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Acetylcholinesterase (AChE) is a pivotal enzyme that is closely related with multiple neurological diseases, such as brain disorders or alterations in the neurotransmission and cancer. The development of convenient methods for imaging AChE activity in biological samples is very important to understand its mechanisms and functions in a living system. Herein, a fluorescent probe exhibiting emission in the near-infrared (NIR) region is developed to detect AChE and visualize biological AChE activities. This probe exhibits a quick response time, reasonable detection limit, and a large Stokes shift accompanied by the NIR emission. The probe has much better reactivity toward AChE than butyrylcholinesterase, which is one of the significant interfering substances. The outstanding specificity of the probe is proved by cellular imaging AChE activity and successful mapping in different regions of zebrafish. Such an effective probe can greatly contribute to ongoing efforts to design emission probes that have distinct properties to assay AChE in biological systems.

The type-I two-Higgs-doublet model in the inverted Higgs scenario can retain the theoretical stability all the way up to the Planck scale. The Planck-cutoff scale, $\Lambda_{\rm cut}^{\rm Planck}$, directly impacts the mass spectra such that all the extra Higgs boson masses should be light below about 160 GeV. However, the observation of the light masses of new Higgs bosons does not indicate the high cutoff scale because a low cutoff scale can also accommodate the light masses. Over the viable parameter points that satisfy the theoretical requirements and the experimental constraints, we show that the trilinear Higgs couplings for low $\Lambda_{\rm cut}$ are entirely different from those for the Planck-cutoff scale. The most sensitive coupling to the cutoff scale is from the $h$-$h$-$h$ vertex, where $h$ is the lighter CP-even Higgs boson at a mass below 125 GeV. Among the multi-Higgs productions mediated by Higgs bosons, the gluon fusion processes of $gg \to h h $ and $gg \to AA$ are insensitive to the cutoff scale, yielding a small variation of $\mathcal{O}(1)\,{\rm fb}$ according to $\Lambda_{\rm cut}$. The smoking-gun signature is from the triple Higgs production of $q\bar{q}' \to W^* \to H^\pm hh$, which solely depends on the $h$-$h$-$h$ vertex. The cross section for $\Lambda_{\rm cut}=1\,{\rm TeV}$ is about $10^3$ times larger than that for the Planck-cutoff scale. Since the decay modes of $H^\pm \to W^* h/W^* A$ and $h/A \to bb$ are dominant, the process yields the $6b+\ell\nu$ final state, which enjoys an almost background-free environment. Consequently, the precision measurement of $pp \to H^\pm hh$ can probe the cutoff scale of the model., Comment: Final version to appear in PRD

The present work describes the design and biological applications of a novel colorimetric and fluorescence turn-on probe for hydrosulfide detection. The probe was designed to introduce hemicyanine as the fluorescent skeleton and 7-nitro-1,2,3-benzoxadiazole as the recognition site. The optical properties and responses of the probe towards HS-, anions and some biothiols indicate an impressively high selectivity of the probe towards HS- such that it can be effectively used as an indicator for monitoring the level of HS- in living cells. In biological experiments using the probe, the H2S levels are found to be higher in cancer cells than in normal cells. In addition, the probe is shown to specifically and rapidly detect endogenous H2S, which is produced primarily in the mitochondria of cancer cells, as demonstrated by a co-localization experiment using specific trackers for the detection of cellular organelles in pharmacological inhibition or stimulation studies, without any significant cytotoxic effects. Thus, the results of the chemical and biological experiments described herein demonstrate the potential of this novel probe to specifically, safely, and rapidly detect H2S to distinguish cancer cells from normal cells by targeting it specifically in mitochondria.

Nano-biomaterial hybridization is a promising strategy to generate unique and advanced material properties that are not available with nano- or biomaterials alone. In particular, the surface stabil...

In the type-I two-Higgs-doublet model, existing theoretical and experimental constraints still permit the light charged Higgs boson with a mass below the top quark mass. We present a complete roadmap for the light charged Higgs boson at the LHC through the comprehensive phenomenology study, focusing on the normal scenario where the lighter \textit{CP}-even Higgs boson is the observed Higgs boson. In type-I, it is challenging to simultaneously accommodate the light mass of the charged Higgs boson and the constraints from theory, electroweak precision data, Higgs data, $b\to s \gamma$, and direct search bounds. Consequently, the parameter space is extremely curtailed, which predicts somewhat definite phenomenological signatures. We find that the mass of the pseudoscalar Higgs boson, $M_A$, is the most crucial factor in the phenomenology of the charged Higgs boson. If $M_A$ is light, the charged Higgs boson decays mainly into $A W^\pm$. When $M_A$ is above the $A W^\pm$ threshold, the dominant decay mode is into $ \tau^\pm \nu$. Over the whole viable parameter space, we study all the possible production and decay modes of charged Higgs bosons at the LHC, and suggest three efficient channels: (i) $pp \to H^+ H^-\to [\tau \nu] [\tau \nu]$; (ii) $pp \to HA/HH/AA \to H^\pm W^\mp H^\pm W^\mp \to [\tau \nu] [\tau \nu] W W$; (iii) $pp \to H^+ H^-\to [b \bar b W ] [b \bar b W ] $. Based on the sophisticated signal-background analyses including detector simulation, we showed that the significance of the first final state is large, that of the second one is marginal around three, but the third one suffers from huge $t\bar t$ related backgrounds., Comment: The final version to appear in PRD

