Mesoporous titania based yolk-shell nanoparticles as multifunctional theranostic platforms for SERS imaging and chemo-photothermal treatment

Recently surface-enhanced Raman scattering (SERS) imaging guided theranostic nanoplatforms have attracted considerable attention. Herein, we developed novel yolk-shell gold nanorod@void@mesoporous titania nanoparticles (AuNR@void@mTiO(2) NPs) for simultaneous SERS imaging and chemo-photothermal therapy. Our work showed three highlighted features: first, we proposed a facile and versatile up to down SERS labeling strategy for the drug delivery system, in which empty carriers were pre-synthesized, followed by co-loading of Raman reporters on AuNR and anti-cancer drug doxorubicin (DOX) in mTiO(2) in sequence. The acquired SERS signal was strong enough for tracking NPs at both living cells and mice levels. Second, we selected mTiO(2) as a novel drug loading material instead of the widely used mesoporous silica (mSiO(2)). The mTiO(2) shared satisfactory drug loading and release behavior as mSiO(2) but it was chemically inert. This property not only provided a facile way to form a yolk-shell structure but also rendered it with superior structural stability in a biological system. Third, the near infrared (NIR) light absorbing property of the AuNR SERS substrate was also explored for drug release regulation and photothermal treatment. Significantly greater MCF-7 cell killing was observed when treated together with DOX-loaded NPs and NIR laser irradiation, attributable to the synergistic chemo-thermal therapeutic effect. Our results indicated the established SERS labeled yolk-shell NP as a promising theranostic platform and suggested its potential in vivo applications.