WestCHEM School of Chemistry, University of Glasgow , Joseph Black Building, University Avenue, Glasgow G12 8QQ, U.K.
Adsorption & Advanced Materials Laboratory, Department of Chemical Engineering & Biotechnology, University of Cambridge , Pembroke Street, Cambridge CB2 3RA, U.K.
ACS Appl Mater Interfaces. 2018 Feb 14;10(6):5255-5268. doi: 10.1021/acsami.7b17756. Epub 2018 Feb 2.
The high drug-loading and excellent biocompatibilities of metal-organic frameworks (MOFs) have led to their application as drug-delivery systems (DDSs). Nanoparticle surface chemistry dominates both biostability and dispersion of DDSs while governing their interactions with biological systems, cellular and/or tissue targeting, and cellular internalization, leading to a requirement for versatile and reproducible surface functionalization protocols. Herein, we explore not only the effect of introducing different surface functionalities to the biocompatible Zr-MOF UiO-66 but also the efficacy of three surface modification protocols: (i) direct attachment of biomolecules [folic acid (FA) and biotin (Biot)] introduced as modulators for UiO-66 synthesis, (ii) our previously reported "click-modulation" approach to covalently attach polymers [poly(ethylene glycol) (PEG), poly-l-lactide, and poly-N-isopropylacrylamide] to the surface of UiO-66 through click chemistry, and (iii) surface ligand exchange to postsynthetically coordinate FA, Biot, and heparin to UiO-66. The innovative use of a small molecule with metabolic anticancer activity, dichloroacetate (DCA), as a modulator during synthesis is described, and it is found to be compatible with all three protocols, yielding surface-coated, DCA-loaded (10-20 w/w %) nano-MOFs (70-170 nm). External surface modification generally enhances the stability and colloidal dispersion of UiO-66. Cellular internalization routes and efficiencies of UiO-66 by HeLa cervical cancer cells can be tuned by surface chemistry, and anticancer cytotoxicity of DCA-loaded MOFs correlates with the endocytosis efficiency and mechanisms. The MOFs with the most promising coatings (FA, PEG, poly-l-lactide, and poly-N-isopropylacrylamide) were extensively tested for selectivity of anticancer cytotoxicity against MCF-7 breast cancer cells and HEK293 healthy kidney cells as well as for cell proliferation and reactive oxygen species production against J774 macrophages and peripheral blood lymphocytes isolated from the blood of human donors. DCA-loaded, FA-modified UiO-66 selectively kills cancer cells without harming healthy ones or provoking immune system response in vitro, suggesting a significant targeting effect and great potential in anticancer drug delivery. The results provide mechanistic insight into the design and functionalization of MOFs for drug delivery and underline the availability of various in vitro techniques to potentially minimize early-stage in vivo animal studies following the three Rs: reduction, refinement, and replacement.
金属有机骨架（MOFs）具有高载药率和出色的生物相容性，已被应用于药物传递系统（DDS）。纳米颗粒表面化学在控制 DDS 的生物稳定性和分散性的同时，也控制着它们与生物系统、细胞和/或组织靶向以及细胞内化的相互作用，因此需要多功能且可重复的表面功能化方案。在此，我们不仅探讨了向生物相容性 Zr-MOF UiO-66 引入不同表面官能团的效果，还研究了三种表面改性方案的效果：（i）直接附着生物分子[叶酸（FA）和生物素（Biot）]，作为 UiO-66 合成的调节剂；（ii）我们之前报道的“点击调节”方法，通过点击化学将聚合物[聚乙二醇（PEG）、聚 L-乳酸和聚 N-异丙基丙烯酰胺]共价连接到 UiO-66 表面；（iii）通过后合成配位将 FA、Biot 和肝素配位到 UiO-66 表面，实现表面配体交换。本文还创新性地使用具有代谢抗癌活性的小分子二氯乙酸（DCA）作为合成过程中的调节剂，结果发现它与所有三种方案均兼容，生成表面包覆、载有 DCA（10-20 w/w%）的纳米 MOF（70-170nm）。外部表面改性通常可以提高 UiO-66 的稳定性和胶体分散性。表面化学可以调节 HeLa 宫颈癌细胞对 UiO-66 的细胞内化途径和效率，以及载 DCA 的 MOF 的抗癌细胞毒性与内吞效率和机制相关。具有最有前途涂层（FA、PEG、聚 L-乳酸和聚 N-异丙基丙烯酰胺）的 MOF 经过了广泛的测试，以评估其对 MCF-7 乳腺癌细胞和 HEK293 健康肾细胞的抗癌细胞毒性的选择性，以及对 J774 巨噬细胞和外周血淋巴细胞的细胞增殖和活性氧产生的选择性，J774 巨噬细胞和外周血淋巴细胞是从人类供体血液中分离出来的。载 DCA、FA 修饰的 UiO-66 选择性地杀死癌细胞而不伤害健康细胞，也不会在体外引发免疫系统反应，这表明其具有显著的靶向作用和在抗癌药物传递方面的巨大潜力。这些结果为 MOF 的设计和功能化用于药物传递提供了机制见解，并强调了各种体外技术的可用性，这些技术可能会最大程度地减少后续三 R 原则（减少、优化和替代）的早期体内动物研究。
