Thermoresponsive Nanogels from Dendronized Copolymers for Complexation, Protection and Release of Nucleic Acids

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 (Tcps), 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.