Monday, May 16, 2022

A polymer-DNA gel that could be used in tissue regeneration and robotics

DNA design brings predictability to polymer gels.

For a long time, scientists have been finding better ways to develop gels that can be used in various applications, including in the fields of medicine and engineering. Such gels should be predictable in nature, self-healing, and durable for severe jobs.

DNA duplexes are ideal crosslinkers for building such gels. These gels have excellent sequence addressability and flexible tunability in bond energy. However, the mechanical responses of most DNA gels are complicated and unpredictable.

Scientists from Hokkaido University have created a polymer-DNA gel that is tuneable, elastic, and temperature-sensitive. They used complementary DNA strands to connect star-shaped polymer molecules.

DNA strands have high biocompatibility, water solubility, and temperature sensitivity. Thanks to their ability to form complementary bonds, they are ideal for linking polymer molecules. However, it isn’t easy to use DNA links to develop homogeneous gels with on-demand elastic properties.

Scientists solved this problem by using software programs to simulate the formation of different DNA sequences and their complementary strands. Through this, they determined how these double strands respond to changes in temperature. They also identified complementary DNA sequences that would only disconnect above 63°C to ensure a potential gel’s stability in the human body.

Scientists chose a pair of complementary DNA sequences based on the simulation to link four-armed molecules of polyethylene glycol (PEG). They prepared the gel by dissolving DNA strands and PEG separately in buffer solutions before mixing them in a test tube immersed in a hot water bath that cooled to ambient temperature. Finally, they conducted a series of experiments and analyses to evaluate the resulting gel’s properties.

The gel was performed as predicted by simulations. It remains elastic, self-healing, and solid until its melting temperature of 63°C over multiple testing cycles.

Scientists also found that the DNA double strands homogeneously link the PEG molecules. When the strands separate, it leads to liquid formation.

Xiang Li at Hokkaido University said“Our findings suggest that we will be able to fabricate DNA gels with on-demand viscoelastic properties by making use of already available data on DNA thermodynamics and kinetics. The aim will be to improve the understanding and applications of this class of gel.”

Journal Reference:

  1. Masashi Ohira,Takuya Kawashima et al. Star-Polymer–DNA Gels Showing Highly Predictable and Tunable Mechanical Responses. DOI: 10.1002/adma.202108818

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