International. Researchers have developed a technique for coating gold nanorods with silica shells, allowing engineers to create large amounts of nanorods and give them greater control over the thickness of the shell.
Gold nanorods are being investigated for use in a wide variety of biomedical applications, and this breakthrough paves the way for a more stable product and to chemically functionalize the surface of shells.
Gold nanorods have a lot of potential applications, as they have a resonance of surface plasmons – meaning they can absorb and scatter light. And by controlling the dimensions of nanorods, specifically their aspect ratio (or length divided by width), you can control the wavelength of the light they absorb.
Gold nanorods are efficient for photothermal heating, the process of converting absorbed light into heat. If excess light shines on the gold nanorods they can lose their rod shape and change it into spheres, losing their desirable optical properties.
The researchers say one way to help gold nanorods retain their shape during photothermal heating is to coat them with silica shells, which confine the nanorods to their original shape but allow light to pass through. For different applications, it is important to be able to control the thicknesses of the shells. With thin shells, the change in the size of nanorods is minimal, and gold nanorods can still be stuffed into dense assemblies. On the other hand, thick shells can act as buffers, preventing nanorods from clumping tightly together and protecting them from their environment.
