A colorimetric and fluorescent signaling probe for assaying Pd2+ in practical samples

We developed an optical signaling probe to detect Pd2+ ions in Pd-containing catalyst and drug candidate. The Pd2+ signaling probe (Res-DT) was readily prepared by reacting the versatile fluorochrome resorufin with phenyl chlorodithioformate. In a phosphate-buffered saline solution (pH 7.4) containing sodium dodecyl sulfate (SDS) as a signal-boosting surfactant, Res-DT exhibited a pronounced colorimetric response with a chromogenic yellow to magenta shift, leading to a substantial increase in the fluorescence intensity. The Pd2+ signaling performance of Res-DT was attributed to the Pd2+-promoted hydrolysis of the dithioate moiety. The probe displayed high selectivity toward Pd2+ ions and remained unaffected by commonly encountered coexisting components. Moreover, the detection limit of Res-DT for Pd2+ ions was 10 nM, and the signaling was achieved within 7 min. Furthermore, to demonstrate the real-world applicability of Res-DT, a Pd2+ assay was performed in Pd-containing catalyst and drug candidate using an office scanner as an easily accessible measurement device. Our results highlight the prospects of Res-DT as a tool to detect Pd2+ ions in various practical samples, with potential applications in catalysis, medicine, and environmental science.

Colorimetric screening of elevated urinary mercury levels by a novel Hg2+-selective probe of resorufin phosphinothioate

Urinary mercury levels are the most reliable indicators of mercury exposure but identifying them requires complex techniques and heavy instruments. In this research, we reported a simple and convenient urinary mercury analysis method using a readily available office scanner. Probe MP-1 synthesized by the reaction of resorufin and dimethylthiophosphinoyl chloride revealed Hg²⁺-selective chromogenic and fluorescent signaling behavior. Signaling was realized through Hg²⁺-induced deprotection of the phosphinothioate protecting group in the resorufin-based probe MP-1 to yield the parent fluorochrome. A pronounced colorimetric response of color change from light yellow to pink alongside a turn-on type fluorescence enhancement was perceived exclusively toward Hg²⁺ ions over other metal ions and anions. The colorimetry provided a more advantageous ratiometric approach than the simple fluorometric analysis exhibiting an off–on type response, with a detection limit of 12 nM (2.4 ppb). The Hg²⁺ signaling of the MP-1 probe was not disturbed by the presence of coexisting metal ions and anions. The sensitive and convenient diagnosis of clinically important neurological symptoms and fatal inorganic mercury levels in urine was successfully demonstrated using a standard office scanner.

A Hg²⁺ selective signaling probe, resorufin phosphinothioate, for the colorimetric diagnosis of clinically elevated mercury levels in urine samples using an office scanner was developed.

Determination of thallium(iii) ions by oxidative hydrolysis of rhodamine–hydroxamate

A colorimetric and turn-on type fluorescence Tl³⁺ signaling probe for the early screening of elevated urinary thallium levels in acute poisoning cases using a readily available smartphone was developed.

The first hydride-Meisenheimer adduct of electron-deficient 3-nitronaphthalimide: application to colorimetric borohydride determination

The first hydride-Meisenheimer adduct of 3-nitronaphthalimide was used for the colorimetric borohydride assay. To explain the regioselectivity of the adduct, the reaction enthalpies of the two most plausible Meisenheimer adducts were obtained via computational calculation. Using the adduct formation, the assay of borohydride reagents was successfully conducted.

Novel Hg2+-Selective Signaling Probe Based on Resorufin Thionocarbonate and its μPAD Application

In this study, a novel resorufin thionocarbonate-based Hg2+-selective signaling probe (RT) for microfluidic paper-based analytical device (μPAD) applications is reported. The designed probe, RT, was readily synthesized by the one-step reaction of resorufin with phenyl thionochloroformate. The RT probe displayed a prominent color change from yellow to pink and a marked turn-on fluorescence signaling behavior exclusively toward the Hg2+ ion. The signaling of RT was due to Hg2+-induced hydrolysis of the phenyl thionocarbonate moiety to form the parent resorufin dye, which restored its spectroscopic properties. In addition, RT exhibited the Hg2+-selective signaling behavior without interference by coexisting environmentally relevant metal ions. The detection limit for Hg2+ in simulated wastewater samples was estimated to be 5.8 × 10-8 M. In particular, an RT-equipped μPAD prepared using a wax printing technique enabled simple and convenient determination of Hg2+ ions in simulated wastewater samples, with a detection limit of 5.9 × 10-6 M.

