DNA Origami-templated Silica nanostructures for applications in biomedicine and catalysis

许多探索DNA折纸在现实生活中潜在应用的尝试都面临着它在非水条件下或在生物环境中通常遇到的固有不稳定性的麻烦。另一方面，二氧化硅纳米粒子在生物医学和催化方面的研究已经进入平台期，几乎没有新的突破报道。在这里，我建议通过利用它们的组合特性来促进这两个领域的发展。我将以DNA纳米结构模板二氧化硅纳米结构的形式，将结构DNA纳米技术与材料科学结合起来。DNA折纸将被用来创造不同的纳米级形状，这将作为模板，形成具有纳米级精确特征的任何所需形状的二氧化硅纳米结构，目前无法通过标准合成方法获得。这些结构将被研究它们的细胞摄取机制和动力学以及潜在的下游治疗应用的细胞内行为。这些新的二氧化硅纳米结构增加了更多的功能，DNA原基将被由多肽核酸(PNA)制成的突出的“手柄”链修饰。由于它们的中性电荷，不会在这些手柄上发生二氧化硅沉积，因为这是由阳离子二氧化硅前体和多阴离子DNA主干之间的静电吸引所控制的。因此，在DNA折纸结构转录成硅胶后，PNA手柄将从硅胶结构中突出，可用于与其他核酸杂交。这就产生了完全可定点寻址的二氧化硅结构，并可以通过核酸杂交进行定点修饰，将DNA折纸的准确寻址能力与二氧化硅的化学稳定性结合在一起。然后这些结构将分别用于细胞内和细胞外的反义治疗和免疫治疗。通过定点定位肿瘤坏死因子超家族配体在二氧化硅表面特定的几何形状(例如六角形)，这些配体可以通过与细胞外死亡受体的模式特异性相互作用而导致细胞死亡，导致“几何细胞死亡”。此外，这些新颖的二氧化硅结构为实现高效的酶级联提供了完美的平台。利用在一定距离内放置受控数量的不同酶的能力，并有可能在硅化DNA折纸结构的保护“孔”内这样做，将允许酶保护和底物通道。此外，位于酶周围的PNA手柄与不同的带电分子结合，可以精确地调节每种酶周围局部微环境的pH。这些因素将导致催化剂产量的大幅增加，为创建高效的酶纳米工厂打开了可能性。

Many attempts to explore potential real-life applications of DNA origami have faced the trouble of its inherent instability in non-aqueous conditions or those commonly met within biological environments. On the other hand, Silica nanoparticle research in biomedicine and catalysis has reached a plateau with little new breakthroughs being reported. Here I propose the advancement of both areas by harnessing their combined properties. I will combine structural DNA nanotechnology with materials science in the form of DNA nanostructure-templated Silica nanostructures. DNA origami will be used to create different nanoscale shapes, which will serve as a template for the formation of Silica nanostructures of any desired shape with nanometer-scale precision features, currently not accessible through standard synthesis methods. These structures will be investigated for their cellular uptake mechanism and kinetics and intracellular behaviour for potential downstream therapeutic applications. Adding more functionality to these new Silica nanostructures, DNA origamis will be modified with protruding “handle” strands made from peptide nucleic acids (PNAs). Due to their neutral charge, no Silica deposition can occur on these handles, as this is governed by electrostatic attraction between cationic Silica precursors and the poly-anionic DNA backbone. Therefore after transcription of the DNA origami structure into Silica, PNA handles will protrude from the Silica structure, available for hybridization with other nucleic acids. This results in Silica structures which are fully site-specifically addressable and can be site-specifically modified via nucleic acid hybridization, combining the accurate addressability of DNA origami with the chemical robustness of Silica. These structures will then be utilized both intra- and extracellularly for anti-sense therapy and immunotherapy respectively. By site-specifically positioning tumour necrosis factor superfamily ligands on the Silica surface in a specific geometry (e.g. hexagonally), these can cause cell death by pattern-specific interactions with extracellular death receptors, leading to “cell death by geometry”. Additionally, these novel Silica structures present perfect platforms for the realization of highly efficient enzyme cascades. Harnessing the ability to place a controlled number of different enzymes within a certain distance to one another, with the possibility to do so within the protective “pore” of a silicified DNA origami structure, will allow for enzyme protection and substrate channeling. Furthermore the conjugation of PNA handles positioned around the enzyme with different charged molecules can allow for precise engineering of pH in the local microenvironment around each enzyme. These factors will lead to highly increased catalytic throughput, opening up the possibility to create highly efficient enzymatic nano-factories.