Cd Probe Research Articles

A difunctional NMR&CD probe for specific detection and enantiomeric recognition of biothiols in complex mixtures

BackgroundBiothiols are important for numerous cellular processes, such as resisting oxidative stress and protecting cell health. Their abnormal levels and molecular configurations have been associated with various diseases. So, establishing an effective and reliable method for the specific detection and enantiomeric discrimination of diverse biothiols is highly meaningful. ResultsWe have developed a new NMR and CD probe using 1,4-dinitroimidazole, specifically targeting the thiol group. This probe allows for the specific detection and enantiomeric recognition of biothiols in complex mixtures. We achieved this by identifying the distinguishable 1H NMR signals of 2nd in imidazole-ring of the resulting 4NI-biothiols in the downfield region at 7–8 ppm and newly discovered induced CD signals within 290-430 nm. Using this probe, the limits of detection of Cys, GSH, and Hcy, the recovery rates, and the concentration of GSH extracted from HEK293T cells were determined by measuring the unique downfield 1H NMR signals. Moreover, Cys, GSH, and Hcy can be discriminated simultaneously in complicated samples at a pH range of 2–3.5. Furthermore, this probe can also be utilized to sense chiral thiol-drugs. SignificanceThis method offers a cost-effective and accurate sensing solution for the specific detection of biothiols in complex mixtures, with stereochemical recognition.

Trimeric and Tetrameric Cationic Styryl Dyes as Novel Fluorescence and CD Probes for ds-DNA and ds-RNA.

The wide use of mono- or bis-styryl fluorophores in biomedical applications prompted the presented design and study of a series of trimeric and tetrameric homo-analogues, styryl moieties arranged around a central aromatic core. The interactions with the most common biorelevant targets, ds-DNA and ds-RNA, were studied by a set of spectrophotometric methods (UV-VIS, fluorescence, circular dichroism, thermal denaturation). All studied dyes showed strong light absorption in the 350-420 nm range and strongly Stokes-shifted (+100-160 nm) emission with quantum yields (Φf) up to 0.57, whereby the mentioned properties were finely tuned by the type of the terminal cationic substituent and number of styryl components (tetramers being red-shifted in respect to trimers). All studied dyes strongly interacted with ds-DNA and ds-RNA with 1-10 nM-1 affinity, with dye emission being strongly quenched. The tetrameric analogues did not show any particular selectivity between ds-DNA or ds-RNA due to large size and consequent partial, non-selective insertion into DNA/RNA grooves. However, smaller trimeric styryl series showed size-dependent selective stabilization of ds-DNA vs. ds-RNA against thermal denaturation and highly selective or even specific recognition of several particular ds-DNA or ds-RNA structures by induced circular dichroism (ICD) bands. The chiral (ICD) selectivity was controlled by the size of a terminal cationic substituent. All dyes entered efficiently live human cells with negligible cytotoxic activity. Further prospects in the transfer of ICD-based selectivity into fluorescence-chiral methods (FDCD and CPL) is proposed, along with the development of new analogues with red-shifted absorbance properties.

Impact of Disease Severity on Presentation Subtype and OnabotulinumtoxinA Utilization in Patients With Cervical Dystonia: Results From the CD PROBE Completer Population

Impact of Disease Severity on Presentation Subtype and OnabotulinumtoxinA Utilization in Patients With Cervical Dystonia: Results From the CD PROBE Completer Population

Perturbed Angular Correlation Technique at ISOLDE/CERN Applied for Studies of Hydrogenated Titanium Dioxide (TiO2): Observation of Cd-H Pairs

