Investigations on diffusion limitations of biocatalyzed reactions in amphiphilic polymer conetworks in organic solvents

Abstract

The use of enzymes as biocatalysts in organic media is an important issue in modern white biotechnology. However, their low activity and stability in those media often limits their full-scale application. Amphiphilic polymer conetworks (APCNs) have been shown to greatly activate entrapped enzymes in organic solvents. Since these nanostructured materials are not porous, the bioactivity of the conetworks is strongly limited by diffusion of substrate and product. The present manuscript describes two different APCNs as nanostructured microparticles, which showed greatly increased activities of entrapped enzymes compared to those of the already activating membranes and larger particles. We demonstrated this on the example of APCN particles based on PHEA-l-PDMS loaded with α-Chymotrypsin, which resulted in an up to 28,000-fold higher activity of the enzyme compared to the enzyme powder. Furthermore, lipase from Rhizomucor miehei entrapped in particles based on PHEA-l-PEtOx was tested in n-heptane, chloroform, and substrate. Specific activities in smaller particles were 10- to 100-fold higher in comparison to the native enzyme. The carrier activity of PHEA-l-PEtOx microparticles was tenfold higher with some 25-50-fold lower enzyme content compared to a commercial product.

Amphiphilic Polymer Conetworks Based on Interconnected Hydrophobic Star Block Copolymers: Synthesis and Characterization

“…For solid electrolytes, a polar continuous nanophase is employed to house the lithium cations, while a hard continuous nanophase is utilized to provide stiffness and shape consistency to the material . Finally, because nanophase separation within these materials leads to the formation of a large interfacial area, APCNs have been used as the scaffolds for phase transfer catalysis, both enzymatic and organocatalysis …”

“…More hydrophobic APCN samples swell less in water, thus exposing any defects to only a smaller extent, favoring morphologies with longer‐range order. Such more regular morphologies will result in APCNs better‐suited for all above‐mentioned applications …”

Poly(2‐ethyloxazoline) as matrix for highly active electrospun enzymes in organic solvents

“…So far, the most promising method is to find a suited carrier material that allows activation and stabilization of enzymes in organic solvents, for example, silica, polyurethanes, and acrylate resins as used for the commercial lipase formulation Novozyme 435 (Adlercreutz, ; Luckarift et al, ; Tielmann et al, ). In our group, this approach has been particularly successful for enzymes in amphiphilic polymer conetworks (APCNs) which activate these biocatalysts by several orders of magnitude in membranes (Dech et al, ; Sittko et al, ) and particles (Savin et al, ; Schoenfeld et al, ) in organic solvents and even supercritical CO 2 (Bruns and Tiller, ; Bruns et al, ). Furthermore, chiral APCNs allow controlling the enantioselectivity of enzymes in organic solvents (Tobis and Tiller, ; Tobis et al, , ).…”

Post‐Polymerization of Urease‐Induced Calcified, Polymer Hydrogels

“…In previous work, “urease‐induced calcification” was introduced as the first method for intrinsic calcification of a macroscopic hydrogel throughout the whole material . The work is based on the structural advantages of amphiphilic polymer conetworks, which stabilize entrapped enzymes and make them applicable for biocatalysis and biosensors in organic solvents . Following the approach of entrapping enzymes into such conetworks by dissolving the proteins in the monomeric and prepolymer mixtures allows introducing homogeneously dispersed, immobilized urease into segmented hydrogel conetworks as well.…”