Layer-by-Layer modified DNA Origami Nanostructures as a Smart Tool for Drug Delivery

DNA折纸纳米结构是由长的单链DNA和短的连接寡核苷酸组成的三维结构，在细胞内作为智能药物递送系统（sDDS）的应用中具有高度的通用性。与其他DDS相比，它们可以通过在结构上添加锁定元件来方便地配备“可编程”盖子，可以通过特定的钥匙打开。然而，对于生物医学应用，仍然存在几个缺点：由于低摄取和具有特定功能组分的有限设备，对所需细胞的可控应用和细胞质的可及性受到严重限制。特别是，在富含蛋白酶和酶的环境中以及低盐浓度下，稳定性非常有限;通常在血清和内溶酶体细胞区室中发现的条件。在这个项目中，我们的重点是通过研究以不同方法在折纸上逐层（LbL）的聚合物涂层来解决这些缺点：1）将通过整合折纸纳米结构设计微米大小的混合载体（3-5µm）（可转换性，受控爆发释放）（保护、受控折纸释放、功能部件/关键元件的独立组装）组装在球形模板上。结合这两种载体类型的优点，可以以确定的方式研究折纸特性，并且已经可以使用多功能药物递送载体。2)这种混合载体将被缩小尺寸（100- 500 nm），以增强血液中的运输性能。3)LbL技术将通过调整生物聚合物涂层条件转移到折纸纳米结构（40- 120 nm）本身上。在所有三种方法中，重点是保留锁开口以及向多层添加功能组件。 在这种情况下，设计，所需的效果和效率将在模型和细胞条件下，以及通过应用模型和特定（siRNA）代理进行研究。这些调查将大大加强确定交付的选择。

DNA origami nanostructures, three-dimensional formations made of long single-stranded scaffold DNA and short connecting staple oligonucleotides, possess a high versatility in application as smart drug delivery systems (sDDS) in cells. Compared to other DDS, they can be conveniently equipped with “programmable” lids by adding lock elements to the structure, which can be opened by a specific key. However, for biomedical applications several drawbacks still remain: A controllable application to the desired cells and the accessibility of the cytoplasm are severely limited due to low uptake and limited equipment with specific functional components. Particularly, stability is very restricted in protease- and enzyme-rich environments as well as low salt concentrations; conditions usually found in blood serum and endolysosomal cell compartments.In this project our emphasis is on those drawbacks by investigating layer-by-layer (LbL) based polymer coating on origami in different approaches: 1) Micrometer-sized hybrid carriers (3-5µm) will be designed by integrating origami nanostructures (switchability, controlled burst release) in a LbL multilayer (protection, controlled origami release, independent assembly of functional components/key elements) assembled on a spherical template. Combining the advantages of both carrier types, origami properties can be investigated in a defined way as well as a multifunctional carrier for drug delivery is already available. 2) This hybrid carrier will be down-sized (100-500nm) to enhance the transport properties in blood. 3) The LbL technique will be transferred onto the origami nanostructure (40-120nm) itself by adapting the biopolymer coating conditions.Within all three approaches, the emphasis is on the preservation of the lock opening as well as the addition of functional components to the multilayer. In this context, design, desired effect and efficiency will be studied under model and cellular conditions as well as by application of model and specific (siRNA) agents. Those investigations will strongly enhance the options of defined delivery.