A new near infrared fluorescent probe was designed and prepared to detect ATP and target lysosomes in cells. The non-fluorescent probe was turned on during the interaction with ATP, affording a 115-fold increase in fluorescence intensity. The colorless probe turned purple upon interaction with ATP. The probe displayed high sensitivity and selectivity toward ATP compared with other biomolecules, such as AMP, ADP, GMP, and CMP. Such significant spectroscopic changes derive from a structural change of the probe’s spirocyclic moiety to its ring-opened form. This occurs through electrostatic and π,π-stacking interactions between the probe and ATP. This probe was also used in selective lysosome staining and for real-time ATP level monitoring. It exhibits great advantages in cell imaging studies, such as excellent photostability, low cytotoxicity, and good cell membrane permeability.

The deposition of amyloid-β (Aβ) aggregates in the brain is a hallmark of the Alzheimer's disease (AD)-affected brain. Various aggregated Aβ species, including oligomers and fibrils, are generated upon the aggregation process, and these Aβ aggregates have distinct biological properties. To non-invasively monitor the aggregation pathways of Aβ and identify the existence of certain Aβ species in biological environments, an effective strategy to detect Aβ species is necessary. Herein, we report a turn-on near-infrared (near-IR) fluorescent probe, 1, for Aβ aggregates, which consists of a donor-π-acceptor system with an Aβ-interacting moiety. Our probe, 1, shows a noticeable increase in near-IR fluorescence at ca. 710 nm in the presence of Aβ aggregates in aqueous media. In addition, the fluorescent response of 1 was altered depending on the degree of Aβ aggregation. Moreover, 1 indicates turn-on fluorescence with Aβ aggregates in living cells and is nontoxic under the condition used for live-cell imaging.

Formaldehyde (FA) is a colorless, flammable, foul-smelling chemical used in building materials and in the production of numerous household chemical goods. Herein, a fluorescent chemosensor for FA is designed and prepared using a selective organ-targeting probe containing naphthalimide as a fluorophore and hydrazine as a FA-binding site. The amine group of the hydrazine reacts with FA to form a double bond and this condensation reaction is accompanied by a shift in the absorption band of the probe from 438 nm to 443 nm upon the addition of FA. Further, the addition of FA is shown to enhance the emission band at 532 nm relative to the very weak fluorescent emission of the probe itself. Moreover, a high specificity is demonstrated towards FA over other competing analytes such as the calcium ion (Ca2+), magnesium ion (Mg2+), acetaldehyde, benzaldehyde, salicylaldehyde, glucose, glutathione, sodium sulfide (Na2S), sodium hydrosulfide (NaHS), hydrogen peroxide (H2O2), and the tert-butylhydroperoxide radical. A typical two-photon dye incorporated into the probe provides intense fluorescence upon excitation at 800 nm, thus demonstrating potential application as a two-photon fluorescent probe for FA sensing. Furthermore, the probe is shown to exhibit a fast response time for the sensing of FA at room temperature and to facilitate intense fluorescence imaging of breast cancer cells upon exposure to FA, thus demonstrating its potential application for the monitoring of FA in living cells. Moreover, the presence of the phenylsulfonamide group allows the probe to visualize dynamic changes in the targeted Golgi apparatus. Hence, the as-designed probe is expected to open up new possibilities for unique interactions with organ-specific biological molecules with potential application in early cancer cell diagnosis.

An assay to detect carbon monoxide (CO), one of the gaseous signaling molecules, has been prepared using a new palladium complex probe. The ethylenediamine group linked to the naphthalimide fluorophore coordinates to Pd(II) which intramolecularly quenches the emission. Upon treatment with CO, the absorbance of the turn-on fluorescent sensor changes due to the formation of a complex between Pd(II) and CO at room temperature in a phosphate buffer. As the concentration of CO increases, the probe peak emission intensity at 527 nm gradually increases. Other analyte controls, such as K+, Mg2+, Al3+, Zn2+, Cr3+, Hg2+, Fe3+, alanine, glycine, leucine, lysine, serine, threonine, tyrosine, F-, Cl-, Br-, NO, NO2-, NO3-, HCO3-, CH3COO-, H2O2, •OH, and tBuOO•, exhibit no significant effect on emission intensity. The response time of the probe to CO was quite fast because of the relatively weak coordination of Pd(II) to the pendent ethylenediamine group. The Pd probe is capable of detecting CO in aqueous buffer as well as in living cells with high selectivity and stability, providing a potential real-time indicator for studying CO-involved reactions in biological systems.

Multi-metallic Pd@FePt core&ndash, shell nanoparticles were synthesized using a direct seed-mediated growth method, consisting of facile and mild procedures, to increase yield. The Fe/Pt ratio in the shell was easily controlled by adjusting the amount of Fe and Pt precursors. Furthermore, compared with commercial Pt/C catalysts, Pd@FePt nanoparticles exhibited excellent activity and stability toward the methanol oxidation reaction (MOR), making them efficient in direct methanol fuel cells (DMFC).

