Hydrogen peroxide (H(2)O(2)) acts as a signaling molecule in a wide variety of signaling transduction processes and an oxidative stress marker in aging and disease. However, excessive H(2)O(2) production is implicated with various diseases. Nitric oxide (NO) serves as a secondary messenger inducing vascular smooth muscle relaxation. However, mis-regulation of NO production is associated with various disorders. To disentangle the complicated inter-relationship between H(2)O(2) and NO in the signal transduction and oxidative pathways, fluorescent reporters that are able to display distinct signals to H(2)O(2), NO, and H(2)O(2)/NO are highly valuable. Herein, we present the rational design, synthesis, spectral properties, and living cell imaging studies of FP-H(2)O(2)-NO, the first single-fluorescent molecule, that can respond to H(2)O(2), NO, and H(2)O(2)/NO with three different sets of fluorescence signals. FP-H(2)O(2)-NO senses H(2)O(2), NO, and H(2)O(2)/NO with a fluorescence signal pattern of blue-black-black, black-black-red, and black-red-red, respectively. Significantly, we have further demonstrated that FP-H(2)O(2)-NO, a single fluorescent probe, is capable of simultaneously monitoring endogenously produced NO and H(2)O(2) in living macrophage cells in multicolor imaging. We envision that FP-H(2)O(2)-NO will be a unique molecular tool to investigate the interplaying roles of H(2)O(2) and NO in the complex interaction networks of the signal transduction and oxidative pathways. In addition, this work establishes a robust strategy for monitoring the multiple ROS and RNS species (H(2)O(2), NO, and H(2)O(2)/NO) using a single fluorescent probe, and the modularity of the strategy may allow it to be extended for other types of biomolecules.
Hypochlorous acid (HOCl), a reactive oxygen species (ROS), plays a significant biological role in living systems. However, abnormal levels of HOCl are implicated in many inflammation-associated diseases. Therefore, the detection of HOCl is of great importance. In this work, we describe the HOCl-promoted cyclization of rhodamine-thiosemicarbazides to rhodamine-oxadiazoles, which is then exploited as a novel design strategy for the development of a new fluorescence turn-on HOCl probe 2. On the basis of the fluorescence resonance energy transfer (FRET) signaling mechanism, 2 was further converted into 1a and 1b, which represent the first paradigm of FRET-based ratiometric fluorescent HOCl probes. The outstanding features of 1a and 1b include well-resolved emission peaks, high sensitivity, high selectivity, good functionality at physiological pH, rapid response, low cytotoxicity, and good cell-membrane permeability. Furthermore, these excellent attributes enable us to demonstrate, for the first time, the ratiometric imaging of endogenously produced HOCl in living cells by using these novel ratiometric probes. We expect that 1a and 1b will be useful molecular tools for studies of HOCl biology. In addition, the HOCl-promoted cyclization reaction of rhodamine-thiosemicarbazides to rhodamine-oxadiazoles should be widely applicable for the development of different types of fluorescent HOCl probes.
Coumarin-rhodamine-based compounds 1a,b were rationally designed and synthesized as novel FRET ratiometric fluorescent chemodosimeters. Ratiometric chemodosimeters 1a,b exhibit several favorable features, including a large variation in the emission ratio, well-resolved emission peaks, high sensitivity, high selectivity, low cytotoxicity, and good cell membrane permeability. Importantly, these excellent attributes enable us to demonstrate ratiometric imaging of Cu(2+) in living cells by using these novel ratiometric fluorescent chemodosimeters.
Abstract:Crop productivity in cold waterlogged paddy fields can be constrained by chronic flooding stress and low temperature. Farmers typically use chemical fertilizer to improve crop production, but this conventional fertilization is not very effective in a cold waterlogged paddy field. Biochar amendment has been proposed as a promising management approach to eliminating these obstacles. However, little is known about the performance of biochar when combined with N fertilizer and P fertilizer in cold waterlogged soils. The aim of this study was, therefore, to assess the main effects and interactive effects of rice straw biochar, N and P fertilizer on rice growth and soil properties in a cold waterlogged paddy field. The field treatments consisted of a factorial combination of two biochar levels (0 and 2.25 t ha −1 ), two N fertilizer levels (120.0 and 180.0 kg ha −1 ) and two P fertilizer levels (37.5 and 67.5 kg ha −1 ) which were arranged in a randomized block design, with three replicates. Results confirmed that biochar application caused a significant increase in the soil pH due to its liming effect, while this application resulted in a significant decrease in soil exchangeable cations, such as exchangeable Ca, Mg, Al and base cations. The interactive effect of N fertilizer, P fertilizer and biochar was significant for soil total N. Moreover, a negative effect of biochar on the internal K use efficiency suggested that K uptake into rice may benefit from biochar application. According to the partial Eta squared values, the combined application of N fertilizer and biochar was as effective as pure P fertilization at increasing straw P uptake. The addition of biochar to farmers' fertilization practice treatment (180.0 kg N ha −1 , 67.5 kg P 2 O 5 ha −1 and 67.5 kg K 2 O ha −1 ) significantly increased rice yield, mainly owing to improvements in grains per panicle. However, notable effects of biochar on rice yield and biomass production were not detected. More studies are required to assess the long-term behavior of biochar in a cold waterlogged paddy field. This study may lay a theoretical foundation for blended application of biochar with fertilizer in a cold waterlogged paddy field.
We described the development of Cou-Rho-NO as the first small-molecule suitable for ratiometric fluorescent imaging of endogenously produced nitric oxide in macrophage cells.
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