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.
Highlights
We showed that the 3D structures of nanomaterials can be programmed efficiently via nucleic acid sequence, and that it is possible to direct the formation of percolating networks with DNA self-assembly
The situation is reversed and longer spacers constructed more solid-like hydrogels when using DNA/nanomaterial conjugates as crosslinkers. This is because the carbon nanotubes (CNTs) and AuNPs we used are much larger in scale compared to DNA molecules; having longer spacers helped to build more and more stable bridges between nanomaterial/crosslinker components
We found that shorter spacers form more solid-like hydrogels when combined with pure DNA crosslinkers, while longer spacers construct more solid-like hydrogels when assembled with DNA/nanomaterial crosslinkers
Summary
Self-assembly by molecular recognition is a fundamental property of soft matter that can be utilized as a building tool to construct nanoscale to macroscale materials via bottom-up approaches. Beyond self-assembly, DNA is biocompatible and can be readily conjugated with other bio-/nanomaterials including proteins and conductive polymers [6,7,8,9]. Leveraging these capabilities, DNA-based hydrogels have drawn a lot of attention starting with basic research and moving to applications such as biomedicine, biosensing, and drug delivery [10,11,12,13,14,15]
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