Biomaterials are used within or in close proximity to the body, and therefore must be absolutely safe and reliable. We are developing the ultimate body-friendly biomaterial by combining two types of materials: DNA, which resides in all living beings on earth, and polyethylene glycol, which is widely used in cosmetics and food additives. In this development process, we used a special four-stranded DNA structure called “DNA G-quadraplexes” and a manufacturing method called “liquid-phase large-scale DNA synthesis technique,” which both of them have received little attention till date. -

DNA stores information in sequences of four nucleobases: adenine (A), thymine (T), guanine (G), and cytosine (C). DNA G-quadraplexes are likely to form when the DNA sequence consists of consecutive G bases. Usually, DNA adopts the famous right-handed double helix structure, which features A-T and G-C base pairs. The G base behaves somewhat differently from the other bases; four G bases will chase each other like a dog chasing its tail, creating a loop. Sodium ions and potassium ions help in formation of G-quadraplexes. Therefore, in sequences containing four G bases, the G bases will connect together, resulting in a quadraplex structure. These DNA G-quadraplexes are created in our body by telomeres, which are sequences at each end of a chromosome which determines the life of the cells therein. -



A notable feature of DNA G-quadraplexes is that they are much more stable than common double helix structures. Therefore, if one lays down G.G.G.G. structures at each end of a polyethylene glycol string, one can create a gel material that will harden immediately with the addition of sodium or potassium ions. There is an abundance of sodium ions in blood and other body fluids. The “DNA G-quadraplex gel” we have developed will harden immediately when it reacts with a body fluid (such as blood, tears, sweat, or saliva). The effect may be too quick for certain applications, making it necessary to find ways to slow down the process. It is also very easy to use the gel to form gel beads and strings.

- Another advantage of our gel material is that the production technique?liquid-phase large-scale DNA synthesis?can produce incomparably vaster quantities than is possible with solid phase synthesis, the technique that dominates today. Using polyethylene glycol as a delivery carrier, we succeeded in obtaining a gel material under laboratory conditions, featuring tens of grams of DNA as its principal component.

- We have already confirmed that the material is not toxic to cells, and so we believe that it has great potential as a drug delivery carrier.