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News Article | February 15, 2017
Site: cen.acs.org

A new small-molecule strategy could help target cancer drugs selectively to tumors with the help of click chemistry (Nat. Chem. Biol. 2017, DOI: 10.1038/nchembio.2297). Many cancer drugs attack healthy tissue in addition to tumors, leading to harmful side effects. So scientists want to target therapeutics to cancer cells more selectively. One such approach that has reached the clinic is antibody-drug conjugates. Antibodies recognize antigens, such as HER2 on some breast cancer cells, allowing antibody-attached drugs to kill those cancer cells selectively. But disease-specific antigens aren’t always available, and antibody-drug conjugates are costly and must be administered intravenously. A group led by Jianjun Cheng of the University of Illinois, Urbana-Champaign (UIUC), Lichen Yin of Soochow University, and Xuesi Chen of Changchun Institute of Applied Chemistry has now come up with a strategy called active tissue targeting via anchored click chemistry (ATTACK) that they’ve tested in mice and that may have advantages over antibody-drug conjugates. In the two-step ATTACK process, the researchers first give tumor-bearing mice an ether-protected sugar that carries an azide group. Cells can deprotect and then metabolize the sugar, which then gets attached to glycoproteins in the cell membrane. Because cancer cells proliferate quickly, they overexpress some enzymes, two of which catalyze deprotection of the azido sugar. This makes cancer cells more likely than normal cells to be tagged by the bioorthogonal azide groups. In the second step, researchers give the mice an anticancer drug conjugated to dibenzocyclooctyne (DBCO). DBCO’s alkyne group undergoes a selective click-chemistry reaction with azides, thus recruiting the conjugated drug selectively to azide-decorated cancer cells. In the mice, ATTACK improved drug-targeting selectivity 50% for treated tumors over untreated ones. And a DBCO-doxorubicin conjugate was significantly more effective and much less toxic than doxorubicin alone at treating colon cancer and two forms of breast cancer in mice—improvements the researchers plan to quantify in future work. ATTACK has potential advantages over antibody-drug conjugates: It doesn’t require that a given cancer have a cell-surface antigen because the method creates its own targets; and ATTACK’s small-molecule agents could be orally available and less expensive to make. The strategy “is very elegant” for achieving selective action because the ether is deprotected primarily in cancer cells, comments targeted drug delivery expert Liangfang Zhang of the University of California, San Diego. “It’s great work that will generate a lot of interest in the field.” “The approach is clever in that it translates an intracellular molecular signature, cancer-related enzyme expression, to a cell-surface signature, azide groups that allow for targeting,” says bioorthogonal chemistry specialist Carolyn R. Bertozzi of Stanford University, adding that she is interested to see if the approach can be developed commercially.


