Partnered Excited-State Intermolecular Proton Transfer Fluorescence (P-ESIPT) Signaling for Nitrate Sensing and High-Resolution Cell-Imaging

Abstract

Nitrite (NO2−) is a common pollutant and is widely present in the environment and in human bodies. The development of a rapid and accurate method for NO2− detection is always a very important task. Herein, we synthesized a partnered excited-state intermolecular proton transfer (ESIPT) fluorophore using the “multi-component one pot” method, and used this as a probe (ESIPT-F) for sensing NO2−. ESIPT-F exhibited bimodal emission in different solvents because of the solvent-mediated ESIPT reaction. The addition of NO2− caused an obvious change in colors and tautomeric fluorescence due to the graft of NO2− into the ESIPT-F molecules. From this basis, highly sensitive and selective analysis of NO2− was developed using tautomeric emission signaling, achieving sensitive detection of NO2− in the concentration range of 0~45 mM with a detection limit of 12.5 nM. More importantly, ESIPT-F showed the ability to anchor proteins and resulted in a recognition-driven “on-off” ESIPT process, enabling it to become a powerful tool for fluorescence imaging of proteins or protein-based subcellular organelles. MTT experimental results revealed that ESIPT-F is low cytotoxic and has good membrane permeability to cells. Thus, ESIPT-F was further employed to image the tunneling nanotube in vitro HEC-1A cells, displaying high-resolution performance.

Simple and Efficient Synthesis of Highly Functional 2-Oxonicotino­nitriles from 2-Chloronicotinonitriles

“…2-Oxonicotinonitrile derivatives are often characterized by fluorescence in solutions and (or) solid state, including mechanochromic emission. 9 , 12 13 14 15…”

“…2-Oxonicotinonitrile derivatives are often characterized by fluorescence in solutions and (or) solid state, including mechanochromic emission. 9,[12][13][14][15] 2-Oxonicotinonitrile core is the main structural unit in various drugs and constantly attracts the attention of researchers due to its extremely diverse biological properties. There are -amylase and -glucosidase enzyme inhibitors, 16 EGFRWT and EGFRT790M inhibitors, 17 PIM-1/2 kinase inhibitors, 18 Mcl-1 inhibitors, 19 DNA gyrase active inhibitors, 20,21 potential inhibitors against Alzheimer's dis-ease, 4 and anticancer agents with dual VEGFR-2/HER-2 inhibitory activity.…”

“…Derivatives of 2-oxo-1,2-dihydropyridine-3-carbonitrile (2-oxonicotinonitrile, 3-cyanopyridone) are important representatives of heterocyclic compounds with practically important properties. These compounds have been used in many fields, including creation of organic light-emitting diodes (OLEDs), 1 dye-sensitized solar cells, 2 organometallic compounds, 3,4 organic dyes, 5 fluorescent tags for latent fingerprints (LFP) visualization, 5,6 chemosensors for cadmium(II), 7 copper(II) and nickel(II) ions, 8 nitrites, 6,9 a polaritysensitive fluorescent probe, 10 and an image-sensor colorant. 11 The tandem effect of the pyridone fragment and the carbonitrile group significantly enhances the emission properties of the molecules.…”