Electrochemically synthesized polyaniline as support for lipase immobilization

Electrochemical synthesis of polyaniline support for enzyme immobilization provides easier control over the properties of obtained polymer and reduced risk of biocatalyst inactivation with residues of toxic compounds. In the present study, immobilization of lipase from Candida rugosa on electrochemically synthesized PANI (activated with glutaraldehyde) resulted with high lipase loadings up to 93.7 mg of proteins per gram of dry support. The activation of support and immobilization were optimized, with respect to activity yield. The optimum concentration of glutaraldehyde was 2% (w/v) and optimum concentration of enzyme was 4 mg ml−1. Modification of enzyme surface with carbodiimide and ethylenediamine was performed in order to increase concentration of amino groups. Aminated lipase exhibited higher specific activity (52%) and thermal stability (3 times) after immobilization, compared with non-modified lipase. Also, reusability of immobilized enzyme was significantly increased with amination, especially if immobilization was performed at pH 10, so in such a way obtained derivative retained 91% of activity after 15 reaction cycles.

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► Polyaniline support was synthesized using galvanostatic technique.
► High protein loads, up to almost 100 mg g−1 of dry support, were achieved in lipase immobilization.
► Lipase surface was enriched with amino groups using carbodiimide and ethylene diamine.
► Amination of lipase leads to significant increase of both, thermal stability and reusability of immobilized lipase.