News Article | April 12, 2016
Site: cen.acs.org

An international research team has prepared a set of lanthanide antimony clusters that represent the first isolable compounds containing an all-metal antiaromatic ring. The achievement continues to expand the concept of aromaticity beyond its humble beginnings 150 years ago. Researchers including Xue Min and Zhong-Ming Sun of Changchun Institute of Applied Chemistry and Ivan A. Popov and Alexander I. Boldyrev of Utah State University created a series of anions, [Ln(Sb ) ]3–, where Ln is La, Y, Ho, Er, or Lu. They made the anions by treating lanthanide benzyl complexes with the Zintl cluster complex K Sb in pyridine solvent and then isolating the anions as potassium cryptand salts. On the basis of X-ray crystal structures and computational bonding analysis, the team says the rhombic Sb rings that serve as ligands to the lanthanide metals are antiaromatic (Angew. Chem. Int. Ed. 2016, DOI: 10.1002/anie.201600706). The concept of antiaromaticity has a storied history. In 1865, German chemist August Kekulé proposed the concept of aromaticity to explain the unusual properties of benzene, a planar carbon ring that exhibits high stability and low reactivity. In 1931, German chemist Erich Hückel added to the definition that aromatic compounds have a delocalized 4n + 2 π-electron system. In 1965, on the centennial of Kekulé’s proposal, Columbia University’s Ronald Breslow proposed the idea of antiaromaticity—the antonym of aromaticity—to characterize planar carbon rings with a 4n π-electron system that exhibit low stability and high reactivity. Aromaticity and antiaromaticity were originally thought to be purely the domain of organic chemistry. But during the past 20 years, chemists have shown that this organic boundary is flexible. In 1995, Gregory H. Robinson and coworkers of the University of Georgia isolated the sodium salt of a phenyl-substituted Ga ring with two π electrons, introducing the concept of metalloaromaticity. In 2003, Boldyrev’s group in collaboration with Lai-Sheng Wang, now at Brown University, followed suit by reporting Li Al –, which includes an antiaromatic Al 4– ring containing four π electrons. However, the gaseous molecule was created in a laser-based experiment and couldn’t be trapped in a condensed state. With the [Ln(Sb ) ]3– series, chemists now have the first examples of isolable inorganic antiaromatic compounds. As a key feature, each Sb ring stabilized by the lanthanide metal has four delocalized π electrons. The Sb unit is analogous to cyclobutadiene, Boldyrev says, which is the quintessential antiaromatic organic compound. “Antiaromaticity in these all-metal systems is very nice,” Breslow tells C&EN. “It is gratifying to see that our proposal, which was quite unexpected when we first made it for organic systems, has such generality.” Further advances of aromaticity and antiaromaticity into metal territory will be valuable for understanding the properties of metal clusters, bulk metals, and alloys, Boldyrev and Sun add, which could be handy for making thin-film electronic materials. “From a conceptual perspective, this is another example of the concept of aromaticity—in this case antiaromaticity or antimetalloaromaticity—being extended beyond the realm of carbon,” Robinson says. “More important, taking all of this work into consideration, aromaticity and metalloaromaticity seem to be foundational principles throughout the whole of chemistry.” This article has been translated into Spanish by Divulgame.org and can be found here.


News Article | January 27, 2016
Site: news.yahoo.com

Chinese scientists have developed a flexible lithium-based battery that is based on Chinese brush painting. More Scientists in China have developed a flexible, rollable, foldable battery inspired by traditional Chinese calligraphy involving ink on paper. Worldwide demand for flexible electronics is rapidly growing, because the technology could enable such things as video screens and solar panels to bend, roll and fold. These flexible electronics require batteries that are equally flexible to power them, but conventional batteries are too rigid and bulky to be used in flexible electronics. Chinese scientists, however, have developed a flexible lithium-based battery that is based on Chinese brush painting. [5 Crazy Technologies That Are Revolutionizing Biotech] Lithium-ion batteries power most portable devices, from smartphones to tablet computers to laptops. However, so-called lithium-air batteries could, in principle, hold five to 10 times as much energy as a lithium-ion battery of the same weight. This means that lithium-air batteries could theoretically give electric cars the same range as gasoline ones. Batteries usually contain two electrodes — the anode and the cathode. In a lithium-air battery, the anode is generally made of lithium metal, while the cathode is typically a porous carbon material that allows the surrounding air into the battery. As the lithium reacts with oxygen in the air, it discharges electricity. Recharging the device reverses the process. The scientists noted that the main component of black painting ink is carbon, and that paper is porous, thin, flexible, light and cheap. They reasoned that ink drawn on paper could serve as a cathode for a lithium-air battery in a very simple manner. "Due to the ultra-high theoretical energy density of lithium-oxygen batteries, they may be one of the most suitable candidates in the future for the development of flexible electronics," study senior author Xinbo Zhang, a materials scientist at the Changchun Institute of Applied Chemistry in China, told Live Science. The researchers constructed a battery from a sandwich of three layers — an ink-paper cathode, a sheet of lithium foil as the anode, and a sheet made of glass fibers between the anode and the cathode that permits electrically charged ions to flow between the cathode and anode. Zhang and his colleagues found their prototype batteries possessed energy-storage capacities comparable to commercial lithium-ion batteries, even after 1,000 cycles of flexing back and forth. They could also easily fold these sheets into battery packs. In the future, Zhang said he and his colleagues will explore lightweight flexible coatings for these batteries to protect them from corrosion. Zhang and his colleagues detailed their findings in the Dec. 22 issue of the journal Advanced Materials. Copyright 2016 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.


