聚乙烯亞胺修飾之明膠包覆超順磁性氧化鐵奈米微粒於磁振造影之影像對比劑之研究

近幾年來，癌症是醫學上亟需解決的問題之一，但由於現行採用的治療方式，如：化療、放療、侵入式手術等方式仍然無法有效解決。所以，我們希望開發出多功能性的奈米磁粒，同時結合MRI磁振造影、基因治療、藥物傳輸的功能。本實驗的奈米磁粒是由明膠包覆氧化鐵奈米微粒，再經由低分子量的聚乙烯亞胺修飾成帶正電，使其同時為基因傳輸的載體。明膠為可分解性生物高分子，具有良好的生物相容性，表面具有許多官能基能作修飾與鍵結。氧化鐵奈米微粒為磁振造影的對比劑，採用化學共沉澱法製成，具有低磁矯頑力與高飽和磁化量的超順磁性的性質，且有很高的T2弛緩率。本實驗中利用二階段去溶劑法成功將明膠包覆超順磁性氧化鐵奈米微粒，再將PEI修飾在其表面。利用動態光散射儀 (DLS)、穿透式電子顯微鏡 (TEM)、X光粉末繞射儀 (XRD)、熱重分析儀 (TGA)、超導量子干涉儀 (SQUID)確認所製備的粒徑大小、表面電位、表面型態、結晶結構、磁性等性質。DNA retardation assay中顯示PEI-GIOPs具有良好的DNA吸附能力。細胞活性實驗中，利用MTT assay將PEI-GIOPs與NIH-3T3纖維母細胞培養並與SPIONs、GIOPs比較，可發現低分子量PEI修飾後仍然具有良好的生物活性。細胞吸收量採用普魯士藍染色法，與利用感應耦合電漿質譜儀作定量分析。經磁振造影的樣本分析，PEI-GIOPs與SPIONs比較，具有較高的T2弛緩率。在活體實驗中，經老鼠尾部靜脈注射後發現在體內肝、脾、腎的T2加權影像有更好的對比效果。因此，由此實驗中可證實，所製備的奈米磁粒能作為磁振造影之影像對比劑，以及基因治療與藥物傳輸的多重功用。

關鍵字

明膠；超順磁性氧化鐵奈米微粒；聚乙烯亞胺；基因傳輸；磁振造影

並列摘要

Over the past few years, cancer has been one in urgent need for solving in medical science. Nowadays the cancer treatment is major by dependent on chemotherapy, radiotherapy and surgery, but these methods do not achieve our expectation and solve problems well. So we develop multifunctional magnetic nanoparticles for MRI image diagnosis, gene therapy and drug delivery. The developed magnetic nanoparticles are composed of iron oxide nanoparticles encapsulated in gelatin nanoparticles and then modified by low molecule polyethylenimine (PEI) to have positive charge. Gelatin is biodegradable polymer. With high biocompatibility and multifunctional group makes it as a suitable candidate for further modification. Iron Oxide nanoparticles are used as MRI contrast agent with high T2 relaxivity and are made by co-precipitation. The superparamagnetic character of iron oxide nanoparticles are low magnetic coercivity and high saturation magnetization. In this study, we have successfully developed two-step desolvation method to encapsulate iron oxide into gelatin nanoparticles and then modified by PEI (PEI-GIOPs). The characteristics of their size, zeta potential, morphology, crystalline structure and magnetism are determined by using dynamic light scattering (DLS), transmission electron microscopy (TEM), x-ray diffraction (XRD), thermogravimetric analysis (TGA) and superconducting quantum interference device (SQUID). The DNA retardation assay demonstrated that PEI-GIOPs showed good DNA binding efficiency. The cytotoxicity of the PEI-GIOPs to NIH-3T3 fibroblast was assessed by MTT assay and compared with SPIONs、GIOPs. The results showed that modified by low molecule PEI still had high biocompatibility. The cellular uptake was assayed by Prussian blue staining and quantified by inductively coupled plasma spectroscopy (ICPS). MRI scanning of samples revealed that the T2 relaxivity of PEI-GIOPs were higher than that of SPIONs、GIOPs. Moreover, in vivo study revealed that after tail vein injection, liver, spleen and kidney had better effect and turned darker on T2 weighted image. Therefore, all of these results indicated that PEI-GIOPs have multifunction and can serve as MRI contrast agent and for gene and drug delivery system.

並列關鍵字

gelatin ； superparamagnetic iron oxide nanoparticles (SPIONs) ； polyethylenimine (PEI) ； gene delivery system ； magnetic resonance imaging (MRI)

參考文獻

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聚乙烯亞胺修飾之明膠包覆超順磁性氧化鐵奈米微粒於磁振造影之影像對比劑之研究

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