A series of thermoresponsive cationic dendronized copolymers and their corresponding nanogels containing dendritic oligoethylene glycol (OEG) units and guanidine groups were prepared, and their complexation, protection, and release of nucleic acids were investigated. The dendritic OEGs endow these copolymer materials with good biocompatibility and characteristic thermoresponsiveness, while cationic guanidine groups can efficiently bind with the nucleic acids. The dendritic topology also affords the copolymers specific shielding effect which plays an essential role in protecting the activity of nucleic acids. At room temperature, dendronized copolymers and the corresponding nanogels could efficiently capture and condense the nucleic acids, while above their cloud points (T_cps), more than 75% of siRNA could be released in 1 h triggered by ATP. More importantly, the copolymer showed protective capability to siRNA, while nanogels exhibit even better protection when compared to the copolymers due to the synergetic effect from the three-dimensional cross-linked network and high density of dendritic units in vicinity. This kind of smart dendronized copolymer nanogels form a novel class of scaffolds as promising materials for biomedical applications.

制备了一系列具有树突状低聚乙二醇（OEG）单元和胍基的热响应性阳离子树枝状共聚物及其相应的纳米凝胶，并研究了它们的络合，保护和核酸的释放。树突状的OEG赋予这些共聚物材料良好的生物相容性和特征性的热响应性，而阳离子胍基团可以有效地与核酸结合。树状拓扑结构还提供共聚物特有的屏蔽作用，该作用在保护核酸活性中起着至关重要的作用。在室温下，树枝化的共聚物和相应的纳米凝胶可以有效地捕获和浓缩核酸，而其浊点以上（T _cps），在ATP触发的1小时内，可释放超过75％的siRNA。更重要的是，该共聚物显示出对siRNA的保护能力，而纳米凝胶与该共聚物相比则表现出更好的保护作用，这归因于三维交联网络的协同效应以及附近高密度的树状单元。这种智能的树突化共聚物纳米凝胶形成了一类新型的支架，成为有前途的生物医学材料。