Mesoporous silica-coated plasmonic nanostructures for surface-enhanced Raman scattering detection and photothermal therapy.

The design and fabrication of core-shell and yolk-shell nanostructures with surface plasmon resonance (SPR)-active center protected by permeable mesoporous channels can raise the new vitality into the catalysis and biological applications. Hybrid plasmonic-mesoporous silica nanocarriers consisting of Ag and Au-Ag alloy nanoparticles are fabricated through spatially confined galvanic replacement approach. The plasmonic absorption peaks can be finely controlled to the near-infrared (NIR) region (500-790 nm) that is beneficial for tissue transmittance. The mesoporous silica shell facilitates also protection of Au-Ag cores and affords the channels between the exterior and interior capsule environments, thereby endowing the multiple applications. In the present work, it is successfully demonstrated that mesoporous silica-coated Au-Ag alloy core-shell and yolk-shell nanocarriers can serve as good substrates for surface-enhanced Raman scattering (SERS) detection. The SERS signal intensities of nanocarriers are highly dependent on the SPR peaks and the contents of gold. Simultaneously, the synthesized Au-Ag@mSiO2 nanocarriers with SPR peak at ≈790 nm can be applied in NIR-sensitive SERS detection and photothermal therapy.