Reversible and Remote Thermoregulation of a Recyclable DNAzyme/pNIPAM Microgel Catalyst Formed via a Microfluidic Device

Abstract The regulation of the catalytic activities of DNAzymes is of great significance for their biosensing and biomedical applications. Herein, thermoregulation of the catalytic activity of DNAzyme is achieved through the immobilization of DNAzymes into the crosslinked polymeric matrix of poly‐N‐isopropylacrylamide (pNIPAM) microgels prepared with a microfluidic device. At a temperature lower than the lower critical solution temperature (LCST) of pNIPAM, the immobilized DNAzymes exhibit lower catalytic performance due to the restricted entry of DNA substrates into the polymeric networks; while at a temperature higher than the LCST, the hydrophilic DNAzyme structures are exposed to exhibit high catalytic activity due to the shrinking of the pNIPAM networks. Results show a more than 60% of increase in catalytic activity by raising the temperature from 29 to 34 °C and reversible regulation of the DNAzyme catalytic activity is achieved by cyclic raising and lowering of the solution temperature. Through a simple heating‐centrifugation process, the DNAzyme/pNIPAM microgels can be recycled for further applications. Moreover, by introducing photothermal MXene nanosheets, the remote control of the catalytic activity of the DNAzyme by near‐infrared light irradiation is achieved. These DNAzyme/pNIPAM microgels as low‐cost, stable, reversible, and recyclable biocatalyst may have potential in biosensing and biomedical applications.