Profound understanding of the local electronic and defect structure in semiconductors always plays a vital role in the further developing of applications of such materials. In the present work an investigation of the electronic structure in hydrogenated TiO2 (rutile) thin films is conducted by virtue of Time-Differential γ-γ Perturbed Angular Correlation spectroscopy (TDPAC or PAC) with 111mCd/Cd isotope, produced and implanted at ISOLDE/CERN. The measurements were performed at 581 K as a function of the temperature of the samples during hydrogenation. Despite the fact, that rutile single crystals usually show the presence of two local environments, when are studies with Cd/In isotopes, the current pristine thin films sample had a single electric field gradient. Upon various degrees of hydrogenation, Cd probe atoms showed underwent alterations, resulting in up to 3 different local surroundings, generally with high electric field gradients. Broad EFG distributions are likely due to randomly distributed point defects in the neighbourhood of Cd acceptors. Observed results suggest that hydrogenations performed at RT and 423 K are not able to promote unique defect configurations, while in the range of 473-573 K the formation of such configurations is observed. Therefore, one may assume that the formation of Cd-defect complexes (Cd-H pairs) is temperature enhanced. At higher levels of hydrogenation (663 K), the samples become partly amorphous that further hinders any atomistic studies with strong damped PAC spectra. Cd-H complexes seem to be stable up to annealing up to 581 K annealing. The obtained results give a deep insight into complex hydrogen defects, their interactions and bond formations with Cd acceptor.

Impact of Disease Severity on Presentation Subtype and OnabotulinumtoxinA Utilization in Patients with Cervical Dystonia: Results from the CD PROBE Completer Population (P17-11.006)

Impact of Disease Severity on Presentation Subtype and OnabotulinumtoxinA Utilization in Patients with Cervical Dystonia: Results from the CD PROBE Completer Population (P17-11.006)

A highly sensitive fluorogenic “turn-on” chemosensor for the recognition of Cd2+ based on a hybrid purine-quinoline Schiff base

Herein, a novel purine-quinoline Schiff base chemosensor NPQ has readily been synthesized and applied to be fluorogenic “turn-on” probe for Cd 2+ . The NPQ exhibited remarkable selectivity towards Cd 2+ and with an obvious color change in EtOH/H 2 O (v/v = 9:1, pH = 7.4). The NPQ -Cd 2+ complex generated in situ displayed good selectivity for monitoring HPO 4 2− via fluorescence quenching. The binding mechanism of NPQ to Cd 2+ was fully clarified by the Job’s plot, 1 H NMR and density functional theory (DFT) study. The detection limit (LOD) (3σ/K) value of NPQ for Cd 2+ was estimated to be 41.0 nM. What’s more, the results of real applications including test papers and cell imaging were well demonstrated that NPQ was capable of recognizing Cd 2+ both in environmental and biological systems. A new purine-quinoline based Schiff base sensor ( NPQ) showed high selectivity and sensitivity towards Cd 2+ ions with an obvious visual color change. The fluorescence emission intensity of NPQ for Cd 2+ enhanced can be explained by the mechanism of CHEF.

Turning on the Photoelectrochemical Responses of Cd Probe-Deposited g-C3N4 Nanosheets by Nitrogen Plasma Treatment toward a Selective Sensor for H2S.

A selective photoelectrochemical (PEC) sensor has been designed for the signal-on detection of H2S using g-C3N4 nanosheets that were treated with N2 plasma for depositing Cd probes. It was discovered that the yielded Cd/N@g-C3N4 nanocomposites could present enhanced photocurrents of specific responses to H2S under visible light irradiation, in contrast to the ones without the pretreatment of N2 plasma showing no H2S response. Herein, the Cd probes deposited on g-C3N4 nanosheets might react with H2S to generate CdS on Cd/N@g-C3N4, forming the efficient heterojunctions. Especially, the plasma-derived N contents might act as the "bridge" to promote charge transfer between the generated CdS and g-C3N4, resulting in the "signal-on" PEC responses to H2S. A selective PEC sensor was thereby developed for sensing H2S of concentrations linearly ranging from 40.0 to 10,000 pM, with a detection limit of about 21 pM. Also, the feasibility of sensing H2S in industrial waste gas was demonstrated by recovery tests. More importantly, this N2 plasma treatment route for g-C3N4 nanosheets may open a new door toward the construction of a Cd probe-based heterojunction for the signal-on PEC sensing platform, which is promising for the wide application in the fields of environmental monitoring, food safety, and biomedical analysis.

Detection of toxin-producing Corynebacterium diphtheriae from throat swabs of diphtheria patients using duplex real-time PCR.