The efficient and selective light-driven conversion of carbon dioxide to formate is a scientific challenge for green chemistry and energy science, especially utilizing visible-light energy and earth-abundant catalytic materials. In this report, two mononuclear Ni(II) complexes of pyridylbenzimidazole (pbi) and pyridylbenzothiazole (pbt), such as Ni(pbt)(pyS)2 (1) and Ni(pbi)(pyS)2 (2) (pyS = pyridine-2-thiolate), were prepared and their reactivities studied. The two Ni complexes were examined for CO2 conversion using eosin Y as a photosensitizer upon visible-light irradiation in a H2O/ethanol solvent. The photoreaction of CO2 catalyzed by complexes 1 and 2 selectively affords formate with a high efficiency (14 000 turnover number) and a high catalytic selectivity of ∼99%. Undesirable proton reduction pathways were completely suppressed in the photocatalytic reactions with these sulfur-rich Ni catalysts under CO2. Hydrogen photoproduction was also studied under argon. Their kinetic isotope effects and influence of solution pH for formate and H2 production in the photocatalytic reactions are described in relation to the reaction mechanisms. These bioinspired Ni(II) catalysts with N/S ligation in relation to [NiFe]-hydrogenases are the first examples of early transition metal complexes affording such high selectivity and efficiencies, providing a future path to design solar-to-fuel processes for artificial photosynthesis.

The organic chromophore 2,2′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(thiophene-3-carboxylic acid), T2-BTD, was prepared and investigated along with metal complex [Ru(bda)(pyP)2] (bda = 2,2′-bipyridine-6,6′-dicarboxylate; pyP = 3-(pyridine-4-yloxy)propyl)phosphonic acid), RuC, for light-driven water splitting in dye-sensitized photoelectrochemical cells. The resulting co-loaded organic chromophore plus catalyst surface assembly was evaluated by photocurrent transient measurement and direct O2 detection using a collector–generator cell. The complete SnO2/TiO2 core–shell-based photoanode exhibited an enhanced photocurrent (∼38 μA cm–2) compared to that with only the chromophore (∼24 μA cm–2). A modest Faradaic efficiency of 12% was recorded for O2 generation under 1 sun illumination in pH 3.9, 0.1 M acetate buffer solutions.

Three ruthenium complexes containing a bidentate piq ligand, [(piq)Ru(bpy) 2 ] 2+ ( 1 ), [(piq)Ru(phen) 2 ] 2+ ( 2 ), and [(piq)Ru(DIP) 2 ] 2+ ( 3 ) (piq = phenylisoquinolinate, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, DIP = 4,7-diphenyl-1,10-phenanthroline), were prepared. The DNA binding properties of complexes 1 – 3 to double-stranded DNA were studied. The binding of 1 – 3 to calf-thymus DNA (ct-DNA) yielded lower emission intensities than those observed with the corresponding Ru complexes alone. To explore potential interactions of complexes 1 – 3 with lipid-rich organs in live cells, the emission properties of the Ru probes were studied with liposomes. The emission intensities of complexes 1 – 3 were enhanced to similar extents upon interaction with liposomes. The cytotoxic activities of the complexes against MDA-MB-231 and HUVECs were evaluated in vitro. The effects of complexes 1 – 3 on the survival of MDA-MB-231 cells were examined and compared with that of cis -platin. Complexes 2 and 3 were more cytotoxic to cancer cells than cis -platin. Complexes 1 – 3 showed cellular uptakes of 1.1, 10.6, and 76.6%, respectively, indicating that the greatest amount of complex 3 entered the cancer cells. Inhibition of cell migration by complexes 1 – 3 was also evaluated by the wound healing assay.

The electrocatalytic activity of two new molecular rhodium catalysts was investigated in a hydrogen evolution system in the presence of a proton source using glassy carbon electrodes in acetonitrile and water. Rhodium complexes supported by pbi and pbt ligands, i.e., [Cp*Rh(pbt)Cl](PF 6 ) ( 1 ) and [Cp*Rh(pbi)Cl] ( 2 ) (where Cp* is pentamethylcyclopentadienyl, pbt is 2-(2′-pyridyl)benzothiazole, and pbi is 2-(2′-pyridyl)benzimidazole), were observed to electrocatalytically evolve H 2 at potential of −0.90 V vs Ag/AgCl in CH 3 CN and CH 3 CN/H 2 O. Cyclic voltammetry of 1 and 2 in the presence of acid revealed redox waves consistent with the Rh(III)/Rh(I) couple. Bulk electrolysis were used to confirm the catalytic nature of the process for complexes 1 and 2 , with turnover numbers in excess of 100 and essentially quantitative faradaic yields for H 2 production. The potentials at which these Rh complexes catalyzed H 2 evolution were close to the thermodynamic potentials for the production of H 2 from protons in CH 3 CN and CH 3 CN/H 2 O, with the small overpotential being 50 mV for 1 as determined by electrochemistry. The complex 1 with more positive Rh(III/I) redox potentials exhibited higher activity for H 2 production.