Reaction-based fluorometric analysis of N-bromosuccinimide by oxidative deprotection of dithiane

In this study, a fluorescent probe is developed for the first time for N-bromosuccinimide (NBS), a synthetically and analytically important compound. Pyrene-dithiane-based probe 1 showed prominently selective and sensitive signaling behavior toward NBS owing to the oxidative cleavage of the dithiane protecting group of 1-pyrenecarboxaldehyde. The NBS-selective signaling of the probe was possible under competitive conditions in the presence of common metal ions and anions as a background. The detection limit of the probe for NBS was found to be 5.6 × 10-8 M (10.0 ppb). The signaling product was sufficiently stable under the oxidative stress of NBS in contrast to another tested compound, 6-methoxy-2-naphthaldehyde-based dithiane derivative 2, which showed a gradually decaying response because of the reaction of the signaling product with the residual NBS. In the practical application of the probe, a smartphone was used as a stand-alone device, and the fluorometric assays of the commercial NBS reagents could be conducted rapidly and in a convenient manner.

A simple hypochlorous acid signaling probe based on resorufin carbonodithioate and its biological application

A novel HOCl signaling probe based on the oxidative hydrolysis of resorufin carbonodithioate to generate resorufin dye was investigated and applied to cell imaging.

Electronic Effect on the Molecular Motion of Aromatic Amides: Combined Studies Using VT-NMR and Quantum Calculations

Rotational barrier energy studies to date have focused on the amide bond of aromatic compounds from a kinetic perspective using quantum calculations and nuclear magnetic resonance (NMR). These studies provide valuable information, not only regarding the basic conformational properties of amide bonds but also the molecular gear system, which has recently gained interest. Thus, we investigate the precise motion of the amide bonds of two aromatic compounds using an experimental rotational barrier energy estimation by NMR experiments and a theoretical evaluation of the density functional theory calculation. The theoretical potential energy surface scan method combined with the quadratic synchronous transit 3 method and consideration of additional functional group rotation with optimization and frequency calculations support the results of the variable temperature ¹H NMR, with deviations of less than 1 kcal/mol. This detailed experimental and theoretical research strongly supports molecular gear motion in the aromatic amide system, and the difference in kinetic energy indicates that the electronic effect from the aromatic structure has a key role in conformational movements at different temperatures. Our study provides an enhanced basis for future amide structural dynamics research.

Novel water filtration of saline water in the outermost layer of mangrove roots

The scarcity of fresh water is a global challenge faced at present. Several desalination methods have been suggested to secure fresh water from sea water. However, conventional methods suffer from technical limitations, such as high power consumption, expensive operating costs, and limited system durability. In this study, we examined the feasibility of using halophytes as a novel technology of desalinating high-concentration saline water for long periods. This study investigated the biophysical characteristics of sea water filtration in the roots of the mangrove Rhizophora stylosa from a plant hydrodynamic point of view. R. stylosa can grow even in saline water, and the salt level in its roots is regulated within a certain threshold value through filtration. The root possesses a hierarchical, triple layered pore structure in the epidermis, and most Na⁺ ions are filtered at the first sublayer of the outermost layer. The high blockage of Na⁺ ions is attributed to the high surface zeta potential of the first layer. The second layer, which is composed of macroporous structures, also facilitates Na⁺ ion filtration. This study provides insights into the mechanism underlying water filtration through halophyte roots and serves as a basis for the development of a novel bio-inspired desalination method.

Visible-light-induced regioselective synthesis of polyheteroaromatic compounds

A method for visible-light-induced synthesis of heteroaryl-substituted polyheteroaromatics was developed.

An investigation of the role increasing π-conjugation has on the efficiency of dye-sensitized solar cells fabricated from ferrocene-based dyes

A series of ferrocene-based dyes have been prepared and dye-sensitized solar cells have been fabricated.

Pb3[C6(CH3)3(CO2)3H6]2[DMF]3: first layered Pb-Kemp's triacid complex

The first layered Pb-Kemp's triacid material, Pb₃[C₆(CH₃)₃(CO₂)₃H₆]₂[DMF]₃, reveals reversible solvent coordination, intercalative addition, and higher selectivity of Cd²⁺ over Pb²⁺.

