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Cysteine (Cys) as an essential amino acid for life plays important roles in the synthesis of various proteins and human metabolism. The detection and monitoring of the concentration of cysteine in vitro and in vivo is significant for the diagnosis of related diseases. Herein, we designed and synthesized a novel fluorescent probe NC-Cys for the detection of cysteine, which employed dihydronaphthalene as the fluorophore. After the addition of Cys, colorimetric naked eye detection of Cys was achieved by the color change from purple to bright yellow. Moreover, the fluorescence intensity at 536 nm in the presence of Cys showed about a 90-fold fluorescent signal increase compared to that with no Cys addition. The probe NC-Cys exhibited satisfactory sensitivity and selectivity to Cys. A good linear relationship between I536 and the concentration of Cys (0–100 μM) was also observed with a calculated detection limit of 2.1 × 10−8 M. Importantly, the probe NC-Cys was successfully applied in the fluorescence imaging of Cys in living cells and tissues with low cytotoxicity. This newly developed fluorescent probe would be a potentially useful tool for the imaging of Cys in wider physiological and pathological processes.

Peroxynitrite anion (ONOO-), one of the reactive nitrogen species (RNS), plays momentous roles in physiological and pathological processes especially in a range of oxidative stress-related diseases. Moreover, abundant ONOO- is generated in the liver tissues of drug-induced liver injury. We report herein a novel small molecule fluorescent probe KC-ONOO for monitoring ONOO- based on boronate. The probe displayed high sensitivity and good selectivity towards ONOO-. A good linear relationship was observed between the fluorescent intensity at 530 nm and the concentration of ONOO- ranged 0–10 μM with a detection limit of 1.5 × 10−8 M. Furthermore, our probe was successfully applied for imaging ONOO- in living cells and drug-damaged liver tissues with low cytotoxicity, demonstrating the probe KC-ONOO has great potential to further elucidate more biological roles of ONOO-.

Hydrogen peroxide (H2O2), as an important biomolecule, is involved in various physiology and pathologic processes such as cellular signal transduction, host defense, and pathogen invasion. Thus, convenient and efficient detection of H2O2 in living organisms is of paramount significance and has drawn tremendous interest from researchers worldwide. In the present study, a novel H2O2-recognition moiety, the acetyl group, was proposed. Based on this unique recognition moiety, a new near-infrared (NIR) fluorescence probe was designed and synthesized for detecting H2O2. With numerous advantages including high selectivity and sensitivity, good compatibility and low cytotoxicity, this probe not only has the great competence to monitor endogenous H2O2 in cells, tissues, and in vivo but also has the huge potentiality to be employed in the diagnosis of H2O2-related cancers.

Nowadays, ozone has been widely applied in industry and medical therapies. However, excessive exposure to ozone can lead to lung dysfunction and many respiratory symptoms. As a member of reactive oxygen species (ROS), ozone was also involved in various physiology and pathology process. Given the fact of this, the effective detection of ozone in the atmosphere and biological system is of vital significance. Herein, we reported a novel dicyanomethylene-4H-pyran (DCM)-based fluorescent probe DCM-O3 with butenyl being the recognition moiety for monitoring ozone. The probe displayed high selectivity towards ozone, and its response towards ozone could be completed within 5 min under the optimal condition. Besides, a good linear correlation was obtained between the ozone concentrations (0–50 μM) and the corresponding fluorescent intensity at 560 nm, and the limit of detection (LOD) was calculated to be 6.2 × 10−7 M. Moreover, the probe DCM-O3 showed low cytotoxicity and was successfully applied to detect ozone in live cells. Given all the merits, the probe DCM-O3 could function as a robust tool for researchers to investigate ozone-related diseases in the complex biological environment.

As a member of the reactive nitrogen species (RNS) family, peroxynitrite (ONOO−) as an oxidant and nitrating mediator plays a significant role in some physiopathologic processes. The excessive production of peroxynitrite anion in a drug-damaged liver is a culprit of hepatotoxicity. The detection of peroxynitrite is of vital importance for the treatment of some diseases including cancer and liver injury. In this study, a novel turn-on fluorescent probe IC-ONOO with new chalcone fluorophore was designed and synthesized for the detection of in vitro and in vivo. The probe responded rapidly towards ONOO− (only within 15 min did the fluorescent intensity maximize), and was endowed with high sensitivity and excellent selectivity. Given the fact that the linear correlation between the fluorescent intensity at 560 nm and the concentrations of the probe ranged from 0 to 9 μM, the limit of detection (LOD) was calculated to be 3.1 × 10−8 M. With all the merits, probe IC-ONOO was qualified as a robust tool to monitor peroxynitrite anion under physiopathologic condition. Moreover, it was successfully applied in the imaging of endogenous peroxynitrite in living MCF-7 cells (Human breast carcinoma cells) and mouse drug-damaged liver tissue with low cytotoxicity. Given all the extraordinary merits, great potential has been seen in its application to other peroxynitrite related diseases.

Copper (Cu) plays a significant role in the process of oxygenic photosynthesis in living systems. The detection of copper ion (Cu2+) is valuable and meaningful for further investigating the functions of Cu2+ under physiological and pathological conditions. In this paper, a novel fluorescence probe DCM-Cu based on the near-infrared (NIR) fluorophore dicyanomethylene-4H-pyran (DCM) was designed for Cu2+ detection. The probe DCM-Cu possessed characteristic of “turn-on” fluorescent signal in the presence of Cu2+ through the enhanced ICT process. It exhibited satisfactory sensitivity and selectivity toward Cu2+. A good linear correlation was observed between the concentrations of Cu2+ and the fluorescence intensities at 700 nm. The detection limit (LOD) of DCM-Cu toward Cu2+ was calculated to be 2.54 × 10−8 M. Importantly, DCM-Cu was successfully applied in the detection of Cu2+ in living MCF-7 cells and tumor tissue with low cytotoxicity. Therefore, this probe would have the potential to monitor cellular Cu2+ in the living system and be applied to the diagnosis of related diseases.