Background and Objectives:Diphtheria is a potentially fatal disease caused by toxigenic bacterial infection, particularly from Corynebacterium diphtheriae (C. diphtheriae). Isolation of C. diphtheriae is technically lacking in sensitivity, and Elek’s test to detect toxin production has several difficulties associated with its application. Duplex real-time PCR to throat swab of suspected diphtheria patients can detect both bacteria and toxin-encoding genes simultaneously, faster, with higher sensitivity and specificity.Materials and Methods:A total of 89 consecutive throat swabs from suspected diphtheria patients were collected from Sulianti Saroso Infectious Disease Hospital, Jakarta, during 2018 to 2019. Two pairs of primers and probes, targeting the rpoB gene of C. diphtheriae and the A-subunit of the diphtheria toxin gene, were used in this study. Parameters including annealing temperature, concentration of primers and probes, inhibitors, cross-reaction and detection limit were all optimized. Elek’s toxigenicity test and clinical data were analyzed for comparison.Results:The optimum annealing temperature was 55°C. The concentrations of Cd primer, Tox primer, Cd probe and Tox probe were 0.4, 0.6, 0.5 and 0.625 µM, respectively. DNA elution and template volumes were 50 µL and 5 µL. The detection limit was 2 CFU/mL. No cross-reaction with other microorganisms was observed. Of the 89 samples, duplex real-time PCR gave better results than the standard test, with 19 (21.3%) and 10 (11.2%) patients diagnosed with diphtheria, respectively.Conclusion:Duplex real-time PCR increases the rate of laboratory diagnosis of diphtheria, compared to the standard method to detect potentially toxigenic C. diphtheriae.

Naphthalene diimide-amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA.

Two novel unnatural amino acids, prepared by linking a dicationic purple-coloured and fluorescent naphthalene diimide (NDI) at core position to amino acid side chains of variable length, strongly interacted with ds-DNA/RNA by threading intercalation. Different from a reference NDI dye with identical visible range absorbance (520–540 nm) and Stokes shifts in emission (+60 nm, quantum yield > 0.2), only these amino acid–NDI conjugates showed selective fluorimetric response for GC-DNA in respect to AT(U)-polynucleotides. The DNA/RNA binding-induced circular dichroism (ICD) response of NDI at 450–550 nm strongly depended on the length and rigidity of the linker to the amino acid unit, which controls the orientation of the NDI unit inside within the intercalative binding site. The ICD selectivity also depends on the type of polynucleotide, thus the studied NDI dyes act as dual fluorimetric/ICD probes for sensing the difference between here used GC-DNA, AT-DNA and AU-RNA.

Synthesis of the porphyrin-calix[4]arene conjugatesviaPd-catalyzed amination and their evaluation as fluorescent chemosensors

The synthesis of the porphyrin-calix[4]arene conjugates was carried out using the Pd(0)-catalyzed amination of Zn(II) meso-(3-bromophenyl)porphyrinate with bis(3-aminopropoxy)substituted calix[4]arenes (in cone and 1,3-alternate conformations). One of the conjugates was demetalated to give free porphyrin base derivative. The investigation of the fluorescence of the conjugates was studied in the presence of 18 metal perchlorates. The zinc porphyrinate derivatives were found to quench fluorescence in the presence of Cu(II), Al(III) and Cr(III) cations as well as on protonation. Metal-free conjugate was shown to act as a molecular probe for Zn(II), Cu(II) and Cd(II) cations due to strong and different changes of the emission caused by these metals.

Minimal clinically important change in patients with cervical dystonia: Results from the CD PROBE study

ObjectiveTo determine the minimal clinically important change (MCIC) on Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) scores using data from Cervical Dystonia Patient Registry for Observation of OnabotulinumtoxinA Efficacy (CD PROBE), which captured real-world practices and outcomes. MethodsChanges in the baseline TWSTRS scores (point and percentage changes) were compared to changes in the Patient and Clinician Global Impression of Change (PGIC and CGIC) ratings. Using logistic regression, the discrimination of the model was determined. ResultsAmong the 479 patients who completed all TWSTRS assessments, the mean TWSTRS Total score significantly decreased from baseline (39.2) to the final visit (27.1) (P < .0001). TWSTRS Total score point changes that compared with PGIC assessments “very much improved,” “much improved” or better, and “minimally improved” or better were −11, −9, and −8, respectively, and were similar to previously published changes (ie, a decrease of ≥10 points). TWSTRS Total score data met indicators of good cutoffs for discrimination of the model including ≥70% percentage of outcomes correctly classified when compared with PGIC ratings. The TWSTRS Total score mapped to PGIC and CGIC ratings better than any TWSTRS subscale score. ConclusionsThe MCIC for improvement was ≥8 points based on mean TWSTRS Total scores in patients with cervical dystonia when compared against the patient-based evaluation of benefit (PGIC).

