posted on 2015-01-20, 00:00authored byYanming Shen, Quanjuan Zhang, Xuhong Qian, Youjun Yang
Nitrite is a heavily assayed substrate
in the fields of food safety,
water quality control, disease diagnosis, and forensic investigation
and more recently in basic biological studies on nitric oxide physiology
and pathology. The colorimetric Griess assay and the fluorimetric
2,3-diaminonaphthalene (DAN) assay are the current gold standards
for nitrite quantification. They are not without limitations, yet
have amazingly survived 156 and 44 years, respectively, due to the
lack of a practical alternative. Both assays exhibit slow detection
kinetics due to inactivation of nucleophiles under strongly acidic
media, require an extensive incubation time for reaction to go completion,
and hence offer a limited detection throughput. By converting an intermolecular
reaction of the Griess assay intramolecularly, we designed a novel
probe (NT555) for nitrite detection, which displays superior detection
kinetics and sensitivity. NT555 was constructed following our “covalent-assembly”
probe design principle. Upon detection, it affords a gigantic bathochromic
shift of the absorption spectrum and a sensitive turn-on fluorescence
signal from a zero background, both of which are typical of an “assembly”
type probe. Overall, NT555 has addressed various difficulties associated
with the Griess and the DAN assays and represents an attractive alternative
for practical applications.