A turn-on NIR fluorescent probe for risk-assessing oxidative stress in cabbage roots under abiotic stress.

Oxidative stress is closely related to the crop health status under stress conditions. H2O2 is an important signaling molecule in plants under stress. Therefore, monitoring H2O2 fluctuations is of great significance when risk-assessing oxidative stress. However, few fluorescent probes have been reported for the in situ tracking of H2O2 fluctuations in crops. Herein, we designed a "turn-on" NIR fluorescent probe (DRP-B) to detect and in situ-image H2O2 in living cells and crops. DRP-B exhibited good detection performance for H2O2 and could image endogenous H2O2 in living cells. More importantly, it could semi-quantitatively visualize H2O2 in cabbage roots under abiotic stress. Visualization of H2O2 in cabbage roots revealed H2O2 upregulation in response to adverse environments (metals, flood, and drought). This study provides a new method for risk-assessing oxidative stress in plants under abiotic stress and is expected to provide guidance for the development of new antioxidant defense strategies to enhance plant resistance and crop productivity.

A turn-on near-infrared fluorescent probe for visualization of endogenous alkaline phosphatase activity in living cells and zebrafish.

Alkaline phosphatase (ALP) is an essential hydrolase and widely distributed in living organisms. It plays important roles in various physiological and pathological processes. Herein, a turn-on near-infrared (NIR) fluorescent probe (DXMP) was developed for sensitive detection of ALP activity both in vitro and in vivo based on the intramolecular charge transfer (ICT) mechanism. Upon incubation with ALP, DXMP exhibited a strong fluorescence increment at 640 nm, which was attributed to the fact that ALP-catalyzed cleavage of the phosphate group in DXMP induced the transformation of DXMP into DXM-OH. The probe exhibited prominent features including outstanding selectivity, high sensitivity, and excellent biocompatibility. More importantly, it has been successfully used to detect and image endogenous ALP in living cells and zebrafish.

A near-infrared fluorescent probe for monitoring and imaging of ß-galactosidase in living cells.

ß-Galactosidase (ß-gal) which is overexpressed in primary ovarian cancer can be employed as a valuable biomarker for ovarian cancer. Thus, monitoring and imaging endogenous ß-gal in living cells is of great importance. Herein, a dicyanoisophorone-based near-infrared (NIR) fluorescent probe 2-(5,5-dimethyl-3-((E)-4-(((2R,3S,4R,5S,6S)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)styryl)cyclohex-2-en-1-ylidene)malononitrile named DP-ßgal, was rationally designed and synthesized for the monitoring of ß-gal activity in living cells. In the presence of ß-gal, with the breaking of the glycosidic bond, the NIR fluorescence of the dicyanoisophorone derivative gradually recovered, enabling the fluorescence "off-on" quantitative determination of ß-gal activity. DP-ßgal has the advantages of good selectivity and high sensitivity for the detection of ß-gal, with the limit of detection (LOD) of 3.2 × 10-3 U. Furthermore, based on its advantages of long-wavelength emission and excellent biocompatibility, the practical applications of DP-ßgal in NIR imaging of ß-gal in living ovarian cancer cells (SKOV-3) were demonstrated.

A colorimetric and near-infrared ratiometric fluorescent probe for hydrazine detection and bioimaging.

Hydrazine (N2H4) is extensively used in industry but highly toxic; hence, highly sensitive detection of N2H4 is extremely meaningful. Herein, a colorimetric and near-infrared (NIR) ratiometric fluorescent probe named DXM-OH was rationally designed and synthesized based on oxanthrene malononitrile derivative for the specific detection of N2H4. The dicyanovinyl group in DXM-OH was served as the recognition unit for N2H4. DXM-OH showed high sensitivity to N2H4 in the range of 1-900 µM, with the limit of detection (LOD) of 0.09 µM (2.87 ppb), which is much lower than the U.S. Environmental Protection Agency standard (10 ppb). Furthermore, the practical applications of DXM-OH in detecting N2H4 in real water samples and imaging of N2H4 in living cells were demonstrated, indicating its potential utility for N2H4 sensing in environmental and biological samples.

A near-infrared excitation/emission fluorescent probe for imaging of endogenous cysteine in living cells and zebrafish.

