LAUSR

In a proof of concept study, a series of nonionic surfactant blends derived from Tween 80 and Span 80 were used to prepare catalytic microgels from stabilized droplets in miniemulsions. The goal of this study is to optimize the catalytic efficiency of microgels by decreasing their particle size with surfactants that are custom-made for the respective prepolymerization mixture. The effectiveness of the approach is examined by evaluating the catalytic efficiency of the resulting microgels in comparison to their counterparts made in the presence of ionic sodium dodecyl sulfate (SDS) solution. Spherical particles with hydrophilic–lipophilic balance (HLB) value dependent mean hydrodynamic diameters between 99 and 200 nm are obtained. Addition of Cu­(II) ions and selected other transition metal ions activated the dormant catalysts for cleavage of glycosidic bonds in 2-[4-(2-hydroxyethyl)­piperazin-1-yl]­ethanesulfonic acid (HEPES) buffer at pH 7.00 and 37 °C using a fluorescent model substrate. The highest proficiency for the catalytic hydrolysis was observed for Cu­(II)-containing microgels (kcat/KM × knon = 870 000) with the lowest diameter indicating an almost twofold better stabilization of the transition state compared to a microgel prepared in the presence of ionic SDS solution. The study establishes a correlation of the HLB value of the nonionic surfactant blend used during material synthesis to the particle size and catalytic performance of the resulting microgels.