以碳摻雜二氧化鈦奈米粉末藉由聲動力療法作癌症治療

Abstract

癌症已經連續40年高居美國十大死因的前兩名，每分鐘都有人因為癌症而喪生。雖然目前醫學上已具有許多有效的癌症治療方法，但也伴隨著為數不少的副作用，因此尋找較低副作用的療法刻不容緩。聲動力療法是以穿透力良好的超音波，藉由空化作用的產生，激發病患體內的聲敏感材料，並產生自由基，以有效清除癌細胞。但受限於目前大部分聲敏感材料皆為卟啉結構的有機材料，一旦注射入動物體內後，吸收特定波段的光或能量，會造成分子變化，產生光毒性(Phototoxicity)，造成皮膚發紅並腫脹。同時，由於大部分的聲敏感材料在生理環境中會因其疏水性與易於團聚等特性，而使得聲動力治療時之ROS的生成量下降。然而，奈米材料被視為是一個能有效解決此問題的方法，而其中二氧化鈦奈米粉末因為出色的材料特性而最受人注目。因此在本研究中我希望利用碳摻雜的二氧化鈦奈米粉末，並藉由超音波的作用產生ROS，達到更好的清除癌細胞效果。 在本研究中利用溶膠凝膠法(sol-gel)製備出具球狀碳摻雜二氧化鈦，藉由電子顯微鏡與粒徑分析，其粒徑大小約為157 nm且大小均一分散均勻。透過XRD確認材料結晶結構為銳鈦礦型的二氧化鈦，並透過EDS和AES的分析，確認在二氧化鈦中有碳的摻雜，以XPS進一步了解碳摻雜進材料中，形成C-Ti-O的鍵結。在細胞實驗的部分，碳摻雜二氧化鈦具有良好的生物相容性。聲動力治療組和其他組別相比，能造成更多ROS自由基的產生，顯著地對乳癌細胞產生細胞毒性，使其細胞活性降低。同時在LIVE/DEAD的分析上也觀察到相同的結果。在動物實驗的部分，聲動力治療組與其他組別相比，腫瘤的增生速度明顯減緩，在治療的第七天已經出現統計上的差異，證實碳摻雜二氧化鈦奈米粉末經由超音波的作用下，藉由慣性空化作用熱解的氫氧自由基和聲致發光激發材料產生的單重態氧加成的效果下，能有效抑制乳癌細胞的增生。

Cancer has been the top two leading cause of death in US for consecutive 40 years. Every minute there are people died of cancer. Although currently there are a lot of effective cancer treatments, however, these treatments have some side effects. Thus, alternative therapies with fewer side effects are urgently required. Sonodynamic therapy is an effective treatment for eliminating tumor cells by irradiating sonosentitizer in patient’s body with higher penetration ultrasound and inducing the free radicals. Nevertheless, most recent sonosensitizers made of porphyrin-based organic materials that have phototoxicity on the skin under a certain wavelength of light or energy irradiation. Likewise, most sonosensitizers were hydrophobic and easy to aggregate in physiological condition, leading to reduction of their ROS production. Nonetheless, the development of nanoparticles shows a promising potential to solve these problems. Titanium dioxide has appealed for the most attention due to its properties among many nanosensitizers. Hence, in this study, carbon doped titanium dioxide, one of inorganic materials, is applied to avoid the foregoing, and furthermore, carbon doped titanium dioxide is used to generate ROS under ultrasound irradiation to eliminate tumor cells. Spherical carbon doped titanium dioxide nanoparticles are synthesized by sol-gel process, and it was shown that particle size of the material is around 157 nm via EM and Zetasizer analysis. Through XRD analysis, it was indicated that the crystal structure of carbon doped titanium dioxide was anatase, this was reconfirmed by TEM diffraction pattern result. By EDS, AES and XPS analysis, it was also confirmed that carbon has been doped in titanium dioxide through the bonding with titanium. The forming of C-Ti-O bond may also induce defects in lattice which would be beneficial for the phenomenon of sonoluminescence to improve the effectiveness of sonodynamic therapy. By dint of DCFDA, WST-1, LDH and Live/Dead test, carbon doped titanium dioxide nanoparticles are shown to be a biocompatible material which may induce ROS radicals to suppress the proliferation of 4T1 breast cancer cell under ultrasound treatment. From in vivo study, carbon doped titanium dioxide nanoparticles activated by ultrasound may inhibit the growth of the 4T1 tumor, and it showed significant difference between SDT and the other groups on the seventh day of the treatment. The results are corroborated that carbon doped titanium dioxide nanoparticles activated by ultrasound are able to inhibit the proliferation of 4T1 tumor cell through the enhancement of hydroxyl radicals and singlet oxygen.