Effective lipase immobilization on crosslinked functional porous polypyrrole aggregates

Abstract

Enzyme immobilization is an efficient and growing method for the stabilization, separation and reutilization of the expensive and hard-to-extract enzymes used in industrial biocatalysts. A 3D porous functionalized polypyrrole (PPy) material is designed with superior properties for improved performance of covalently immobilized model enzymes. This was uniquely achieved by choosing biodegradable carboxymethylcellulose (CMC) crosslinker of different molecular weights (Mw) to alter the strength of porous aggregates. The ensemble-averaged aggregates radius of gyration 〈Rg〉 increased monotonically almost three-fold with crosslinkers’ Mw along with an open structure formation compared to phytic acid crosslinked aggregates. This improvement was connected with more than a 20-fold increase in adsorbed N2 and a resulting increase in the specific surface area for aggregates crosslinked with CMC compared to phytic acid counterparts. A larger number of COOH groups on the CMC surface combined with optimal pore size achieved with its decreasing Mw facilitated the enzymes’ free diffusion to the functional groups and their retention. The phenomena further allowed a larger fraction of covalent bond formation of enzyme-substrate, resulting in higher specific activity and stability for Candida rugosa and Candida Antarctica, found in commercial biocatalysts, which will guide the formation of improved biocatalysts on porous polymer supports in the future.