779-27-1Relevant academic research and scientific papers
Chemical enhancement by nanomaterials under X-ray irradiation
Cheng, Neal N.,Starkewolf, Zane,Davidson, R. Andrew,Sharmah, Arjun,Lee, Changju,Lien, Jennifer,Guo, Ting
, p. 1950 - 1953 (2012)
We report here a new phenomenon of dynamic enhancement of chemical reactions by nanomaterials under hard X-ray irradiation. The nanomaterials were gold and platinum nanoparticles, and the chemical reaction employed was the hydroxylation of coumarin carboxylic acid. The reaction yield was enhanced 2000 times over that predicted on the basis of the absorption of X-rays only by the nanoparticles, and the enhancement was found for the first time to depend on the X-ray dose rate. The maximum turnover frequency was measured at 1 × 10-4 s-1 Gy-1. We call this process chemical enhancement, which is defined as the increased yield of a chemical reaction due to the chemical properties of the added materials. The chemical enhancement described here is believed to be ubiquitous and may significantly alter the outcome of chemical reactions under X-ray irradiation with the assistance of nanomaterials.
Selective tracking of ovarian-cancer-specific γ-glutamyltranspeptidase using a ratiometric two-photon fluorescent probe
Shi, Ben,Zhang, Zhenyu,Jin, Qingqing,Wang, Zhiqiang,Tang, Jie,Xu, Ge,Zhu, Tianli,Gong, Xueqing,Tang, Xinjing,Zhao, Chunchang
, p. 7439 - 7443 (2018)
Real-time tracking of GGT enzymatic activity in human ovarian cancer cells is a reliable method for accurate prediction of cancer diagnosis and management. Here, we report the two-photon ratiometric tracking of GGT activity in cancer cells based on a probe with switchable F?rster resonance energy transfer properties. In the absence of GGT, the designed probe showed two well-resolved emission bands at 461 and 610 nm, corresponding to the 7-hydroxycoumarin donor and BODIPY acceptor, respectively. In contrast, GGT catalyzed cascade reactions including cleavage of the γ-glutamyl group and subsequent aromatic hydrocarbon transfer from the S to N atom increased the distance between the two chromophores, thus decreasing the FRET efficiency, with the recovery of the donor fluorescence at 461 nm. By exploiting this enzyme-triggered ratiometric measurement, successful differentiation of ovarian cancer cells from normal cells with this probe was realized by two-photon fluorescence confocal microscopy.
X-ray and solution structures of CuIIGHK and CuIIDAHK complexes: Influence on their redox properties
Hureau, Christelle,Eury, Helene,Guillot, Regis,Bijani, Christian,Sayen, Stephanie,Solari, Pier-Lorenzo,Guillon, Emmanuel,Faller, Peter,Dorlet, Pierre
, p. 10151 - 10160 (2011)
The Gly-His-Lys (GHK) peptide and the Asp-Ala-His-Lys (DAHK) sequences are naturally occurring high-affinity copper(II) chelators found in the blood plasma and are hence of biological interest. A structural study of the copper complexes of these peptides was conducted in the solid state and in solution by determining their X-ray structures, and by using a large range of spectroscopies, including EPR and HYSCORE (hyperfine sub-level correlation), X-ray absorption and 1H and 13C NMR spectroscopy. The results indicate that the structures of [CuII(DAHK)] in the solid state and in solution are similar and confirm the equatorial coordination sphere of NH2, two amidyl N and one imidazole N. Additionally, a water molecule is bound apically to CuII as revealed by the X-ray structure. As reported previously in the literature, [CuII(GHK)], which exhibits a dimeric structure in the solid state, forms a monomeric complex in solution with three nitrogen ligands: NH2, amidyl and imidazole. The fourth equatorial site is occupied by a labile oxygen atom from a carboxylate ligand in the solid state. We probe that fourth position and study ternary complexes of [CuII(GHK)] with glycine or histidine. The CuII exchange reaction between different DAHK peptides is very slow, in contrast to [CuII(GHK)], in which the fast exchange was attributed to the presence of a [CuII(GHK)2] complex. The redox properties of [CuII(GHK)] and [CuII(DAHK)] were investigated by cyclic voltammetry and by measuring the ascorbate oxidation in the presence of molecular oxygen. The measurements indicate that both Cu II complexes are inert under moderate redox potentials. In contrast to [CuII(DAHK)], [CuII(GHK)] could be reduced to Cu I around -0.62 V (versus AgCl/Ag) with subsequent release of the Cu ion. These complete analyses of structure and redox activity of those complexes gave new insights with biological impact and can serve as models for other more complicated CuII-peptide interactions. Copyright
Noncovalent multivalent assembly of jun peptides on a leucine zipper dendrimer displaying fos peptides
Zhou, Min,Ghosh, Indraneel
, p. 3561 - 3564 (2004)
(Chemical Equation Presented) The synthesis and characterization of a new leucine-zipper dendrimer (LZD) is reported that displays four copies of the peptide corresponding to the coiled-coiled dimerization domain of Fos. Circular dichroism spectroscopy, fluorescence titration, and sedimentation equilibrium experiments demonstrate that Fos-LZD can noncovalently assemble four copies of the peptide corresponding to the coiled-coil domain of Jun. This work provides the basis for the future construction of noncovalently assembled multivalent protein assemblies displaying any protein of interest.
