Thermoswitchable Nanoparticles Based on Elastin-like Polypeptides

The design of biocompatible particles with defined size on the nanometer scale has proven to be a challenging task in current biomedical research. Here we present an approach toward temperature-responsive nanoparticles by covalently cross-linking micelles based on trimeric constructs of elastin-like polypeptides. These trimers can be triggered to assemble into micelles by heating the solution above a specific transition temperature (<i>T</i>_t) which was shown in previous studies. Here we show that the disassembly of the micelles below the <i>T</i>_t can be prevented by the incorporation of covalent cross-links in the core of the micelles. This facilitates a temperature-triggered swelling and collapsing by around 35% in diameter, as determined by dynamic light scattering. Size distribution was confirmed by fluorescence correlation spectroscopy, atomic force microscopy, and transmission electron microscopy. We show switchable nanoparticles with reversible volume changes in the temperature region between 30 and 40 °C, making these particles promising candidates for switchable drug delivery carriers