Adaptive-angle scanning method for 3D measurement with atomic force microscopy

Three-dimensional atomic force microscopy (3D-AFM) plays a critical role in true 3D measurement, which is potentially required in the manufacture of integrated circuits and in materials science. However, obtaining a 3D profile from a single scan is still a challenge because the probe has to be adjusted to a proper state to measure unknown features. So 3D-AFM is usually time consuming due to repeated scanning in the same area. Here we propose a new scanning strategy, called adaptive-angle scanning, in which the approaching angle of the probe is updated to an appropriate value according to the local surface gradient that is estimated in real time. Meanwhile, the fast scan direction is switched between the y -axis and the z-axis to realize the measurement of top–bottom features and sidewalls. This method is incorporated in a homemade 3D-AFM system to demonstrate its application. Two feedback loops, one integrated in the AFM head and the other under the sample stage, are responsible for changing the approach angle. Experiments are carried out on some standard samples with a tailored CD probe. The 3D-AFM system performs with excellent repeatability on the measurement of the line structure. There is no obvious tip wear observed after continuously scanning 20 times, and the obtained 3D images validate well the method’s capability of measuring different structures.

A New Fluorescent Probe for Selective Cd2+ Detection and Cell Imaging

A new highly selective fluorescent probe, (E)‐4‐(4‐([2,2′:6′,2′′‐terpyridin]‐4′‐yl)styryl)‐1‐octadecylpyridin‐1‐ium bromide (ZC‐F8), was designed and synthesized for cadmium detection and cell imaging. The fluorescence spectra of ZC‐F8 exhibited its excellent response towards Cd2+ via intramolecular charge transfer effect and aggregation induced emission effect. The cell‐imaging experiment was carried out to estimate the actual biological application of ZC‐F8. The probe displayed ideal membrane permeable and labeled property for cadmium, indicating its promising application for metal ions detection and tracing in living cells.

Hydrothermal synthesis of carbon dots codoped withnitrogen and phosphorusas a turn-on fluorescent probe for cadmium(II).

Nitrogen and phosphorus co-doped carbon dots (N,P-CDs) have been synthesized via hydrothermal method starting from o-phosphorylethanolamine and citric acid. The blue-green fluorescence of the N,P-CDs (with excitation/emission peaks at 325/435nm) isgradually enhanced on sequential addition of Cd(II) ions. This fluorometric assay works in the 0.5μM to 12.5μM Cd(II) concentration range and has a 0.16μM detection limit. The phenomenon may be attributed to chelation enhanced fluorescence that is induced by the formation of Cd(II)-N,P-CDs complex with functional groups present on the surface. The method has applied to the detection of Cd(II) in spiked serum and urine samples and gave satisfying results. Graphical abstract Schematic presentation of the synthesis of nitrogen and phosphorus co-doped carbon dots (N,P-CDs) and their application as a turn-on fluorescence probe for Cd(II) detection.

A fluorescent probe for Cd2+ detection based on the aggregation-induced emission enhancement of aqueous Zn–Ag–In–S quantum dots

A sensitive and selective fluorescent probe for the cadmium ion (Cd2+) was developed based on the aggregation-induced emission enhancement (AIEE) of Zn–Ag–In–S quantum dots (ZAIS QDs).

Pyrrolocytosine–pyrene conjugates as fluorescent and CD probes for the fine sensing of ds-polynucleotide secondary structure and specific recognition of poly G

Multipurpose dual method (fluorescence and CD) probes differentiate between various ds-RNA/RNA structures and specifically recognise Watson–Crick pairing complementary poly G.

Synthesis and Unprecedented Complexation Properties of β-Cyclodextrin-Based Ligand for Lanthanide Ions.

