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https://www.readbyqxmd.com/read/28821158/synthesis-characterization-bioactivity-and-potential-application-of-phenolic-acid-grafted-chitosan-a-review
#1
REVIEW
Jun Liu, Huimin Pu, Shuang Liu, Juan Kan, Changhai Jin
In recent years, increasing attention has been paid to the grafting of phenolic acid onto chitosan in order to enhance the bioactivity and widen the application of chitosan. Here, we present a comprehensive overview on the recent advances of phenolic acid grafted chitosan (phenolic acid-g-chitosan) in many aspects, including the synthetic method, structural characterization, biological activity, physicochemical property and potential application. In general, four kinds of techniques including carbodiimide based coupling, enzyme catalyzed grafting, free radical mediated grafting and electrochemical methods are frequently used for the synthesis of phenolic acid-g-chitosan...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821132/the-effect-of-%C3%AE-cyclodextrin-on-poly-pseudo-rotaxane-nanoparticles-self-assembled-by-protoporphyrin-modified-poly-ethylene-glycol-for-anticancer-drug-delivery
#2
Taotao Xu, Junhua Li, Jun Cao, Wenxia Gao, Li Li, Bin He
Poly(pseudo)rotaxane (PPR) nanoparticles was facilely prepared using poly(ethylene glycol) (PEG) modified with protoporphyrin (PpIX) and α-cyclodextrin (α-CD) via host-guest interaction, the effect of α-CD number on the nanoparticle properties was investigated. The PEG with protoporphyrin (PEG-PpIX) end capping was synthesized via coupling reaction and the poly(pseudo)rotaxane nanoparticles with different amount of α-CD were fabricated by host-guest interaction between mPEG-PpIX and α-CDs. The final product was characterized by nuclear magnetic spectrum ((1)H NMR), X-ray diffraction (XRD), atomic force microscope (AFM) and dynamic light scattering (DLS)...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821115/rheology-and-bioactivity-of-high-molecular-weight-dextrans-synthesised-by-lactic-acid-bacteria
#3
Kenza Zarour, Mª Goretti Llamas, Alicia Prieto, Patricia Rúas-Madiedo, María Teresa Dueñas, Pilar Fernández de Palencia, Rosa Aznar, Mebrouk Kihal, Paloma López
Dextrans synthesised by three Leuconostoc mesenteroides strains, isolated from mammalian milks, were studied and compared with dextrans produced by Lc. mesenteroides and Lactobacillus sakei strains isolated from meat products. Size exclusion chromatography coupled with multiangle laser light scattering detection analysis demonstrated that the dextrans have molecular masses between 1.74×10(8)Da and 4.41×10(8)Da. Rheological analysis of aqueous solutions of the polymer revealed that all had a pseudoplastic behaviour under shear conditions and a random, and flexible, coil structure...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821111/a-facile-sodium-alginate-based-approach-to-improve-the-mechanical-properties-of-recycled-fibers
#4
Yuan-Yuan Bai, Yan-Hao Lei, Xiao-Jun Shen, Jing Luo, Chun-Li Yao, Run-Cang Sun
The application of recycled fibers is steadily increasing in various paper products recently. It is necessary to improve the mechanical properties of paper products made from these fibers. An eco-friendly polymeric additive, sodium alginate (SA), was prepared from waste seaweeds and developed as functional additives. The properties of SA were characterized by proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermal gravity analysis, gel permeation chromatography, and compared with the commercial SA...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821097/thiolated-pectin-doxorubicin-conjugates-synthesis-characterization-and-anticancer-activity-studies
#5
Kamonrak Cheewatanakornkool, Sathit Niratisai, Somkamol Manchun, Crispin R Dass, Pornsak Sriamornsak
In this paper, pectin was cross-linked by a coupling reaction with either thioglycolic acid or cystamine dihydrochloride to form thiolated pectins. The thiolated pectins were then coupled with doxorubicin (DOX) derivative to obtain thiolated pectin-DOX conjugates by two different methods, disulfide bond formation and disulfide bond exchange. The disulfide bond exchange method provided a simple, fast, and efficient approach for synthesis of thiolated pectin-DOX conjugates, compared to the disulfide bond formation...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28820988/integrating-printed-microfluidics-with-silicon-photomultipliers-for-miniaturised-and-highly-sensitive-atp-bioluminescence-detection
#6
M F Santangelo, S Libertino, A P F Turner, D Filippini, W C Mak
Bioluminescence has been widely used for important biosensing applications such as the measurement of adenosine triphosphate (ATP), the energy unit in biological systems and an indicator of vital processes. The current technology for detection is mainly based on large equipment such as readers and imaging systems, which require intensive and time-consuming procedures. A miniaturised bioluminescence sensing system, which would allow sensitive and continuous monitoring of ATP, with an integrated and low-cost disposable microfluidic chamber for handling of biological samples, is highly desirable...
