Label-free luminescent mesoporous silica nanoparti-cles for imaging and drug delivery

We report herein a straightforward and label-free approach to prepare luminescent mesoporous silica nanoparticles. We found that calcination at 400 °C can grant mesoporous organosilica na-noparticles with strong fluorescence of great photo- and chemical stability. The luminescence is found to originate from the carbon dots generated from the calcination, rather than the defects in the silica matrix as was believed previously. The calcination does not impact the particles' abilities to load drugs and conjugate to biomolecules. In a proof-of-concept study, we demonstrated that doxorubicin (Dox) can be efficiently encapsulated into these fluorescent mesoporous silica nanoparticles. After coupled to c(RGDyK), the nanoconjugates can efficiently home to tumors through interactions with integrin avf33 overexpressed on the tumor vasculature. This calcination-induced luminescence is expected to find wide applications in silica-based drug delivery, nanoparticle coating, and immunofluorescence imaging.