DNA折纸术研究进展

DNA折纸术是近年来提出的一种全新的DNA自组装的方法,是DNA纳米技术与DNA自组装领域的一个重大进展。与传统的DNA自组装技术不同,DNA折纸术通过将一条长的DNA单链（通常为基因组DNA）与一系列经过设计的短DNA片段进行碱基互补,能够可控地构造出高度复杂的纳米图案或结构,在新兴的纳米领域中具有广泛的潜在应用。本文在介绍DNA折纸术相关原理的基础上,就DNA折纸术的起源、发展及其在DNA芯片、纳米元件与材料等领域的潜在应用进行了概述,探讨了DNA折纸术未来可能的发展方向。     

DNA纳米机器:梦想照进现实

可进体内治病救人的纳米机器人一直是人们梦寐以求的未来科技和医疗手段.最近,国家纳米科学中心的丁宝全、聂广军等在这个方向取得了重要的突破,成功开发了基于DNA纳米机器的癌症免疫治疗疫苗.他们首先利用DNA折纸术构筑了一个可精确负载抗原和佐剂的管状结构,通过皮下注射递送至淋巴结,经由内吞在树突细胞内涵体内发生pH响应性的锁链打开,暴露抗原和佐剂,从而激活树突细胞,产生抗原特异性的T细胞,有效杀伤肿瘤细胞.该疫苗不仅可以有效抑制肿瘤的生长和复发,还诱导特异性记忆效应,可持续产生特异性的保护.这提供了一个精准递送分子药物的平台,让人看到成功发展纳米机器人的曙光,有望给医学和医疗保健带来重要变革.     

DNA折纸术纳米反应器

基于DNA折纸技术,构建具有纳米尺度可寻址的新型DNA纳米反应器,是DNA纳米技术领域的一个最新研究思路和方向。它的优势首先在于其纳米定位能力,通过不同的化学或生物相互作用,已能够实现对包括化学小分子、生物大分子及人工纳米材料等的纳米级精确定位;其次,DNA折纸结构的丰富多样性,使构建纳米级仿生限域环境成为了可能;此外,DNA折纸结构本身的生物相容性及优良的产率,也保证了这一材料的可应用性。本文首先介绍了在DNA折纸结构上,对不同材料和分子进行纳米定位的一般方法和最新进展。然后,着重阐述了基于纳米定位技术,以DNA折纸结构作为纳米反应器,对一些化学、生化反应的成功调控。最后,基于现有的工作基础,我们提出了DNA折纸术纳米反应器概念在未来的发展方向及应用前景展望。     

DNA纳米结构在药物转运载体和智能载药中的应用进展

纳米材料具有荷载效率高、靶向性能好、半衰期较长等优点, 非常适于作为药物转运载体, 可有效提高药物的水溶性、稳定性和疾病治疗效果.目前, 开发具有良好生物相容性、可控靶向释放能力和精确载药位点的理想药物转运载体, 仍是该领域存在的挑战性问题和当前研究的重点.自组装DNA纳米结构是一类具有精确结构、功能多样的纳米生物材料, 具有良好的生物相容性和稳定性、较高的膜渗透性和可控靶向释放能力等优点, 是理想的药物转运载体和智能载药材料.本文总结了DNA纳米结构的发展历程、DNA纳米结构作为药物转运载体的研究现状、动态DNA纳米结构在智能载药中的应用进展, 并对其发展前景进行了展望.     

DNA自组装结构在纳米诊疗中的应用

DNA分子具有良好的生物相容性和可编程性,被广泛用于构建新型纳米生物材料.研究者利用DNA纳米技术已构建了尺寸、形貌及对称性精确可控且可对环境条件做出特异性响应的DNA自组装结构,它们在生物成像及检测、药物的精准输送等纳米诊疗领域有着极大的应用潜力.然而, DNA纳米材料应用于活体系统存在稳定性不足、细胞摄取效率不高以及药物的包裹及可控释放程度不够等问题.本文简述了DNA自组装结构的构建方法以及将这些结构用于生物成像、生物检测和药物载带方面的进展,概括了提高DNA自组装结构体内稳定性及细胞摄取效率的方法,最后讨论了DNA自组装结构应用于纳米诊疗中所面临的机遇与尚待解决的问题.     

