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Calorimetry

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https://www.readbyqxmd.com/read/28346731/exploring-the-influence-of-mpa-capped-cdte-quantum-dots-on-the-structure-and-function-of-lysozyme-probing-by-spectroscopic-and-calorimetric-methods
#1
Lining Zhao, Tao Sun, Xun Zhang, Wei Song, Rutao Liu
The effect of 3-mercaptopropionic acid (MPA)-capped CdTe quantum dots (QDs) on lysozyme was systematically investigated by spectroscopic methods, enzyme activity assay, and calorimetry techniques. Results show that the MPA-capped CdTe QDs binded to lysozyme through van der Walls forces and hydrogen bondings, causing the decrement of α-helical content (∼7%) and increment of β-sheet content (∼11%) of lysozyme. The binding caused static quenching of the fluorescence, while the microenvironment of aromatic amino acid residues did not show any significant alteration...
March 27, 2017: Journal of Biochemical and Molecular Toxicology
https://www.readbyqxmd.com/read/28346376/blend-hydrogel-microspheres-of-carboxymethyl-chitosan-and-gelatin-for-the-controlled-release-of-5-fluorouracil
#2
Vanarchi Rajini Kanth, Praveen B Kajjari, Priya M Madalageri, Sakey Ravindra, Lata S Manjeshwar, Tejraj M Aminabhavi
Carboxymethyl chitosan (CMCS) was synthesized and blended with gelatin (GE) to prepare hydrogel microspheres by w/o emulsion cross-linking in the presence of glutaraldehyde (GA), which acted as a cross-linker. 5-Fluorouracil (5-FU) was encapsulated to investigate its controlled release (CR) characteristics in acidic (pH 1.2) and alkaline (pH 7.4) buffer media. The microspheres which formed were spherical in nature, with smooth surfaces, as judged by the scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) confirmed the carboxymethylation of CS and the chemical stability of 5-FU in the formulations...
March 27, 2017: Pharmaceutics
https://www.readbyqxmd.com/read/28345903/molecular-imprinting-on-inorganic-nanozymes-for-hundred-fold-enzyme-specificity
#3
Zijie Zhang, Xiaohan Zhang, Biwu Liu, Juewen Liu
Enzyme-mimicking nanomaterials (nanozymes) are more cost-effective and robust than protein enzymes, but they lack specificity. Herein, molecularly imprinted polymers were grown on Fe3O4 nanozymes with peroxidase-like activity to create substrate binding pockets. Electron microscopy confirmed a shell of nanogel. By imprinting with an adsorbed substrate, moderate specificity was achieved with neutral monomers. Further introducing charged monomers led to nearly 100-fold specificity for the imprinted substrate over the non-imprinted compared to that of bare Fe3O4...
March 27, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28345865/human-milk-oligosaccharide-specificities-of-human-galectins-comparison-of-electrospray-ionization-mass-spectrometry-and-glycan-microarray-screening-results
#4
Km Shams-Ud-Doha, Elena N Kitova, Pavel I Kitov, Yves St-Pierre, John S Klassen
The affinities of thirty-two free human milk oligosaccharides (HMOs) for four human galectin proteins - a stable mutant of hGal1 (hGal-1), a C-terminal fragment of hGal-3 (hGal-3C), hGal-7 and an N-terminal fragment of hGal-9 (hGal-9N) - were measured using electrospray ionization mass spectrometry (ESI-MS). The binding data show that each of the four galectins recognize the majority of the HMOs tested (hGal-1 binds thirty-two HMOs, hGal-3C binds twenty-six, hGal-7 binds thirty-one and hGal-9N binds twenty-six)...
March 27, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28345718/probing-the-binding-affinity-of-plasma-proteins-adsorbed-on-au-nanoparticles
#5
Xiaoning Zhang, Junting Zhang, Fan Zhang, Shaoning Yu
Nanoparticle (NP) surfaces are modified immediately by the adsorption of proteins when exposed to human blood, leading to the formation of a protein corona. The adsorption of serum proteins is the key process for exploring the bioapplication and biosafety of NPs. In this study, NP-protein binding affinity (Ka) was investigated. Some serum proteins, such as human serum albumin (HSA), trypsin (TRP), hemoglobin (Hb), myoglobin (MB), immunoglobulin G (IgG), carbonic anhydrase (CA), fibrinogen (FIB), chymotrypsin and r-globulin, were used with gold nanoparticles (AuNPs) to address binding affinity according to isothermal titration calorimetry (ITC) combined with dynamic light scattering (DLS) and fluorescence quenching...
