Deep eutectic solvents – a new additive in the encapsulation of lipase B from Candida antarctica: biocatalytic applications

Enzyme encapsulation in a sol–gel matrix can be improved using some additives acting on enzyme activity and/or stability. Ionic liquids, polyhydroxy compounds, sugars, etc. have been previously reported as additives. This study focuses on the possibility to use deep eutectic solvents as additives in the immobilization of lipase B from Candida antarctica (CaL-B) through sol–gel encapsulation. The transesterification of 1-phenylethanol was chosen as a model reaction. Process optimization was successfully performed regarding the most important reaction parameters (an alcohol/lipase weight ratio of 20 : 1, an alcohol/acyl donor molar ratio of 1 : 2, n-hexane as a solvent, 30 °C reaction temperature, vinyl acetate as an acyl donor and a substrate concentration of 100 mM). Under the optimal conditions, the reaction mediated by the most active biocatalyst (SG-3, containing a deep eutectic solvent formed from choline chloride and fructose, as a 30% aqueous solution) reached ∼48% after only four hours, maintaining almost 85% of its initial activity even after eight reaction cycles.