Rapid and dual-mode nitrite detection with improved sensitivity by nanointerface-regulated ultrafast Griess assay.

Background: The rapid and sensitive detection of nitrite is important to human health protection due to its carcinogenic and teratogenic risks with excessive intake. The Griess assay is widely applied for the design of nitrite detection system. However, its relatively slow reaction kinetics and sole colorimetry mode might limit it's the sensitivity and practical application. Therefore, it is highly desirable to explore new detection method with rapid kinetics and multi-mode recognition characters.

Results: We report a rapid and colorimetry and fluorimetry dual-mode sensing of nitrite by using N-(1-naphthalene)-ethylenediamine-derivated carbon dots (NETH-CDs) as the reporters. NETH-CDs show maximum excitation and emission around 359 nm and 431 nm, accompanying with a quantum yield of 27.1 %. The carbonization of NETH not only increases the fluorescence sensing mode, but also promotes the nanointerfacial Griess assay reaction kinetics within 1 min. High selectivity of dual-mode sensing is exhibited due to the specific reaction. The linear ranges in colorimetry and fluorimetry modes are 0.2-100 μM, and the corresponding limit of detection values are determined to be 0.10 and 0.08 μM, respectively. In addition, the accurate nitrite analysis in urine and serum samples with NETH-CDs nanoprobes. Moreover, the visual nitrite detection is achieved based on NETH-CD-loaded test strips.

Significance: This work reports a new dual mode nitrite detection method for the first time by NETH-CDs supported ultrafast interfacial Griess assay, it not only explores sensitive nitrite detection probe, but also provides deep understanding of the relationship between chemical reaction kinetics and interfacial interaction on nanosurface. We believe our findings would benefit the exploration of rapid and sensitive detection systems toward various targets by regulating interfacial chemistry.