Enzyme-Powered Hollow Nanorobots for Active Microsampling Enabled by Thermoresponsive Polymer Gating

Achieving molecular sample capture at micro/nanoscales while integrating functions of controllable loading and real-time monitoring of cargo molecules is of great significance in the development of intelligent micro/nanorobots. Herein, we prepare a temperature-responsive microsampling nanorobot by encapsulating metal (Au) nanodots inside hollow mesoporous silica nanoparticles and grafting a temperature-responsive polymer, poly(N-isopropylacrylamide), on their external surface. The molecular gate of nanochannels accessing the internal hollow reservoir can be switched between "open" and "closed" states by regulating the temperature, allowing on-demand loading and releasing of small molecules. The internally embedded surface-enhanced Raman scattering hotspots of gold nanodots can serve as sensing probes for real-time detection of the molecular cargo load inside the hollow nanorobots. Furthermore, we demonstrate temperature-dependent self-propulsion behavior of the nanorobots driven by enzymatic reactions. The active motion behavior can favorably regulate the loading efficiency of molecular cargos. In addition, by further introducing the magnetic component Ni, the nanorobots can accomplish effective transportation of cargo molecules by magnetic guidance under real-time Raman monitoring. The current strategy is expected to provide a manipulable nanorobot platform for precise biomedical sampling, which holds promising potential for disease diagnosis or controlled drug delivery in precision medicine.