Here, we report that Fe ions delivered into human mesenchymal stem cells (hMSCs) by bioreducible metal nanoparticles (NPs) enhance their angiogenic and cell-homing efficacy by controlling ion-triggered intracellular reactive oxygen species (ROS) and improve cell migration, while reducing cytotoxicity. Endosome-triggered iron-ion-releasing nanoparticles (ETIN) were designed to be low-pH responsive to take advantage of the low-pH conditions (4-5) of endosomes for in situ iron-ion release. Due to the different redox potentials of Fe and Au, only Fe could be ionized and released from our novel ETIN, while Au remained intact after ETIN endocytosis. Treatment with an optimal amount of ETIN led to a mild increase in intracellular ROS levels in hMSCs, which enhanced the expression of HIF-1α, a key trigger for angiogenic growth factor secretion from hMSCs. Treatmetn of hMSCs with ETIN significantly enhanced the expression of angiogenesis- and lesion-targeting-related genes and proteins. Transplantation of ETIN-treated hMSCs significantly enhanced angiogenesis and tissue regeneration in a wound-closing mouse model compared with those in untreated mice and mice that underwent conventional hMSC transplantation.

Multi-metallic nanoparticles continue to attract attention, due to their great potential in various applications. In this paper, we report a facile aqueous-phase synthesis for multi-metallic nanoparticles, including AgPt, AgPd, CuPt, and AgCuPt, by a co-reduction method within a short reaction time of 10 min. The atomic ratio of bimetallic nanoparticles was easily controlled by varying the ratio of each precursor. In addition, we found that AgCuPt trimetallic nanoparticles had a core-shell structure with an Ag core and CuPt shell.

A poly(ethylene glycol)-based thermogel can capture an iron ion (Fe3+) through a crown ether-like coordination bond between the oxygen atom and metal ions, thus, providing a sustained Fe3+-releasing system. Poly(ethylene glycol)-l-poly(alanine) thermogel was used in this study. The polypeptide forms a rather robust gel, and the degradation products are a neutral amino acid, which provides cyto-compatible neutral pH environments during the cell culture. During the heat-induced sol-to-gel transition at 37 °C, tonsil-derived mesenchymal stem cells (TMSCs) and iron ions were incorporated, leading to the formation of a three-dimensional matrix toward neuronal differentiation of the incorporated TMSCs. The initial concentration of the iron ions was varied between 0, 15, 30, and 60 mM. About 10% of the loaded iron ions was released over 21 days, which continuously supplied iron ions to the cells. The incorporation of iron ions not only increased the gel modulus at 37 °C from 107 to 680 Pa, but also promoted cell aggregation with a significant secretion of the cell adhesion signal of FAK. Expression of biomarkers related to the neuronal differentiation of TMSCs, including NFM, MAP2, GFAP, NURR1, NSE, and TUBB3, increased 4-35-fold at the mRNA level in the Fe3+-containing system compared to that of the system without Fe3+. Immunofluorescence studies also confirmed pronounced cell aggregation and a significant increase in neuronal biomarkers at the protein level. This study suggests that an iron ion-releasing thermogelling system can be a promising injectable scaffold toward neuronal differentiation of stem cells.

Injecting human mesenchymal stem cells (hMSCs) at wound sites is known to have a therapeutic effect, however, hMSCs have several limitations, such as low viability and poor engraftment after injection, as well as a potential risk of oncogenesis. The use of a conditioned medium (CM) was suggested as an alternative method for treating various wounds instead of direct hMSC administration. In addition to not having the adverse effects associated with hMSCs, a CM can be easily mass produced and can be stored for long-term, thereby making it useful for clinical applications. In general, a CM is collected from hMSCs with low passage number, whereas, the hMSCs with high passage number are usually discarded because of their low therapeutic efficacy as a result of reduced angiogenic factor secretion. Herein, we used a CM collected from high passage number (passage 12, P12) hMSCs treated with gold-iron nanoparticles (AuFe NPs). Our AuFe NPs were designed to release the iron ion intracellularly via endocytosis. Endosomes with low pH can dissolve iron from AuFe NPs, and thus, the intracellularly released iron ions up-regulate the hypoxia-inducible factor 1&alpha, and vascular endothelial growth factor (VEGF) expression. Through this mechanism, AuFe NPs improve the amount of VEGF expression from P12 hMSCs so that it is comparable to the amount of VEGF expression from low passage number (passage 6, P6), without treatment. Furthermore, we injected the CM retrieved from P12 MSCs treated with AuFe NPs in the mouse skin wound model (AuFe P12 group). AuFe P12 group revealed significantly enhanced angiogenesis in the mouse skin wound model compared to the high passage hMSC CM-injected group. Moreover, the result from the AuFe P12 group was similar to that of the low passage hMSC CM-injected group. Both the AuFe P12 group and low passage hMSC CM-injected group presented significantly enhanced re-epithelization, angiogenesis, and tissue remodeling compared to the high passage hMSC CM-injected group. This study reveals a new strategy for tissue regeneration based on CM injection without considering the high cell passage count.

