US EPA

9320805 

Journal Article 

Zwitterionic poly(carboxybetaine) microgels for enzyme (chymotrypsin) covalent immobilization with extended stability and activity 

Erfani, A; Zarrintaj, P; Seaberg, J; Ramsey, JD; Aichele, CP 

2021 

Yes 

Journal of Applied Polymer Science
ISSN: 0021-8995
EISSN: 1097-4628 

138 

22 

10.1002/app.50545 

WOS:000614794700001 

There is emerging evidence that biocompatible zwitterionic materials can prevent nonspecific interactions within protein systems and increase protein stability. Here, a zwitterionic microgel was synthesized from poly (carboxybetaine methyl methacrylate) (pCB) using an inverse emulsion, free radical polymerization reaction technique. The microgel was loaded with a model enzyme, alpha-chymotrypsin (ChT), using a post-fabrication loading technique. A reaction scheme was developed and studied for covalent immobilization of ChT within the microgel. Confocal laser microscopy studies showed that immobilized ChT (i-ChT) was distributed within the hydrogel. The enzyme-immobilized microgels showed excellent reusability (72% of its initial activity after 10 uses) and could undergo several freezing/drying/rehydration cycles while retaining enzymatic activity. The i-ChT activity, half-life, and conformational stability were studied at varying pH and temperatures with results compared to free ChT in buffer. ChT immobilized within pCB hydrogel showed increased enzymatic stability as observed by a 13 degrees C increase in the temperature at which i-ChT loses activity compared to free ChT. Furthermore, enzyme half-life increased up to seven-fold for the pCB immobilized ChT, and the increased stability resulted in higher activity at elevated pH. The i-ChT was most active at pH of 8.5 and was partially active up to the pH of 10.2. 

bioengineering; biomedical applications; biomimetic; emulsion polymerization