Reported herein is the highly efficient quenching of fluorescent organic nanoparticles by 2,4-dinitrotoluene and 2,4,6-trinitrotoluene. These fluorescent nanoparticles are formed from the hydrophobic collapse of fluorescent polymer chains and display quenching efficiencies that are in line with the highest reported literature values. Moreover, the fluorescent quenching occurs only for the fluorescent nanoparticles, and not for the precursor polymer solutions, which display marked insensitivity to the presence of nitroaromatics. This aggregation-dependent fluorescent quenching has numerous applications for the detection of small-molecule electron-deficient analytes. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4150-4155