介孔二氧化硅基智能递送体系的构建及其在各类疾病治疗中的应用

利用先进纳米技术开发的药物递送体系能够改善药物的理化性质和治疗效果,同时削弱其毒副作用,因而纳米药物递送体系成为现代药剂学研究的热点和主流方向。其中,介孔二氧化硅作为纳米载体的基质材料具有比表面积大、形貌结构可调、表面易于修饰及生物相容性良好等优点,引发生物医学研究人员的广泛关注,为构筑新型智能药物递送体系提供了新的设计思路。本文就介孔二氧化硅基智能递送体系在设计构筑和疾病治疗应用等方面的最新研究进展进行了综述。首先,本文对介孔硅的发展历程、制备方法及结构特性进行了简要概述;其次,从药物装载和门控释放两大角度系统阐述了近些年介孔硅基智能递送体系的构建策略,重点介绍了各种刺激响应性介孔硅基递送体系的门控开关(如聚合物、无机纳米颗粒、超分子组装体及生物大分子等)及其可控释放机制;随后,详细描述了介孔硅基控释体系在各种类型疾病(包括癌症、细菌感染、糖尿病和阿尔茨海默病等)治疗中的应用进展;最后,总结和分析了介孔硅基智能纳米载体研究中存在的问题并对其未来发展作了展望。     

磁应答型药物递送载体的设计与构建

复合磁性生物材料的发展和应用已引起生物医学领域的极大关注。磁性纳米粒子因其易功能化而具有靶向药物传递、可控药物释放及磁成像特性逐渐成为药物传递和新型诊疗领域最有前途的材料之一。基于磁性纳米粒子或掺杂的铁氧化物构建的远程触发磁性载药递送系统,有望实现在运输过程中携载药物不泄露的情况下,提高药物递送效率且对病灶周围的健康细胞无毒或低毒性。为构建理想的可控靶向磁性药物递送系统,多种材料或配体可以与磁性纳米粒子复合来构建更安全有效的磁性药物递送系统。一些生物分子、聚合物及天然产物等通过与磁性纳米粒子相结合,构建出可用于药物传递且具有独特性质的磁性复合新材料。迄今为止,具有磁场应答能力的磁性药物递送载体已经在远程控制药物释放领域得到了长足发展。本文总结了近年来磁性药物递送载体作为远程控制治疗体系在设计与构建上的研究进展。重点关注了磷脂分子、聚合物、多孔微纳米材料以及天然产物等与其构建的复合材料,并对当前磁性复合特定给药载体的优点、局限及发展前景等做了简要阐述。     

微纳米马达在药物递送中的应用

受到自然界中高效生物马达的启发,研究人员提出了人工微纳米马达的概念,即人工微纳米动力装置。目前,通过结合化学与其他交叉学科的先进技术,研究人员已制备出具有不同结构、驱动方式以及控制方式的人工微纳米马达。这些微纳米马达在传感、环境治理、生物医用等方面展现出广阔的应用前景。其中,药物递送是生物医用领域的重要方向。在这一方面,利用微纳米马达可以实现药物的有效递送,给癌症等疾病的治疗带来新的可能。本文将针对用于药物递送的微纳米马达的驱动机理、基本结构、运动控制这几个方面进行综述,首先介绍了马达的运动机理,其驱动机理可分为自场驱动和外场驱动;其次,分别介绍了可用于药物递送的微纳米马达的结构,主要包括聚合物囊泡、空心管、纳米线等;为了实现精准有效的药物递送,微纳米马达的可控运动非常重要,本文将具体阐述微纳米马达的开-关控制、方向控制和速度控制。最后,分析了药物递送微纳米马达的研究现状,并对本领域的未来方向进行了展望。     

铂类抗癌药物的多功能纳米递送体系

以顺铂为代表的小分子铂类抗癌药物是临床应用的一线化疗药物,但其严重的毒副作用和难以克服的耐药性限制了铂类药物的临床应用和研发。运用纳米药物递送技术可以实现药物的靶向递送和可控释放,来提高药物的生物利用度,降低药物的毒副作用以及耐药性,为癌症的治疗带来新的希望。此外,丰富多样的纳米递送体系易于实现药物与具有生物学活性试剂的共运输,从而为各种治疗策略以及诊疗策略的联用提供可能,为最终实现癌症的精准治疗展现广阔前景。本文从靶向递药、药物可控释放、联合治疗、诊疗一体化四个方面对铂类抗癌药物的多功能纳米递送体系在癌症治疗中的最新研究进展进行综述,同时通过列举最新研究成果,展示了新材料、新技术以及新颖设计思想在铂基纳米递送体系中的应用。     

功能性聚氨基酸纳米凝胶

聚合物纳米凝胶具有稳定的三维结构、高载药效率、刺激响应性等特性,在药物递送、基因治疗和生物成像等多个生物医学领域应用前景可期。聚氨基酸纳米凝胶由于其优异的生物相容性、性能易于调节、降解产物安全无毒等特性,在生物医学领域获得了广泛的关注。特别地,具有内源性刺激(例如:还原性、活性氧、pH和酶)或外源性刺激(例如:光和温度)响应能力的功能性聚氨基酸纳米凝胶可通过适度的转变达到药物递送可控的目的。本文系统地介绍了不同功能性聚氨基酸纳米凝胶的制备、应用和面临的挑战。     

