A Supra‐photoswitch Involving Sandwiched DNA Base Pairs and Azobenzenes for Light‐Driven Nanostructures and Nanodevices

A supra‐photoswitch is designed for complete ON/OFF switching of DNA hybridization by light irradiation for the purpose of using DNA as a material for building nanostructures. Azobenzenes, attached to D ‐threoninols that function as scaffolds, are introduced into each DNA strand after every two natural nucleotides (in the form (NNX)n where N and X represent the natural nucleotide and the azobenzene moiety, respectively). Hybridization of these two modified strands forms a supra‐photoswitch consisting of alternating natural base pairs and azobenzene moieties. In this newly designed sequence, each base pair is sandwiched between two azobenzene moieties and all the azobenzene moieties are separated by base pairs. When the duplex is irradiated by visible light, the azobenzene moieties take the trans form and this duplex is surprisingly stable compared to the corresponding native duplex composed of only natural oligonucleotides. On the other hand, when the azobenzene moieties are isomerized to the cis form by UV light irradiation, the duplex is completely dissociated. Based on this design, a DNA hairpin structure is synthesized that should be closed by visible light irradiation and opened by UV light irradiation at the level of a single molecule. Indeed, perfect ON/OFF photoregulation is attained. This is a promising strategy for the design of supra‐photoswitches such as photoresponsive sticky ends on DNA nanodevices and other nanostructures.     

Biomimetic Compartments Scaffolded by Nucleic Acid Nanostructures

The behaviors of living cells are governed by a series of regulated and confined biochemical reactions. The design and successful construction of synthetic cellular reactors can be useful in a broad range of applications that will bring significant scientific and economic impact. Over the past few decades, DNA self‐assembly has enabled the design and fabrication of sophisticated 1D, 2D, and 3D nanostructures, and is applied to organizing a variety of biomolecular components into prescribed 2D and 3D patterns. In this Concept, the recent and exciting progress in DNA‐scaffolded compartmentalizations and their applications in enzyme encapsulation, lipid membrane assembly, artificial transmembrane nanopores, and smart drug delivery are in focus. Taking advantage of these features promises to deliver breakthroughs toward the attainment of new synthetic and biomimetic reactors.     

On‐Electrode Synthesis of Shape‐Controlled Hierarchical Flower‐Like Gold Nanostructures for Efficient Interfacial DNA Assembly and Sensitive Electrochemical Sensing of MicroRNA

The performance for biomolecular detection is closely associated with the interfacial structure of a biosensor, which profoundly affects both thermodynamics and kinetics of the assembly, binding and signal transduction of biomolecules. Herein, it is reported on a one‐step and template‐free on‐electrode synthesis method for making shape‐controlled gold nanostructures on indium tin oxide substrates, which provide an electrochemical sensing platform for ultrasensitive detection of nucleic acids. Thus‐prepared hierarchical flower‐like gold nanostructures (HFGNs) possess large surface area that can readily accommodate the assembly of DNA probes for subsequent hybridization detection. It is found that the sensitivity for electrochemical DNA sensing is critically dependent on the morphology of HFGNs. By using this new strategy, a highly sensitive electrochemical biosensor is developed for label‐free detection of microRNA‐21 (miRNA‐21), a biomarker for lung cancers. Importantly, it is demonstrated that this biosensor can be employed to measure the miRNA‐21 expression level from human lung cancer cell (A549) lysates and worked well in 100% serum, suggesting its potential for applications in clinical diagnosis and a wide range of bioanalysis.     

Functional DNA Nanostructures for Photonic and Biomedical Applications

DNA nanostructures, especially DNA origami, receive close interest because of the programmable control over their shape and size, precise spatial addressability, easy and high‐yield preparation, mechanical flexibility, and biocompatibility. They have been used to organize a variety of nanoscale elements for specific functions, resulting in unprecedented improvements in the field of nanophotonics and nanomedical research. In this review, the discussion focuses on the employment of DNA nanostructures for the precise organization of noble metal nanoparticles to build interesting plasmonic nanoarchitectures, for the fabrication of visualized sensors and for targeted drug delivery. The effects offered by DNA nanostructures are highlighted in the areas of nanoantennas, collective plasmonic behaviors, single‐molecule analysis, and cancer‐cell targeting or killing. Finally, the challenges in the field of DNA nanotechnology for realistic application are discussed and insights for future directions are provided.     

Amorphous Ni(OH)2 Nanoboxes: Fast Fabrication and Enhanced Sensing for Glucose

Inspired by Pearson's hard and soft acid‐base (HSAB) principle, uniform amorphous Ni(OH)₂ nanoboxes with intact shell structures and various sizes are quickly fabricated by deliberately selecting S₂O₃^2? as the coordinating etchant toward Cu₂O templates and optimizing the reaction conditions. It is found that not only the solvent system but also the employing of a surfactant is vital for the fabrication of the nanoboxes. Ni(OH)₂ nanoboxes, as an example, demonstrate an improved electrochemical sensing ability for glucose, which might be due to their amorphous and hollow structural features.     

DNA Nanostructures Carrying Stoichiometrically Definable Antibodies

Targeted drug delivery is one of the key challenges in cancer nanomedicine. Stoichiometric and spatial control over the antibodies placement on the nanomedicine vehicle holds a pivotal role to overcome this key challenge. Here, a DNA tetrahedral is designed with available conjugation sites on its vertices, allowing to bind one, two, or three cetuximab antibodies per DNA nanostructure. This stoichiometrically definable cetuximab conjugated DNA nanostructure shows enhanced targeting on the breast cancer cells, which results with higher overall killing efficacy of the cancer cells.     