July 27, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28820987/a-new-label-free-electrochemical-immunosensor-based-on-dendritic-core-shell-aupd-au-nanocrystals-for-highly-sensitive-detection-of-prostate-specific-antigen
#7
Rui Wang, Wei-Dong Liu, Ai-Jun Wang, Yadong Xue, Liang Wu, Jiu-Ju Feng
Herein, bimetallic dendritic core-shell AuPd@Au nanocrystals (AuPd@Au NCs) were prepared by a simple one-pot aqueous method using xanthine as a green growth-directing agent. By virtue of the enhanced peak currents in the H2O2 reduction catalyzed by AuPd@Au NCs, a label-free immunosensor was constructed for the detection of prostate specific antigen (PSA). The immunosensor exhibited significantly improved analytical performance for the assay of PSA with wide linear range of 0.1-50ngmL(-1) and low detection limit of 0...
August 10, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28820983/a-sensitive-method-for-the-separation-and-quantification-of-low-level-adenine-nucleotides-using-porous-graphitic-carbon-based-liquid-chromatography-and-tandem-mass-spectrometry
#8
Sonia Bustamante, Robert B Gilchrist, Dulama Richani
A liquid chromatography coupled to heated electrospray ionization/tandem mass spectrometry (LC-HESI-MS/MS) method was developed for the simultaneous quantitative analysis of low nanomolar level adenine nucleotides AMP, ADP, ATP, cyclic AMP (cAMP), and the nucleoside adenosine. For analyte retention and separation, reverse phase chromatography using porous graphitic carbon (PGC) was employed as it provided full resolution. The erratic chromatographic behaviour characteristic of PGC, including deterioration of analyte resolution and increased peak tailing (leading to decreased sensitivity), was mitigated by incorporating acidic equilibration within runs using a quaternary gradient...
July 29, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/28820953/a-fluorescence-based-high-throughput-assay-for-the-identification-of-anticancer-reagents-targeting-fructose-1-6-bisphosphate-aldolase
#9
Eun Jeong Cho, Ashwini K Devkota, Gabriel Stancu, Ramakrishna Edupunganti, Garth Powis, Kevin N Dalby
A high rate of glycolysis, which supplies energy and materials for anabolism, is observed in a wide range of tumor cells, making it a potential pathway to control cancer growth. ALDOA is a multifunctional enzyme in the glycolytic pathway and also promotes HIF-1α, which is of importance in hypoxic solid tumors. The current method for assaying ALDOA activity involves monitoring the consumption of NADH in vitro using absorbance or intrinsic fluorescence via a coupled enzymatic reaction. Here, we report the development of a homogeneous biochemical assay that can overcome limitations of current methods, in particular for the application of high-throughput drug screening...
August 1, 2017: SLAS Discovery
https://www.readbyqxmd.com/read/28820904/parametric-studies-of-metabolic-cooperativity-in-escherichia-coli-colonies-strain-and-geometric-confinement-effects
#10
Joseph R Peterson, John A Cole, Zaida Luthey-Schulten
Characterizing the complex spatial and temporal interactions among cells in a biological system (i.e. bacterial colony, microbiome, tissue, etc.) remains a challenge. Metabolic cooperativity in these systems can arise due to the subtle interplay between microenvironmental conditions and the cells' regulatory machinery, often involving cascades of intra- and extracellular signalling molecules. In the simplest of cases, as demonstrated in a recent study of the model organism Escherichia coli, metabolic cross-feeding can arise in monoclonal colonies of bacteria driven merely by spatial heterogeneity in the availability of growth substrates; namely, acetate, glucose and oxygen...
