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Vol 17, No 2 (2014)
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Cyclodextrin glucanotransferase immobilisation onto functionalized magnetic double mesoporous core-shell silica nanospheres | Ibrahim | Electronic Journal of Biotechnology
doi:10.1016/j.ejbt.2014.01.001
Electronic Journal of Biotechnology, Vol 17, No 2 (2014)

Cyclodextrin glucanotransferase immobilisation onto functionalized magnetic double mesoporous core-shell silica nanospheres

Abdelnasser Salah Shebl Ibrahim, Ali Al-Salamah, Ahmed El-Toni, Yahya Elbadawi, Mohamed El-Tayeb



Abstract

Background: Cyclodextrin glucanotransferase (CGTase) from Amphibacillus sp. NPST-10 was covalently immobilized onto amino-functionalized magnetic double mesoporous core-shell silica nanospheres (mag@d-SiO2@m-SiO2-NH2), and the properties of the immobilized enzyme were investigated. The synthesis process of the nanospheres included preparing core magnetic magnetite (Fe3O4) nanoparticles, coating the Fe3O4 with a dense silica layer, followed by further coating with functionalized or non-functionalized mesoporous silica shell. The structure of the synthesized nanospheres was characterized using TEM, XRD, and FT-IR analyses. CGTase was immobilized onto the functionalized and non-functionalized nanospheres by covalent attachment and physical adsorption.

Results: The results indicated that the enzyme immobilization by covalent attachment onto the activated mag@d-SiO2@m-SiO2-NH2, prepared using anionic surfactant, showed highest immobilization yield (98.1%), loading efficiency (96.2%), and loading capacity (58 µg protein [CGTase]/mg) nanoparticles which were among the highest yields reported so far for CGTase. Compared with the free enzyme, the immobilized CGTase demonstrated a shift in the optimal temperature from 50ºC to 50-55ºC, and showed a significant enhancement in the enzyme thermal stability. The optimum pH values for the activity of the free and immobilized CGTase were pH 8 and pH 8.5, respectively, and there was a significant improvement in pH stability of the immobilized enzyme. Moreover, the immobilized CGTase exhibited good operational stability, retaining 56% of the initial activity after reutilizations of ten successive cycles.

Conclusion: The enhancement of CGTase properties upon immobilization suggested that the applied nano-structured carriers and immobilization protocol are promising approach for industrial bioprocess for production of cyclodextrins using immobilized CGTase.




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ISSN:  0717-3458

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