A new pH-responsive hydrogel biomaterial, that is composed of solely two popular biocompatible materials, oligodeoxynucleotides (ODN) and polyethylene glycol (PEG) have been prepared. Merely five deoxycytidine residues were elongated to the ends of linear or 4-arm PEG in ×1000 larger scale than conventional systems by using liquid-phase DNA synthesis technique, and applied them as a macromonomer for the preparation of hydrogels. The syntheses of the conjugates are simply elongating ODN onto the ends of PEG as a semisolid phase substrate using standard phosphoramidite chemistry. The resulting dC5-PEG conjugates gave quite stable and stiff hydrogels triggered by the formation of a unique DNA quadruplex, i-motif. Introduction of only one chemical linkage between two linear conjugates resulted in unexpectedly high thermal stabilities for the melting temperatures of i-motifs themselves. Nonlinearly improved rheological properties compared to the original linear conjugates were also observed, probably because of topological entanglement between macromonomers of fused circles.

中文翻译：

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通过液相、大规模 DNA 合成制备散装 pH 响应 DNA 四联体水凝胶

一种新的 pH 响应水凝胶生物材料，仅由两种流行的生物相容性材料，寡脱氧核苷酸 (ODN) 和聚乙二醇 (PEG) 组成。通过使用液相DNA合成技术，仅将五个脱氧胞苷残基以比常规系统大1000倍的规模延伸到线性或4臂PEG的末端，并将它们用作制备水凝胶的大分子单体。缀合物的合成只是使用标准亚磷酰胺化学将ODN延伸到作为半固相底物的PEG末端上。由此产生的 dC5-PEG 缀合物产生了由独特的 DNA 四链体 i-motif 形成引发的相当稳定和坚硬的水凝胶。在两个线性共轭物之间仅引入一个化学键导致 i-基序本身的熔化温度具有出乎意料的高热稳定性。与原始线性共轭物相比，还观察到非线性改善的流变特性，这可能是由于稠环大分子单体之间的拓扑纠缠。