2017: PloS One
https://www.readbyqxmd.com/read/28820879/a-kinetic-view-of-gpcr-allostery-and-biased-agonism
#11
J Robert Lane, Lauren T May, Robert G Parton, Patrick M Sexton, Arthur Christopoulos
G-protein-coupled receptors (GPCRs) are one of the most tractable classes of drug targets. These dynamic proteins can adopt multiple active states that are linked to distinct functional outcomes. Such states can be differentially stabilized by ligands interacting with the endogenous agonist-binding orthosteric site and/or by ligands acting via spatially distinct allosteric sites, leading to the phenomena of 'biased agonism' or 'biased modulation'. These paradigms are having a major impact on modern drug discovery, but it is becoming increasingly apparent that 'kinetic context', at the level of both ligand-receptor and receptor-signal pathway kinetics, can have a profound impact on the observation and quantification of these phenomena...
August 18, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28820839/smaller-diameter-anastomotic-coupling-devices-have-higher-rates-of-venous-thrombosis-in-microvascular-free-tissue-transfer
#12
Summer E Hanson, Matthew B Mitchell, Nihanth Palivela, S Andrew Peng, Lei Feng, Rene D Largo, Charles E Butler, Patrick B Garvey
BACKGROUND: Smaller anastomotic coupling devices may increase the risk of complications in free flap reconstructions; however, the relationship between coupler size and venous thrombosis rates has not been adequately evaluated. We hypothesized that smaller-diameter coupling devices are associated with higher rates of venous thrombosis than larger diameter devices in free tissue transfer. METHODS: We retrospectively reviewed data prospectively entered into a central departmental database for all patients who underwent microsurgical free tissue transfer at our institution in 2001-2013...
August 8, 2017: Plastic and Reconstructive Surgery
https://www.readbyqxmd.com/read/28820602/intricate-resonant-raman-response-in-anisotropic-res2
#13
Amber McCreary, Jeffrey R Simpson, Yuanxi Wang, Daniel Rhodes, Kazunori Fujisawa, Luis Balicas, Madan Dubey, Vincent H Crespi, Mauricio Terrones, Angela R Hight Walker
The strong in-plane anisotropy of rhenium disulfide (ReS2) offers an additional physical parameter that can be tuned for advanced applications such as logic circuits, thin-film polarizers, and polarization-sensitive photodetectors. ReS2 also presents advantages for optoelectronics, as it is both a direct-gap semiconductor for few-layer thicknesses (unlike MoS2 or WS2) and stable in air (unlike black phosphorus). Raman spectroscopy is one of the most powerful characterization techniques to non-destructively and sensitively probe the fundamental photo-physics of a 2D material...
August 18, 2017: Nano Letters
https://www.readbyqxmd.com/read/28820597/deterministic-symmetry-breaking-of-plasmonic-nanostructures-enabled-by-dna-programmable-assembly
#14
Matthew R Jones, Kevin L Kohlstedt, Matthew N O'Brien, Jinsong Wu, George C Schatz, Chad A Mirkin
The physical properties of matter rely fundamentally on the symmetry of constituent building blocks. This is particularly true for structures that interact with light via the collective motion of their conduction electrons (i.e., plasmonic materials), where the observation of exotic optical effects, such as negative refraction and electromagnetically induced transparency, require the coupling of modes that are only present in systems with nontrivial broken symmetries. Lithography has been the predominant fabrication technique for constructing plasmonic metamaterials, as it can be used to form patterns of arbitrary complexity, including those with broken symmetry...
August 18, 2017: Nano Letters
https://www.readbyqxmd.com/read/28820592/copper-i-no-g-reductive-coupling-producing-a-trans-hyponitrite-bridged-dicopper-ii-complex-redox-reversal-giving-copper-i-no-g-disproportionation
#15
Gayan B Wijeratne, Shabnam Hematian, Maxime A Siegler, Kenneth D Karlin
A copper complex, [CuI(tmpa)(MeCN)]+, effectively reductively couples NO(g) at RT in methanol, giving a structurally characterized hyponitrito-dicopper(II) adduct. Hydrogen-bonding from MeOH is critical for the hyponitrite complex formation and stabilization. This complex exhibits the reverse redox process in aprotic solvents, giving CuI + NO, leading to CuI-mediated NO disproportionation. The relation-ship of this chemistry to biological iron and/or copper mediated NO reductive coupling to give N2O(g) is discussed...
