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Publication
Journal: Advanced Science
November/25/2019
Abstract
Low ionic conductivity at room temperature and limited electrochemical window of poly(ethylene oxide) (PEO) are the bottlenecks restricting its further application in high-energy density lithium metal battery. Herein, a differentiated salt designed multilayered PEO-based solid polymer electrolyte (DSM-SPE) is exploited to achieve excellent electrochemical performance toward both the high-voltage LiCoO2 cathode and the lithium metal anode. The LiCoO2/Li metal battery with DSM-SPE displays a capacity retention of 83.3% after 100 cycles at 60 °C with challenging voltage range of 2.5 to 4.3 V, which is the best cycling performance for high-voltage (≥4.3 V) LiCoO2/Li metal battery with PEO-based electrolytes up to now. Moreover, the Li/Li symmetrical cells present stable and low polarization plating/stripping behavior (less than 80 mV over 600 h) at current density of 0.25 mA cm-2 (0.25 mAh cm-2). Even under a high-area capacity of 2 mAh cm-2, the profiles still maintain stable. The pouch cell with DSM-SPE exhibits no volume expansion, voltage decline, ignition or explosion after being impaled and cut at a fully charged state, proving the excellent safety characteristic of the DSM-SPE-based lithium metal battery.
Publication
Journal: Langmuir
January/13/2014
Abstract
Cobalt sputter deposition on a nanostructured polystyrene-block-poly(ethylene oxide), P(S-b-EO), template is followed in real time with grazing incidence small-angle X-ray scattering (GISAXS). The polymer template consists of highly oriented parallel crystalline poly(ethylene oxide) (PEO) domains that are sandwiched between two polystyrene (PS) domains. In-situ GISAXS shows that cobalt atoms selectively decorate the PS domains of the microphase-separated polymer film and then aggregate to form surface metal nanopatterns. The polymer template is acting as a directing agent where cobalt metal nanowires are formed. At high metal load, the characteristic selectivity of the template is lost, and a uniform metal layer forms on the polymer surface. During the early stage of cobalt metal deposition, a highly asymmetric nanoparticles agglomeration is dominating structure formation. The cobalt nanoparticles mobility in combination with the high tendency of the nanoparticles to coalescence and to form immobile large-sized particles at the PS domains are discussed as mechanisms of structure formation.
Publication
Journal: Acta neuropathologica communications
December/17/2019
Abstract
Variations in the POLG1 gene encoding the catalytic subunit of the mitochondrial DNA polymerase gamma, have recently been associated with Parkinson's disease (PD), especially in patients diagnosed with progressive external ophthalmoplegia (PEO). However, the majority of the studies reporting this association mainly focused on the genetic identification of the variation in POLG1 in PD patient primary cells, and determination of mitochondrial DNA copy number, providing little information about the cellular alterations existing in patient brain cells, in particular dopaminergic neurons. Therefore, through the use of induced pluripotent stem cells (iPSCs), we assessed cellular alterations in novel p.Q811R POLG1 (POLG1Q811R) variant midbrain dopaminergic neuron-containing spheroids (MDNS) from a female patient who developed early-onset PD, and compared them to cultures derived from a healthy control of the same gender. Both POLG1 variant and control MDNS contained functional midbrain regionalized TH/FOXA2-positive dopaminergic neurons, capable of releasing dopamine. Western blot analysis identified the presence of high molecular weight oligomeric alpha-synuclein in POLG1Q811R MDNS compared to control cultures. In order to assess POLG1Q811R-related cellular alterations within the MDNS, we applied mass-spectrometry based quantitative proteomic analysis. In total, 6749 proteins were identified, with 61 significantly differentially expressed between POLG1Q811R and control samples. Pro- and anti-inflammatory signaling and pathways involved in energy metabolism were altered. Notably, increased glycolysis in POLG1Q811R MDNS was suggested by the increase in PFKM and LDHA levels and confirmed using functional analysis of glycolytic rate and oxygen consumption levels. Our results validate the use of iPSCs to assess cellular alterations in relation to PD pathogenesis, in a unique PD patient carrying a novel p.Q811R variation in POLG1, and identify several altered pathways that may be relevant to PD pathogenesis.
Publication
Journal: Journal of Biomedical Materials Research - Part B Applied Biomaterials
December/9/2013
Abstract
Reducing the osseointegration time for biomedical titanium implants in surgical patients is an important goal. However, a huge controversy exists over the effectiveness of osseointegration of the surface layer by plasma electrolytic oxidation (PEO), which is a widely favored surface modification for titanium-based implants. In this study, various surface coatings, including anatase-TiO2 (A-TiO2 ), rutile-TiO2 (R-TiO2 ), hydroxyapatite (HAp), strontium-containing hydroxyapatite (Sr-HAp), and dual-phase HAp-TiO2 were synthesized on titanium implants by PEO. A comparative study of osseointegration performance (both in vitro and in vivo) and bone/implant adhesion strength conducted using push-out thrust tests were demonstrated. The in vitro experimental test results agree strongly with the in vivo test results: the dual-phase HAp-TiO2 coating exhibits the superior cell adhesion and differentiation condition among all of the coatings in the in vitro tests and therefore has the highest push-out bonding strength of 5.37 MPa after 12 wk of implantation in the in vivo test. The HAp-containing coatings benefit from its bioactivity and therefore perform the others in terms of long-term osteocyte growth (from the in vitro results) and the extent of osseointegration (from the in vivo results). The dual-phase HAp-TiO2 coating provides the advantages of both the bioactive HAp and structural enhancement by the TiO2 , effectively promoting osseointegration.
