Targeted sonodynamic therapy using protein-modified TiO2 nanoparticles

Our previous study suggested new sonodynamic therapy for cancer cells based on the delivery of titanium dioxide (TiO₂) nanoparticles (NPs) modified with a protein specifically recognizing target cells and subsequent generation of hydroxyl radicals from TiO₂ NPs activated by external ultrasound irradiation (called TiO₂/US treatment). The present study first examined the uptake behavior of TiO₂ NPs modified with pre-S1/S2 (model protein-recognizing hepatocytes) by HepG2 cells for 24 h. It took 6 h for sufficient uptake of the TiO₂ NPs by the cells. Next, the effect of the TiO₂/US treatment on HepG2 cell growth was examined for 96 h after the 1 MHz ultrasound was irradiated (0.1 W/cm², 30 s) to the cells which incorporated the TiO₂ NPs. Apoptosis was observed at 6 h after the TiO₂/US treatment. Although no apparent cell-injury was observed until 24 h after the treatment, the viable cell concentration had deteriorated to 46% of the control at 96 h. Finally, the TiO₂/US treatment was applied to a mouse xenograft model. The pre-S1/S2-immobilized TiO₂ (0.1 mg) was directly injected into tumors, followed by 1 MHz ultrasound irradiation at 1.0 W/cm² for 60 s. As a result of the treatment repeated five times within 13 days, tumor growth could be hampered up to 28 days compared with the control conditions.     

Enhanced sonodynamic therapy by carbon dots-shelled microbubbles with focused ultrasound

Sonodynamic therapy involving the non-invasive and local generation of lethal reactive oxygen species (ROS) via ultrasound (US) with sonosensitizers has been proposed as an emerging tumor therapy strategy. However, such therapy is usually associated with inertial cavitation and unnecessary damage to healthy tissue because current sonosensitizers have insufficient sensitivity to US. Here, we report the use of a new proposed sonosensitizer, carbon dots (C-dots), to assemble microbubbles with a gas core (C-dots MBs). As the C-dots were directly integrated into the MB shell, they could effectively absorb the energy of inertial cavitation and transfer it to ROS. Our results revealed the appearance of ¹O₂, •OH, and H₂O₂ after US irradiation of C-dots MBs. In in vitro experiments, treatment with C-dots MBs plus US induced lipid peroxidation, elevation of intracellular ROS, and apoptosis in 32.5%, 45.3%, and 50.1% of cells respectively. In an animal solid tumor model, treatment with C-dots MBs plus US resulted in a 3-fold and 2.5-fold increase in the proportion of ROS-damaged cells and apoptotic cells, respectively, compared to C-dots MBs alone. These results will pave the way for the design of novel multifunctional sonosensitizers for SDT tumor therapy.     

TiO2柱撑蒙脱土的制备及其对品红降解的催化反应

基于TiO2光催化剂的优良光催化活性,采用酸性溶胶法合成了TiO2柱撑蒙脱土复合光催化剂,利用IR,UV-Vis,TG/DTA,XRD及SEM等手段对复合催化剂进行了表征,通过太阳光对酸性品红光催化降解实验,考察了催化剂的光催化活性。该催化剂比纳米TiO2对酸性品红的光催化降解反应表现出更高的催化活性,而且更易于沉降、回收。当TiO2柱撑蒙脱土光催化剂的用量为0.2 g.(100 mL)-1,酸性品红溶液的pH值为3时,在太阳光下40 min内酸性品红基本降解完全,而且该降解过程符合Langmuir-Hin-shelwood方程。X射线衍射(XRD)分析表明钛柱撑蒙脱土的层间距较钠基蒙脱土有明显的增大,紫外-可见吸收光谱表明TiO2柱撑蒙脱土比纳米TiO2具有更高的光吸收效率。