Thermal- and dispersion-stable lipase-installed gold colloid: PEGylation of enzyme-installed gold colloid

Gold colloid possessing both lipase and PEG-tethered chains on the surface was prepared by the adsorption of lipase, followed by the immobilization of the PEG/polycation block copolymer on the colloid surface. The obtained colloid showed high dispersion stability up to 0.3 M NaCl concentration. The enzymatic activity of the lipase on the colloid complex was equivalent to the native enzyme. Surprisingly, more than 95% of the initial enzymatic activity was retained after repeated thermal treatments (five times) at 58 °C for 10 min. The PEG condensed layer between the immobilized enzyme on the gold colloid may prevent the denaturation of the enzyme at high temperature. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.