Mechanical and Electrical Properties of DNA Hydrogel-Based Composites Containing Self-Assembled Three-Dimensional Nanocircuits

Abstract

Molecular self-assembly of DNA has been developed as an effective construction strategy for building complex materials. Among them, DNA hydrogels are known for their simple fabrication process and their tunable properties. In this study, we have engineered, built, and characterized a variety of pure DNA hydrogels using DNA tile-based crosslinkers and different sizes of linear DNA spacers, as well as DNA hydrogel/nanomaterial composites using DNA/nanomaterial conjugates with carbon nanotubes and gold nanoparticles as crosslinkers. We demonstrate the ability of this system to self-assemble into three-dimensional percolating networks when carbon nanotubes and gold nanoparticles are incorporated into the DNA hydrogel. These hydrogel composites showed interesting non-linear electrical properties. We also demonstrate the tuning of rheological properties of hydrogel-based composites using different types of crosslinkers and spacers. The viscoelasticity of DNA hydrogels is shown to dramatically increase by the use of a combination of interlocking DNA tiles and DNA/carbon nanotube crosslinkers. Finally, we present measurements and discuss electrically conductive nanomaterials for applications in nanoelectronics.

Towards conductive hydrogels in e-skins: a review on rational design and recent developments

“…As mentioned above, self-assembly is also a critical approach to fabricate supramolecular hydrogels, endowing the hydrogels with self-healing ability, which plays a signicant role for electronic skins. 129 Owing to the various categories of driving forces, such as p-p stacking, [126][127][128][129][130][131] hydrophobic interaction, 36,135,136 van der Waals forces, 137 hydrogen bonds 134 and electrostatic interactions, 132,133 self-assembly can be adopted into different kinds of hydrogel synthesis, conferring a superior degree of selfhealing capacity in the materials.…”

“…Compared with polymerization, conductive hydrogels prepared by self-assembly can typically achieve weaker interactions such as p-p stacking, electrostatic interactions, van der Waals forces, hydrogen bonds, and hydrophobic interactions. [126][127][128][129][130][131][132][133][134][135][136][137] Accordingly, better functionalities, mechanical properties, and interfacial affinity can be achieved for self-assembled hydrogels, improving the biocompatibility of synthetic polymers. 38 Moreover, self-assembly plays a vital role in generating multifunctional conductive hydrogels in comparison with the copolymerization and doping strategies because no reactions are involved during this process.…”

“…149 In most cases, the hydrophobic interaction takes place between nanoparticles, driving the formation of self-assembled networks. 135,136 Xu et al developed an electroconductive hydrogel based on selfassembling PEDOT:PSS and PEG-peptide together, which is mainly driven by hydrophobic interactions between PEDOT nanoparticles, and p-p stacking among PSS and PEDOT, attributing to the self-healing ability of the hydrogel, and it can be applied in adopting cell cultures. 135 Recently, Gao and co-authors successfully developed a DNA-based hydrogel, which was incorporated by conductive CNTs and AuNPs nanoparticles through self-assembly.…”

“…135 Recently, Gao and co-authors successfully developed a DNA-based hydrogel, which was incorporated by conductive CNTs and AuNPs nanoparticles through self-assembly. 136 In their work, the DNA chains are wrapped around the CNT walls via strong hydrophobic interactions, promoting the assembly of the hydrogel, which exhibits excellent conductivity and mechanical properties, approaching a more desirable application in exible electronic devices. 136 Hydrogen bond and hydrophobic powered conductive hydrogels demonstrate a strong impact in the applications of electronic skins, especially for exible strain sensors for monitoring devices in the biomedical eld.…”

“…136 In their work, the DNA chains are wrapped around the CNT walls via strong hydrophobic interactions, promoting the assembly of the hydrogel, which exhibits excellent conductivity and mechanical properties, approaching a more desirable application in exible electronic devices. 136 Hydrogen bond and hydrophobic powered conductive hydrogels demonstrate a strong impact in the applications of electronic skins, especially for exible strain sensors for monitoring devices in the biomedical eld. 150,151 Liu et al prepared a strain sensor based on GelMA-TA-carbon hydrogel, which was driven by hydrogen bonding with superior mechanical properties, exibility, and adhesiveness.…”