Multivalent Aptamer-modified DNA Origami as Drug Delivery System for Targeted Cancer Therapy

In spite of great development in nanoparticle-based drug delivery systems(DDSs)for improved therapeutic efficacy,it remains challenging for effective delivery of chemotherapeutic drugs to targeted tumor cells.In this work,we report a triangle DNA origami as targeted DDS for cancer therapy.DNA origami shows excellent biocompatibility and stability in cell culture medium for 24 h.In addition,the DNA origami structures conjugated with multivalent aptamers enable for efficient delivery of anticancer drug doxorubicin(Dox)into targeted cancer cell due to their targeting function,reducing side effects associated with nonspecific distribution.Moreover,we also demonstrated that the multivalent aptamer-modified DNA origami loading Dox exhibits prominent therapeutic efficacy in vitro.Accordingly,this work provides a good paradigm for the development of DNA origami nanostructure-based targeted DDS for cancer therapy.     

DNA origami as a carrier for circumvention of drug resistance

Although a multitude of promising anti-cancer drugs have been developed over the past 50 years, effective delivery of the drugs to diseased cells remains a challenge. Recently, nanoparticles have been used as drug delivery vehicles due to their high delivery efficiencies and the possibility to circumvent cellular drug resistance. However, the lack of biocompatibility and inability to engineer spatially addressable surfaces for multi-functional activity remains an obstacle to their widespread use. Here we present a novel drug carrier system based on self-assembled, spatially addressable DNA origami nanostructures that confronts these limitations. Doxorubicin, a well-known anti-cancer drug, was non-covalently attached to DNA origami nanostructures through intercalation. A high level of drug loading efficiency was achieved, and the complex exhibited prominent cytotoxicity not only to regular human breast adenocarcinoma cancer cells (MCF?7), but more importantly to doxorubicin-resistant cancer cells, inducing a remarkable reversal of phenotype resistance. With the DNA origami drug delivery vehicles, the cellular internalization of doxorubicin was increased, which contributed to the significant enhancement of cell-killing activity to doxorubicin-resistant MCF?7 cells. Presumably, the activity of doxorubicin-loaded DNA origami inhibits lysosomal acidification, resulting in cellular redistribution of the drug to action sites. Our results suggest that DNA origami has immense potential as an efficient, biocompatible drug carrier and delivery vehicle in the treatment of cancer.     

A DNA Origami-Based Gene Editing System for Efficient Gene Therapy in Vivo

DNA nanostructures have played an important role in the development of novel drug delivery systems. Herein, we report a DNA origami-based CRISPR/Cas9 gene editing system for efficient gene therapy in vivo. In our design, a PAM-rich region precisely organized on the surface of DNA origami can easily recruit and load sgRNA/Cas9 complex by PAM-guided assembly and pre-designed DNA/RNA hybridization. After loading the sgRNA/Cas9 complex, the DNA origami can be further rolled up by the locking strands with a disulfide bond. With the incorporation of DNA aptamer and influenza hemagglutinin (HA) peptide, the cargo-loaded DNA origami can realize the targeted delivery and effective endosomal escape. After reduction by GSH, the opened DNA origami can release the sgRNA/Cas9 complex by RNase H cleavage to achieve a pronounced gene editing of a tumor-associated gene for gene therapy in vivo. This rationally developed DNA origami-based gene editing system presents a new avenue for the development of gene therapy.     

DNA Nanostructures for Targeted Antimicrobial Delivery

We report the use of DNA origami nanostructures, functionalized with aptamers, as a vehicle for delivering the antibacterial enzyme lysozyme in a specific and efficient manner. We test the system against Gram‐positive (Bacillus subtilis) and Gram‐negative (Escherichia coli) targets. We use direct stochastic optical reconstruction microscopy (dSTORM) and atomic force microscopy (AFM) to characterize the DNA origami nanostructures and structured illumination microscopy (SIM) to assess the binding of the origami to the bacteria. We show that treatment with lysozyme‐functionalized origami slows bacterial growth more effectively than treatment with free lysozyme. Our study introduces DNA origami as a tool in the fight against antibiotic resistance, and our results demonstrate the specificity and efficiency of the nanostructure as a drug delivery vehicle.     

Growth and Origami Folding of DNA on Nanoparticles for High‐Efficiency Molecular Transport in Cellular Imaging and Drug Delivery

A novel three‐dimensional (3D) superstructure based on the growth and origami folding of DNA on gold nanoparticles (AuNPs) was developed. The 3D superstructure contains a nanoparticle core and dozens of two‐dimensional DNA belts folded from long single‐stranded DNAs grown in situ on the nanoparticle by rolling circle amplification (RCA). We designed two mechanisms to achieve the loading of molecules onto the 3D superstructures. In one mechanism, ligands bound to target molecules are merged into the growing DNA during the RCA process (merging mechanism). In the other mechanism, target molecules are intercalated into the double‐stranded DNAs produced by origami folding (intercalating mechanism). We demonstrated that the as‐fabricated 3D superstructures have a high molecule‐loading capacity and that they enable the high‐efficiency transport of signal reporters and drugs for cellular imaging and drug delivery, respectively.     