Liu S.,Guangxi University | Liu S.,Institute of Applied Chemistry | Liu G.,Guangxi University | Liu G.,Yulin Normal University | Feng Q.,Guangxi University
Journal of Porous Materials | Year: 2010

Aluminium-doped TiO2 mesoporous material was successfully fabricated by solid-state reaction with cetyltrimethylammonium bromide as a template agent and tetrabutyl orthotitanate as a precursor. The characteristic results from low-angle and wide-angle X-ray diffraction, high resolution transmission electron microscopy and energy dispersive spectroscopy, N 2 absorption-desorption, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet visible light spectroscopy and X-ray photoelectron spectroscopy (XPS) clearly showed that the mesoporous architecture of aluminium-doped TiO2 was composed of crystal wall and micro-/mesopore formed gradually by the mesopore degradation of anatase TiO 2, and aluminium had been doped into the framework of anatase TiO2. The mesoporous Al-doped TiO2 material, not only possessed high thermal stability hexahedral mesostructure, large BET surface area and narrow distribution of pore size, but also showed excellent photodegradation behavior for Congo Red. Furthermore the medium UV-Vis absorption peak of mesoporous aluminium-doped TiO2 in the range 210-370 nm was the absorption peak of aluminium oxide nanoparticles locating the extraframework of TiO2. A small quantity of aluminium doped into anatase TiO2 could obviously improve photodegradation activity, and the photodegradation activity of aluminiumdoped TiO2 was higher than that of pure TiO2. © 2009 Springer Science+Business Media, LLC.


News Article | October 24, 2016
Site: www.cemag.us

Photodetectors, which are used in a wide range of systems and devices — from smartphones to space stations — are typically only sensitive to light within a certain narrow bandwidth, which causes numerous problems to product developers. Together with their colleagues from China and Saudi Arabia, scientists at Moscow Institute of Physics and Technology (MIPT) have found a way to address this. According to their study, published in Advanced Functional Materials ("Ultrahigh Gain Polymer Photodetectors with Spectral Response from UV to Near-Infrared Using ZnO Nanoparticles as Anode Interfacial Layer"), treating an ordinary photodetector with UV light can turn it into a high bandwidth device. “There is a lot of demand for photodetectors that are sensitive to a wide range of frequencies, but they are difficult to design. It’s hard to find the right materials, because the substances that permit ultraviolet light tend to be nontransparent to infrared radiation, and vice versa. We found a way to ‘broaden’ the spectral response of photodetectors,” says Vadim Agafonov, head of the Molecular Electronics Center at MIPT, a coauthor of the paper. The research team that also includes his colleagues from the Changchun Institute of Applied Chemistry and King Saud University studied polymer photodetectors based on the internal photoelectric effect, i.e., the redistribution of electrons within a polymer under the influence of light, resulting in electrical conductivity. Photodetectors based on organic materials have a number of advantages over their conventional inorganic counterparts, including their low cost, easier manufacturing, and physical flexibility. It turned out that by interacting with the surfaces of certain elements of the device, UV radiation can alter its sensitivity. The researchers conducted an experiment whereby a polymer-based photodetector incorporating zinc oxide (ZnO) nanoparticles was exposed to UV light for 30 seconds. As a result of this, they achieved a high-performance photodetector with a much broader spectral response and a maximum external quantum efficiency (EQE) of 140,000 percent, as compared to the 30 percent measured before UV treatment. The EQE of a photodetector is an important figure of merit defined as the ratio between the number of “dislodged” electrons and the number of incident photons. To put that in perspective, whereas before irradiation 10 photons generated just three electrons, after UV treatment the same number of photons produced 14,000 photoelectrons. However, the amount of noise experienced by the device was also greater due to an increased dark current, which is generated in the detector even when no photons are entering the device. The researchers attribute the dramatic effect of UV light on detectors to the detachment of oxygen atoms from the zinc oxide molecules. During the manufacturing of a photodetector, oxygen molecules are adsorbed onto the surface of the semiconductor particles, whereby oxygen captures electrons from the conduction band. As a result, the captured electrons can no longer act as charge carriers. This means that the zinc oxide layer becomes a barrier that affects electron transport. UV light treatment causes some of the valence electrons to migrate into the conduction band, driven by the radiation absorbed by the ZnO particles. The freed up electrons can then act as charge carriers, generating photocurrent even at the minimal measurable optical power intensity of 60 pW x cmv-2 (picowatts per cm2) under the bias voltage of -0.5 V. “You can thus convert a polymer-based photodetector into a highly sensitive broadband device. The process itself is quick, cheap, and efficient, which is important for practical applications,” says Agafonov. According to the paper, it is sufficient to treat a photodetector with UV light once during its manufacturing in order to achieve the broad spectral response. Moreover, the newly acquired properties of the device will remain unchanged after the manufacturing process is over, as the semiconductor layer will be sealed by a layer of aluminum protecting it from oxygen. The researchers hope to eliminate the “side effects” that arise after irradiating the detector with UV light (e.g., a sharp increase in dark current), without sacrificing the high performance and wide spectral range of the device. Photodetectors that have been treated in the proposed way could be used anywhere from imaging to atmospheric sensing.


