β-Cyclodextrin grafted polyethyleneimine hydrogel immobilizing hydrophobically modified glucose oxidase

초록

Hydrogels which release their contents in response to glucose concentration were prepared by immobilizing glucose oxidase (GOD) into beta-cyclodextrin grafted polyethyleneimine hydrogels (PEI-beta CD hydrogel). For the tight immobilization, hydrophobically modified GOD (HmGOD) was prepared by reacting GOD with palmitic acid-N-hydroxysuccinimide ester (PA-NHS) in the molar ratio of 1:40. According to trinitrobenzene sulfonic acid (TNBS) assay, five palmitic acids were covalently attached to one GOD molecule. The activity of HmGOD was about 76% of native enzyme. The swelling ratios of HmGOD loaded hydrogels increased from about 960% to 1190% in 24 h, when glucose concentration was varied from 0 to 100 mg/dl. The % release in 48 h of fluorescein isothiocyanate dextran increased from about 53% to 89%, when glucose concentration was varied in the same range. Gluconic acid, produced by the enzymatic reaction, would protonate and swell the PEI-beta CD hydrogel, leading to a higher release. (C) 2011 Elsevier B.V. All rights reserved.

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