脂質包覆之奈米粒子應用於雙模組影像之前導分析

Abstract

具多影像模組之探針在生物醫學上的發展日益廣泛，磁振造影(MRI)可非侵入性追蹤生物體內某特殊標定之物質，亦可顯影人體內部器官，若搭配光學技術的應用(如:螢光)，將可獲取更細節的次細胞(subcellualr)影像資訊。 氧化鐵為MRI之顯影劑，利用其順磁性的特性，在磁場的作用下，干擾附近組織的磁場，藉此增強與其他部位的對比；量子點具穩定且強的螢光特性，可重複激發，發光時效持久，在螢光光學上有良好的應用。本實驗即是以脂質包覆氧化鐵及量子點，發展兼具螢光及MRI顯影之雙重奈米粒子應用於細胞標定、組織顯影及治療診斷。脂質包覆之雙重奈米粒子尺寸大小介於80至100 nm。以混合型奈米粒子標定細胞具有劑量依賴性，在外加磁場的作用下，可於短時間內完成細胞標定。受雙重奈米粒子標定之CT-26腫瘤細胞存活率達八成以上，能在活體內生長並造成MRI顯影，未來在活體內可應用於細胞追蹤。 實驗進一步將雙重奈米粒子包裹抗癌藥物喜樹鹼，此一奈米粒子之藥物承載率及包覆率分別為46 %及88 %。雙重藥物奈米粒子比起未包裹脂質之喜樹鹼能有效進入CT-26細胞之中並展現其抗癌功能毒殺癌細胞，其半數抑制濃度分別為28 μM及52 μM。藉磁振造影在活體中可即時監測雙重藥物奈米粒子於生物體內的動向與分布，尾靜脈注射雙重藥物奈米粒子2.5小時後，T2加權影像開始有明顯變化，意味著藥物奈米粒子在進入全身血液循流後可堆積於腫瘤處。此一奈米粒子有效結合藥物治療及顯像技術，未來有助於發展及建立治療惡性病灶之進程。

The development of multimodal probes in biomedicine is important recently. Traditionally, MR imaging can track specific lesion in vivo. For bimodal images, MRI contrast agents could incorporate another optical modality for retrieving subcellualr information in living organisms. The iron oxide nanoparticles is one type of contrast agents for MR imaging. It possess paramagnetic property and strengthen the contrast with other tissues. Alternatively, quantum dots have stable fluorescence with extensive application in optics. The experiments designed here are to encapsulate iron oxide nanoparticles and quantum dots in lipid nanocapsules and to develop these probes for fluorescent and MRI contrast in cell labeling, tissue imaging and therapy. The size of lipid-coated nanoparticles (L-NPs) was about 80 - 100 nm. They behaved a dose-dependent manner in cell labeling. These results showed that CT-26 cells could be labeled by L-NPs efficiently if additional magnetic field was applied. The viability of these L-NPs- labeled CT-26 cells was about 80 % in 2 days. They could grow normally to form tumor with enhancing MRI contrast in mice. L-NPs were further used to encapsulate camptothecin. The drug-loading capacity was 46 % (w/w). Treatment of drug-loaded L-NPs could inhibit CT-26 cells growth bettter than camptothecin alone. The half-inhibition concentration for free drug and drug-loaded L-NPs were calculated as 28μM and 52μM , respectively. It could be monitored their distribution and movement of drug nanoparticles in realtime using MRI. The T2-weighted image reflected accumulation of drug-loaded L-NPs in tumor. It had obvious change in 2.5h after injection of drug-loaded L-NPs. The designed drug-loaded L-NPs could combine medication, real-time imaging and monitor tumor treatment in the future.