News Article | October 24, 2016
Site: www.rdmag.com

Photodetectors, which are used in a wide range of systems and devices--from smartphones to space stations--are typically only sensitive to light within a certain narrow bandwidth, which causes numerous problems to product developers. Together with their colleagues from China and Saudi Arabia, scientists at MIPT have found a way to address this. According to their study, published in Advanced Functional Materials, treating an ordinary photodetector with UV light can turn it into a high bandwidth device. "There is a lot of demand for photodetectors that are sensitive to a wide range of frequencies, but they are difficult to design. It's hard to find the right materials, because the substances that permit ultraviolet light tend to be nontransparent to infrared radiation, and vice versa. We found a way to 'broaden' the spectral response of photodetectors," says Vadim Agafonov, head of the Molecular Electronics Center at MIPT, a coauthor of the paper. The research team that also includes his colleagues from the Changchun Institute of Applied Chemistry (China) and King Saud University (Saudi Arabia) studied polymer photodetectors based on the internal photoelectric effect, i.e., the redistribution of electrons within a polymer under the influence of light, resulting in electrical conductivity. Photodetectors based on organic materials have a number of advantages over their conventional inorganic counterparts, including their low cost, easier manufacturing, and physical flexibility. It turned out that by interacting with the surfaces of certain elements of the device, UV radiation can alter its sensitivity. The researchers conducted an experiment whereby a polymer-based photodetector incorporating zinc oxide (ZnO) nanoparticles was exposed to UV light for 30 seconds. As a result of this, they achieved a high-performance photodetector with a much broader spectral response and a maximum external quantum efficiency (EQE) of 140,000%, as compared to the 30% measured before UV treatment. The EQE of a photodetector is an important figure of merit defined as the ratio between the number of "dislodged" electrons and the number of incident photons. To put that in perspective, whereas before irradiation 10 photons generated just three electrons, after UV treatment the same number of photons produced 14,000 photoelectrons. However, the amount of noise experienced by the device was also greater due to an increased dark current, which is generated in the detector even when no photons are entering the device. The researchers attribute the dramatic effect of UV light on detectors to the detachment of oxygen atoms from the zinc oxide molecules. During the manufacturing of a photodetector, oxygen molecules are adsorbed onto the surface of the semiconductor particles, whereby oxygen captures electrons from the conduction band. As a result, the captured electrons can no longer act as charge carriers. This means that the zinc oxide layer becomes a barrier that affects electron transport. UV light treatment causes some of the valence electrons to migrate into the conduction band, driven by the radiation absorbed by the ZnO particles. The freed up electrons can then act as charge carriers, generating photocurrent even at the minimal measurable optical power intensity of 60 pW?×?cm?² (picowatts per cm²) under the bias voltage of ?0.5 V. "You can thus convert a polymer-based photodetector into a highly sensitive broadband device. The process itself is quick, cheap, and efficient, which is important for practical applications," says Vadim Agafonov. According to the paper, it is sufficient to treat a photodetector with UV light once during its manufacturing in order to achieve the broad spectral response. Moreover, the newly acquired properties of the device will remain unchanged after the manufacturing process is over, as the semiconductor layer will be sealed by a layer of aluminum protecting it from oxygen. The researchers hope to eliminate the "side effects" that arise after irradiating the detector with UV light (e.g., a sharp increase in dark current), without sacrificing the high performance and wide spectral range of the device. Photodetectors that have been treated in the proposed way could be used anywhere from imaging to atmospheric sensing.


