Hannes Landmann博士，Sartorius Lab Instruments(德國哥廷根)

Kristin Menzel博士、科學作家(德國哥廷根)

1908年，Paul Ehrlich受到“Zauberkugel”概念的啟發(fā)，首次在理論上描述了將毒性藥物組裝到所謂的“納米載體”上。¹ 如今，納米載體已在現(xiàn)代​醫(yī)學和生物技術(shù)領域有多種應用。這些特殊納米材料的一項關鍵應用就是藥物定向輸送，它們可發(fā)揮藥物活性成分轉(zhuǎn)運模塊 (即：納米顆粒、囊泡或膠束) 的作用。^2,3,4,5人們推測這種方式與傳統(tǒng)給藥方法相比對人體更為有效，且毒性更低。⁶除了藥物輸送外，過去數(shù)十年間還發(fā)展出其他一些應用納米載體的領域，例如利用金屬納米顆粒進行磁共振成像或干細胞基因治療，^7,8 或者利用量子點進行光學成像。⁹

納米載體可以按照其初始材料 (即；金屬、脂質(zhì)、聚合物和蛋白) 以及制成后的構(gòu)成 (即：囊泡、顆粒和膠束) 進行分類。一般而言，水性介質(zhì)中納米顆�；鞈乙夯蚰遗莘稚⒁旱闹苽浒�括三個步驟：a) 納米載體組裝 (例如通過注射、薄膜水化或反相蒸發(fā))、b) 純化 (例如：色譜、透析或超濾) 和 c) 濃縮 (如超濾或蒸發(fā))。

這份短篇綜述舉例介紹了近期關于納米載體制備的一些文獻。重點介紹了濃縮和純化步驟，該步驟使用不同孔徑 (相應的截留分子量 (MWCO)) 的Sartorius Vivaspin^® 或Vivaflow^® 設備通過超濾完成。Vivaspin^® 系列產(chǎn)品的體積范圍是從0.5 mL至20 mL，而Vivaflow^® 系統(tǒng)則涵蓋了從0.05升到5升的范圍。因此，Sartorius能夠處理的樣本體積、膜材料和MWCO范圍無與倫比，可滿足不同預期用途的需求。這方面的挑戰(zhàn)包括合成后的緩沖液更換、脫鹽和清洗^10,11、去除溶解的化合物^12,13,14 或聚集物。¹⁵

純化過程十分重要，通過純化可以達到等滲狀態(tài)，以便在體內(nèi)應用時避免發(fā)生聚集或凝聚，還可去除毒性藥物、配體或其他可能引起副作用的物質(zhì)。濃縮步驟的重要意義在于調(diào)節(jié)藥物中活性成分的含量，以便達到預期的治療或診斷效果。

純化時，通過分子排阻色譜 (SEC) 將游離物質(zhì) (起始材料) 與預期得到的納米載體分離，這不可避免地導致產(chǎn)物稀釋，并且需要后續(xù)的濃縮步驟。相比之下，透析過濾純化時不會導致顯著的稀釋，但如果需要較高的納米載體濃度，仍需要使用濃縮步驟。兩種分離方法均需要大量昂貴且耗時的手工操作。通過Vivaspin^® 離心或者使用Vivaflow^® 系統(tǒng)的蠕動泵進行超濾可克服這一缺點。該技術(shù)成本較低，操作迅速，人工操作極少。值得一提的是，純化和濃縮步驟可同時進行。¹⁶

納米載體純化后，通常需要測定載藥量 (偶聯(lián)或包囊效率)。偶聯(lián)或包囊效率是描述和鑒定納米載體的一個參考值。其他重要性質(zhì)包括ζ電位和粒徑分布，后者可通過光子相關光譜 (PCS)、高分辨率傳遞電子顯微鏡 (HRTEM) 成像或動態(tài)光散射 (DLS) 測定。在進行這些不同的鑒定前，需要成功地對混懸液或分散液進行純化和濃縮。

下表為您概括列出了使用超濾步驟對各種納米載體進行純化和濃縮的文獻。該表還可指導您使用多大的MWCO。

表1匯總了使用Sartorius Vivaspin^® 或Vivaflow^® 進行納米載體超濾的應用示例：

SD = 粒徑分布

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