The effect of potential supramolecular-bond promoters on the DNA-interacting abilities of copper-terpyridine compounds
Grau, Jordi,Brissos, Rosa F.,Salinas-Uber, Jorge,Caballero, Ana B.,Caubet, Amparo,Roubeau, Olivier,Korrodi-Gregório, Luís,Pérez-Tomás, Ricardo,Gamez, Patrick
, p. 16061 - 16072 (2015)
Three copper(ii) coordination compounds have been prepared from three different 2,2′:6′,2′′-terpyridine-based ligands, which have been selected to investigate the potential role of supramolecular interactions on the DNA-interacting and cytotoxicity properties of the corresponding metal complexes. Hence, the ligands 4′-((naphthalen-2-yl)methoxy)-2,2′:6′,2′′-terpyridine (Naphtpy) and 4′-((1H-benzo[d]imidazol-2-yl)methoxy)-2,2′:6′,2′′-terpyridine (Bimztpy) have been synthesized from commercially-available 4′-chloro-2,2′:6′,2′′-terpyridine (Cltpy), and their copper(ii) complexes have been obtained by reaction with copper(ii) nitrate. The DNA-interacting abilities of the corresponding compounds [Cu(Cltpy)(H2O)(NO3)2] (1), [Cu(naphtpy)(NO3)(H2O)](NO3)(MeOH) (2) and [Cu(bimztpy)(NO3)(H2O)](NO3) (3) have been investigated using different techniques, and cytotoxicity assays with several cancer cell lines have revealed interesting features, viz. the more efficient complex is 2, which although it does not act as a DNA cleaver, displays the most effective DNA-interacting and cytotoxic properties, compared to 1 and 3.
Simultaneous Fluorescence Imaging Reveals N-Methyl- d -aspartic Acid Receptor Dependent Zn2+/H+ Flux in the Brains of Mice with Depression
Bai, Xiaoyi,Gong, Yulin,Li, Ping,Lu, Shuyi,Su, Di,Tang, Bo,Wang, Xin,Zhang, Wen,Zhang, Yandi
, (2020)
Depression is immensely attributed to the overactivation of N-methyl-d-aspartic acid (NMDA) receptor in the brains. As regulatory binding partners of NMDA receptor, both Zn2+ and H+ are intimately interrelated to NMDA receptor's activity. Therefore, exploring synergistic changes on the levels of Zn2+ and H+ in brains will promote the knowledge and treatment of depression. However, the lack of efficient, appropriate imaging tools limits simultaneously tracking Zn2+ and H+ in living mouse brains. Thus, a well-designed dual-color fluorescent probe (DNP) was fabricated for the simultaneous monitoring of Zn2+ and H+ in the brains of mice with depression. Encountering Zn2+, the probe evoked bright blue fluorescence at 460 nm. Meanwhile, the red fluorescence at 680 nm was decreased with H+ addition. With blue/red dual fluorescence signal of DNP, we observed the synchronous increased Zn2+ and H+ in PC12 cells under oxidative stress. Notably, in vivo imaging for the first time revealed the simultaneous reduction of Zn2+ and pH in brains of mice with depression-like behaviors. Further results implied that the NMDA receptor might be responsible for the coinstantaneous fluctuation of Zn2+ and H+ during depression. Altogether, this work is conducive to the knowledge of neural signal transduction mechanisms, advancing our understanding of the pathogenesis in depression.
