- Regulative peroxidase activity of DNA-linked hemin by graphene oxide for fluorescence DNA sensing
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The inhibition effect of graphene oxide toward the peroxidase activity of DNA-linked hemin was identified and conveniently utilized in the design of a homogenous fluorescence strategy for DNA sensing with high sensitivity. This journal is the Partner Organisations 2014.
- Wang, Quanbo,Xu, Nan,Lei, Jianping,Ju, Huangxian
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- Resveratrol-ZnO nanohybrid enhanced anti-cancerous effect in ovarian cancer cells through ROS
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The use of nanotechnology in medicine and more specifically in drug delivery is expected to spread rapidly. Currently many substances are under investigation for drug delivery and more specifically for cancer therapy. Nano-conjugation of the drug is likely to provide protection against degradation, increasing bioavailability, and improvement in intracellular penetration, enhanced efficacy and control delivery of the drug. In this study, ZnO nanoparticles (NPs) conjugated with a well-known anti-proliferative and chemopreventive trans-resveratrol (RSV) has been designed, characterized and found to be a potential drug for ovarian cancer treatment. Nano-conjugate (RSV-ZnO) has been characterized by FTIR, Raman scattering and Transmission electron microscopy (TEM). Picosecond-resolved fluorescence studies of RSV-ZnO nano-conjugate reveal efficient electron migration from ZnO NPs to RSV, eventually enhancing the ROS activity compared to free RSV. Various in vivo and in vitro studies including MTT assay and apoptosis studies on ovarian cancer (PA1) cell lines reveals the RSV-ZnO nano-conjugate to be more effective in cancer cell death in comparison to free RSV. DCFH assay (in vitro) and DCFDA method (in vivo in PA1 cell lines) demonstrate the huge enhancement of antioxidant property (through ROS) in case of nano-conjugate. JC-1 staining method unravels the increase in depolarization of the mitochondrial membrane in the PA1 cell upon nano-conjugate, consistent with mitochondrial dysfunction. Finally we have performed a Western blot study by expression of some proteins like actin, Bax, Bcl-2 and Caspase-9 to confirm apoptosis.
- Khatun, Mahamuda,Choudhury, Susobhan,Liu, Bo,Lemmens, Peter,Pal, Samir Kumar,Mazumder, Santasree
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p. 105607 - 105617
(2016)
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- Metal-binding and redox properties of substituted linear and cyclic ATCUN motifs
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The amino-terminal copper and nickel binding (ATCUN) motif is a short peptide sequence found in human serum albumin and other proteins. Synthetic ATCUN-metal complexes have been used to oxidatively cleave proteins and DNA, cross-link proteins, and damage cancer cells. The ATCUN motif consists of a tripeptide that coordinates Cu(II) and Ni(II) ions in a square planar geometry, anchored by chelation sites at the N-terminal amine, histidine imidazole and two backbone amides. Many studies have shown that the histidine is required for tight binding and square planar geometry. Previously, we showed that macrocyclization of the ATCUN motif can lead to high-affinity binding with altered metal ion selectivity and enhanced Cu(II)/Cu(III) redox cycling (Inorg. Chem. 2013, 52, 2729-2735). In this work, we synthesize and characterize several linear and cyclic ATCUN variants to explore how substitutions at the histidine alter the metal-binding and catalytic properties. UV-visible spectroscopy, EPR spectroscopy and mass spectrometry indicate that cyclization can promote the formation of ATCUN-like complexes even in the absence of imidazole. We also report several novel ATCUN-like complexes and quantify their redox properties. These findings further demonstrate the effects of conformational constraints on short, metal-binding peptides, and also provide novel redox-active metallopeptides suitable for testing as catalysts for stereoselective or regioselective oxidation reactions.
- Neupane, Kosh P.,Aldous, Amanda R.,Kritzer, Joshua A.
