鹼性胺基酸改質氧化鐵奈米粒子

Modification of Iron Oxide Nanoparticles with Basic Amino Acids

本研究在25℃及不同的pH條件下，以鹼性胺基酸改質氧化鐵奈米粒子，並探討這些粒子對質體的吸附性質。TEM分析顯示改質前後並未改變粒子之粒徑大小，且這些官能化的粒子之磁性呈現超順磁現象，在水溶液中亦有極佳的分散性。在兩種改質條件下(pH 3.6及pH 10.5)，鹼性胺基酸改質後的粒子之界面電位都比改質前的粒子提高，顯示胺基酸分子已有效地改變粒子的特性。又，經由界面電位及熱重量分析可確認，不同的胺基酸種類與不同的改質條件會導致胺基酸的吸附方式與吸附量不同。熱重量分析數據證明，鹼性改質條件下(pH 10.5)，胺基酸分子僅以物理吸附方式吸附在粒子表面，而酸性改質條件下(pH3.6)，胺基酸分子可以是化學吸附方式吸附在粒子表面。無論如何，粒子的界面電位越正值，對質體(plasmids)的吸附效率越高；此外，每一種粒子對質體的吸附模式皆符合蘭革牟等溫吸附(Langmuirisotherm) ， 各種粒子對質體的吸附效率比較如下： pH3.6/Fe3O4-arginine ＞ pH3.6/Fe3O4-histidine ＞pH3.6/Fe3O4-lysine ＞ pH10.5/Fe3O4-arginine ＞ pH10.5/Fe3O4-histidine ＞ pH10.5/Fe3O4-lysine ＞ unmodifiedFe3O4。

In this report, modification of iron oxide nanoparticles with basic amino acids in an aqueous solution with controlled pH at 25℃ and their adsorption property of plasmid were reported. TEM analyses showed that the size of the modified nanoparticles was same as the unmodified nanoparticles. These functionalized nanoparticles had a superparamagnetic property and could be re-dispersed well in aqueous media. In both of modified condition (pH 3.6 and pH 10.5), the values of zeta potential of the modified nanoparticles were more positive than that of unmodified nanoparticles. This phenomenon revealed an effective change of the particle properties after the modification of nanoparticles. In addition, we also confirmed from Zeta potential and TGA analyses that both the modified conditions and various basic amino acids could affect the adsorption type and the adsorption amount of basic amino acids. The TGA data proved that amino acids were adsorbed physically on the particle surface under the modified condition of pH 10.5 and chemisorptions occurred when the modified condition was pH 3.6. However, introducing basic amino acids onto the particle surfaces led to more positive of zeta potential and hence increased the efficiency of plasmid binding. In addition, the behavior of their adsorption of plasmid was in agreement with Langmuir isotherm. Comparing the efficiencies of their adsorption of plasmids, the order was pH3.6/Fe3O4-arginine＞pH3.6/Fe3O4-histidine＞pH3.6/Fe3O4-lysine＞pH10.5/Fe3O4-arginine＞ pH10.5/Fe3O4-histidine＞pH10.5/Fe3O4-lysine＞unmodified Fe3O4.