Formaldehyde (FA) is a colorless, flammable, foul-smelling chemical used in building materials and in the production of numerous household chemical products. To develop a fluorescent chemosensor for FA, a newly prepared probe 1 containing napthalimide as a fluorophore and hydrazine as a binding site of FA was designed and prepared. The amine group of the hydrazine reacts with FA to form an imide bond. Indeed, the absorption band of probe 1 at 438 nm shifted to 443 nm upon the addition of FA, indicating that the condensation reaction occurred. Also, the addition of FA to probe 1 induced a large enhancement of the emission band at 532 nm compared with the relatively very weak fluorescent emission of probe 1 alone. This high specificity toward FA was observed over other competing analytes such as Ca2+, Mg2+, acetaldehyde, benzaldehyde, salicylaldehyde, glucose, glutathione, Na2S, NaHS, H2O2, and tert-butylhydroperoxy radical. The typical two-photon dye present in probe 1 also afforded intense fluorescence upon excitation, even at 800 nm, demonstrating that probe 1 could be used for a two-photon fluorescent probe for FA sensing. Probe 1 had a quick response time in the sensing of FA at room temperature. In addition, breast cancer cells treated with probe 1 exhibited intense fluorescence imaging upon exposure to FA, indicating that probe 1 could be used for monitoring FA in living cells. This probe can lead to new possibilities for unique interactions with biological molecules for applications.

Two new dinuclear iridium (Ir) complexes bridged by a conjugated aromatic tppz ligand, (bhq)2Ir(tppz)Ir(bhq)2 (1) and (ppy)2Ir(tppz)Ir(ppy)2 (2) (bhq = benzo(h)quinolone, ppy = phenyl-pyridine, tppz = tetrapyrido[3,2-a:2′,3′-c:3′′,2′′-h:2′′′,3′′′-j]phenazine), were prepared. The DNA binding properties of complexes 1 and 2 were studied using single-stranded DNA, double-stranded DNA, and G-quadruplex DNA. G-Quadruplex binding was characterized by higher emission enhancements than those observed with other control DNA strands. Photophysical properties of complexes 1 and 2 indicated that 1 displayed selective G-quadruplex binding affinity, but 2 did not. The emission properties of complexes 1 and 2 were also studied using liposomes in order to understand their possible interactions with lipid-rich organelles in live cells. The phosphorescence intensity of 1 and 2 was enhanced upon interaction with liposomes, but 2 showed greater enhancement. We also confirmed that 1 and 2 could be used as probes in live cells. Complexes 1 and 2 were intensely stained in HeLa cervical cancer cells. Excitation with a λ = 488 nm laser showed red emission localized in the cytosol of cells. Cellular studies showed that 1 and 2 were located inside HeLa cells, but neither complex passed through the nuclear membrane. However, complexes 1 and 2 possessed superior photostability, indicating their role as good luminescent agents for imaging and tracking the endoplasmic reticulum (ER) in live cells. Overall, complex 1 exhibited better selectivity for G-quadruplexes, liposomes, and ER staining.

For the practical use of a photobioreactor for artificial photosynthesis, efficient visible light-absorbing materials have to link reduction and oxidation catalysts for an efficient energy flow. As a step toward this goal of an NADH regeneration system and enzymatic production of solar fuels from CO2, we report the synthesis of a new polydiacetylene compound that is covalently connected with [Ru(phen-NH2) (bpy)2]2+ (bpy =2,2′-bipyridine, phen =1,10-phenonthroline-5-amine). The [(bpy)2Ru(phen-NH−)]-polydiacetylene absorbed a wide range of visible light because of the presence of two chromophores, the Ru complex and polydiacetylene. The polyacetylene backbone was converted from blue to red by conformational changes under the catalytic reaction conditions in a buffer solution. The electron transfer from the photoexcited [Ru(phen)(bpy)2]2+ to the polydiacetylene backbone was observed. In a visible light-driven photocatalytic NAD+ reduction by (cyclopentadienyl)Rh(bpy)(H2O)2+ with [(bpy)2Ru(phen-NH−)]-polydiac...

Two iron catalysts ([Fe(bpc)Cl2][Et4N] (1a) and [Fe(Me2bpb)Cl2][Et3NH] (1b)) displayed efficient catalysis in oxidation of various alcohols to the corresponding carbonyl products using t-BuOOH as an oxidant in the presence of N-hydroxyphthalimide (NHPI) under mild conditions. 1a having an electron-withdrawing group showed a little better catalytic activity than that of 1b with an electron-donating group. The mechanistic studies through Hammett plot, deuterium isotope effect, and the use of 2-methyl-1-phenylprop-2-yl hydroperoxide (MPPH) as a mechanistic probe suggested that the reactive oxidants responsible for the alcohol oxidation possibly involved FeIV O species, alkoxy radical (RO ), and phthalimide N-oxyl radical (PINO ). On the other hand, the presence of imidazole increased the heterolytic cleavage of Fe-OOR intermediate to form FeV O species and accelerated its O O bond cleavage rate. In particular, the formation of FeV O intermediate via the heterolytic cleavage of Fe-OOR species in the presence of imidazole in the catalytic oxidation systems of nonheme iron complexes with t-BuOOH was substantialized, for the first time, to the best of our knowledge.