The fluorescence imaging technique provides an essential tool for studying biological systems. However, due to the interference of autofluorescence of biological tissues, the application of short-wavelength fluorescent probes in biological imaging was limited. The near-infrared (NIR) excitation/emission fluorescent probe possesses unique advantages in optical imaging in vivo, including less light scattering, minimal photo-damage to biological samples, deep tissue penetration, and weak autofluorescence interference from complicated biological systems. In this work, a convenient fluorophore (E)-2-[2-(6-hydroxy-2,3-dihydro-1H-xanthen-4-yl)vinyl]-3- methylbenzo[d]thiazol-3-ium iodide (DXM-OH) with NIR excitation and emission was rationally designed and developed. What's more, DXM-OH was applied to construct an "OFF-ON" fluorescent probe (E)-2-{2-[6-(acryloyloxy)-2,3-dihydro-1H- xanthen-4-yl]vinyl}-3-methylbenzo[d]thiazol-3-ium iodide (DXM) for sensitive and selective detection of cysteine (Cys). The experimental results showed that DXM had the advantages of good cell permeability, low toxicity, and excellent optical properties (NIR excitation/emission) and it was successfully applied to image Cys of living cells and zebrafish.

Visualization of endogenous ß-galactosidase activity in living cells and zebrafish with a turn-on near-infrared fluorescent probe.

ß-Galactosidase (ß-gal) is an important biomarker for primary ovarian cancers. Developing noninvasive bioimaging probes for studying the activity of ß-gal is highly desirable for cancer diagnosis. Herein, a turn-on near-infrared (NIR) fluorescent probe， 2-((6-(((2S, 3R, 4S, 5R, 6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran -2-yl)oxy)-2,3-dihydro-1H-xanthen-4-yl)methylene)malononitrile named DXM-ßgal, was rationally designed based on enzymatic reaction for the detection of ß-gal activity both in vitro and in vivo. Upon incubating with ß-gal, DXM-ßgal displayed a significant fluorescence enhancement at 640 nm, accompanying by a color change of solution color from red to purple. DXM-ßgal exhibited high selectivity and sensitively to ß-gal with low limit of detection (2.92 × 10-4 U mL-1). Besides, based on its advantages of long-wavelength emission and excellent biocompatibility, DXM-ßgal was successfully applied to imaging ß-gal in living cells and zebrafish. Given these prominent properties, we believe that DXM-ßgal will be a potential tool for investigating ß-gal activity in biomedical research.

Quantitative Analysis of Eight Triterpenoids and Two Sesquiterpenoids in Rhizoma Alismatis by Using UPLC-ESI/APCI-MS/MS and Its Application to Optimisation of Best Harvest Time and Crude Processing Temperature.

Rhizoma Alismatis (RA), widely known as "Ze-Xie" in China, is the tuber of Alisma orientale (Sam.) Juzep (Alismaceae), a Chinese herbal medicine that has been used to treat hyperlipidemia, diabetes, hypertension, dysuria, and inflammation. In this study, a sensitive and reliable method based on an ultra-performance liquid chromatography (UPLC) couple with two ionisation modes, including electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI) tandem mass spectrometry (MS), namely, UPLC-ESI/APCI-MS/MS was developed and validated to simultaneously determine 8 triterpenoids (ESI mode) and 2 sesquiterpenoids (APCI mode) in RA. Ten marker compounds were analysed with a Waters' CORTECS UPLC C18 column (200 mm × 2.1 m, 1.6 µm) and gradient elution with water (contained 0.1% formic) and acetonitrile within 7 min. The established method was validated for linearity, intra- and interday precisions, accuracy, recovery, and stability. The calibration curve for 10 marker compounds showed good linear regression (r > 0.9971). The limits of detection and quantification for analytes were 0.14-1.67 ng/mL and 0.44-5.65 ng/mL, respectively. The relative standard deviations (RSD, %) and accuracy (RE, %) of intra- and interday precisions were less than 3.83% and 1.21% and 3.22% and 1.46%, repeatability and stability for real samples were less than 2.78% and 3.19%, respectively. All recoveries of the 10 marker compounds ranged from 97.24% to 102.49% with RSDs less than 4.05%. The developed method efficiently determined the 10 marker compounds in RA and was subsequently applied to optimise harvest time and crude processing temperature. The result indicated the 90% wilted phase and 70°C (or lower) may be the best harvest time and the processing temperature of RA.