Single molecular multianalyte signaling of sulfide and azide ions by a nitrobenzoxadiazole-based probe

Sulfide- and azide-selective multianalyte optical signaling using nitrobenzoxadiazole-pivalate was realized by regioselective cleavage of the probe under the same conditions.

Detection of iron-labeled single cells by MR imaging based on intermolecular double quantum coherences at 14 T

To evaluate the efficiency and feasibility of intermolecular multiple quantum coherence (iMQC) magnetic resonance (MR) imaging for single cell detection, we obtained intermolecular double quantum coherence (iDQC) and conventional gradient echo (GE) images of macrophage cells labeled by contrast agents in gel. The iDQC images obtained with echo-planar readout visualized the labeled cells effectively and with a higher contrast than seen in conventional GE images, especially at low planar resolutions and with thick slices. This implies that iDQC imaging with contrast agents could be a good alternative to conventional MR imaging for detecting labeled single cells or cell tracking under favorable conditions.

Self-assembled growth of GaAs anti quantum dots in InAs matrix by migration enhanced molecular beam epitaxy

Self-assembled GaAs anti quantum dots (AQDs) were grown in an InAs matrix via migration enhanced molecular beam epitaxy. The transmission electron microscopy image showed that the 2D to 3D transition thickness is below 1.5 monolayers (MLs) of GaAs coverage. The average diameter and height of the GaAs AQDs for 1.5 ML GaAs coverage taken from the atomic force microscopy image were approximately 29.0 nm and 1.4 nm, respectively. The density was approximately 6.0 x 10(10) cm(-2). The size of the AQDs was enlarged in the InAs matrix compared with that on the surface. These results indicate that the GaAs AQDs in the InAs matrix under tensile strain can be effectively formed with the assistance of the migration enhanced epitaxy method.

Fluorescence signaling of Zr4+ by hydrogen peroxide assisted selective desulfurization of thioamide

Thioamide derivative with a pyrene fluorophore was smoothly transformed to its corresponding amide by Zr(4+) ions in the presence of hydrogen peroxide. The transformation was evidenced by (1)H NMR spectroscopy and the signaling was completed within 10 min after sample preparation. Interference from Ag(+) and Hg(2+) ions in Zr(4+)-selective fluorescence signaling was readily suppressed with the use of Sn(2+) as a reducing additive. Discrimination of Zr(4+) from closely related hafnium, which is a frequent contaminant in commercial zirconium, was not possible. Prominent Zr(4+)-selective turn-on type fluorescence signaling was possible with a detection limit of 4.6 × 10(-6) M in an aqueous 99% ethanol solution.

Value of alpha-foetoprotein for screening of recurrence in hepatocellular carcinoma post resection

INTRODUCTION

The aim of this study was to establish the value of alpha-foetoprotein (AFP) for the screening of recurrences in hepatocellular carcinoma (HCC) in patients who have undergone curative hepatic resection.

METHODS

72 HCC patients who had curative resection/liver transplant in 2000-2006 were monitored for recurrence by evaluating the three- or six-monthly AFP and computed tomography images. Patients without recurrence were followed up for a mean duration of 7.27 years.

RESULTS

Out of the 72 patients, 34 (47.2%) suffered from HCC recurrence. 65.4% of recurrent cases had AFP values showing an upward trend. Patients with recurrence had higher AFP values than those without at last follow-up (119.45 μg/L vs. 3.1 μg/L, p < 0.001). AFP at recurrence was independent of gender, race, history of alcohol consumption and hepatitis C or cirrhosis status. Patient with hepatitis B or those with tumours larger than 5 cm had higher AFP values. The best cut-off AFP indicative of HCC recurrence was 5.45 μg/L (sensitivity 84.4%; specificity 77.1%). High preoperative AFP was associated with high AFP at recurrence (correlation coefficient 0.553, p = 0.01).

CONCLUSION

AFP alone is an inadequate screening test for HCC recurrence since only about two-thirds of patients showed upward AFP trend on recurrence. Our study found a relatively low cut-off point for detection of recurrence (5.54 μg/L). Patients with high preoperative AFP tended to have high AFP on recurrence. Imaging is recommended for patients with AFP levels > 5.45 μg/L, especially when AFP shows a rising trend.