Self-assembly of Micrometer-long DNA Nanoribbons with Four Oligonucleotides

DNA nanostructures have found widespread applications in areas including nanoelectronics and biomedicine. However, traditional DNA origami needs a long single‐stranded virus DNA and hundreds of short DNA strands, which make this method complicated and money‐consuming. Here, we present a protocol for the assembly of DNA nanoribbons with only four oligonucleotides. DNA nanoribbons with different dimensions were successfully assembled with a 96‐base scafford strand and three short staples. These biotinylated nanoribbons could also be decorated with streptavidins. This approach suggests that there exist great design spaces for the creation of simple nucleic acid nanostructures which could facilitate their application in plasmonic or drug delivery.     

Spatiotemporal Control over Polynucleotide Brush Growth on DNA Origami Nanostructures

DNA nanotechnology provides an approach to create precise, tunable, and biocompatible nanostructures for biomedical applications. However, the stability of these structures is severely compromised in biological milieu due to their fast degradation by nucleases. Recently, we showed how enzymatic polymerization could be harnessed to grow polynucleotide brushes of tunable length and location on the surface of DNA origami nanostructures, which greatly enhances their nuclease stability. Here, we report on strategies that allow for both spatial and temporal control over polymerization through activatable initiation, cleavage, and regeneration of polynucleotide brushes using restriction enzymes. The ability to site-specifically decorate DNA origami nanostructures with polynucleotide brushes in a spatiotemporally controlled way provides access to “smart” functionalized DNA architectures with potential applications in drug delivery and supramolecular assembly.     

Surface Assembly of DNA Origami on a Lipid Bilayer Observed Using High-Speed Atomic Force Microscopy

The micrometer-scale assembly of various DNA nanostructures is one of the major challenges for further progress in DNA nanotechnology. Programmed patterns of 1D and 2D DNA origami assembly using specific DNA strands and micrometer-sized lattice assembly using cross-shaped DNA origami were performed on a lipid bilayer surface. During the diffusion of DNA origami on the membrane surface, the formation of lattices and their rearrangement in real-time were observed using high-speed atomic force microscopy (HS-AFM). The formed lattices were used to further assemble DNA origami tiles into their cavities. Various patterns of lattice–tile complexes were created by changing the interactions between the lattice and tiles. For the control of the nanostructure formation, the photo-controlled assembly and disassembly of DNA origami were performed reversibly, and dynamic assembly and disassembly were observed on a lipid bilayer surface using HS-AFM. Using a lipid bilayer for DNA origami assembly, it is possible to perform a hierarchical assembly of multiple DNA origami nanostructures, such as the integration of functional components into a frame architecture.     

Multifunctional DNA Origami Nanoplatforms for Drug Delivery

DNA nanotechnology has been employed in the construction of self‐assembled nano‐biomaterials with uniform size and shape for various biological applications, such as bioimaging, diagnosis, or therapeutics. Herein, recent successful efforts to utilize multifunctional DNA origami nanoplatforms as drug‐delivery vehicles are reviewed. Diagnostic and therapeutic strategies based on gold nanorods, chemotherapeutic drugs, cytosine–phosphate–guanine, functional proteins, gene drugs, and their combinations for optoacoustic imaging, photothermal therapy, chemotherapy, immunological therapy, gene therapy, and coagulation‐based therapy are summarized. The challenges and opportunities for DNA‐based nanocarriers for biological applications are also discussed.     

Fabrication of Defined Polydopamine Nanostructures by DNA Origami‐Templated Polymerization

A versatile, bottom‐up approach allows the controlled fabrication of polydopamine (PD) nanostructures on DNA origami. PD is a biosynthetic polymer that has been investigated as an adhesive and promising surface coating material. However, the control of dopamine polymerization is challenged by the multistage‐mediated reaction mechanism and diverse chemical structures in PD. DNA origami decorated with multiple horseradish peroxidase‐mimicking DNAzyme motifs was used to control the shape and size of PD formation with nanometer resolution. These fabricated PD nanostructures can serve as “supramolecular glue” for controlling DNA origami conformations. Facile liberation of the PD nanostructures from the DNA origami templates has been achieved in acidic medium. This presented DNA origami‐controlled polymerization of a highly crosslinked polymer provides a unique access towards anisotropic PD architectures with distinct shapes that were retained even in the absence of the DNA origami template.