A julolidine-containing naphthylamine probe (EW1) was prepared for sensing specific metal ions. Probe EW1 afforded a broad low fluorescence at 500–600 nm in acetonitrile, but gave a relatively stronger fluorescence at 540 nm in methanol. EW1 showed a selective turn-on emission for Cr3+ in CH3CN. Upon treatment with Cr3+, a strong emission was observed at 515 nm, but other metal ions, such as K+, Ag+, Ca2+, Zn2+, Co2+, Ni2+, Cu2+, Cd2+, Hg2+, Fe2+, and Fe3+, failed to induce such an emission band. A clean isosbestic point appeared at 405 nm in the UV–vis titration with Cr3+. The emission intensity of EW1 was enhanced with incremental addition of Cr3+, indicating the formation of a 1:1 complex of the probe EW1 and chromium ion. However, EW1 showed a selective turn-off response with Cu2+ in CH3OH. The emission band of EW1 at 540 nm was quenched only with Cu2+ and not with other control metal ions. The absorption band of EW1 at 410 nm progressively decreased, and a new absorption at 390 nm appeared upon progressive addition of Cu2+. All spectroscopic titration experiments and ESI mass data provided evidence for the formation of a 1:1 complex between EW1 and Cu2+.

Investigating the interactions of biomolecules DNA/RNA with carbon nanomaterials is very important for applications in bioassay and bioanalysis. Graphene and graphene oxide (GO) and carbon nanotube have been successfully adopted by exploiting the binding affinity difference between single-stranded oligonucleotides (ssDNA) and double-stranded oligonucleotides (dsDNA) to graphene sheets. In this work, we describe the electrochemical DNA oxidation with [Ru(bpy)3]2+ to understand the interaction between dsDNA (and corresponding ssDNA) and reduced graphene oxide (rGO). The electrochemical oxidation rate of guanine bases of ssDNA bound to rGO by electrochemically generated [Ru(bpy)3]3+ was much slower than that unbound to rGO. Our study revealed that ssDNA constrained on rGO was significantly protected from the electron transfer to [Ru(bpy)3]3+ because of π,π-stacking interaction between nucleobases and rGO. On the other hand, the oxidation rates of 11-, 20-, and 27-mer dsDNA bound to rGO increased relative to those of dsDNA alone, demonstrating that the guanine bases of dsDNA on interacting with rGO became more accessible to [Ru(bpy)3]3+. Our electrochemical data illustrated that dsDNA could be totally or partially dehybridized and bind to rGO to form ssDNA/rGO. Furthermore, absorption, circular dichroism spectra, and fluorescence measurements of ethidium bromide using ssDNA and dsDNA with rGO supported the dehybridization of dsDNA in the presence of rGO and CNT.

The synthesis of Pd@Pt core&ndash, shell nanocubes was achieved through a direct seed-mediated growth method. This process represents a simple and cost-effective way to produce core&ndash, shell nanocubes. The morphology of the Pd@Pt core&ndash, shell nanocubes varied from simple cubic to concave cubic, depending on the reducing agent and the Pt content. The selection of the reducing agent is important because the reduction rate is directly related to the shell growth. The catalytic activity and stability of the Pd@Pt core&ndash, shell nanocubes in the methanol oxidation reaction were different for the nanocubes with partial and full Pt shells.

Three new transition metal (Co(II), Ni(II) and Cu(II)) complexes of Schiff’s base ligand were prepared in situ by refluxing stoichiometric amounts of respective metal salts with 2-hydroxy-1-naphthaldehyde and 2-picolylamine. The structural feature of the synthesized complexes was derived from spectral (FT-IR, UV–Vis and ESI-mass) studies and elemental analysis. The single crystal X-ray diffraction analysis of complex 3 showed the structure as dimeric form [Cu(2-hnppa)Cl]2 and each copper atom is penta-coordinated. The calculated τ value of [Cu(2-hnppa)Cl]2 was 0.25 (where α = 157.84 and β = 172.18) indicating the square pyramidal geometry. Binding of these complexes (1–3) with calf thymus DNA was investigated by UV–Vis, fluorescence, viscosity measurements and computer aided molecular docking studies and the Kb value of complexes 1–3 were 2.4 × 105, 5.9 × 105 and 2.0 × 104M−1, respectively. The relative binding energies of the metal complexes 1–3 docked with DNA were −151.82, −151.86 and −151.80 eV, respectively. Complexes (1–3) exhibited a good binding capability with bovine serum albumin (BSA) with relatively high binding constant values. The complexes also act as a catalyst that enables efficient aerobic oxidation of a broad range of alcohols (benzyl alcohol, n-octanol) to the corresponding aldehydes at room temperature with ambient air as the oxidant.

Pregnancy is a known predisposing factor for central serous chorioretinopathy (CSC). Choroidal thickness (CT) increases in patients with CSC. This study was designed to evaluate CT in pregnant women.Patients and methodsThis was a prospective study. Fourteen healthy pregnant women and seven patients with pre-eclampsia were included. Twenty-one normal subjects were also recruited. CT was measured using enhanced-depth imaging optical coherence tomography.The mean CT of normal subjects, healthy pregnant women and patients with pre-eclampsia were 264.95±21.03, 274.23±29.30 and 389.79±25.13 μm, respectively (normal subjects vs healthy gravidas: P0.05; normal subjects vs pre-eclampsia: P0.001; healthy gravidas vs pre-eclampsia: P0.001). CT decreased from 381.05±22.96 μm to 335.17±9.97 μm 1 week after delivery in patients with pre-eclampsia.Pregnancy itself did not increase CT, whereas pre-eclampsia did appear to result in increased CT. This suggests that additional unknown factors induce hyperpermeability in pregnant women.

