Construction Of Black Titanium Dioxide-based Nanoprobes And Their Application In Visualized Theranostics Of Tumors

As a new kind of photothermal conversion nanomaterials,black titanium dioxide?b-TiO₂?showed potential applications in photothermal therapy?PTT?of tumors.In this dissertation,to constructing b-TiO₂-based visualized theranostic nanoprobes,Ce6/Mn²⁺-chelated polydopamine?PDA?@b-TiO₂?b-P25@PDA-Ce6?Mn??and b-TiO₂@manganese dioxide?b-P25@MnO₂?were respectively synthesized.Moreover,by modeling breast cancer nude mice,the performances of magnetic resonance imaging?MRI?,PTT and photodynamic therapy?PDT?of the nanoprobes were investigated.The main research results were summarized as follows:?1?b-P25@PDA-Ce6?Mn?nanoprobe was constructed for MRI and PTT/PDT of breast cancer.The results showed that the b-P25@PDA-Ce6?Mn?nanoprobe possessed excellent T₁-weighted MRI,reactive oxygen generation,and enhanced photothermal conversion performance,in which the T₁-weighted MR relaxativity was 78.33 mM^-1·s^-1,and the photothermal conversion efficiency was up to 32.12%.Under the irradiation of low-dose 671nm and 808 nm laser,4T1 tumor was completely disappeared by the synergistic effect of PTT/PDT.?2?Glutathione?GSH?-responsive b-P25@MnO₂ nanoprobe was constructed for MRI and PTT of breast cancer cells.The results showed that the b-P25@MnO₂ had enhanced photothermal performance with a higher photothermal conversion efficiency of 30.67%,compared with that of b-P25.Under the presence of GSH,Mn⁴⁺was reduced to Mn²⁺,resulting in the recovery of MRI performance.By irradiating 808 nm laser with a power density of 1.2 W/cm²,the survival rate of 4T1 cells was reduced to 11.5%.