Crystal Violet-Loaded Bi(III)-Based Metal–Organic Framework Boosting Enhanced Photothermal Effect for Breast Cancer Treatment

Recently, metal-organic frameworks (MOFs) have emerged as promising platforms to fabricate photothermal therapeutic materials to cure tumors, but the toxic heavy metals in many MOFs may pose great threats to normal cells. In consideration of the low toxicity of bismuth, herein we made great efforts to synthesize porous bismuth-based MOFs (Bi-MOFs) to construct photothermal conversion materials for cancer treatment. By the reaction of 4,4',4''-tricarboxylic triphenylamine (H₃TCA) and Bi(NO₃)₃ under solvothermal conditions, a porous Bi-MOF was obtained with the formula of {[Bi₂(TCA)₂(H₂O)₃]·6DMF·21H₂O}_<i>n</i> (<b>Bi-TCA</b>). Structural analysis revealed that complex <b>Bi-TCA</b> displayed a three-dimensional (3D) coordination framework featuring abundant accessible channels and cages with a porosity of 73.3% according to the calculating results of PLATON. Due to the high porosity, complex <b>Bi-TCA</b> could effectively encapsulate the dye crystal violet (CV) into the voids and the resulting dye-loaded composite <b>CV@Bi-TCA</b> exhibited extended red-shifted light-absorbing property and enhanced photothermal conversion capability under 455 nm laser irradiation. Further anticancer experiments demonstrated that composite <b>CV@Bi-TCA</b> could efficiently inhibit the growth of breast cancer cells both in vitro and in vivo under 455 nm laser irradiation. This work may promote investigations on the low-toxicity Bi-MOFs for photothermal cancer therapy.