In the past years, enzymes (natural and biodegradable catalysts) have become a central part in green chemistry in order to reduce the use of chemical routes for synthesis of common chemical products. Apart from the high product quality the use of enzymes is accompanied by lower manufacturing costs, less toxic waste disposal and reduced energy consumption which stimulates growth of sustainable societies by utilizing biochemical pathways that already exist in nature [1]. In most large-scale biocatalytic processes however, enzymes are immobilized in order to improve the recycling, continuous use as well as the thermal and pH stability [2, 3]. The recent synthesis of magnetic nanocomposites opened new possibilities in biocatalysis and enzymes have been immobilized on different magnetic supports (mainly iron oxide). However, the inability of the current magnetic carriers to be efficiently recycled from large volumes (lower magnetic saturation) impedes their further usage in industrial processes. The development of a core/shell-enzyme nanomaterial with a very high magnetic saturation (> 150 emu/g) enables us to efficiently perform magnetic biocatalysis and very quickly (< 30 s) separate the enzyme from solution in large volumes (15 L) by a custom made magnetic separator. Such small and magnetically separable catalysts combine the advantages of easy and fast separation with high dispersion and reactivity [4].

In this study Co/C nanoparticles were chemically functionalized (diazonium chemistry), activated for bioconjugation (N, N-Disuccinimidyl carbonate) and subsequently used in enzyme immobilization [5]. Three enzymes: β-glucosidase, α-chymotrypsin and lipase B were successfully covalently immobilized on the magnetic nanosupport. The enzymes on particles retained up to 55 % enzymatic activity after immobilization compared to the free enzymes in solution. In addition the immobilized enzymes showed improved storage stabilities and were efficiently recycled from millilitre to litre scales in short recycle times.

References:

[1] - M. Alcalde, M. Ferrer, F. J. Plou, A. Ballesteros, Trends Biotechnol 2006, 24,6

[2] - J. Kim, J. W. Grate, P. Wang, Chem. Eng. Sci. 2006, 61, 1017 - 1026

[3] - U. T. Bornscheuer Angew. Chem. Int. Ed. 2003, 28, 42(29):3336-7

[4] - A.H. Lu, E.L. Salabas, F. Schüth Angew. Chem. Int. Ed. 2007, 46; 1222 - 1244

[5] - V. Zlateski, R. Fuhrer, F.M. Koehler, S. Wharry, M. Zeltner, W.J. Stark, T.S. Moody and R.N. Grass Bioconjugate Chem. 2014, 25. 677-684

Vladimir Zlateski

ETH Zurich

Appearances