Kinetically Interlocking Multiple-Units Polymerization of DNA Double Crossover and Its Application in Hydrogel Formation

Constructing Stiffness Tunable DNA Hydrogels Based on DNA Modules with Adjustable Rigidity

DNA hydrogel represents a potent material for crafting biological scaffolds, but the toolbox to systematically regulate the mechanical property is still limited. Herein, we have provided a strategy to tune the stiffness of DNA hydrogel through manipulating the rigidity of DNA modules. By introducing building blocks with higher molecular rigidity and proper connecting fashion, DNA hydrogel stiffness could be systematically elevated. These hydrogels showed excellent dynamic properties and biocompatibility, thus exhibiting great potential in three-dimensional (3D) cell culture. This study has offered a systematic method to explore the structure-property relationship, which may contribute to the development of more intelligent and personalized biomedical platforms.

Preparation Strategies, Functional Regulation, and Applications of Multifunctional Nanomaterials-Based DNA Hydrogels

With the extensive attention of DNA hydrogels in biomedicine, biomaterial, and other research fields, more and more functional DNA hydrogels have emerged to match the various needs. Incorporating nanomaterials into the hydrogel network is an emerging strategy for functional DNA hydrogel construction. Surprisingly, nanomaterials-based DNA hydrogels can be engineered to possess favorable properties, such as dynamic mechanical properties, excellent optical properties, particular electrical properties, perfect encapsulation properties, improved magnetic properties, and enhanced antibacterial properties. Herein, the preparation strategies of nanomaterials-based DNA hydrogels are first highlighted and then different nanomaterial designs are used to demonstrate the functional regulation of DNA hydrogels to achieve specific properties. Subsequently, representative applications in biosensing, drug delivery, cell culture, and environmental protection are introduced with some selected examples. Finally, the current challenges and prospects are elaborated. The study envisions that this review will provide an insightful perspective for the further development of functional DNA hydrogels.

Rational Design of DNA Hydrogels Based on Molecular Dynamics of Polymers

In recent years, DNA has emerged as a fascinating building material to engineer hydrogel due to its excellent programmability, which has gained considerable attention in biomedical applications. Understanding the structure-property relationship and underlying molecular determinants of DNA hydrogel is essential to precisely tailor its macroscopic properties at molecular level. In this review, the rational design principles of DNA molecular networks based on molecular dynamics of polymers on the temporal scale, which can be engineered via the backbone rigidity and crosslinking kinetics, are highlighted. By elucidating the underlying molecular mechanisms and theories, it is aimed to provide a comprehensive overview of how the tunable DNA backbone rigidity and the crosslinking kinetics lead to desirable macroscopic properties of DNA hydrogels, including mechanical properties, diffusive permeability, swelling behaviors, and dynamic features. Furthermore, it is also discussed how the tunable macroscopic properties make DNA hydrogels promising candidates for biomedical applications, such as cell culture, tissue engineering, bio-sensing, and drug delivery.

Reinforcing supramolecular hyaluronan hydrogels via kinetically interlocking multiple-units strategy

Supramolecular hydrogels exhibit promising potential in biological and clinical fields due to their special dynamic properties. However, most existing supramolecular hydrogels suffer from poor mechanical strength, which severely limits their applications. Here in this study, the Kinetically Interlocking Multiple-Units (KIMU) strategy was applied to the hyaluronan networks by introducing different supramolecular interaction motifs in an organized and alternative manner. Our strategy successfully elevated the energy barrier of crosslinker dissociation to 103.0 kJ mol^-1 and increased the storage modulus of hydrogels by 78 % with the intrinsic dynamic properties preserved. It can be expected that this method would bring a convenient and effective route to fabricate novel supramolecular materials with excellent mechanical properties.

