Entrapment in HydrIL gels: hydro-ionic liquid polymer gels for enzyme immobilization

Enzyme entrapment in hydro-ionic liquid gels (HydrIL gels) was explored as an enzyme immobilization strategy. The liquid phase of the gels was a mixture of buffer and tributyl methyl phosphonium alkanesulfonate [P₄₄₄₁][RSO₃] ionic liquids. The ionic liquid modifies the liquid phase creating a more “organic” hydrophobic microenvironment around the enzyme. In the esterification of a secondary alcohol by Candida antarctica Lipase B, a 20-fold enhancement in final substrate conversion was achieved using an HydrIL gel compared to a standard poly(acrylamide) hydrogel. Co-polymerization of the poly(acrylamide) matrix with acrylate monomers led to further increases in reaction rate. A CalB HydrIL gel was reused over 10 reaction cycles, achieving a consistent performance from the fifth cycle. IL leaching became undetectable from the third reaction cycle.