Carbon dots fluorescence can be used to distinguish isobaric peptide and to monitor protein oligomerization dynamics.

Carbon dots (CD) are widely investigated particles with interesting fluorescent properties which are reported to be used for various purposes, as they are biocompatible, resistant to photobleaching and with tuneable properties depending on the specific CD surface chemistry. In this work, we report on the possibility to use opportunely designed CD to distinguish among isobaric peptides almost undistinguishable by mass spectrometry, as well as to monitor protein aggregation phenomena. Particularly, cell-penetrating peptides containing the carnosine moiety at different positions in the peptide chain produce sequence specific fluorescent signals. Analogously, different insulin oligomerization states can also be distinguished by the newly proposed experimental approach. The latter is here described in details and can be potentially applied to any kind of peptide or protein.