The team's approach exploits the remarkable properties of gold nanoclusters such as strong photostability and tunable size-dependent fluorescence properties. The labelled human transferrin exhibits good stability in solution and its protein functionality is conserved.

"If you want to use these modified proteins for biological applications, it's crucial to look at the cytotoxicity and the activity after labelling" explained Xavier Le Guevel, who took part in the work.

Data confirmed the ability of the fluorescent transferrin to i) uptake iron, one of its major functions in vivo, and ii) to recognize a specific polyclonal antibody. Furthermore, cell viability tests verified the non-toxic nature of the labelled proteins in A549 cells and cellular uptake of the iron-loaded fluorescent transferrin could be demonstrated.

These first results highlight the potential of a new type of fluorescent transferrin for biological application.

"The next step will be to investigate the specific cellular uptake of the labelled transferrin with and without iron" added Nicole Daum, another member of the HIPS-UdS team.

The findings were presented in the journal Nanotechnology.