1, The University of Texas at Austin, Austin, Texas, United States
In this work, we report innovative concept, design, and fabrication of three-dimensional (3-D) nanoporous SERS nanosensors for dual-functionally ultrasensitive detection and tunably release of molecules. The nanosensor consists of a gold (Au) nanorod core and a silica shell with embedded superstructural nanopores, where large arrays of plasmonic silver (Ag) nanoparticles can be synthesized with controlled size and distributions both on the outer surfaces but also inside the nanopores. The rationally increased number of hot spots at the junctions of Ag nanoparticles, as well as the near-field electromagnetic coupling between the Ag nanoparticles on the surface and those embedded in the 3-D structure provide substantially enhanced Raman sensitivity for detection of biochemicals. The 3-D porous structures provides high surface areas for drug loading. Furthermore, when place in an external electric (E-) field, molecules on the nanosensors can be controllably released with tunable rates due to the induced E-field generated at the junctions of Ag nanoparticles, where the hotspots not only effectively enhance the Raman detection of molecules but also induce electrokintic effects to tune the release rate of molecules. Finally, these nanosensors are motorized, including both transport and rotation, owing to the electrically polarized metallic nanocores, which is highly potent for single-cell biological research and precision medicine.