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- Ruthenium-porphyrin complexes induce apoptosis by inhibiting the generation of intracellular reactive oxygen species in the human hepatoma cell line (HepG2)
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Two ruthenium(II)-porphyrin complexes, [(3-Py)Ru(phen)2(tmopp)] [1; phen = phenanthroline, tmopp = 5,10,15,20-tetrakis(4-methoxyphenyl) porphyrin] and [(4-Py)Ru(phen)2(tmopp)] (2), have been synthesized and characterized for the first time. It was found that the two ruthenium(II)-porphyrin complexes show significant antitumor activity in HepG2 cells. Flow cytometric analysis showed that complex 1 arrested the cell cycle in the G0/G1 phase and induced apoptosis in HepG2 cells. Fluorescence microscopy and flow cytometric analyses demonstrated that the generation of intracellular reactive oxygen species (ROS) was significantly inhibited in cells treated with either complex. The total antioxidant capacity of the complexes was detected by a 2,2′-azinobis(3-ethylbenzthiazoline-6- sulfonic acid) (ABTS) assay; this showed that both complexes are good free-radical scavengers. Ruthenium(II)-porphyrin complex 1 also was found to scavenge hydroxy radicals, as measured by the Fenton system. These data demonstrate that ruthenium(II)-porphyrin complexes exhibit antioxidant properties, probably through the involvement of a direct scavenging effect on a hydroxy radical. Taken together, the findings show that ruthenium(II)-porphyrin complexes induce apoptosis in HepG2 cells by inhibiting the generation of ROS and are potential anticancer therapeutic agents.
- Liu, Yanan,Zhang, Xiaonian,Zhang, Rong,Chen, Tianfeng,Wong, Yum-Shing,Liu, Jie,Zheng, Wen-Jie
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- G-quadruplex DNAzyme as the turn on switch for fluorimetric detection of genetically modified organisms
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A novel fluorescent sensor for detection of genetically modified organisms was developed, and in the sensor G-quadruplex DNAzyme (G-quadruplex-hemin complex) was used as the turn on switch.
- Qiu, Bin,Zheng, Zhen-Zhu,Lu, Yu-Jing,Lin, Zhen-Yu,Wong, Kwok-Yin,Chen, Guo-Nan
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- Plasmonic Enhanced Reactive Oxygen Species Activation on Low-Work-Function Tungsten Nitride for Direct Near-Infrared Driven Photocatalysis
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Realizing near-infrared (NIR) driven photocatalytic reaction is one of the promising strategies to promote the solar energy utilization and photocatalytic efficiencies. However, effective reactive oxygen species (ROS) activation under NIR irradiation remains to be great challenge for nearly all previously reported photocatalysts. Herein, the cubic-phase tungsten nitride (WN) with strong plasmonic NIR absorption and low-work function (≈3.59?eV) is proved to be able to mediate direct ROS activation by both of experimental observation and theoretical simulation. The cubic WN nanocubes (NCs) are synthesized via the hydrothermal-ammonia nitridation process and its NIR-driven photocatalytic properties, including photocatalytic degradation, hydroxylation, and de-esterification, are reported for the first time in this work. The 3D finite element simulation results demonstrate the size dependent and wavelength tuned plasmonic NIR absorption of the WN NCs. The NIR-driven photocatalytic mechanism of WN NCs is proposed based on density functional theory (DFT) calculated electronic structure and facet dependent O2 (or H2O) molecular activation, radicals scavenging test, spin trapped electron paramagnetic resonance measurements, and ultraviolet photoelectronic spectrum (UPS). Overall, the results in this work pave a way for the application of low-work-function materials as highly reactive NIR photocatalyst.
- Huang, Weicheng,Gao, Yan,Wang, Jinxin,Ding, Pengcheng,Yan, Mei,Wu, Fengmin,Liu, Jian,Liu, Danqing,Guo, Chongshen,Yang, Bin,Cao, Wenwu
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- Pyrocatalytic oxidation-strong size-dependent poling effect on catalytic activity of pyroelectric BaTiO3nano- And microparticles
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Pyrocatalysis is an emerging advanced oxidation process for wastewater remediation with the potential for thermal energy harvesting and utilization. Although several studies explored the potential of new pyrocatalyst materials to degrade harmful organic water pollutants, the role of important material properties and electric poling procedures on the pyrocatalytic activity is still unclear. In this work, we investigate the interdependence between particle size, electric poling and pyrocatalytic activity of BaTiO3 powders with nominal particle sizes of 100, 200 and 500 nm by using the dichlorofluorescein redox assay. Depending on the particle size, the influence of surface area or phase composition on the pyrocatalytic activity predominates. Moreover, we demonstrate that poling of pyrocatalysts leads to a strong size-dependent increase of pyrocatalytic activity. This poling effect increases with particle size up to +247% and can be explained with size-dependent changes in phase composition and domain structure. Combining all results, the progression of the pyrocatalytic activity as a function of particle size was derived and a future strategy for maximizing the catalytic performance of pyrocatalysts was developed. This study greatly improves the understanding about the role of important material properties and electric poling on pyrocatalytic activity, thus enabling an effective catalyst design. With the help of highly active catalysts, the pyrocatalytic process can take the next step in its development into a new and energy-efficient advanced oxidation process for water remediation.
