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標題: | 酸鹼敏感型幾丁聚醣奈米顆粒之製備與應用 Preparation and Application of pH-Sensitive Chitosan Nanoparticles |
作者: | Yu-Li Lin 林雨利 |
指導教授: | 謝學真(Hsyue-Jen Hsieh) |
關鍵字: | 幾丁聚醣,聚異丙基丙烯醯胺,自組裝,奈米顆粒,酸鹼敏感,茶鹼,控制釋放, chitosan,PNIPAAm,self-assemble,nanoparticle,pH-sensitive,theophylline,controlled release, |
出版年 : | 2011 |
學位: | 碩士 |
摘要: | 本實驗目的是製備具酸鹼敏感性的幾丁聚醣奈米顆粒。在製備材料的方面主要分為兩部分,首先製備帶有羧酸根之聚異丙基丙烯醯胺,隨後將之接枝於幾丁聚醣上並利用自組裝法製作奈米顆粒。在應用層面則採用親水性的茶鹼作為乘載藥物進行藥物釋放之相關探討。
在材料製備的第一部分中,發現聚合反應中先加入鏈轉移劑(MAA),將會大幅降低聚異丙基丙烯醯胺的分子量。而後利用不同比例的 MAA 進行自由基聚合反應,各組別間的分子量分布差異並不明顯。以不同比例的起始劑(KPS)製備帶有羧酸根之聚異丙基丙烯醯胺,從實驗結果可以發現隨著 KPS的濃度增加,有另一分子量較大的產物出現。綜合各項因素,選定以較低比例 MAA 及 KPS 進行聚合而得之 100/10/1(異丙基丙烯醯胺/MAA/KPS,莫耳比)的產物進行第二部分製備。 在材料製備的第二部分中,利用鍵結於聚異丙基丙烯醯胺尾端的羧酸根與幾丁聚醣的胺基以 EDC/NHS 進行接枝,並將複合材料做成膜材以探討其是否適合細胞之貼附,可發現骨母細胞雖難以貼附,但仍保有一定活性,因此認為材料不具細胞毒性。量測材料的低臨界溶液溫度,可知大部分的組別均落於 35.5℃,只有 50/75 (幾丁聚醣:聚異丙基丙烯醯胺=0.50:0.75,重量比)的組別呈現較高的低臨界溶液溫度(38℃)。接著在不同溫度下量測 1 wt%複合材料溶液之微胞尺寸,可知在高於臨界溫度時,分子量分佈指數有明顯變小的趨勢,顯示自組裝現象的發生可能使得微胞的形狀趨於一致,即球形。 利用 SEM 觀察乾燥後之奈米顆粒可知,以微胞化濃度 0.1 wt%的複合材料溶液進行顆粒製備,均可以製備出平均粒徑為 130 nm 至 180 nm 的顆粒。但若將濃度提升至 1 wt%,只有 15/75 及 10/75 能夠有效製備出奈米顆粒。若以 TEM 觀察奈米顆粒結構,則可發現顆粒呈現多孔或中空的結構。 以粒徑分析儀量測奈米顆粒的平均粒徑,並與 SEM 圖中利用軟體量測所得之平均粒徑做比較,可發現兩者具有類似趨勢,且奈米顆粒在水中膨潤至 350 nm 至 800 nm。奈米顆粒之尺寸大小在水中隨著微胞化濃度增高而增加。相同微胞化濃度,不同組別所製備出的奈米顆粒大小略隨幾丁聚醣比例增加而增加。奈米顆粒表面電位皆大於 35.5 mV,故可於常溫下穩定存在且不易聚集。 在應用方面,以茶鹼作為乘載藥物進行奈米顆粒的藥物釋放,則可發現在 pH=7.4 時,藥物較容易釋放,可有高達 50 %以上之釋放率。若是於 pH=2.0的情況下,釋放率僅為 10 %左右,推測是因茶鹼上的嘌呤與嘧啶基團在酸性條件下成為電子受體,茶鹼因而與複合材料奈米顆粒產生離子作用力而難以釋放。若升高溫度,則可因聚異丙基丙烯醯胺與茶鹼產生的氫鍵作用力使得藥物釋放量減少。從釋放曲線之趨勢可明顯看出,本研究製成的複合材料奈米顆粒同時具有酸鹼敏感性質與溫度敏感性質,因此在藥物控制釋放方面具有相當的應用潛力。 The aim of this research is to prepare pH-sensitive chitosan nanoparticles. The preparation of the material could be mainly separated into two parts. First, PNIPAAm-COOH was prepared. Second, it was grafted onto chitosan and self-assembly method was used to prepare nanoparticles. For application, hydrophilic theophylline was chosen for drug release study. In the first part of the material preparation, adding chain transfer agent (MAA) would dramatically lower the molecular weight of PNIPAAm. And then, using different amounts of MAA for polymerization showed no significant difference in molecular weight distribution. When using higher amounts of initiator (KPS) to prepare PNIPAAm-COOH, the peak representing for higher molecular weight products appeared. The 100/10/1 (NIPAAm/MAA/KPS, molar ratio) product was chosen for using lowest amount of MAA and KPS. In the second part of the material preparation, we used EDC/NHS to graft PNIPAAm-COOH onto the amino group of chitosan. Then, the material was prepared as a film and used for cell culture. Although the attachment of osteoblasts was poor, osteoblasts still showed activity on it. So, the material is regarded as being nontoxic. The lower critical solution temperature (LCST) of the most materials were 35.5℃, only 50/75 set (chitosan:PNIPAAm-COOH = 0.50:0.75, weight ratio) showed higher LCST in 38℃. When measuring micelle diameters under solution concentration equaled to 1 wt% at different temperatures, it was observed that polydispersity index decreased when the temperature was higher than LCST. It indicates that the morphology of the micelles became uniform (spherical). By using SEM, it was observed that the dried nanoparticles with diameters of 130 nm to 180 nm could be prepared when the micellization concentration equaled to 0.1 wt%. If the micellization concentration increased to 1 wt%, only 15/75 and 10/75 sets could effectively form nanoparticles. Via TEM, nanoparticles showed porous or hallow structures. When measuring the average diameter of the nanoparticles by a nanosizer, it could be observed that the results were consistent to SEM photograph analysis and the nanoparticles in water swelled from 350 nm to 800 nm. The average diameter of the nanoparticles increased when the micellization concentration increased. For the same micellization concentration, average diameter of the nanoparticles slightly increased when the proportion of chitosan increased. The zeta potentials for the nanoparticles were above 34.5 mV, which indicates that the nanoparticles would not gather under room temperature. In application, nanoparticles were loaded with theophylline and used for drug release study. When pH value of solution was 7.4, theophylline was released easily; the cumulative release could be up to 50 %. When pH value was 2.0, the cumulative release only reached to 10 %. When in a low pH environment, the purine and pyrimidine bases on theophylline became electron acceptor and the ionic interaction was formed between theophylline and chitosan, thus making the release of theophylline difficult. If raising the temperature, the hydrogen bond interaction between PNIPAAm and theophylline became stronger and thus lower the cumulative release. According to the drug release profiles, chitosan/PNIPAAm-COOH nanoparticles exhibit pH-sensitive and thermo- sensitive features. It shows great promise in drug release-related application. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/29396 |
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顯示於系所單位: | 化學工程學系 |
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