發展牛血清蛋白包覆磁性奈米粒子作為藥物傳遞載體 於光動力治療之應用

Development of Albumin Coated Iron Oxide Nanoparticles as Drug Delivery Vehicles in Photodynamic Therapy

胡淳育(Chun-Yu Hu)

指導教授 ： 黃郁棻

國立清華大學/原子科學院/生醫工程與環境科學系/碩士(2014年)

https://doi.org/10.6843/NTHU.2014.00434

摘要

光動力治療 (Photodynamic therapy, PDT)，是一種結合光敏劑(photosensitizer, PS)、光及氧之非侵入式治療且已廣泛應用於臨床癌症應用上。由於現階段的光敏劑大多為疏水性結構，在生物體應用上受限於溶解性不佳等問題而影響其治療之效率。故本研究利用具有三維結構與水溶性佳等特性之牛血清蛋白，與疏水性的光敏劑 (Protoporphyrin IX, PpIX)間，具有良好親和性以改善溶解性等問題，再者以微乳化合成方式包覆疏水性中空孔洞磁性鐵奈米粒子，以開發新型診斷治療制劑。動態光散射分析儀 (Dynamic light scattering, DLS)與穿透式電子顯微鏡 (Transmission electron microscope, TEM)鑑定結果顯示，此奈米複合體(BSA:PpIX:PHNPs)為團簇結構，其平均水合半徑為152.9 ± 29.0 nm。從吸收與螢光光譜鑑定結果證實此載體可有效裝載PpIX，並可長時間穩定於複雜生理緩衝環境。透過老鼠前列腺癌細胞之存活率分析顯示，以632 nm波長Xe燈照射30分鐘條件下，載體上之光敏劑可有效生成單態氧與自由基，達到毒殺癌細胞之目的；未照光組別無顯著的細胞毒性產生。此複合材料在本體系中進一步扮演磁共振造影對比劑的顯影功能，利用表面的血清蛋白與水分子良好的交互作用，可提升其影像對比度。
在生物體應用上，許多文獻記載奈米載體上修飾聚乙二醇分子可有效降低奈米載體與血清的交互作用、減少被內皮網狀系統的巨噬細胞所吞噬及延長於血液循環中的時間等，提升其治療之效率。故本研究利用Methoxy PEG succinimidyl carboxymethyl ester上的NHS-Ester與血清蛋白上的一級胺反應形成具有PEG修飾之血清蛋白。此血清蛋白亦可與PpIX間具有良好親和性，透過微乳化方式開發一聚乙二醇修飾之奈米藥物載體。研究結果證實載體修飾PEG的比例不同，可調控巨噬細胞吞噬之作用。
光動力治療也可搭配化學性療法以提升其治療效率。本研究可開發雙藥物於單一載體作為化學-光動力之結合治療，利用血清蛋白與中空孔洞奈米粒子，在微乳化方式，將化學治療藥物Dox及光敏劑PpIX有效裝載 (BSA:Dox:PpIX:PHNPs)。從光譜鑑定顯示BSA:Dox:PpIX:PHNPs具有良好的藥物裝載率(Dox: 82%及PpIX:98%)，再者細胞存活率分析證實結合化學-光動力治療可成功改善單藥物載體之治療效率。
本研究之奈米複合體系統透過簡單而且快速的合成方式，成功裝載疏水性光感物質PpIX，改善其生物體內溶解性不佳等問題，再者可利用PEG修飾或者搭配化學性藥物的結合治療下，提升生物體應用及治療之效率。

關鍵字

牛血清蛋白 ； 中空孔洞磁性奈米粒子 ； 光敏劑

並列摘要

Photodynamic therapy (PDT) requires combination of a photosensitizer (PS), light and oxygen; it is a non-invasive therapeutic modality which is widely used in cancer clinical trial. Most existing PSs are hydrophobic in nature. PDT’s oxidative damage is significantly reduced by the low efficiency of reactive oxygen species (ROS) production. Owing to the high binding affinity of serum albumin toward Protoporphyrin IX (PpIX), bovine serum albumin (BSA) was applied as a carrier for PDT drug in the current study.The high aqueous solubility of BSA makes it an ideal candidate to stabilize hydrophobic porous hollow Fe3O4 nanoparticles (PHNPs). This process is done through one step oil-in-water emulsion under optimal ultrasonication condition.
The morphology and particle size of the BSA:PpIX:PHNPs were characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The resultant nanocluster demonstrated a narrow size distribution with a mean hydrodynamic diameter of 152.9 ± 29.0 nm. Spectroscopic measurement confirmed high PpIX-loading efficiency, which was biocompatible and stable in various buffers. Furthermore, in vitro cytotoxicity of BSA:PpIX:PHNPs was tested in Tramp C1 cells via MTT assay and significant improvement in therapeutic efficacy was achieved with 30 min-red laser (632 nm) irradiation. This result was also consistent with an increase of ROS generation in cancer cells and was demonstrated using flow cytometry. In addition, BSA:PpIX:PHNPs exhibit high transverse relaxivity in MRI as the contrast agents (CAs).PEGylated nanoparticles have been proposed as enabling evasion by RAW 264.7 cells and reducing blood plasma protein adsorption. In this work, methoxy PEG succinimidyl carboxymethyl ester was covalently attached to BSA and followed by NHS ester-amine reaction in phosphate buffer (pH 8). PEG-BSA and hydrophobic porous hollow Fe3O4 nanoparticles (PHNPs) were stabilized through one step oil-in-water emulsion under optimal ultrasonication condition. Our results demonstrate that PEGylation of BSA:PpIX:PHNPs can modulate cellular uptake by RAW 264.7 cells.BSA:PpIX:PHNPs have shown great potential both in drug delivery and photodynamic therapy.Herein, we developed a doxorubicin (Dox)-loaded BSA:PpIX:PHNPs to facilitate combined chemotherapy and photodynamic therapy in one system. BSA:Dox:PpIX:PHNPs, show high loading efficiency of Dox and PpIX. Comparing in vitro cytotoxicity assays of BSA:Dox:PHNPs & BSA:PpIX:PHNPs with BSA:Dox:PpIX:PHNPs, we demonstrated that BSA:Dox:PpIX:PHNPs have higher therapeutic efficacy during photodynamic therapy. The ability of BSA:Dox:PpIX:PHNPs to combine local specific chemotherapy with external photodynamic therapy significantly improves therapeutic efficacy of cancer treatment.Our findings suggest that albumin coated magnetic nanoparticles exhibit great potential as a diagnostic & therapeutic system in cancer therapy.

並列關鍵字

bovine serum albumin ； porous hollow Fe3O4 nanoparticles ； photosensitizer

參考文獻

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