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Enzyme immobilization in a biomimetic silica support


Robust immobilization techniques that preserve the activity of biomolecules have many potential applications1,2,3,4,5,6,7,8. Silicates, primarily in the form of sol-gel composites or functionalized mesoporous silica, have been used to encapsulate a wide variety of biomolecules1,4,5,6,7,8 but the harsh conditions required for chemical synthesis limit their applicability1,8. Silaffin polypeptides from diatoms catalyze the formation of silica in vitro at neutral pH and ambient temperature and pressure9. Here we show that butyrylcholinesterase entrapped during the precipitation of silica nanospheres retained all of its activity. Ninety percent of the soluble enzyme was immobilized, and the immobilized enzyme was substantially more stable than the free enzyme. The mechanical properties of silica nanospheres facilitated application in a flow-through reactor. The use of biosilica for enzyme immobilization combines the excellent support properties of a silica matrix with a benign immobilization method that retains enzyme activity.

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Figure 1
Figure 2: Stability of butyrylcholinesterase activity at 25 °C in free and biosilica-immobilized enzyme systems.
Figure 3: Stability of biosilica-immobilized butyrylcholinesterase in a flow-through system.


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The work was supported by funding from the US Air Force Office of Scientific Research. H.R.L. was supported by a postdoctoral fellowship from the Oak Ridge Institute for Science and Education (US Department of Energy).

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Correspondence to Jim C Spain.

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Luckarift, H., Spain, J., Naik, R. et al. Enzyme immobilization in a biomimetic silica support. Nat Biotechnol 22, 211–213 (2004).

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