Paper accepted: “Physicochemical characterization of FRET-labelled chitosan nanocapsules and model degradation studies”

Today, the next manuscript of Stefan Hoffmann from the Goycoolea group was accepted for publication in the Journal “Nanomaterials”. This is an elegant study to investigate the release of drugs from chitosan-coated nanocapsules. Nanocapsules have an oily core surrounded by an amphiphilic layer of lecithin and stabilized by an outermost layer of chitosan, making them ideally suited for the sustained delivery of lipophilic drugs. In order to develop such drug delivery systems based on nanocapsules, the release of these drugs into an aqueous environment such as blood or the gastrointestinal fluid needs to be tightly controlled. To monitor payload release, Stefan developed and characterized a system of two hydrophobic fluorescent dyes which are exhibiting FRET when in close proximity. Thus, as long as they are contained within the nanocapsule, they exhibit FRET, but not once they are released into the medium. Using this system, he was able to show that chitosan-coated nanocapsules can be degraded slowly by pancreatin, a mixture of mostly lipolytic enzymes, releasing the payload. When the nanocapsules were incubated in a solution containing serum albumin, a protein corona formed around the nanocapsules which delayed, but did not prevent payload release. This was an in vitro study, but in collaboration with Dr. Christian Gorzelanny from Hamburg, who also is a co-author of this paper, we are now aiming to use this system to also quantify and visualize payload release in vivo - an essential step towards biomedical applications.