Search

It is crucial to monitor intracellular pH values and their fluctuation since the organelles of cells have different pH distribution. Herein we construct a new small molecule fluorescent probe HBT-O for monitoring the subtle pH values within the scope of neutral to acid in living cells. The probe exhibited good water solubility, a marked turquoise to olivine emission color change in response to pH, and tremendous fluorescence hypochromatic shift of ∼50 nm (1718 cm −1 ) as well as the increased fluorescence intensity when the pH value changed from neutral to acid. Thus, the probe HBT-O can distinguish the subtle changes in the range of normal pH values from neutral to acid with significant fluorescence changes. These properties can be attributed to the intramolecular charge transfer (ICT) process of the probe upon protonation in buffer solutions at varied pH values. Moreover, the probe was reversible and nearly non-toxic for living cells. Then the probe was successfully used to detect pH fluctuation in living cells by exhibiting different fluorescence colors and intensity. These findings demonstrate that the probe will find useful applications in biology and biomedical research. [ABSTRACT FROM AUTHOR]

Due to favourable efficiency and low cost, dual-response fluorescent probes play critical roles in the development of fluorescence assay system. Herein, a novel dual-response fluorescent probe (RDCN) was designed and synthesized for the detection of two environmental contaminants: hydrazine (N 2 H 4) and cyanide (CN−). Probe RDCN exhibited discriminative sensing behaviors to N 2 H 4 and CN− with different reaction mechanisms, allowing the high selectivity and sensitivity detection for N 2 H 4 and CN−. The probe itself displayed red-emitting fluorescence as a result of strong intramolecular charge transfer (ICT) between diethylamino and dicyano. After mixing with hydrazine, a new corresponding hydrazone came into being with an intense yellow fluorescence. While, the probe could also largely switch to blue fluorescence in response to CN−. Furthermore, the probe RDCN was successfully employed to determine N 2 H 4 and CN− in water samples with the detection limits of 0.08 μM and 0.33 μM, and to visualize N 2 H 4 and CN− in live cells by means of different fluorescence channels (blue and yellow channels), revealing that probe RDCN has potential applications for discriminative detection N 2 H 4 and CN− in biological environment. Image 1 • A dual-response fluorescent probe RDCN was developed for detection of hydrazine and cyanide. • Probe RDCN displayed significantly discriminative fluorescence signal towards hydrazine (red) and cyanide (yellow) based on different reaction mechanisms. • Probe RDCN could respectively and sensitively determine hydrazine (DL = 0.08 μM) and cyanide (DL = 0.33 μM). • The probe RDCN was successfully applied for imaging hydrazine and cyanide in living cells. [ABSTRACT FROM AUTHOR]

As a typical kind of endogenous reactive nitrogen species, peroxynitrite (ONOO−) is believed heavily involved in the pathogenesis of many diseases such as inflammation, neurodegenerative conditions, and cardiovascular disorders. Precisely estimating ONOO− level in cell compartments is crucial for unraveling the biological relevance of ONOO− and enabling effective control of ONOO−-associated pathogenicity but suffers from serious difficulty owing to the daunting elusive features of ONOO−, namely nanomolar level physiological concentration and millisecond level biological half-life. A new fluorescent probe capable of detecting ONOO− with limit of detection down to 1.2 nM, response time less than 1s, and high recognition specificity over other similarly interfering species was developed in this work. For the probe constructed by conjugating an isatin moiety with an electron-withdrawing tricyanofuran (TCF) moiety, the former enabled a highly selective ONOO−-mediated oxidative decarbonylation reaction while the latter significantly improved the electrophilicity of the 3-position carbonyl group of isatin moiety and therefore accelerate the ONOO−-mediated nucleophilic attack, which eventually enabled prompt and efficient recognition reaction. For the decarbonylated product featured with a released primary aniline moiety, TCF acted as an acceptor for enabling an intramolecular charge transfer (ICT) process and the remarkable change in electronic feature upon reaction with ONOO−, which generated turn-on fluorescence with large contrast and therefore the basis for ONOO− sensing. The cell fluorescence imaging performed in this work definitely verified the capability of the probe for mapping intracellular ONOO−, despite the daunting elusive features of such physiological species. A new type of fluorescent probe enabling highly specific detection of peroxynitrite anion (ONOO−) with limit of detection down to 1.2 nM, response time less than 1s, and high recognition specificity over other similar interferents was developed and its potential for mapping exogenous and endogenous ONOO− in living cells was confirmed. Image 1 • A new type of fluorescent probe for peroxynitrite anion (ONOO−) sensing with limit of detection down to 1.2 nM was developed. • The unprecedented recognition rate for ONOO− sensing with response time less than 1 s was verified. • The ability of the probe for mapping fluctuation of intracellular endogenous ONOO− was confirmed. [ABSTRACT FROM AUTHOR]