Cryopreservation of DNA Origami Nanostructures

Although DNA origami nanostructures have found their way into numerous fields of fundamental and applied research, they often suffer from rather limited stability when subjected to environments that differ from the employed assembly conditions, that is, suspended in Mg²⁺‐containing buffer at moderate temperatures. Here, means for efficient cryopreservation of 2D and 3D DNA origami nanostructures and, in particular, the effect of repeated freezing and thawing cycles are investigated. It is found that, while the 2D DNA origami nanostructures maintain their structural integrity over at least 32 freeze–thaw cycles, ice crystal formation makes the DNA origami gradually more sensitive toward harsh sample treatment conditions. Whereas no freeze damage could be detected in 3D DNA origami nanostructures subjected to 32 freeze–thaw cycles, 1000 freeze–thaw cycles result in significant fragmentation. The cryoprotectants glycerol and trehalose are found to efficiently protect the DNA origami nanostructures against freeze damage at concentrations between 0.2 × 10^?3 and 200 × 10^?3 m and without any negative effects on DNA origami shape. This work thus provides a basis for the long‐term storage of DNA origami nanostructures, which is an important prerequisite for various technological and medical applications.     

Chiral Shell Core–Satellite Nanostructures for Ultrasensitive Detection of Mycotoxin

Herein, the design of a DNA‐based chiral biosensor is described utilizing the self‐assembly of shell core–gold (Au) satellite nanostructures for the detection of mycotoxin, ochratoxin A (OTA). The assembly of core–satellite nanostructures based on OTA‐aptamer binding exhibits a strong chiral signal with an intense circular dichroism (CD) peak. The integrity of the assembly of core–satellite nanostructures is limited to some extent in the presence of different levels of OTA. Correspondingly, the chiral intensity of assembly is weakened with increasing OTA concentrations, allowing quantitative determination of the target. The developed chiral sensor shows an excellent linear relationship between the CD signal and concentrations of OTA in the range of 0.1–5 pg mL^?1 with a limit of detection as low as 0.037 pg mL^?1. The effectiveness of the biosensor in a sample of red wine is verified and a good recovery rate is obtained. These results suggest that the strategy has great potential for practical application.     

DNA纳米结构在药物载体与控制释放中的应用

本文首先介绍了G四链体、双链结构、纳米管、折纸和立体笼状结构等DNA纳米结构用于药物载体时的载药特点;随后根据不同的刺激方式,从生物分子、pH、光和其他响应四个方面介绍了DNA纳米结构控制药物释放的途径及其利弊;进而对后续的研究提出了两点发展建议。     

Mechano‐Based Transductive Sensing for Wearable Healthcare

Wearable healthcare presents exciting opportunities for continuous, real‐time, and noninvasive monitoring of health status. Even though electrochemical and optical sensing have already made great advances, there is still an urgent demand for alternative signal transformation in terms of miniaturization, wearability, conformability, and stretchability. Mechano‐based transductive sensing, referred to the efficient transformation of biosignals into measureable mechanical signals, is claimed to exhibit the aforementioned desirable properties, and ultrasensitivity. In this Concept, a focus on pressure, strain, deflection, and swelling transductive principles based on micro‐/nanostructures for wearable healthcare is presented. Special attention is paid to biophysical sensors based on pressure/strain, and biochemical sensors based on microfluidic pressure, microcantilever, and photonic crystals. There are still many challenges to be confronted in terms of sample collection, miniaturization, and wireless data readout. With continuing efforts toward solving those problems, it is anticipated that mechano‐based transduction will provide an accessible route for multimode wearable healthcare systems integrated with physical, electrophysiological, and biochemical sensors.     

A Molecular Hero Suit for In Vitro and In Vivo DNA Nanostructures

Precise control of DNA base pairing has rapidly developed into a field full of diverse nanoscale structures and devices that are capable of automation, performing molecular analyses, mimicking enzymatic cascades, biosensing, and delivering drugs. This DNA‐based platform has shown the potential of offering novel therapeutics and biomolecular analysis but will ultimately require clever modification to enrich or achieve the needed “properties” and make it whole. These modifications total what are categorized as the molecular hero suit of DNA nanotechnology. Like a hero, DNA nanostructures have the ability to put on a suit equipped with honing mechanisms, molecular flares, encapsulated cargoes, a protective body armor, and an evasive stealth mode.     

Biocomputing with Nanostructures on Lipid Bilayers

Biocomputation is the algorithmic manipulation of biomolecules. Nanostructures, most notably DNA nanostructures and nanoparticles, become active substrates for biocomputation when modified with stimuli‐responsive, programmable biomolecular ligands. This approach—biocomputing with nanostructures (“nano‐bio computing”)—allows autonomous control of matter and information at the nanoscale; their dynamic assemblies and beneficial properties can be directed without human intervention. Recently, lipid bilayers interfaced with nanostructures have emerged as a new biocomputing platform. This new nano‐bio interface, which exploits lipid bilayers as a chemical circuit board for information processing, offers a unique reaction space for realizing nanostructure‐based computation at a previously unexplored dimension. In this Concept, recent advances in nano‐bio computing are briefly reviewed and the newly emerging concept of biocomputing with nanostructures on lipid bilayers is introduced.