Aqueous sol-gel process for protein encapsulation

被引:306
作者
Bhatia, RB
Brinker, CJ [1 ]
Gupta, AK
Singh, AK
机构
[1] Univ New Mexico, Ctr Microengineered Mat, Albuquerque, NM 87106 USA
[2] Sandia Natl Labs, Albuquerque, NM 87185 USA
[3] Sandia Natl Labs, Biosyst Res Dept, Livermore, CA 94551 USA
关键词
D O I
10.1021/cm000260f
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Porous silica materials made by low-temperature sol-gel process are promising host matrixes for encapsulation of biomolecules. To date, researchers have focused on sol-gel routes using alkoxides such as tetramethyl orthosilicate (TMOS) and tetraethyl orthosilicate (TEOS) for encapsulation of biomolecules. These routes lead to formation of alcohol as a byproduct that can have a detrimental effect on the activity of entrapped biomolecules. We have developed a novel aqueous sol-gel process to encapsulate biological molecules (such as enzymes, antibodies, and cells) that uses neutral pH and room temperature and does not generate alcohol as a byproduct. The process uses sodium silicate as precursor and is carried out in two steps: preparation of a low-pH silicate sol followed by gelation at neutral pH with a suitable buffer containing biomolecules. Two enzymes widely used in biosensing applications, horseradish peroxidase (HRP) and glucose-6-phosphate dehydrogenase (G6PDH), were used to prepare enzyme-doped silica monoliths and to investigate the effect of silica as host matrix on enzyme kinetics. The yield of the encapsulation process was close to 100% for both enzymes, and no significant leaching of enzyme molecules was observed over time. Encapsulated enzymes followed Michaelis-Menten kinetics and maintained good catalytic activity, the specific activity of encapsulated HRP and G6PDH being 73% and 36% of the specific activities of the free enzymes, respectively. The values of the Michaelis constant (K-m) of the encapsulated enzymes were higher than those of the free enzymes, indicating the presence of partitioning and diffusional effects in the pores of the sol-gel matrix. The encapsulated enzymes also exhibited a different pH dependence of catalytic activity; the pH maxima for enzymatic activity for encapsulated enzymes were higher by 0.5-1 pH unit than those for enzymes in solution. These novel enzyme-doped silica matrixes provide promising platforms for development of biosensors, affinity supports, and immobilized enzyme reactors.
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页码:2434 / 2441
页数:8
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