Link to Pubmed [PMID] – 30995713
Link to DOI – 10.1021/acsnano.8b08696
ACS Nano 2018 12; 12(12): 11725-11730
Dipole radiation patterns change when a fluorescent molecule comes close to the boundary between media of different refractive indices. Near-interface molecules emit mostly into the higher-index medium, predominantly around the critical angle. The radiation pattern encodes information about the emitter distance, orientation, and the refractive index of the embedding medium. Analyses of the supercritical angle fluorescence on pupil plane images can retrieve this information and have been applied both for refractometry with subcellular resolution and for the detection of metabolically active cancerous cells. In this issue of ACS Nano, Ferdman et al. employ this strategy in a label-free assay for detecting single bacteria, based on measuring the refractive-index change produced by bacterial growth in a fluorophore-coated microfluidic channel.