Dendronized Hyperbranched Polyethyleneimines with Switchable Thermoresponsiveness and Encapsulation

Hyperbranched polyethyleneimines (PEIs) with multiple layered structures and high density of terminal amino groups have shown great potential for applications in biomedicine, sensors, and catalysis. In this work, a kind of dendronized hyperbranched PEIs (DHPs) is synthesized by modification of PEIs with dendritic oligoethylene glycols (OEGs). These DHPs not only inherit the characteristic thermoresponsive behavior from the OEG dendrons, but also show low cytotoxicity and switchable encapsulation capacities. Their thermoresponsive behavior is found to be mainly dependent on the coverage and amphiphilicity of dendritic OEGs, solution pH, and NaCl concentration. Moreover, DHPs exhibit advantages in thermally-switchable complexation with guest molecules because of their adjustable crowding effect from the densely packed OEG chains. In addition, these DHPs can also be used as nanoreactors, which can reduce metal ions into metal nanoparticles in a convenient way. In virtue of these peculiarities, it is believed that these dendronized hyperbranched PEIs with smart properties can be used as promising scaffolds in drug-controlled release and nanoreactors. A new type of smart dendronized hyperbranched polymer (DHPs) is prepared through modification of hyperbranched polyethyleneimines with oligoethylene glycol (OEG)-based dendrons. These DHPs inherit the characteristic thermoresponsive behavior from OEG dendrons, and exhibit thermally-controlled encapsulation and release of guest molecules. They also can be used as nanoreactors for efficient fabrication of gold nanoparticles.image