Aggregation-induced emission fluorescent probe for monitoring endogenous alkaline phosphatase in living cells.

Alkaline phosphatase (ALP) is a non-specific phosphate monoesterase and often regarded as an important biomarker of hypothyroidism and hepatobiliary diseases in medical diagnosis. In-situ detection of endogenous ALP and exploration of the distribution of ALP in cells are of great importance for the diagnosis of diseases associated with ALP. In this work, we designed and synthesized an aggregation-induced emission (AIE) fluorescent probe, (E)-2-(((9H-fluoren-9-ylidene) hydrazono)methyl)phenyl dihydrogen phosphate (FAS-P), that can respond to ALP with a remarkable large Stokes shift (>200 nm) based on excited state intramolecular proton transfer (ESIPT) mechanism. The probe FAS-P has high selectivity and sensitivity to the detection of ALP. And there is a linear relationship between the fluorescence intensity of FAS-P and ALP activity in the range of 1-100 U L-1, the limit of detection (LOD) is as low as 0.6 U L-1. More importantly, we successfully applied FAS-P to detect ALP in living cells and the monitoring of ALP in real time.

An ESIPT-based fluorescent probe for the detection of phosgene in the solution and gas phases.

Phosgene is a highly toxic gas that poses a serious threat to public health and safety. Herein, we describe the preparation of a ratiometric fluorescence probe (Pi) bearing hydroxyl and imidazole moieties as recognition sites, and employ it for the excited-state intramolecular proton transfer-based (ESIPT-based) detection of phosgene. It is the first time that hydroxyl and imidazole have been exploited as recognition sites for phosgene. In the presence of phosgene, Pi undergoes sequential nucleophilic substitution and cyclization reactions that facilitate a rapid response, high selectivity, and excellent sensitivity (detection limit = 0.14 µM). The sensing mechanism was verified by 1H NMR spectroscopy and high-resolution mass spectrometry. Furthermore, we fabricated a fluorescent test strip (FTS-Pi) for the detection of phosgene in the gas phase that undergoes a fluorescence color change, from green to blue, under 365 nm UV light in the presence of phosgene, which is easily observed with the naked eye.

A highly sensitive naked-eye fluorescent probe for trace hydrazine based on 'C-CN' bond cleavage.

In this work, a colorimetric and ratiometric fluorescent probe, 2,3-bis(((E)-4-(diethylamino)-2-hydroxybenzylidene)amino)maleonitrile (DHM), was developed based on N2H4-induced bond cleavage. Two cyanide groups of DHM were applied to sense hydrazine (N2H4) for the first time, which was demonstrated using 1H NMR and HRMS spectra. The specific 'C-CN' bond cleavage induced by N2H4 showed an excellent fluorescence ratiometric behavior and a visible colorimetric change from purple to yellow. Meanwhile, it showed a low detection limit of 58.1 nM (1.65 ppb), which is far below the safety level (10 ppb) set by the U.S. EPA. Moreover, the probe was successfully employed for the quantitative detection toward N2H4 in real water samples.

Prenatal maternal stress induces visceral hypersensitivity of adult rat offspring through activation of cystathionine-ß-synthase signaling in primary sensory neurons.

Irritable bowel syndrome is a disorder of unknown etiology characterized by widespread, chronic abdominal pain associated with altered bowel movements. Increasing amounts of evidence indicate that stressors presented during gestational periods could have long-term effects on the offspring's tissue structure and function, which may predispose to gastrointestinal diseases. The aim of the present study is to determine whether prenatal maternal stressis a adverse factor affecting gastrointestinal sensitivity and to investigate possible mechanisms underlying prenatal maternal stress-induced visceral hypersensitivity in adult offspring. Prenatal maternal stress was induced in pregnant Sprague-Dawley rats by exposure to heterotypic intermitent stress from gestational day 7 to delivery. Prenatal maternal stress significantly increased visceromotor response to colorectal distention in adult offspring from the age of 6 weeks to 10 weeks. Prenatal maternal stress also enhanced neuronal excitability including depolarization of resting membrane potentials, reduction in rheobase, and an increase in the number of action potentials evoked by 2× and 3× rheobase current stimultion of colon-specific dorsal root ganglion neurons. Prenatal maternal stress remarkably enhanced expression of cystathionine-ß-synthase and Nav1.7 in T13-L2 thoracolumbar dorsal root ganglions both at protein and mRNA levels. Intraperitoneal injection of aminooxyacetic acid, an inhibitor of cystathionine-ß-synthase, attenuated prenatal maternal stress-induced visceral hypersensitivity in a dose-dependent manner. A consecutive seven-day administration of aminooxyacetic acid reversed the hyperexcitability of colon-specific dorsal root ganglion neurons and markedly reduced Nav1.7 expression. These results indicate that the presence of multiple psychophysical stressors during pregnancy is associated with visceral hypersensitivity in offspring, which is likely mediated by an upregualtion of cystathionine-ß-synthase and Nav1.7 expression. Prenatal maternal stress might be a significant contributor to irritable bowel syndrome, and cystathionine-ß-synthase might be a potential target for treatment for chronic visceral hypersensitivity in patients with irritable bowel syndrome.