Fu C.,University of Sichuan | Lei L.,University of Sichuan | Sun K.,Institute of Applied Chemistry | Xia P.,Institute of Applied Chemistry | And 3 more authors.
Renewable Energy | Year: 2012

An unsymmetrical squaraine dye which contains an arylamino group was synthesized and used in dye-sensitized solar cells. The molar extinction coefficient of the dye is 77793 M-1 cm-1. Because our synthesized molecule may have no diradical character or the contribution of the diradicaloid component to resonance is quite small, the newly designed squaraine dye has a maximum absorption at 546 nm in the visible region compared with the NIR squaraine sensitizers. Cyclic voltammetry and time dependent density function theory calculation were accomplished to scrutinize the sensitized performance of the dye. Meanwhile, the novel sensitizer has been used to sensitize nanocrystalline TiO2-based solar cell. Under standard global AM 1.5 solar conditions, the squaraine dye-sensitized cell gives a short circuit photocurrent density (JSC) of 5.84 mA/cm2, an open circuit voltage of (VOC) 0.658 V, and a fill factor (ff) of 0.448, corresponding to an overall conversion efficiency (η) of 1.72%. © 2011 Elsevier Ltd.


Murnieks R.,Institute of Applied Chemistry | Kampars V.,Institute of Applied Chemistry | Malins K.,Institute of Applied Chemistry | Apseniece L.,Institute of Applied Chemistry
Bioresource Technology | Year: 2014

In the present work, wheat straw was hydroliquefied at a temperature of 300°C for 4h in ethanol or toluene in order to obtain bio-components which are useful for fuel purposes. The experiments were performed in a 100mL batch reactor under hydrogen pressure of 70bar. Typically, 2g of straw and 0.1g of catalyst (66%Ni/SiO2-Al2O3) were dispersed in 15g of solvent. The main compounds of the oil produced during the liquefaction of hemicellulose, cellulose and lignin of wheat straw in both solvents are: tetrahydrofuran-2-methanol, 1,2-butanediol and butyrolactone. Besides the mentioned compounds, ethanol favoured the decomposition of bigger molecules to short-chain alcohols such as 1-butanol, 1,2-propanediol and 1,2-ethanediol. Toluene contributes to the production of furans and other cyclic compounds. The light fractions distilled together with the solvent also contain the following: 1-propanol, 2-methyl-cyclopentanone, acetic acid and ethyl acetate. © 2014 Elsevier Ltd.


Chen W.-T.,Institute of Applied Chemistry
Zeitschrift fur Kristallographie | Year: 2013

A novel zinc porphyrin, Zn[(tcpp)(thf)2] (1) (tcpp = meso-tetra(4-carboxyphenyl)porphyrin; thf = tetrahydrofuran), has been prepared via a solvothermal reaction and structurally characterized by single crystal X-ray diffraction. The zinc ion coordinates to four nitrogen and two oxygen atoms. The substance crystallizes orthorhombically in the space group Cmca with a = 30.8367(6), b = 8.7099(5), c = 15.3526(2) A, V = 4123.5(3) A3, C56H44N4O10Zn, Z= 4, Mr = 998.34, Dc = 1.608 g/cm3, S = 0.991, μ(MoK α) = 0.673 mm-1, F(000) = 2072, R = 0.0555 and wR = 0.1338. Photoluminescent investigation shows that complex 1 exhibits an emission in the blue region. The spectral data of FT-IR were also reported. © by Oldenbourg Wissenschaftsverlag, München.


News Article | November 11, 2015
Site: www.nature.com

Ink on paper can act as an electrode in a thin, flexible battery. Inspired by Chinese brush painting, a team led by Xin-Bo Zhang at the Chinese Academy of Sciences' Changchun Institute of Applied Chemistry fabricated a flexible lithium-air battery using lithium foil and paper with a carbon-based ink (pictured). Electrons are stripped from the foil, creating lithium ions that flow to the inked paper electrode, where they combine with oxygen from the air. The resulting battery can hold a charge even after it has been bent 1,000 times. A foldable pack of four batteries, which weighs less than 2 grams, can supply current for 100 hours. The technique paves the way for cheap and easily manufactured flexible batteries, the authors say.

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