March 27, 2017: Nanoscale
https://www.readbyqxmd.com/read/28345386/artifact-correction-in-temperature-dependent-attenuated-total-reflection-infrared-atr-ir-spectra
#6
Brian Sobieski, Bruce Chase, Isao Noda, John Rabolt
A spectral processing method was developed and tested for analyzing temperature-dependent attenuated total reflection infrared (ATR-IR) spectra of aliphatic polyesters. Spectra of a bio-based, biodegradable polymer, 3.9 mol % 3HHx poly[(R)-3-hydroxybutyrate- co-(R)-3-hydroxyhexanoate] (PHBHx), were analyzed and corrected prior to analysis using two-dimensional correlation spectroscopy (2D-COS). Removal of the temperature variation of diamond absorbance, correction of the baseline, ATR correction, and appropriate normalization were key to generating more reliable data...
January 1, 2017: Applied Spectroscopy
https://www.readbyqxmd.com/read/28345107/the-smallest-cucurbituril-analogue-with-high-affinity-for-ag
#7
Yufan Wu, Lixi Xu, Yenan Shen, Yang Wang, Lei Zou, Qiaochun Wang, Xiaoqing Jiang, Jiansen Liu, He Tian
A new host, Me8TD[4], was prepared for the first time from propanediurea-formaldehyde condensation in the presence of CaCl2 as the template and it is the smallest cucurbituril analogue reported so far. Measurements of the thermodynamic quantities (log K, ΔH, and ΔS values) of the interactions of Me8TD[4] with a series of cations by isothermal titration calorimetry indicated that Me8TD[4] binds selectively towards Ag(+) with a high binding constant, K ∼ 1.3 × 10(6) M(-1).
March 27, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28344830/exploring-and-validating-physicochemical-properties-of-mangiferin-through-gastroplus-%C3%A2-software
#8
Rajneet Kaur Khurana, Ranjot Kaur, Manninder Kaur, Rajpreet Kaur, Jasleen Kaur, Harpreet Kaur, Bhupinder Singh
AIM: Mangiferin (Mgf), a promising therapeutic polyphenol, exhibits poor oral bioavailability. Hence, apt delivery systems are required to facilitate its gastrointestinal absorption. The requisite details on its physicochemical properties have not yet been well documented in literature. Accordingly, in order to have explicit insight into its physicochemical characteristics, the present work was undertaken using GastroPlus™ software. RESULTS: Aqueous solubility (0...
March 2017: Future Science OA
https://www.readbyqxmd.com/read/28342789/enhanced-gastric-stability-of-esomeprazole-by-molecular-interaction-and-modulation-of-microenvironmental-ph-with-alkalizers-in-solid-dispersion
#9
Hien Van Nguyen, Namhyun Baek, Beom-Jin Lee
Due to the instability of esomeprazole magnesium dihydrate (EPM), a proton pump inhibitor, in gastric fluid, enteric-coated dosage form is commonly used for therapeutic application. In this study, we prepared new gastric fluid resistant solid dispersions (SDs) containing alkalizers. Then, new mechanistic evidence regarding the effects of pharmaceutical alkalizers on the aqueous stability of EPM in simulated gastric fluid was investigated. The alkalizer-loaded SD were prepared by dissolving or dispersing EPM, hydroxypropyl methylcellulose (HPMC) 6 cps, and an alkalizer, in ethanol 50% (v/v) followed by spray drying...
March 22, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28342783/effect-of-storage-on-the-physical-stability-of-thin-polymethacrylate-perphenazine-films
#10
Kristiina Korhonen, Elina Smolander, Ossi Korhonen, Jarkko Ketolainen, Riikka Laitinen
We evaluated the physical stability of thin polymethacrylate-drug films under three different storage conditions by X-ray powder diffraction, differential scanning calorimetry, scanning electron microscopy, polarized light microscopy, and Fourier transform infrared spectroscopy. Mechanical properties i.e. elongation, mechanical strength, and in vitro drug release from the thin films were also determined during storage. The films consisted of ammonium methacrylate copolymer (RLPO)/dimethylaminoethyl methacrylate copolymer (EPO), polyvinylpyrroline (PVP)/polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus) and perphenazine (PPZ)...