- Braeutigam, Patrick,Buchheim, Johannes R.,Neumeister, Peter,Raufeisen, Sascha,Stelter, Michael
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p. 23464 - 23473
(2020/11/18)
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- Phthalocyanine–Virus Nanofibers as Heterogeneous Catalysts for Continuous-Flow Photo-Oxidation Processes
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The generation of highly reactive oxygen species (ROS) at room temperature for application in organic synthesis and wastewater treatment represents a great challenge of the current chemical industry. In fact, the development of biodegradable scaffolds to support ROS-generating active sites is an important prerequisite for the production of environmentally benign catalysts. Herein, the electrostatic cocrystallization of a cationic phthalocyanine (Pc) and negatively charged tobacco mosaic virus (TMV) is described, together with the capacity of the resulting crystals to photogenerate ROS. To this end, a novel peripherally crowded zinc Pc (1) is synthesized. With 16 positive charges, this photosensitizer shows no aqueous aggregation, and is able to act as a molecular glue in the unidimensional assembly of TMV. A step-wise decrease of ionic strength in mixtures of both components results in exceptionally long fibers, constituted by hexagonally bundled viruses thoroughly characterized by electron and confocal microscopy. The fibers are able to produce ROS in a proof-of-concept microfluidic device, where they are immobilized and irradiated in several cycles, showing a resilient performance. The bottom-up approach also enables the light-triggered disassembly of fibers after use. This work represents an important example of a biohybrid material with projected application in light-mediated heterogeneous catalysis.
- Anaya-Plaza, Eduardo,Aljarilla, Ana,Beaune, Grégory,Nonappa,Timonen, Jaakko V. I.,de la Escosura, Andrés,Torres, Tomás,Kostiainen, Mauri A.
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- Ti(IV) doping: An effective strategy to boost Lewis acidic performance of ZnO catalyst in fluorescein dye synthesis
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Zn1-xTixO NPs were efficiently synthesized using a simple solution free mechanochemical method. The synthesized ZnO and Ti(IV)-doped ZnO catalysts are exhibited polycrystallinity, a hexagonal crystal structure, and roughly spherical agglomerates. The surface areas of the Zn1-xTixO catalysts were positively correlated with the doping percentage of Ti(IV), which also enhanced the Lewis acidity of the NPs. The catalysts exhibited excellent activity during the synthesis of fluorescein dyes. This methodology was also extended to sulfone-fluorescein dye synthesis.
- Jadhav, Nirajkumar H.,Shinde, Dnyaneshwar R.,Sakate, Sachin S.,Rasal, Nishant K.,Pawar, Ramdas A.
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- Electronic and Steric Optimization of Fluorogenic Probes for Biomolecular Imaging
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Fluorogenic probes are invaluable tools for spatiotemporal investigations within live cells. In common fluorogenic probes, the intrinsic fluorescence of a small-molecule fluorophore is masked by esterification until entry into a cell, where endogenous esterases catalyze the hydrolysis of the masking groups, generating fluorescence. The susceptibility of masking groups to spontaneous hydrolysis is a major limitation of these probes. Previous attempts to address this problem have incorporated auto-immolative linkers at the cost of atom economy and synthetic adversity. Here, we report on a linker-free strategy that employs adventitious electronic and steric interactions in easy-to-synthesize probes. We find that X···C = O n→π? interactions and acyl group size are optimized in 2′,7′-dichlorofluorescein diisobutyrate. This probe is relatively stable to spontaneous hydrolysis but is a highly reactive substrate for esterases both in vitro and in cellulo, yielding a bright, photostable fluorophore with utility in biomolecular imaging.