Pauli-Rydberg-London potential: an accurate pair potential function for diatomic systems.

Based on a molecular-orbital theory for H2(+), we have proposed and tested a pair potential function form for the diatomic systems. The new form has included the Pauli repulsive term, Rydberg potential, and London inverse-sixth-power energy, and is accurate at all relevant distances and simple enough for practical application in all-atom computer simulations. We find that an "approximate" universal reduced potential curve for strongly and weakly bound diatomic molecules may exist.

Electronic and structural response of nanomaterials to ultrafast and ultraintense laser pulses.

The interaction of materials with ultrafast and ultraintense laser pulses is a current frontier of science both experimentally and theoretically. In this review, we briefly discuss some recent theoretical studies by the present authors with our method of semiclassical electron-radiation-ion dynamics (SERID). In particular, Zhou et al. and Jiang et al. respectively, determined the optimal duration and optimal timing for a series of femtosecond scale laser pulses to excite a specific vibrational mode in a general chemical system. A set of such modes can be used as a "fingerprint" for characterizing a particular molecule or a complex in a solid. One can therefore envision many applications, ranging from fundamental studies to detection of chemical or biological agents. Allen et al. proved that dimers are preferentially emitted during photofragmentation of C60 under an ultrafast and ultraintense laser pulse. For interactions between laser pulses and semiconductors, e.g., GaAs, Si and InSb, besides experimentally accessible optical properties--epsilon(omega) and chi(2)-Allen et al. offered many other indicators to confirm the nonthermal nature of structural changes driven by electronic excitations and occurring during the first few hundred femtoseconds. Lin et al. found that, after the application of a femtosecond laser pulse, excited electrons in materials automatically equilibrate to a Fermi-Dirac distribution within roughly 100 fs, solely because of their coupling to the nuclear motion, even though the resulting electronic temperature is one to two orders of magnitude higher than the kinetic temperature defined by the nuclear motion.

Upregulation of cystathionine beta-synthetase expression by nuclear factor-kappa B activation contributes to visceral hypersensitivity in adult rats with neonatal maternal deprivation.

BACKGROUND: Irritable bowel syndrome (IBS) is characterized by chronic visceral hyperalgesia (CVH) that manifested with persistent or recurrent abdominal pain and altered bowel movement. However, the pathogenesis of the CVH remains unknown. The aim of this study was to investigate roles of endogenous hydrogen sulfide (H2S) producing enzyme cystathionine beta-synthetase (CBS) and p65 nuclear factor-kappa B subunits in CVH. RESULTS: CVH was induced by neonatal maternal deprivation (NMD) in male rats on postnatal days 2-15 and behavioral experiments were conducted at the age of 7-15 weeks. NMD significantly increased expression of CBS in colon-innervating DRGs from the 7th to 12th week. This change in CBS express is well correlated with the time course of enhanced visceromoter responses to colorectal distention (CRD), an indicator of visceral pain. Administration of AOAA, an inhibitor of CBS, produced a dose-dependent antinociceptive effect on NMD rats while it had no effect on age-matched healthy control rats. AOAA also reversed the enhanced neuronal excitability seen in colon-innervating DRGs. Application of NaHS, a donor of H2S, increased excitability of colon-innervating DRG neurons acutely dissociated from healthy control rats. Intrathecal injection of NaHS produced an acute visceral hyperalgesia. In addition, the content of p65 in nucleus was remarkably higher in NMD rats than that in age-matched controls. Intrathecal administration of PDTC, an inhibitor of p65, markedly reduced expression of CBS and attenuated nociceptive responses to CRD. CONCLUSION: The present results suggested that upregulation of CBS expression, which is mediated by activation of p65, contributes to NMD-induced CVH. This pathway might be a potential target for relieving CVH in patients with IBS.

