Selective and Real-Time Detection of Nitric Oxide by a Two-Photon Fluorescent Probe in Live Cells and Tissue Slices

Abstract

Nitric oxide (NO) is an important signaling molecule involved in many physiological and pathological processes. To understand these NO-mediated processes, it is a key to develop rapid and specific detection methods for NO. In the past 2 decades, numerous excellent fluorescent probes for NO have been designed; however, it still remains limitations such as slow response, low selectivity, and short excitation wavelength (<600 nm). In this Article, a two-photon fluorescent probe, NO-QA5, has been developed with 3-dimethylaminophenyl linking at the 6-position of 5-aminoquinoline as both the active site and prefluorophore for detection of NO. The nonfluorescent NO-QA5 can fast react with NO via a diazonium intermediate to generate two azoic regioisomers, one of which exhibits intramolecular charge transfer (ICT) emission, and two-photon absorption behavior (δΦ = 57 GM), giving a turn-on fluorescence rapid response. The sensing reaction is pH-insensitive in the range of 6-11 and highly selective and well sensitive (LOD = 15 nM), possible undergoing the same intermediate diazonium with the reaction under diazotization condition (NaNO/HCl). Also, as a nitrite fluorescent probe NO-QA5 exhibits highly sensitive (LOD = 7 nM). Therefore, NO-QA5 can serve as a dual functional fluorescent probe for NO and NO. Furthermore, NO-QA5 as a specific imaging agent has been demonstrated by achieving both exogenous and endogenous detections of NO in living cells under both one- and two-photon excitation and high resolution in tissue slices under two-photon excitation.

Epileptic brain fluorescent imaging reveals apigenin can relieve the myeloperoxidase-mediated oxidative stress and inhibit ferroptosis

“…For example, a quinolone-based Schiff base can serve as a staining reagent for imaging metal ions (Cu 2+ and Zn 2+ ) in Aβ plaques; quinolylnitrones can be used as the potential neuroprotective agents (SI Appendix, Scheme S1). Moreover, the quinoline skeleton has excellent two-photon excitation properties that enable the design of two-photon fluorescent probes for deep tissue imaging in living organisms (20,30,46). Inspired by these quinolone-based neuroprotective drugs and imaging agents, we sought a simple condensation reaction to construct a two-photon fluorescent probe based on the principle of intermolecular charge transfer (ICT) (47).…”

Unusual redshift due to selective hydrogen bonding between F− ion and sensor motif: a naked eye colorimetric sensor for F− ions in an aqueous environment

“…During the experiment, when the F À ion concentration was increased gradually, the color of the monomeric sensor changed from light yellow to dark pink in the cuvette, as detected by the naked eye. 36,37 A 537 /A 405 (for monomeric sensors) and A 516 /A 405 (for the polymeric sensor) were linearly and positively correlated with the F À ion concentration, as shown in Fig. 5.…”

“…As a result of the HSAB principle, the F À ion can make a strong H-bonding interaction with partially positively charged H-atoms of NH groups present in both the monomeric and polymeric sensors. 36 Because of this reason, the sensor molecules undergo interaction ratiometrically with F À ions.…”

“…[27][28][29][30][31][32][33][34] Many of the above-mentioned systems can undergo abstraction of a proton by the classical Bronsted acid-base type of interaction at a higher concentration of F À ions. [34][35][36][37][38][39][40][41][42] All the above monomeric systems can detect the analyte at the ppm level through a change in the spectroscopic behavior at a particular wavelength. Among the reported F À ion sensors, very few systems have a ratiometric sensing property, which depends on various factors like concentration, electronic environment, phototransformation, etc.…”

Fast‐Response Fluorogenic Probe for Visualizing Hypochlorite in Living Cells and in Zebrafish

“…MTT assay : The MTT assay was performed as previously reported . Prior to D1 treatment, HeLa cells were cultured in Dulbecco's modified Eagle's medium (DMEM) containing fetal calf serum (FCS, 10 %), streptomycin (100.0 mg mL −1 ), and penicillin (100 IU mL −1 ).…”