A cyclopentadienyl rhodium catalyst derivatized with pyrene was used to study the effects of a reduced graphene oxide (rGO) on visible light-driven photocatalytic hydrogen production using formate and Pt nanoparticles. The pyrene-derivatized rhodium catalyst was immobilized on rGO by π–π stacking interactions. A tight formation of the Rh catalyst on rGO surprisingly enhanced the hydrogen production upon visible light irradiation, in contrast with the results using a thin formation of the catalyst or the unfunctionalized Rh catalyst. Our results also demonstrated that the catalytic stability of the pyrene-functionalized Rh complex dramatically increased when it was immobilized on rGO during the photocatalytic reaction cycle. RGO played a crucial role in efficiently transferring electrons from the Rh(III)-hydrides to the platinum nanoparticles.

Single electron transfer (SET) promoted photoaddition reactions of N-α-trimethylsilylmethyl-N,N-dibenzylamines to fullerene C60 were investigated as part of an effort aimed at developing a general method to prepare various aryl ring containing aminomethylfullerenes and exploring factors that govern photoaddition efficiencies. The results show that the photoaddition reactions take place highly efficiently to form 1,2-adducts. The mechanism for this process involves generation of aminium radicals and C60 anion radical intermediates by a pathway initiated by excited state SET. SET is followed by desilylation of the aminium radicals to produce α-amino radicals that couple with either C60 or its radical anion to form precursors of the 1,2-adducts. The electronic nature of para-substituents on the aryl ring of N-α-trimethylsilylmethyl-N,N-dibenzylamines has a pronounced effect on the efficiency of the photoaddition reaction, with electron donating groups causing a greater than 2-fold enhancement compared to that brought about by electron withdrawing groups.

The selective assay of cyanide ions with a thioamide compound (HNPTU) containing phenol and pyridine as a chemosensor is reported using absorbance changes in a buffered aqueous solution (50 mM HEPES, pH 7.4) containing ethanol. Upon treatment with cyanide ions, the colorless solution of HNPTU turned yellow. No significant changes were observed with other comparable anions, such as F − , Cl − , Br − , I − , and CH 3 COO − . The color change of HNPTU upon treatment with CN − was maintained even in the presence of the comparable monovalent anions. The complex stability constant ( K a = 2.6 × 10 3 ) for the stoichiometric 1:1 complexation of HNPTU with cyanide ions was obtained based on absorbance titrations. The interaction of HNPTU with cyanide ions was proposed to be deprotonation, as shown by NMR and Cu(II) treatment experiments.

A new sensor 2-((E)-(3-(1H-imidazol-1-yl)propylimino)methyl)-5-(diethylamino)phenol (1) based on the combination of diethylaminosalicylaldehyde and imidazole groups was designed and synthesized as a Hg2 + selective colorimetric chemosensor. Upon treatment of 1 with mercury ions, sensor 1 showed a color-change from colorless to yellow in a mixture of H2O/DMF (5:95), while many other ions such as Al3 +, Zn2 +, Cd2 +, Cu2 +, Fe2 +, Mg2 +, Cr3 +, Ag+, Co2 +, Ni2 +, Na+, K+, Ca2 +, Mn2 + and Pb2 + had no influence. Notably, this chemosensor could distinguish clearly Hg2 + from Cu2 +, Ag+, Fe2 + and Pb2 +. The underlying signaling mechanism is a ligand-to-metal charge-transfer (LMCT) process. Compound 1 showed the serial formation of the 1:1 and the 1:2 complexation between 1 and Hg2 +. This two-step binding mode was proposed based on the UV titration, 1H NMR titration and ESI-mass studies.

As a new approach to detect Cu 2+ , colorimetric detection of Cu 2+ via organo radical formation of thiazolothiazole is reported. Upon the addition of Cu 2+ , thiazolothiazole derivatives 1 and 2 form relatively stable organo radicals, resulting in a distinct colorimetric change from greenish yellow to blue. Among the various metal ions, only Cu 2+ showed a new peak appearance at 610 nm. In addition, a selective fluorescence quenching was also observed with Cu 2+ . To understand the origin of the Cu 2+ selectivity of 1 and 2, series of electrochemical data are reported. Finally, EPR (electron paramagnetic resonance) data clearly support the formation of this unique organic radical formation.

