Mesoporous silica shell-coated single gold nanorods as multifunctional orientation probes in dynamic biological environments.

Mesoporous silica shell-coated gold nanorods (AuNRs@mSiO 2 ) can be employed as promising multifunctional orientation probes in biological studies owing to their anisotropic optical properties, enhanced stability, excellent biocompatibility, etc. In this study, the optical properties of single AuNRs@mSiO 2 are characterized under dark-field and differential interference contrast (DIC) microscopy. Furthermore, we presented polarization-dependent, periodic DIC images and intensities of single AuNRs@mSiO 2 at their localized surface plasmon resonance wavelength and investigated their use as multifunctional orientation probes in dynamic biological environments. Moreover, the real-time rotational motions of the AuNRs@mSiO 2 on the HeLa cell membranes were tracked with millisecond temporal resolution. Overall, AuNRs@mSiO 2 demonstrated their capacity to act as multifunctional optical probes owing to the combined effect of the Au core, which can serve as an orientation probe and a local heat generator for phototherapy, and the mesoporous silica shell, which can be used as a reservoir of chemotherapeutics owing to its excellent loading capacity.