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

Processing of (Co)Poly(2-oxazoline)s by Electrospinning and Extrusion from Melt and the Postprocessing Properties of the (Co)Polymers

Poly(2-oxazoline) (POx) matrices in the form of non-woven fibrous mats and three-dimensional moulds were obtained by electrospinning and fused deposition modelling (FDM), respectively. To obtain these materials, poly(2-isopropyl-2-oxazoline) (PiPrOx) and gradient copolymers of 2-isopropyl- with 2-n-propyl-2-oxazoline (P(iPrOx-nPrOx)), with relatively low molar masses and low dispersity values, were processed. The conditions for the electrospinning of POx were optimised for both water and the organic solvent. Also, the FDM conditions for the fabrication of POx multi-layer moulds of cylindrical or cubical shape were optimised. The properties of the POx after electrospinning and extrusion from melt were determined. The molar mass of all (co)poly(2-oxazoline)s did not change after electrospinning. Also, FDM did not influence the molar masses of the (co)polymers; however, the long processing of the material caused degradation and an increase in molar mass dispersity. The thermal properties changed significantly after processing of POx what was monitored by increase in enthalpy of exo- and endothermic peaks in differential scanning calorimetry (DSC) curve. The influence of the processing conditions on the structure and properties of the final material were evaluated having in a mind their potential application as scaffolds.

Characterization of immobilized tyrosinase - an enzyme that is stable in organic solvent at 100 °C

Tyrosinase is a copper-containing enzyme present in plant and animal tissues, which catalyzes the production of melanin and other pigments. In organic solvent, tyrosinase can convert N-acetyl-l-tyrosine ethyl ester (insoluble in aqueous) to a derivative of l-dopamine (a drug used for the treatment of Parkinson's disease). Thus, the performances of tyrosinase in organic solvent have attracted scientific attention since 1980. In this work, we investigated the stability of immobilized tyrosinase at high temperature in anhydrous organic solvent. Triethylaminoethyl cellulose (TEAE-Cellulose) performed the best out of six immobilization platforms. The dry immobilized tyrosinase became extremely thermostable in organic solvent, and the half-life of the dry immobilized tyrosinase in organic solvent is strongly related to the polarity of the organic solvent than their log P value. The immobilized tyrosinase loses its activity instantaneously in aqueous solution at 100 °C, but it keeps enzymatic activity within 10 min in hydrophilic methanol and over one month in hydrophobic hexane (log P: 4.66, non-polar) even incubating at 100 °C. This research provides valuable information for the design of new biocatalysts.

Immobilized tyrosinase in hexane can withstand 100 °C over one week, and the half-life of the dry immobilized tyrosinase in organic solvent is strongly related to the polarity of the organic solvent.