Single-molecule fluorescence techniques have revolutionized protein studies, but fluorescent labels can alter protein structure and interactions. This paper introduces optical horn antennas—a nanophotonic platform enabling label-free detection of single proteins using their intrinsic UV autofluorescence. The design combines plasmonic enhancement, efficient light collection (up to 85°), and background screening. The authors detect autofluorescence from immobilized and diffusing single proteins, monitoring protein unfolding and dissociation during denaturation. This approach offers a promising method for real-time investigation of proteins in their native states.

Aleksandr Barulin, Prithu Roy, Jean-Benoît Claude, Jérôme Wenger