Dual Responsive Emulsions Based on Amphiphilic Elastin-like Polypeptide Bioconjugates

Abstract

To achieve the desired therapeutic response, drug delivery systems must ensure the controlled release of the loaded content at the targeted site. One possible strategy relies on the improvement of conventional drug delivery systems. To do so, smart polymers, able to change their behavior upon chemical, physical, or biological stimuli, can be used. In this context, this study aims to evaluate the potential of natural amphiphilic smart elastin-like polypeptides grafted with alkyl chains (ELP-g-Bu) to stabilize conventional oil-in-water emulsions and trigger the release of loaded molecules upon dual stimuli. With butyl pendant chains and methionine residues, the macromolecular surfactant ELP-g-Bu demonstrated a modification of physicochemical properties, looking at critical aggregation concentration, upon both temperature and oxidation stimuli. The macromolecular surfactant was then able to stabilize a paraffin-oil-in-water emulsion. The ELP-g-Bu emulsion presented a droplet size of 9 ± 1 μm and stability for at least a month at 4 and 25 °C. After successful loading of a fluorescent lipophilic molecule used as a drug model, a complete destabilization of the ELP-g-Bu emulsion and burst release of the content was achieved with thermal triggering at 42 °C. In oxidative conditions, a partial release was measured, which can be improved by increasing the number of oxidable thioether groups. Overall, these dually responsive amphiphilic ELP-g-Bu demonstrated their potential for smart-polymer-based drug delivery systems that can be promising for inflammatory disease treatment as increased temperature and radical oxygen species are present in such cases.