Highly sensitive colorimetric detection of ammonia and respiratory ammonia based on ammonia induced perylene diimide anion radical π-dimer dissociation

Abstract

Ammonia is not only a crucial respiratory biomarker for chronic kidney diseases, but also an important raw material in chemical industry. Ammonia has important economic value, however, it also has harmful effects. Therefore, the sensitive and rapid detection of low concentration ammonia is always a hot and challenging topic in sensing field. Recently, we discovered a type of perylene diimide anionic radical π-dimers which the absorbance spectrum depends on the hydrogen bond between two radical molecules. Herein, the colorimetric detection of NH₃·H₂O, NH₃ gas, and respiratory NH₃ is achieved through the color changes resulting from the hydrogen bond in the π-dimer being broken by NH₃. The π-dimer solution achieving a lowest detection limits of 0.26 ppb for NH₃·H₂O, and provided high precision recognition with approximately 90% accuracy based on UV-vis spectrum and color change. The colorimetric films based on the π-dimer/silica gel can detect NH₃ gases at ppb level, and achieving high precision recognition with about 94% accuracy. The cotton fibers dyed by π-dimers were successfully used in detecting 830 ppb NH₃ gas (the NH₃ concentration in exhaled breath of early chronic kidney diseases) based on the visible color changes. We believe that these environmental sensitive radical derivatives can serve as candidate colorimetric probes, which offers a novel and non-invasive approach for the early warning of chronic kidney disease.