- Chyan, Wen,Kilgore, Henry R.,Gold, Brian,Raines, Ronald T.
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p. 4297 - 4304
(2017/04/28)
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- Identification of ros produced by photodynamic activity of chlorophyll/cyclodextrin inclusion complexes
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Photodynamic therapy (PDT) is a way of treating malignant tumors and hyperproliferative diseases. It is based on the use of photosensitizer, herein the chlorophyll a (chl a), and a light of an appropriate wavelength. The interaction of the photosensitizer (PS) with the light produces reactive oxygen species (ROS), powerful oxidizing agents, which cause critical damage to the tissue. To solubilize chl a in aqueous solution and to obtain it as monomer, we have used cyclodextrins, carriers which are able to interact with the pigment and form the inclusion complex. The aim of this study is to examine which types of ROS are formed by Chl a/cyclodextrin complexes in phosphate buffered solution and cell culture medium, using specific molecules, called primary acceptors, which react selectively with the reactive species. In fact the changes of the absorption and the emission spectra of these molecules after the illumination of the PS provide information on the specific ROS formation. The 1O2 formation has been tested using chemical methods based on the use of Uric Acid (UA), 9,10-diphenilanthracene (DPA) and Singlet oxygen sensor green (SOSG) and by direct detection of Singlet Oxygen ( 1O2) luminescence decay at 1270 nm. Moreover, 2,7-dichlorofluorescin and ferricytochrome c (Cyt Fe3+) have been used to detect the formation of hydrogen peroxide and superoxide radical anion, which reduces Fe3+ of the ferricytochrome to Fe2+, respectively. For the first time, photodynamic activity in vitro of natural Chlorophyll a (Chl a) has been investigated evidencing which types of ROS are formed. Chl a has been solubilized in aqueous solution by means of various cyclodextrins forming inclusion complexes. The ROS production has been carried out in the system using specific molecules, called primary acceptors, which react selectively with the reactive species.
- Cellamare, Barbara M.,Fini, Paola,Agostiano, Angela,Sortino, Salvatore,Cosma, Pinalysa
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p. 432 - 441
(2013/07/19)
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- Singlet oxygen reacts with 2′,7′-dichlorodihydrofluorescein and contributes to the formation of 2′,7′-dichlorofluorescein
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There are controversial reports in the literature concerning the reactivity of singlet oxygen (1O2) with the redox probe 2′,7′-dichlorodihydrofluorescein (DCFH). By carefully preparing solutions in which 1O2 is quantitatively generated in the presence of DCFH, we were able to show that the formation rate of the fluorescent molecule derived from DCFH oxidation, which is 2′,7′- dichlorofluorescein (DCF), increases in D2O and decreases in sodium azide, proving the direct role of 1O2 in this process. We have also prepared solutions in which either 1O2 or dication (MB?2+) and semi-reduced (MB?) radicals of the sensitizer and subsequently super-oxide radical (O2 ?-) are generated. The absence of any effect of SOD and catalase ruled out the DCFH oxidation by O2?-, indicating that both 1O2 and MB?2+ react with DCFH. Although the formation of DCF was 1 order of magnitude larger in the presence of MB?2+ than in the presence of 1O2, considering the rate of spontaneous decays of these species in aqueous solution, we were able to conclude that the reactivity of 1O2 with DCFH is actually larger than that of MB?2+. We conclude that DCFH can continue to be used as a probe to monitor general redox misbalance induced in biologic systems by oxidizing radicals and 1O2.
- Daghastanli, Nasser A.,Itri, Rosangela,Baptista, Mauricio S.
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p. 1238 - 1243
(2008/12/22)
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- Rhodamine dye derivatives and their use for phase change inks
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Compounds of the formula wherein M is either (1) a metal ion having a positive charge of +y wherein y is an integer which is at least 2, said metal ion being capable of forming a compound with at least two chromogen moieties, or (2) a metal-containing moiety capable of forming a compound with at least two chromogen moieties, z is an integer representing the number of chromogen moieties associated with the metal and is at least 2, and R1,R2,R3,R4,R5,R6,R7,a,b,c,d,Y,Q-,A, and CA are as defined herein.
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