A Facile Approach to Upconversion Crystalline CaF2:Yb3+,Tm3+@mSiO2 Nanospheres for Tumor Therapy.

A new facile approach, namely chemical-assisted sol-gel growth (CASGG), was successfully developed to induce the formation of fine CaF2:Yb3+, Tm3+ nanocrytals within the pore channels of mesoporous silica (mSiO2) nanoparticles. A series of upconversion photoluminescent crystalline CaF2:Yb3+,Tm3+@mSiO2 nanospheres with controlled diameters from ~65 nm to ~290 nm were fabricated. All nanospheres presented sound cyto-compatibility and unique ratiometric spectral monitoring functionalities for drug release kinetics. The nanospheres with smallest dimension (UCNP-2.5, ~65nm) induced the most sustained DOX release kinetics. More importantly, the in-vitro study demonstrated that the DOX loaded UCNP-2.5 nanopheres presented the strongest anti-cancer efficacy to MCF-7 human breast cancer cells due to its stronger penetration ability to cell nuclei due to the size effect.