Unique pH-Sensitive RNA Binder for Ratiometric Visualization of Cell Apoptosis
Tian, Minggang,Sun, Jie,Dong, Baoli,Lin, Weiying
, p. 10056 - 10063 (2019)
Fluorescent probes for monitoring cell apoptosis are powerful tools in biological and pathological research. However, ratiometric probes for in situ and real-time visualization of apoptosis with high accuracy are still deficient, which limits the studies relative to cell apoptosis. In this work, a pH-sensitive and positively charged RNA binder was designed and synthesized for the first time for the ratiometric visualization of cell apoptosis. In healthy cells, the probe targets mitochondria with basic matrixes and high membrane potential and displays intense emission in the blue and red channels. During apoptosis, the probe is released from mitochondria, binds to basophilic RNA, and shows emission in only the red channel. Consequently, cell apoptosis caused by drug treatment could be efficiently and clearly monitored in a ratiometric manner. The probe is expected to facilitate the study of cell apoptosis and relative areas.
Histidine-Rich Oligopeptides to Lessen Copper-Mediated Amyloid-β Toxicity
Caballero, Ana B.,Terol-Ordaz, Laia,Espargaró, Alba,Vázquez, Guillem,Nicolás, Ernesto,Sabaté, Raimon,Gamez, Patrick
, p. 7268 - 7280 (2016)
Brain copper imbalance plays an important role in amyloid-β aggregation, tau hyperphosphorylation, and neurotoxicity observed in Alzheimer's disease (AD). Therefore, the administration of biocompatible metal-binding agents may offer a potential therapeutic solution to target mislocalized copper ions and restore metallostasis. Histidine-containing peptides and proteins are excellent metal binders and are found in many natural systems. The design of short peptides showing optimal binding properties represents a promising approach to capture and redistribute mislocalized metal ions, mainly due to their biocompatibility, ease of synthesis, and the possibility of fine-tuning their metal-binding affinities in order to suppress unwanted competitive binding with copper-containing proteins. In the present study, three peptides, namely HWH, HKCH, and HAH, have been designed with the objective of reducing copper toxicity in AD. These tripeptides form highly stable albumin-like complexes, showing higher affinity for CuII than that of Aβ(1-40). Furthermore, HWH, HKCH, and HAH act as very efficient inhibitors of copper-mediated reactive oxygen species (ROS) generation and prevent the copper-induced overproduction of toxic oligomers in the initial steps of amyloid aggregation in the presence of CuII ions. These tripeptides, and more generally small peptides including the sequence His-Xaa-His at the N-terminus, may therefore be considered as promising motifs for the future development of new and efficient anti-Alzheimer drugs.
Distinguishable multi-substance detection based on three-channel NIR fluorescent probe in physiology and pathology of living cells and zebrafish
Li, Sha,Huo, Fangjun,Yue, Yongkang,Ma, Kaiqing,Wen, Ying,Yin, Caixia
, p. 3870 - 3875 (2021)
Mitochondria is the main organelle for the production of reactive sulfur species (RSS), such as homocysteine (Hcy), cysteine (Cys), glutathione (GSH) and sulfur dioxide (SO2). These compounds participate in a large number of physiological processes and play an extremely important role in maintaining the balance of life systems. Abnormal concentration and metabolism are closely related to many diseases. Due to their similarities in chemical properties, it is challenging to develop a single fluorescent probe to distinguish them simultaneously. Here, we synthesized the probe PI-CO[sbnd]NBD with three fluorophores, NBD-Cl and benzopyranate as the reaction sites of GSH/Cys/Hcy and SO2, respectively. Three biothiols all could cleavage ether bond to release benzopyrylium and coumarin moiety, which emitted red and blue fluorescence, but Cys/Hcy also could do intramolecular rearrangement after nucleophilic substitution, resulting in yellow fluorescence. Thus the probe can distinguish Cys/Hcy and GSH. Subsequently, only SO2 could quench red fluorescence by adding C[dbnd]C of benzopyrylium. The probe also could localize well in mitochondria by oxonium ion for all kinds of cells. The probe not only could detect above sulfur-containing active substances of intracellular and extracellular but also monitor the level of them under oxidative stress and apoptosis process in living cells and zebrafish.
A dual-site controlled ratiometric probe revealing the simultaneous down-regulation of pH in lysosomes and cytoplasm during autophagy
Tian, Minggang,Liu, Chuang,Dong, Baoli,Zuo, Yujing,Lin, Weiying
, p. 10440 - 10443 (2019)
In this work, a unique dual-site controlled fluorescent probe was presented for the sensitive and concurrent detection of pH in the cytoplasm and lysosomes. With the probe, the simultaneous down-regulation of pH in the lysosomes and cytoplasm during autophagy has been successfully revealed for the first time.
