Division of Physical Biology and Bioimaging Center, Shanghai Synchrotron Radiation Facility, CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, University of Chinese Academy of Sciences , Shanghai 201800, People's Republic of China.
Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, People's Republic of China.
J Am Chem Soc. 2017 Nov 8;139(44):15784-15791. doi: 10.1021/jacs.7b07895. Epub 2017 Oct 26.
DNA has proven of high utility to modulate the surface functionality of metal-organic frameworks (MOFs) for various biomedical applications. Nevertheless, current methods for preparing DNA-MOF nanoparticles rely on either inefficient covalent conjugation or specific modification of oligonucleotides. In this work, we report that unmodified oligonucleotides can be loaded on MOFs with high density (∼2500 strands/particle) via intrinsic, multivalent coordination between DNA backbone phosphate and unsaturated zirconium sites on MOFs. More significantly, surface-bound DNA can be efficiently released in either bulk solution or specific organelles in live cells when free phosphate ions are present. As a proof-of-concept for using this novel type of DNA-MOFs in immunotherapy, we prepared a construct of immunostimulatory DNA-MOFs (isMOFs) by intrinsically coordinating cytosine-phosphate-guanosine (CpG) oligonucleotides on biocompatible zirconium MOF nanoparticles, which was further armed by a protection shell of calcium phosphate (CaP) exoskeleton. We demonstrated that isMOFs exhibited high cellular uptake, organelle specificity, and spatiotemporal control of Toll-like receptors (TLR)-triggered immune responses. When isMOF reached endolysosomes via microtubule-mediated trafficking, the CaP exoskeleton dissolved in the acidic environment and in situ generated free phosphate ions. As a result, CpG was released from isMOFs and stimulated potent immunostimulation in living macrophage cells. Compared with naked CpG-MOF, isMOFs exhibited 83-fold up-regulation in stimulated secretion of cytokines. We thus expect this isMOF design with soluble CaP exoskeleton and an embedded sequential "protect-release" program provides a highly generic approach for intracellular delivery of therapeutic nucleic acids.
DNA 已被证明在将金属有机骨架（MOFs）的表面功能调节用于各种生物医学应用方面具有很高的实用性。然而，目前制备 DNA-MOF 纳米粒子的方法依赖于低效的共价偶联或寡核苷酸的特异性修饰。在这项工作中，我们报告说，未修饰的寡核苷酸可以通过 DNA 骨架磷酸盐与 MOFs 上的不饱和锆位点之间的内在多价配位，以高密度（~2500 个链/颗粒）负载在 MOFs 上。更重要的是，当存在游离磷酸盐离子时，表面结合的 DNA 可以在大体积溶液或活细胞中的特定细胞器中有效地释放。作为在免疫疗法中使用这种新型 DNA-MOF 的概念验证，我们通过内在配位将免疫刺激性 DNA-MOF（isMOFs）构建体在生物相容性的锆 MOF 纳米粒子上配位，然后用磷酸钙（CaP）外骨骼进一步武装。我们证明了 isMOFs 表现出高细胞摄取、细胞器特异性和 Toll 样受体（TLR）触发的免疫反应的时空控制。当 isMOF 通过微管介导的运输到达内溶酶体时，CaP 外骨骼在酸性环境中溶解，并原位产生游离磷酸盐离子。结果，CpG 从 isMOF 中释放出来，并在活巨噬细胞中刺激强烈的免疫刺激。与裸 CpG-MOF 相比，isMOF 刺激细胞因子分泌的上调了 83 倍。因此，我们期望这种具有可溶性 CaP 外骨骼和嵌入式顺序“保护-释放”程序的 isMOF 设计为治疗性核酸的细胞内递送提供了一种高度通用的方法。
