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骨架DNA和短连接的短序列寡核苷酸组成的三维结构，作为细胞内的智能药物递送系统(SDDS)具有很强的通用性。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的盖子，可以用特定的钥匙打开。然而，对于生物医学应用来说，仍然存在一些缺点：由于摄取率低和具有特定功能成分的设备有限，对所需细胞的可控应用和细胞质的可获得性严重受限。在这个项目中，我们的重点是通过不同的方法研究基于层层(LBL)的聚合物涂层在折纸上的这些缺点：1)微米尺寸的杂化载体(3-5微米)将通过将折纸纳米结构(可切换，可控突发释放)集成到在球形模板上组装的LBL多层(保护，受控的折纸释放，功能部件/关键元件的独立组装)来设计。结合这两种载体类型的优点，折纸特性可以用定义的方式进行研究，并且用于药物输送的多功能载体已经可用。2)这种混合载体将缩小尺寸(100-500 nm)，以增强其在血液中的传输特性。3)通过改变生物聚合物涂层的条件，将LBL技术转移到折纸纳米结构(40-120 nm)上，在这三种方法中，重点都是保护锁的开口以及在多层中添加功能成分。在这方面，将在模型和细胞条件下以及通过应用模型和特定的(SiRNA)试剂来研究设计、预期效果和效率。这些调查将有力地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.