微小核醣核酸 (miRNAs)在許多疾病的診斷以以及治療上為一個非常具有潛力的生物標靶分子。目前市售萃取miRNA的萃取套組大多是結合液相萃取及固相萃取以達到萃取miRNA之最大效率。但目前大多的研究專注於萃取出更大量及更高純度的miRNA，而缺乏有關核酸吸附機制之研究，進而限制了萃取核酸的應用及發展。
在固相萃取中，最常以二氧化矽當作是吸附核酸的材料，而二氧化矽和核酸之間的吸附作用力依據不同溶液條件，大致可以分成以下四種(1)核酸和二氧化矽表面之氫鍵鍵結 (2)核酸和二氧化矽表面水分子之輸水效應 (3)分子間的靜電作用力 (4)核酸二氧化矽間之鹽橋效應。此外，我們觀察在Hofmeister series中將鹽離子之水合能力，由較強的kosmotrope至較弱的chaotrope對二氧化矽吸附核酸之吸附行為之影響。我的研究主要是利用恆溫吸附實驗和微熱量滴定卡計(ITC)所得出之熱力學參數分析吸附行為，並以熱力學的角度去觀察上述四種作用力，在不同溶液條件下主導作用力之轉換。
實驗中我們使用不同pH值(靜電作用力、氫鍵)不同鹽濃度以及五種不同種類的鹽(Na2SO4、CaCl2、NaCl、GuHCl、GuSCN)，從恆溫吸附曲線及ITC的數據中，可以發現在低鹽濃度時，雖然在焓(∆H)的部分是些微放熱的，不過自由能(∆G)的貢獻主要來自於熵(∆S)的變化，隨著鹽濃度增加，可以從焓的變化發現Na+和Gu+在高pH值時所扮演的吸附作用力的不同。最後，我們可以從焓(∆H)以及熵(∆S)在不同條件的溶液中發現，上述四種作用力的轉換。

MicroRNAs (miRNAs) are potential biomarkers that could be applied on the diagnosis and treatment of different disease. However, the lack of knowledge of the binding mechanism of using silica as a material for adsorbing nucleic acids limit the improvement and application.
The driving forces of the adsorption process can be divided into four parts based on different solution conditions (1) shielded intermolecular electrostatic forces (2) dehydration of the DNA and silica surfaces, (3) intermolecular hydrogen bond formation in the DNA–silica contact layer and (4)salt bridge effect between silica and DNA.
This work demonstrates the mechanistic aspects underlying the adsorption behaviors of DNA with mesoporous silica particles in aqueous solution. We changing pH value, ionic strength, three types of salt (NaCl, GuHCl, GuSCN). Using the isotherm adsorption experiment combined with isotherm titration calorimetry (ITC), we observe adsorption mechanism from the viewpoint of thermodynamics. From the ITC data, Na+ and Gu+ play different roles in the adsorption process from the change in reaction enthalpy at high pH value. Finally, we observe the relationship between these four driven forces by the change of enthalpy (∆H) and entropy (∆S).

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