March 22, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28342666/stabilization-study-of-inactivated-foot-and-mouth-disease-virus-vaccine-by-size-exclusion-hplc-and-differential-scanning-calorimetry
#11
Yanli Yang, Qizu Zhao, Zhengjun Li, Lijing Sun, Guanghui Ma, Songping Zhang, Zhiguo Su
The inactivated foot and mouth disease virus (FMDV), which has a sedimentation coefficient of 146S, is crucial to the efficacy of vaccine preparations, but extremely unstable in vitro. It is prone to dissociate into smaller particles referred to as 12S with a concomitant decrease in immunogenicity; therefore, it is of great importance to find the best condition for stabilizing the FMDV. In the present work, the effects of solution pH and temperature on the dissociation of 146S was investigated and potential stabilizers were screened, with aid of high-performance size-exclusion chromatography (HPSEC) for rapid and quantitative determination of 146S, together with differential scanning calorimetry (DSC) technology for thermal stability analysis...
March 22, 2017: Vaccine
https://www.readbyqxmd.com/read/28342541/continuous-gradient-temperature-raman-spectroscopy-and-differential-scanning-calorimetry-of-n-3dpa-and-dha-from-100-to-10%C3%A2-c
#12
C Leigh Broadhurst, Walter F Schmidt, Julie K Nguyen, Jianwei Qin, Kuanglin Chao, Steven R Aubuchon, Moon S Kim
Docosahexaenoic acid (DHA, 22:6n-3) is exclusively utilized in fast signal processing tissues such as retinal, neural and cardiac. N-3 docosapentaenoic acid (n-3DPA, 22:5n-3), with just one less double bond, is also found in the marine food chain yet cannot substitute for DHA. Gradient temperature Raman spectroscopy (GTRS) applies the temperature gradients utilized in differential scanning calorimetry (DSC) to Raman spectroscopy, providing a straightforward technique to identify molecular rearrangements that occur near and at phase transitions...
March 22, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28340295/response-of-catalase-of-the-mouse-primary-hepatocytes-to-sodium-dodecylbenzene-sulfonate-and-the-underlying-molecular-mechanisms
#13
Jing Wang, Jiaxi Wang, Lu Zhang, Rutao Liu, Wansong Zong
This study investigated the adverse effects of sodium dodecylbenzene sulfonates (SDBS) on the mouse primary hepatocytes by conducting cell viability, intracellular oxidative stress level and catalase (CAT) activity assays. It was shown that SDBS altered CAT activities, triggered oxidative stress, and thus exhibited cytotoxicity to the hepatocytes. Both the stimulation of intracellular CAT production and the inhibition of molecular CAT activity contributed to intracellular CAT activity change. Molecular mechanisms underlying CAT activity inhibition and structural changes were explored by isothermal titration calorimetry, multi-spectroscopy and molecular docking studies...
March 24, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28338429/study-on-the-release-of-carbon-nanoparticles-of-different-size-and-shape-from-nanocomposite-poly-lactic-acid-film-into-food-simulants
#14
Hristiana Velichkova, Stanislav Kotsilkov, Evgeni Ivanov, Rumiana Kotsilkova, Stanislav Gyoshev, Nikolay Stoimenov, Nikolay K Vitanov
Poly(lactic) acid (PLA) film with 2 wt % mixed carbon nanofillers of graphene nanoplates (GNPs) and multiwall carbon nanotubes (MWCNTs) in weight ratio 1:1 with impurities of fullerene and carbon black (CB) was produced by layer to layer deposition and hot pressing. The release of carbon nanoparticles from the film was studied at varying time-temperature conditions and simulants. Migrants in simulant solvents were examined with laser diffraction analysis and transmission electron microscopy. The film integrity and the presence of migrants on the film surfaces were visualized by scanning electron microscopy...
March 24, 2017: Food Additives & Contaminants. Part A, Chemistry, Analysis, Control, Exposure & Risk Assessment
https://www.readbyqxmd.com/read/28338405/physiological-responses-to-treadmill-running-with-body-weight-support-in-hypoxia-compared-to-normoxia
#15
Ben J Lee, Charles Douglas Thake
CONTEXT: Anecdotal reports suggest elite sports clubs combine lower body positive pressure (LBPP) rehabilitation with a hypoxic stimulus in order to maintain or increase physiological and metabolic strain, which are reduced during LBPP. However the effects of hypoxia on cardiovascular and metabolic response during LBPP rehabilitation is unknown. OBJECTIVE: Evaluate the use of normobaric hypoxia as a means to increase physiological strain during body weight supported (BWS) running...