August 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28820583/processing-2-methyl-l-tryptophan-through-tandem-transamination-and-selective-oxygenation-initiates-indole-ring-expansion-in-the-biosynthesis-of-thiostrepton
#16
Zhi Lin, Jia Ji, Shuaixiang Zhou, Fang Zhang, Jiequn Wu, Yinlong Guo, Wen Liu
Thiostrepton (TSR), an archetypal member of the family of ribosomally synthesized and post-translationally modified thiopeptide antibiotics, possesses a biologically important quinaldic acid (QA) moiety within the side-ring system of its characteristic thiopeptide framework. QA is derived from an independent L-Trp residue; however, its associated transformation process remains poorly understood. We here report that during the formation of QA, the key expansion of an indole to a quinoline relies on the activities of the pyridoxal-5'-phosphate-dependent protein TsrA and the flavoprotein TsrE...
August 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28820538/from-blue-to-full-color-theoretical-design-and-characterization-of-a-series-of-ir-iii-complexes-containing-azoline-ligand-with-potential-application-in-oleds
#17
Ying-Chen Duan, Yong Wu, Xin-Yao Ren, Liang Zhao, Yun Geng, Min Zhang, Guang-Yan Sun, Zhong-Min Su
Two reported Ir(iii) complexes 1a and 1b containing oxazoline and imidazoline in ancillary ligand, respectively, were investigated by DFT/TD-DFT method. In order to obtain full-color display materials, we designed a group of Ir(iii) complexes 2a-3d based on 1a, which exhibits higher quantum efficiency in phosphorescence, by introducing electron-donating/electron-withdrawing moieties to different positions of the ancillary ligand to adjust emission color. In addition to calculating the radiation rate and analyzing its determining factors, we also estimated nonradiative ability by evaluating the spin-orbit coupling matrix element between the ground state (S0) and the lowest triplet state (T1) as well as the reorganization energy from T1 to S0 to estimate quantum efficiency more accurately...
August 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28820537/syn-bn-heteroacene-cored-conjugated-oligomers-with-finely-tuned-blue-violet-luminescent-properties
#18
Wanzheng Zhang, Yubin Fu, Peirong Qiang, Jens Hunger, Shuai Bi, Wenbei Zhang, Fan Zhang
Initiated by the effective dibromination of syn-BN-heteroacenes, a series of BN-containing conjugated oligomers was successfully synthesized upon transition-metal-catalyzed cross coupling. Their electronic structures can be finely tailored through varying the fused backbone or terminal substituents, endowing them with tunable luminescent properties within blue-violet regions.
August 18, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28820534/the-ligand-effect-on-the-oxidative-addition-of-dioxygen-to-gold-i-hydride-complexes
#19
Carlo Alberto Gaggioli, Leonardo Belpassi, Francesco Tarantelli, Jeremy N Harvey, Paola Belanzoni
The ligand effect on the recently uncovered feasible oxidative addition reaction of O2 on [LAuH] complexes has been investigated for a series of fifteen ligands. The activation barriers of this spin-forbidden reaction have been estimated at the minimum energy crossing points (MECP, relativistic scalar level) between the adiabatic triplet (reactants spin state) and singlet (product spin state) potential energy surfaces (PES) and calculated at the transition states by including Spin-Orbit Coupling (SOC) effects, as applied for the mechanistic study of this reaction in a previous study by us [Chem...
August 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28820528/deciphering-the-photosensitization-mechanisms-of-hypericin-towards-biological-membranes
#20
Hugo Gattuso, Marco Marazzi, François Dehez, Antonio Monari
Resorting to state-of-the art molecular modeling and simulation techniques we provide full characterization of the photophysical properties of the naturally occurring hypericin chromophore, currently used in photodynamic therapy. In particular, we reveal the different photophysical pathways leading to intersystem-crossing and hence, triplet manifold population that is necessary for the subsequent production of singlet oxygen. In particular we identify an extended region of quasi-degeneracy between the first singlet excited state and three triplet state surfaces...
August 18, 2017: Physical Chemistry Chemical Physics: PCCP
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