot ometry and circular dichroism (CD). The stability of the enzyme depend ed upon the content and molecular weight of PEG. PEGs (MW 3,350-6,000) with a mixing ratio of 0.2 g PEG to 2.8 x 10(4) catalase activity uni ts showed the highest stability level. The biosensor developed in the present study, therefore, worked well even in 50% (v/v) dioxane soluti on for 2 days; 90% of the initial activity was maintained. The detecti on limit of the sensor was about 140 mM and the response time was 40 s in aqueous buffer and 60-90 s in the organic solvent.