March 24, 2017: Journal of Sport Rehabilitation
https://www.readbyqxmd.com/read/28337516/exploring-the-potential-of-high-resolution-mass-spectrometry-for-the-investigation-of-lignin-derived-phenol-substitutes-in-phenolic-resin-syntheses
#16
Tobias K F Dier, Marco Fleckenstein, Holger Militz, Dietrich A Volmer
Chemical degradation is an efficient method to obtain bio-oils and other compounds from lignin. Lignin bio-oils are potential substitutes for the phenol component of phenol formaldehyde (PF) resins. Here, we developed an analytical method based on high resolution mass spectrometry that provided structural information for the synthesized lignin-derived resins and supported the prediction of their properties. Different model resins based on typical lignin degradation products were analyzed by electrospray ionization in negative ionization mode...
March 23, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28337496/sugar-coated-proteins-the-importance-of-degree-of-polymerisation-of-oligo-galacturonic-acid-on-protein-binding-and-aggregation
#17
Amy Y Xu, Laurence D Melton, Timothy M Ryan, Jitendra P Mata, Geoffrey B Jameson, Agata Rekas, Martin A K Williams, Duncan J McGillivray
We have simplified the structural heterogeneity of protein-polysaccharide binding by investigating protein binding to oligosaccharides. The interactions between bovine beta-lactoglobulin A (βLgA) and oligo-galacturonic acids (OGAs) with various numbers of sugar residues have been investigated with a range of biophysical techniques. We show that the βLgA-OGA interaction is critically dependent on the length of the oligosaccharide. Isothermal titration calorimetry results suggest that a minimum length of 7 or 8 sugar residues is required in order to exhibit appreciable exothermic interactions with βLgA - shorter oligosaccharides show no enthalpic interactions at any concentration ratio...
March 24, 2017: Soft Matter
https://www.readbyqxmd.com/read/28335369/effect-of-nano-sio%C3%A2-on-the-hydration-and-microstructure-of-portland-cement
#18
Liguo Wang, Dapeng Zheng, Shupeng Zhang, Hongzhi Cui, Dongxu Li
This paper systematically studied the modification of cement-based materials by nano-SiO₂ particles with an average diameter of about 20 nm. In order to obtain the effect of nano-SiO₂ particles on the mechanical properties, hydration, and pore structure of cement-based materials, adding 1%, 3%, and 5% content of nano-SiO₂ in cement paste, respectively. The results showed that the reaction of nano-SiO₂ particles with Ca(OH)₂ (crystal powder) started within 1 h, and formed C-S-H gel. The reaction speed was faster after aging for three days...
December 15, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28335215/rapamycin-loaded-solid-lipid-nanoparticles-as-a-new-tool-to-deliver-mtor-inhibitors-formulation-and-in-vitro-characterization
#19
Alice Polchi, Alessandro Magini, Jarosław Mazuryk, Brunella Tancini, Jacek Gapiński, Adam Patkowski, Stefano Giovagnoli, Carla Emiliani
Recently, the use of mammalian target of rapamycin (mTOR) inhibitors, in particular rapamycin (Rp), has been suggested to improve the treatment of neurodegenerative diseases. However, as Rp is a strong immunosuppressant, specific delivery to the brain has been postulated to avoid systemic exposure. In this work, we fabricated new Rp loaded solid lipid nanoparticles (Rp-SLN) stabilized with polysorbate 80 (PS80), comparing two different methods and lipids. The formulations were characterized by differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), wide angle X-ray scattering (WAXS), cryo-transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS) and particle tracking...
May 9, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28334911/mertk-rs4374383-variant-predicts-incident-nonalcoholic-fatty-liver-disease-and-diabetes-role-of-mononuclear-cell-activation-and-adipokine-response-to-dietary-fat
#20
Giovanni Musso, Maurizio Cassader, Franco De Michieli, Elena Paschetta, Silvia Pinach, Francesca Saba, Daria Bongiovanni, Luciana Framarin, Mara Berrutti, Nicola Leone, Stefania Corvisieri, Renato Parente, Federica Molinaro, Antonio Sircana, Bo Simona, Roberto Gambino
The loss-of-function rs4374383 G>A variant in Myeloid-epithelial-reproductive Tyrosine Kinase (MERTK) gene has been linked to hepatic fibrosis in chronic liver diseases. MERTK is expressed by immune and non-immune cells involved in inflammation, metabolism and vascular homeostasis. We assessed the impact of MERTK rs4374383 G>A variant on nonalcoholic fatty liver disease (NAFLD) incidence and severity and on glucose and lipid metabolism.We followed-up 305 healthy nonobese nondiabetic, metabolic syndrome-free insulin sensitive participants in a population-based study, characterized for MERTK G>A polymorphism, adipokine profile and inflammatory markers...
March 8, 2017: Human Molecular Genetics
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