Thermoresponsive Hybrid Nanostructures for Indirect Regulation of Lipase Activity

Stimuli-responsive regulation of enzyme activity is an important strategy to optimize biocatalytic performance across diverse operating environments. Herein, we report a thermoresponsive hybrid nanomaterial (HM) composed of Candida antarctica fraction B (CALB) immobilized on gold nanoparticles (AuNPs) and coated with poly(N-isopropylacrylamide) (PNIPAm). This system exhibits a reversible phase transition temperature (Tcp) at 33°C, enabling temperature-dependent modulation of the enzymatic activity. Our data show that, below Tcp, the extended conformation of PNIPAm acts as a protective layer, limiting substrate access to the CALB catalytic site and inhibiting biocatalysis. Above Tcp, the collapsed PNIPAm chain exposes CALB to the medium, enabling the reaction to proceed with an approximately 5.6-fold increase in the reaction rate. The HM displays reversible behavior in heating-cooling cycles below and above Tcp, in contrast to free CALB, which follows a conventional temperature-dependent response for enzymatic reactions. These findings demonstrate the use of thermoresponsive nanomaterials to enable indirect and reversible regulation of enzyme activity, providing an effective approach to tune biocatalysis across diverse reactions and enzyme systems.