Comparative studies of the trans-cis photoisomerizations of azobenzene and a bridged azobenzene.

Using density-functional-based molecular dynamics simulations, we have performed comparative studies of the trans-cis isomerizations of azobenzene and bridged azobenzene (B-Ab) 5,6-dihydrodibenzo[c,g][1,2]diazocine induced by nπ* electronic excitation. The quantum yields found in our calculations, 45% for the bridged azobenzene versus 25% for azobenzene, are consistent with the experiment. Both isomerization processes involve two steps: (1) Starting from the trans structure, each molecule moves on its S(1) excited-state potential energy surface, via rotation around the NN bond, to an avoided crossing near the S(1)/S(0) conical intersection, where de-excitation occurs. (2) Subsequently, in the electronic ground state, there is further rotation around the NN bond, accompanied by twisting of the phenyl rings around their CN bonds, until the cis geometry is achieved. Because of its lower symmetry and smaller initial CNNC dihedral angle, the bridged azobenzene has a much shorter lifetime for the S(1) excited state, about 30 fs, as compared to about 400 fs for azobenzene. However, we find that the complete isomerizations have approximately the same time scales. Although the bridging feature in trans-B-Ab does not hinder rotation around the NN bond in step 1, it makes twisting of the two phenyl rings around the CN bonds much slower in step 2.

Exact spatiotemporal wave and soliton solutions to the generalized (3+1)-dimensional Schrödinger equation for both normal and anomalous dispersion.

We obtain exact extended traveling-wave and spatiotemporal soliton solutions to the generalized (3+1)-dimensional nonlinear Schrödinger equations for both the normal and the anomalous dispersion.

Analytical light bullet solutions to the generalized (3+1)-dimensional nonlinear Schrödinger equation.

We obtain exact spatiotemporal periodic traveling wave solutions to the generalized (3+1)-dimensional nonlinear Schrödinger equation with distributed coefficients. We utilize these solutions to construct analytical light bullet soliton solutions of nonlinear optics.

Universal scaling features of spectroscopic constants for diatomic systems.

Based on a new criterion that was proposed to search for the universality of spectroscopic constants for bound ground-state diatomics [R. H. Xie and P. S. Hsu, Phys. Rev. Lett. 96, 243201 (2006)], we have found universal scaling relations between spectroscopic constants of diatomic systems with s-, p-, and d-type valence-shell constituents. Our study suggests a useful empirical approach for the prediction of molecular spectroscopic constants.

Universal reduced potential function for diatomic systems.

The potential energy functions of 200 diatomic systems, with dissociation energies De ranging from few eV to hundreds of mueV, are well described by a new three-parameter potential energy function. Identification of the evaluated values of a dimensionless quantity, xin=L2/Ln [Ln=(n!De/fn)1/n, a scaled length parameter, and fn, the nth force constant evaluated at the equilibrium internuclear distance Re], is proposed as a reliable criterion to search for the universal scaling features of potentials and spectroscopic constants for bound diatomic systems. Our study suggests a useful approach to predicting future molecular spectroscopic constants.

Structure, stability, and NMR properties of lower fullerenes C38-C50 and azafullerene C44N6.

A systematic survey of the complete set of isomers of fullerenes C(38), C(40), C(42), C(44), C(46), C(48), C(50) and azafullerene C(44)N(6) is reported. All isomeric structures were optimized using first-principle density functional theory at the B3LYP/6-31G level. The isomeric structures with the lowest energies are C(38):17, C(40):38, C(42):45, C(44):75, C(44):89, C(46):109, C(48):171, and C(50):270. The ground-state structure of the azafullerene C(44)N(6) in the framework of C(50):270 has D(3) symmetry. The (13)C NMR chemical shifts and nucleus-independent chemical shifts (NICS) for the stable isomers of each fullerene are presented.