DNA hydrogel
Scientists have long been looking for ways to develop gels that would be customizable, self-healing and sufficiently durable. Hydrogels consist of polymer molecules connected by chemical bonds; when the polymers are joined, the material becomes denser, and when they break in response to stress, the material turns into a liquid.
Due to their high biocompatibility, water solubility and temperature sensitivity, DNA strands with their ability to form complementary bonds can be used to connect polymer molecules.
Japanese researchers have created a controllable, elastic and temperature-sensitive gel using complementary DNA strands to connect polymer molecules in the form of stars. The gel and the method used to develop it will help in the development of tissue regeneration technologies, drug delivery and soft robotics. He led a group of researchers Xiang Li from Hokkaido University.
Lee and his colleagues used computer simulations to simulate different DNA sequences and their complementary chains to determine how these double strands would respond to temperature changes. The goal was to identify DNA sequences that only separate at temperatures above 63°C to ensure the stability of a potential gel in the human body.
The gel consists of complementary DNA strands (red and blue) connected to polyethylene glycol molecules (black). At lower temperatures, DNA strands form complementary bonds, forming a gel; as the temperature rises, the bonds break and the gel liquefies.
Based on the simulation results, they selected a pair of complementary DNA sequences to bind polyethylene glycol (PEG) molecules with four arms. To create a gel, DNA and PEG strands were separately placed in buffer solutions, and then combined in a test tube immersed in a container with hot water, which was then cooled to ambient temperature.
The researchers conducted a series of experiments and analyses to evaluate the properties of the resulting gel. It acted as predicted in the simulation, remaining elastic, self-healing and solid to its melting temperature of 63°C for several test cycles. The experiments also showed that PEG molecules were uniformly bound to each other by double strands of DNA and that liquid formation occurred when the strands separated.
The results obtained show that the new method allows to produce DNA gels with various viscoelastic properties using already available data on the thermodynamics and kinetics of DNA. The authors' next goal is to improve the understanding and application of this class of gels.
The article by M.Ohira et al. Star-Polymer-DNA Gels Showing Highly Predictable and Tunable Mechanical Responses is published in the journal Advanced Materials.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on materials from Hokkaido University: DNA design brings predictability to polymer gels.