探討不同大小奈米粒子結合超音波作用之空穴效應

Abstract

本論文研製之探討添加不同大小奈米粒子結合超音波所產生之空穴效應是否達到增益，空穴效應是否為治療癌症的主要反應機制。透過Weissler反應為基礎的碘化鉀試驗，生成不同濃度之三碘離子，利用紫外光可見光光譜分析法分析其吸收光譜。主要量測三碘離子在350 nm吸收度之差異，間接量化暫態空穴效應，分析添加不同大小之奈米粒子是否有增益空穴效應之現象。本文以奈米金粒子及聚苯乙烯粒子為試驗材料，由於所使用奈米粒子為膠體溶液，而碘化鉀為電解質，因為電雙層受到電性異性相吸影響變薄，膠體與膠體之間會彼此吸引凝集，必須先找到其臨界凝聚濃度，降低沉澱發生機率。其中發現添加奈米金粒子與碘離子容易發生反應，影響三碘離子之吸收光譜。根據軟硬酸鹼學說，金容易與碘發生反應，產生金碘錯合物，因此含奈米金粒子之溶液無法適用於此試驗法觀察空穴效應。而聚苯乙烯粒子雖然不會與三碘離子發生反應，所添加之粒子數目過量時，容易產生阻擋光線之現象，亦會影響光譜量測準確性，超音波作用完成後，可採用離心法分離聚苯乙烯粒子來達到改善。試驗結果發現添加聚苯乙烯粒子之實驗組別 (52.4 nm、97 nm、204.3 nm、310 nm) 所得到三碘離子之350 nm吸收度，與未添加奈米粒子之控制組所得到三碘離子之350 nm吸收度無明顯之差異。因此推斷在相同超音波能量之下，添加固定濃度不同大小之聚苯乙烯粒子，並沒有明顯增益空穴效應之現象發生。

To investigate the degree to which different sized nanoparticles increase the generation of inertial cavitation upon ultrasound exposure. Increases in cavitation may be a mechanism by which nanoparticles enhance ultrasound effectiveness in treating solid cancers. Methods: use of the Weissler reaction, where triiodide ion is produced in proportion to the level of cavitation present, in differing suspensions containing nanoparticles of different sizes. Triiodide ion produced is quantified through UV-visible absorbance spectrometry, with measurements made at 350 nm. Both gold and polystyrene nanoparticles were examined. Potassium iodide solution is a kind of electrolyte. Because nanoparticles are a type of colloid, upon collision between them and ions, their electrostatic bilayer will thin. The distance between particles will be reduced. Subsequently, coagulation occurs. Therefore, we needed to find the critical coagulation concentration of KI to minimize coagulation and precipitation. We found that gold nanoparticles react with the iodide ion, which in turn affects triiodide ion levels. According to HSAB theory, gold has strong affinity with iodine. Since they form gold-iodine complexes, the KI dosimeter is not suitable for measuring cavitation in suspensions containing gold nanoparticles. Although polystyrene particles will not interact with triiodide, excessive particle numbers virtually block all light transmission and render spectrum measurements meaningless. This problem was resolved by removing polystyrene particles post-sonication via centrifugation. No difference in cavitation levels was detected with the addition of polystyrene nanoparticles of various sizes at a given concentration. Polystyrene nanoparticles do not increase the incidence of inertial cavitation in suspension.