Here, we report the synthesis and detailed studies on the coordination chemistry of a novel chemically modified polyaminocarboxylate (5) based on β-cyclodextrin (CD) scaffold for lanthanides. The target ligand is prepared in a highly efficient manner (seven total steps) from β-CD using the readily available iminodiacetic acid as a starting material. A propargyl group is attached to the iminodiacetate via N-alkylation, and the obtained derivative is efficiently conjugated to the β-CD scaffold via the copper(I)-mediated 1,3-dipolar cycloaddition. The generated 1,2,3-triazolmethyl residues advantageously provide a competent chelating group while displacing the metal coordination center away from the primary rim of β-CD, to afford the required conformational flexibility. The functional groups from each of the two adjacent glucopyranosyl units of β-CD complete a uniquely created octavalent coordination sphere for lanthanides while still sparing one site for dynamic water coordination. To help study the coordination chemistry of CD ligand 5, we also design a relevant maltoside ligand 6, which faithfully represents one submetal-binding section of ligand 5. Thanks to HRMS and NMR studies, we successfully elucidate the coordination chemistries of synthesized ligands. The octavalent coordination sphere of ligand 5 shows strong binding affinity to lanthanides. By potentiometric titration experiments, ligand 5 is found to bind gadolinium(III), forming 1:1, 1:2, and 1:3 multinuclear complexes with lanthanides, thus possessing great capacity for catalyzing the dynamic water-exchange. Further NMR studies also reveal that the formed ligand 5/Gd(III) complexes show significantly better abilities to alter T1 relaxivities of coordinated water than DOTA-Gd(III) and also some of the synthetic CD probes reported in the literature.

Turn‐on fluorescent probe for Cd 2+ detection by gold nanoclusters/graphene oxide nanocomplex

This work reported the fabrication of bovine serum albumin stabilised gold nanoclusters (BSA-Au NCs)-graphene oxide nanocomplex (BSA-Au NCs-GO) as a `turn-on' fluorescent probe for the detection of Cd 2+ . The prepared BSA-Au NCs showed an intense red fluorescence, and the fluorescence of BSA-Au NCs was reduced significantly by graphene oxide due to its excellent quenching properties. However, in the presence of 65 μmol l -1 Cd 2+ , the fluorescence intensity recovered to 82.5% of the intensity of BSA-Au NCs, and the fluorescence intensity increased 1.3-fold relative to the BSA-Au NCs-GO nanocomplex. This proposed probe expands the application of BSA-Au NCs, which can be used as a reversible fluorescence nanoswitch for inexpensive, label free and simple detection of Cd 2+ in the aqueous samples.

Two-stage pressure-induced Yb valence change in the hexagonal Laves phase YbAg2 : Investigation by time differential perturbed angular γ−γ correlation spectroscopy method and density functional calculations

We have studied the C14 hexagonal Laves phase of YbAg$_2$ at normal conditions and under external pressure up to 19 GPa by the time-differential perturbed angular $\gamma-\gamma$ correlation spectroscopy (TDPAC) using $^{111}$Cd probe nuclei. Under pressure the valence of Yb undergoes a two stage transition from 2.8 to 3. The two stage scenario is characterized by two distinct quadrupole frequencies of $^{111}$Cd probes in silver sublattice, monotonically increasing with pressure and saturating at 8 and 16 GPa. Our experimental data are compared with the density functional studies of the electron band structure of YbAg$_2$, whose results are used for discussion and interpretation of these experiments. We have found that there are two different electric field gradients at inequivalent silver sites and that $4d$-states of silver participate in metal bonding, allowing for the formation of the hexagonal Laves phase.

TDPAC study of Fe-implanted titanium dioxide thin films

Fe-doping in TiO2 has been proven to improve several of its properties, including the photocatalytic activity. Time-differential perturbed angular correlation (TDPAC) as the applied spectroscopy method is particularly interesting because it can probe the electric and magnetic interactions on a local atomic scale. In this work the hyperfine interactions on 111Cd atoms substituting Ti atoms in TiO2 due to nearby Fe atoms also diluted within the TiO2 lattice were measured as a function of temperature. The results review two fractions with distinct quadrupole interaction parameters. One site, occupied by the 111Cd probes, presents the smaller quadrupole interaction frequency, namely υq1 = 45 MHz, and can be ascribed to sites that are more distant from the Fe substitutional site whereas the second site characterized with υq2 = 62 MHz is related to Cd probe atoms that are closer to the Fe defect. Additionally, the system has been characterized using electron dispersive spectroscopy.