Enzymatic activity preservation and protection through entrapment within degradable hydrogels

Autor: Angela M. Mariani, Peter Kofinas, Mary E. Natoli
Rok vydání: 2013
Předmět:
Zdroj: Biotechnology and Bioengineering. 110:2994-3002
ISSN: 0006-3592
DOI: 10.1002/bit.24971
Popis: This work aims to develop a repeatable enzymeentrapment method that preserves activity within anamicable environment while resisting activity reduction inthe presence of environmental challenges. Advances in suchmethodshavewidepotentialuseinbiosensorapplications.Inthis work b-galactosidase (lactase) enzyme was entrappedwithin hydrogel matrices of acrylamide (ACR) crosslinkedwith N,N 0 -methylenebisacrylamide (BIS, non-degradable) orpoly(ethylene glycol) diacrylate (PEGDA, degradable) tocreate “biogels.” Diffusivity studies of control, enzyme free,hydrogelconstructsshowednear-FickianswellingbehaviorinPBSregardlessofcrosslinkertypeordensity.Asexpected,theswelling rate, K s , decreased when increasing the crosslinkdensity from 78.6 to 14.7min 1 over a range of 1–20mol%PEGDA indicating that diffusivity into the matrix isdependent on crosslink density. Fabricated biogels wereevaluated for maintained enzyme activity in the 7 and 8 pHrange.PEGDAcrosslinkedgelsconsistentlyshowedimprovedenzymatic activity retention as compared to BIS crosslinkedgels. As PEGDAcrosslink density increased from 5 to 10mol%, enzymatic activity retention post-initial entrapmentincreased. Higher PEGDA crosslink densities between 15%and 40% decreased enzymatic activity due to assumed sterichindrance of the entrapped enzyme and also decreasedsubstrateandproductdiffusion.Increasedenzymaticstabilitywas observed in 40mol% PEGDA crosslinked gels. Thebiogels were pH challenged to 8.0 and stability, measured asretention of activity, was observed to be 91%. Free, non-entrapped, solution based enzyme conversion only retained23% activity under the same pH challenge conditions. Nosignificant loss of active enzyme was determined to elute outofthebiogelsduringstorageinPBSorduringbiogelwashandrecycling.Thisentrapmentmethodillustratesthepotentialtosterically hinder and diffusively impede enzymes fromperforming their function. Degradation of the networkcrosslinks can then potentially enable the reactivation of theenzyme at a site and time dictated by the user.Biotechnol. Bioeng. 2013;110: 2994–3002. 2013 Wiley Periodicals, Inc.KEYWORDS: enzyme entrapment; hydrogel; degradable;PEGDA
Databáze: OpenAIRE
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