DNA Materials Assembled from One DNA Strand

Due to the specific base-pairing recognition, clear nanostructure, programmable sequence and responsiveness of the DNA molecule, DNA materials have attracted extensive attention and been widely used in controlled release, drug delivery and tissue engineering. Generally, the strategies for preparing DNA materials are based on the assembly of multiple DNA strands. The construction of DNA materials using only one DNA strand can not only save time and cost, but also avoid defects in final assemblies generated by the inaccuracy of DNA ratios, which potentially promote the large-scale production and practical application of DNA materials. In order to use one DNA strand to form assemblies, the sequences have to be palindromes with lengths that need to be controlled carefully. In this review, we introduced the development of DNA assembly and mainly summarized current reported materials formed by one DNA strand. We also discussed the principle for the construction of DNA materials using one DNA strand.

Small Molecule-Templated DNA Hydrogel with Record Stiffness Integrates and Releases DNA Nanostructures and Gene Silencing Nucleic Acids

Deoxyribonucleic acid (DNA) hydrogels are a unique class of programmable, biocompatible materials able to respond to complex stimuli, making them valuable in drug delivery, analyte detection, cell growth, and shape-memory materials. However, unmodified DNA hydrogels in the literature are very soft, rarely reaching a storage modulus of 10³  Pa, and they lack functionality, limiting their applications. Here, a DNA/small-molecule motif to create stiff hydrogels from unmodified DNA, reaching 10⁵  Pa in storage modulus is used. The motif consists of an interaction between polyadenine and cyanuric acid-which has 3-thymine like faces-into multimicrometer supramolecular fibers. The mechanical properties of these hydrogels are readily tuned, they are self-healing and thixotropic. They integrate a high density of small, nontoxic molecules, and are functionalized simply by varying the molecule sidechain. They respond to three independent stimuli, including a small molecule stimulus. These stimuli are used to integrate and release DNA wireframe and DNA origami nanostructures within the hydrogel. The hydrogel is applied as an injectable delivery vector, releasing an antisense oligonucleotide in cells, and increasing its gene silencing efficacy. This work provides tunable, stimuli-responsive, exceptionally stiff all-DNA hydrogels from simple sequences, extending these materials' capabilities.

Design and application of stimuli-responsive DNA hydrogels: A review

Deoxyribonucleic acid (DNA) hydrogels combine the properties of DNAs and hydrogels, and adding functionalized DNAs is key to the wide application of DNA hydrogels. In stimuli-responsive DNA hydrogels, the DNA transcends its application in genetics and bridges the gap between different fields. Specifically, the DNA acts as both an information carrier and a bridge in constructing DNA hydrogels. The programmability and biocompatibility of DNA hydrogel make it change macroscopically in response to a variety of stimuli. In order to meet the needs of different scenarios, DNA hydrogels were also designed into microcapsules, beads, membranes, microneedle patches, and other forms. In this study, the stimuli were classified into single biological and non-biological stimuli and composite stimuli. Stimuli-responsive DNA hydrogels from the past five years were summarized, including but not limited to their design and application, in particular logic gate pathways and signal amplification mechanisms. Stimuli-responsive DNA hydrogels have been applied to fields such as sensing, nanorobots, information carriers, controlled drug release, and disease treatment. Different potential applications and the developmental pro-spects of stimuli-responsive DNA hydrogels were discussed.

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DNA hydrogel, favored by researchers, combines properties of DNA and hydrogels.

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Both DNA and skeleton, having many response characteristics, can respond to stimuli.

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Sensing, nano robots, information carriers, drug delivery, and disease treatment uses.

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Three stimulus response types: single biological, single abiotic and compound.

Shear-Thinning and Designable Responsive Supramolecular DNA Hydrogels Based on Chemically Branched DNA

A novel supramolecular DNA hydrogel system was designed based on a directly synthesized chemically branched DNA. For the hydrogel formation, a self-dimer DNA with two sticky ends was designed as the linker to induce the gelation of B-Y. By programing the linker sequence, thermal and metal-ion responsiveness could be introduced into this hydrogel system. This supramolecular DNA hydrogel shows shear-thinning, designable responsiveness, and good biocompatibility, which will simplify the hydrogel composition and preparation process of the supramolecular DNA hydrogel and accelerate its biomedical applications.