title: Amphiphilic conetworks as activating carriers for the enhancement of enzymatic activity in supercritical CO2.
abstract: Enzymatic reactions in supercritical carbon dioxide (scCO2) represent a way of combining the advantages of biocatalysis with the environmental benign nature of scCO2 as a solvent. Here we demonstrate that activities of enzymes in scCO2 can be greatly enhanced by incorporating them into amphiphilic conetworks (APCNs), a novel type of enzyme support. Two sets of hydrophilic/scCO2-philic APCNs, poly(2-hydroxyethyl acrylate)-linked by-poly(dimethylsiloxane) (PHEA-l-PDMS) and poly(2-hydroxyethyl acrylate)-linked by-perfluoropolyether (PHEA-l-PFPE), were prepared and loaded with the synthetically relevant lipase from Rhizomucor miehei. The effect of the APCNs' composition on the amount of the absorbed lipase was studied. It is observed that both sets of lipase-loaded APCNs enhance the catalytic activity of the enzyme in scCO2. The chemical nature of the scCO2-philic phase as well as the conetworkscomposition greatly influences the activity of the lipase in the conetworks. Activities obtained with PFPE-basedAPCNS were up to 10-fold higher than those obtained with PDMS-based conetworks. The highest specific activity measured corresponds to a 2,000-fold activation compared to the lyophilized enzyme powder. This activity is 10 times higher than the specific activity of the lipase immobilized on an optimized commercial carrier.
authors.affiliation: Institute for Macromolecular Chemistry and Freiburg Materials Research Center (FMF), Albert-Ludwigs-University Freiburg, Freiburg, Germany.
authors.forename: Nico
authors.initials: N
authors.lastname: Bruns
authors.forename: Willi
authors.initials: W
authors.lastname: Bannwarth
authors.forename: Joerg C
authors.initials: JC
authors.lastname: Tiller
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D004789:Enzyme Activation; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008049:Lipase / Q000737:chemistry*; D011102:Polyhydroxyethyl Methacrylate / Q000031:analogs & derivatives* / Q000737:chemistry; D020103:Rhizomucor / Q000201:enzymology*
chemical_list: D004800:Enzymes, Immobilized; D002245:Carbon Dioxide; D011102:Polyhydroxyethyl Methacrylate; C023037:poly(2-hydroxyethyl acrylate); D008049:Lipase