開發功能性二氧化矽奈米複合載體應用於協同性抗癌治療

Abstract

多重抗藥性（multidrug resistance，MDR）是目前臨床癌症治療的一項重大阻礙，因其限制了化學治療的整體效果。協同性藥物的共同傳遞最近已成為一有前景的策略以克服這項艱鉅的問題。然而，協同性藥物通常具有不同的固有特性（例如：溶解性和親脂性），需要個別使用不同的載體或溶劑，因此限制了同時遞送的可行性。在我們的研究中，開發了兩種大小均勻且分散性良好的二氧化矽奈米複合粒子，並證明它們可用於共同傳遞親水性抗癌藥物阿黴素（Doxorubicin，DOX）和疏水性化學增敏劑薑黃素（Curcumin，Cur）這兩種藥物，以實現協同性增強癌症治療的效果。 第一種用於共同傳遞DOX和Cur的二氧化矽奈米複合粒子（SSNs）是利用油包二甲基亞碸（DMSO）的微乳液系統，並結合氟化鈉（NaF）催化的溶膠 - 凝膠化過程進行合成。高效液相層析儀的鑑定顯示DOX和Cur能成功地共同被裝載於SSNs（DOX/Cur@SSNs），並且具有高包覆效率和藥物持續釋放的行為。藉由形成水溶性較佳的金屬與Cur之配位化合物，可以顯著地提高Cur在此奈米複合載體的負載量至45倍以上。而DOX/Cur@SSNs對DOX的負載能力藉由修飾帶負電荷的矽烷在SSNs表面上，亦能被有效地提高。此外，我們可以把SSNs的直徑調控在25 nm以下，以利用高滲透長滯留效應（EPR）增加奈米粒子積累在生物體內腫瘤的可能性。 第二種奈米複合載體為擴孔性二氧化矽奈米粒子（exMSN），其是利用表面活性劑作為孔洞材料的模板，並結合氨水催化的溶膠 - 凝膠化過程進行合成。我們進而將含氨基和羧基的矽烷修飾在exMSN上以獲得具有高DOX和Cur負載量的奈米複合載體（DOX/Cur@NH2/COOH-exMSN），並且具有可調控的藥物釋放行為。此外，為了評估DOX/Cur@NH2/COOH-exMSNs的協同性抗癌功效，我們進行了體外和體內研究，包括細胞攝取、細胞毒性和生物體內分佈。結果顯示，DOX/Cur@NH2/COOH-exMSNs可顯著增強在人類乳腺癌多重抗藥性細胞 (MCF7/Adr) 的抗癌效果。 綜合以上所述，我們成功地開發了能共同運輸DOX和Cur的二氧化矽奈米複合載體DOX/Cur@SSNs，其材料大小可被調控且藥物裝載方法簡便；另外，也開發了具高藥物負載量和pH感應性藥物釋放機制的DOX/Cur@NH2/COOH-exMSNs。我們期望這兩種可同時裝載DOX和Cur的二氧化矽奈米複合載體可以被繼續發展並應用其協同性抗癌作用解決MDR的難題。

Multidrug resistance (MDR) is a problem that limits the overall effectiveness of chemotherapeutic treatments. Co-delivery of synergistic drugs has recently emerged as a promising tool to overcome this obstacle. However, therapeutic drugs usually have distinct intrinsic properties such as solubility and lipophilicity that require the use of various carriers or solvents and thus restricts the feasibility of simultaneous delivery. In this study, we have developed two kinds of uniform and well-dispersed silica nanohybrids and demonstrated each can be utilized for co-delivering two drugs: the hydrophilic chemotherapeutic drug doxorubicin (DOX) and a hydrophobic chemosensitizer curcumin (Cur), to achieve a synergistic enhancement of cancer therapy. The first nanohybrid for DOX and Cur co-delivery is a solid silica nanoparticle (SSN), synthesized via a sodium fluoride (NaF)-catalyzed sol-gel process combined with a dimethyl sulfoxide (DMSO)-in-oil microemulsion. We use HPLC technique to successfully show the co-loading of DOX and Cur in SSNs (DOX/Cur@SSNs) with high encapsulation efficiency and sustained-release behavior. The loading content of Cur was significantly elevated over 45 times through the formation of soluble metal curcumin complexes. Furthermore, the drug loading capacity of DOX/Cur@SSNs for DOX was effectively increased by modifying the SSNs surface with a negatively charged silane. Moreover, the diameter of SSNs can be controlled to below 25 nm to increase the in vivo tumor accumulation via the enhanced permeability and retention (EPR) effect. A second type of nanohybrid, pore-expanded mesoporous silica nanoparticle (exMSN), was synthesized via an ammonia-catalyzed sol-gel process combined with a surfactant-templating strategy. Here, we further modified exMSNs with amino- and carboxyl-containing silanes to obtain high DOX/Cur loading nanoparticles (DOX/Cur@NH2/COOH-exMSNs) with desired drug releasing profiles. In addition, to evaluate the synergistic anticancer efficacy of DOX/Cur@NH2/COOH-exMSNs, both in vitro and in vivo studies, such as cell uptake, cytotoxicity and biodistribution were conducted. The results have demonstrated that DOX/Cur@NH2/COOH-exMSNs could significantly enhance tumor therapeutic effects in MDR human breast carcinoma MCF7/Adr cells. In conclusion, an easy size-controlled and facile drug-loading approach was developed for the synthesis of DOX/Cur＠SSNs, while a high drug-loading capacity and pH-responsive release behavior were found in DOX/Cur@NH2/COOH-exMSNs. We envision that both two types of the DOX/Cur-loaded silica nanohybrids can be carried forward and applied against MDR by synergistic anticancer therapy.