We report a synthetic method for small and uniform Fe3O4 (magnetite) nanoparticles under mild conditions. Spherical sub-3 nm-sized magnetite nanoparticles were prepared via reverse micelles composed of oleylamine, F127, xylene, and water for the reaction of iron(III) stearate with hydrazine at a reaction temperature of 90 &deg, C in air atmosphere. These synthesized magnetite nanoparticles exhibited good size uniformity. By controlling experimental conditions, we could easily control both size and size uniformity of these magnetite nanoparticles. We further investigated whether Fe3O4 could be used in biomedical applications. Cytotoxicity of Fe3O4 was evaluated with human adipose-derived stem cells (hADSCs). Our results showed that the number of hADSCs did not significantly decrease when these cells were treated with Fe3O4 nanoparticles at a concentration of up to 9 &mu, g/mL. Apoptotic activity and cell proliferation of hADSCs treated with Fe3O4 nanoparticles were similar to those of hADSCs without any treatment. This novel method could be used for synthesizing uniform and biocompatible Fe3O4 nanoparticles with further biomedical applications.

The selective assay of aluminum and cyanide ions is reported using fluorescence enhancement and quenching of a phenol–naphthol based chemosensor (PNI) in aqueous and nonaqueous solvents, respectively. PNI gave no significant fluorescence in water. The binding properties of PNI with metal ions were investigated by UV-vis, fluorescence, and electrospray ionization mass spectrometry in a Bis–Tris buffer solution. The addition of aluminum ions switches on the fluorescence of the sensor PNI in water, comparable to relatively very low fluorescence changes in the presence of various other metal ions. The complex stability constant (Ka) for the stoichiometric 1 : 1 complexation of PNI with aluminium ions was obtained by fluorimetric titrations and NMR experiments. However, upon treatment with cyanide ions, the fluorescence of PNI was selectively turned off and the yellow solution of PNI turned to red in methanol. Other comparable anions, such as F−, Cl−, Br−, I−, CH3COO−, and H2PO4−, afforded no apparent fluorescence quenching. The interaction of PNI with cyanide ions was studied by NMR experiments.

The selective assay of aluminum and gallium ions is reported using fluorescence enhancement of a julolidine-based probe (PJI) in aqueous and nonaqueous solvents. The binding properties of PJI with metal ions were investigated by UV–vis, fluorescence, and electrospray ionization mass spectrometry. PJI gave no fluorescence in water, dimethylformamide, and methanol. The addition of aluminum ions switches on the fluorescence of the sensor PJI in both buffer and dimethylformamide, while other metal ions show no significant fluorescence changes. However, in methanol, its fluorescence can be selectively turned from a turn-on fluorescent sensor for gallium ions. The complex stability constants ( K a ) for the respective stoichiometric 1:1 complexation of PJI with aluminium and gallium ions were obtained by fluorimetric titrations.

The catalytic effect of [M(2,2′-bipyridine) 2 (NO 3 )](NO 3 ) (M(bpy) 2 , M = Cu(II), Zn(II) and Cd(II)) on the super-coiled and double stranded DNA (scDNA and dsDNA) was examined by electrophoresis and a real-time detection linear dichroism (LD) technique. Although the Cu(bpy) 2 complex effectively cleaved both types of DNA, the other two complexes were inactive. This was explained by the electrochemical properties of the metal complexes. The Cu(bpy) 2 complex exhibited a redox potential at − 0.222 V with a peak to peak separation of 0.201 V, whereas the other two metal complexes did not undergo any redox reaction. Both electrophoresis and LD measurements revealed the superoxide radical, ·O 2 − , to be responsible for DNA cleavage. A kinetic study using the LD technique showed that the cleavage of dsDNA consisted of two first order reactions. The fast reaction is believed to reflect the cleavage of one strand, whereas the slow reaction involves the cleavage of the complementary strand at or near the first cleaved site.

Natural photosynthesis utilizes solar energy to convert carbon dioxide and water to energy-rich carbohydrates. Substantial use of sunlight to meet world energy demands requires energy storage in useful fuels via chemical bonds because sunlight is intermittent. Artificial photosynthesis research focuses the fundamental natural process to design solar energy conversion systems. Nicotinamide adenine dinucleotide () and are ubiquitous as electron transporters in biological systems. Enzymatic, chemical, and electrochemical methods have been reported for NADH regeneration. As photochemical systems, visible light-driven catalytic activity of NADH regeneration was carried out using platinum nanoparticles, molecular rhodium and cobalt complexes in the presence of triethanolamine as a sacrificial electron donor. Pt nanoparticles showed photochemical NADH regeneration activity without additional visible light collector molecules, demonstrating that both photoactivating and catalytic activities exist together in Pt nanoparticles. The NADH regeneration of the Pt nanoparticle system was not interfered with the reduction of . Molecular cobalt complexes containing dimethylglyoxime ligands also transfer their hydrides to with photoactivation of eosin Y in the presence of TEOA. In this photocatalytic reaction, the reduction process competed with a proton reduction.

A new zinc ion sensor 1-(anthracen-9-yl)- N -(pyridin-2-ylmethyl)- N -(quinolin-2-ylmethyl)methanamine 1 was synthesized by incorporating a dipicolylamine derivative as a binding unit and an anthracene group as a fluorescence signaling unit. The anthracene-based receptor 1 was highly selective for Zn 2+ with a fluorescence enhancement and a remarkable red shift in aqueous solution, whereas this chemosensor showed no response to other metals, especially Cd 2+ ion. The composition of the complex 1 –Zn 2+ turned out 1:1, based on Job’s plot, ESI-mass analysis, and 1 H NMR titration.