Publication
Journal: In Vivo
August/26/2018
Abstract
Plasma electrolytic oxidation (PEO) is an established electrochemical treatment technique that can be used for surface modifications of metal implants. In this study we to treated titanium implants with PEO, to examine the resulting microstructure and to characterize adhesion and viability of cells on the treated surfaces. Our aim was to identify an optimal surface-modification for titanium implants in order to improve soft-tissue integration.
Three surface-variants were generated on titanium alloy Ti6Al4V by PEO-treatment. The elemental composition and the microstructures of the surfaces were characterized using energy dispersive X-ray spectroscopy, scanning electron microscopy and profilometry. In vitro cytocompatibility of the surfaces was assessed by seeding L929 fibroblasts onto them and measuring the adhesion, viability and cytotoxicity of cells by means of live/dead staining, XTT assay and LDH assay.
Electron microscopy and profilometry revealed that the PEO-surface variants differed largely in microstructure/topography, porosity and roughness from the untreated control material as well as from one another. Roughness was generally increased after PEO-treatment. In vitro, PEO-treatment led to improved cellular adhesion and viability of cells accompanied by decreased cytotoxicity.
PEO-treatment provides a promising strategy to improve the integration of titanium implants with surrounding tissues.
Publication
Journal: Colloids and Surfaces B: Biointerfaces
March/27/2011
Abstract
The effect of molecular characteristics of EO-PO triblock copolymers viz. Pluronic(®) P103 (EO(17)PO(60)PEO(17)), P123 (EO(19)PO(69)EO(19)), and F127 (EO(100)PO(65)EO(100)) on micellar behavior and solubilization of a diuretic drug, hydrochlorothiazide (HCT) was investigated. The critical micellization temperatures (CMTs) and size for empty as well as drug loaded micelles are reported. The CMTs and micelle size depended on the hydrophobicity and molecular weight of the copolymer; a decrease in CMT and increase in size was observed on solubilization. The solubilization of the drug hydrochlorothiazide (HCT) in the block copolymer nanoaggregates at different temperatures (28, 37, 45°C), pH (3.7, 5.0, 6.7) and in the presence of added salt (NaCl) was monitored by using UV-vis spectroscopy and solubility data were used to calculate the solubilization characteristics; micelle-water partition coefficient (P) and thermodynamic parameters of solubilization viz. Gibbs free energy (ΔG(s)°), enthalpy (ΔH(s)°) and entropy (ΔS(s)°). The solubility of the drug in copolymer increases with the trend: P103>P123>F127. The solubilized drug decreased the cloud point (CP) of copolymers. Results show that the drug solubility increases in the presence of salt but significantly enhances with the increase in the temperature and at a lower pH in which drug remains in the non-ionized form.
Publication
Journal: Nano Letters
July/2/2012
Abstract
There is a growing shift from liquid electrolytes toward solid polymer electrolytes, in energy storage devices, due to the many advantages of the latter such as enhanced safety, flexibility, and manufacturability. The main issue with polymer electrolytes is their lower ionic conductivity compared to that of liquid electrolytes. Nanoscale fillers such as silica and alumina nanoparticles are known to enhance the ionic conductivity of polymer electrolytes. Although carbon nanotubes have been used as fillers for polymers in various applications, they have not yet been used in polymer electrolytes as they are conductive and can pose the risk of electrical shorting. In this study, we show that nanotubes can be packaged within insulating clay layers to form effective 3D nanofillers. We show that such hybrid nanofillers increase the lithium ion conductivity of PEO electrolyte by almost 2 orders of magnitude. Furthermore, significant improvement in mechanical properties were observed where only 5 wt % addition of the filler led to 160% increase in the tensile strength of the polymer. This new approach of embedding conducting-insulating hybrid nanofillers could lead to the development of a new generation of polymer nanocomposite electrolytes with high ion conductivity and improved mechanical properties.
Publication
Journal: Journal of Nanoscience and Nanotechnology
June/25/2008
Abstract
The objective of this study was to prepare and characterize electrospun SiO2 nanofibers for composite (particularly dental composite) applications. We investigated (1) tetraethyl orthosilicate (TEOS) as the alkoxide precursor, (2) polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP) as the carrying polymers, (3) several solvents for making the spin dopes, and (4) the morphological and structural properties of the electrospun SiO2 nanofibers and their relationship with the pyrolysis temperatures. We also investigated the morphology durability of the prepared SiO2 nanofibers by subjecting them to vigorous ultrasonic vibrations. The results indicated that the uniform (beads-free) amorphous SiO2 nanofibers with an average diameter of approximately 500 nm were successfully prepared. These SiO2 nanofibers also retained their overall fiber morphology when subjected to vigorous ultrasonic vibrations. The electrospun SiO2 nanofibers were, therefore, nano-scaled glass (amorphous SiO2) fibers, and could be used for reinforcement of dental composites.
Publication
Journal: JIMD Reports
June/30/2015
Abstract
In a 28-year-old male with a mild mitochondrial myopathy manifesting as exercise intolerance and early signs of cardiomyopathy without muscle weakness or ophthalmoplegia, we identified two novel mutations in the SLC25A4 gene: c.707G>C in exon 3 (p.(R236P)) and c.116_137del in exon 2 (p.(Q39Lfs*14)). Serum lactate levels at rest were elevated (12.7 mM). Both the patient's father and brother were heterozygous carriers of the c.707G>C mutation and were asymptomatic. The second mutation causes a 22 bp deletion leading to a frame shift likely giving rise to a premature stop codon and nonsense-mediated decay (NMD). The segregation of the mutations could not be tested directly as the mother had died before. However, indirect evidence from NMD experiments showed that the two mutations were situated on two different alleles in the patient. This case is unique compared to other previously reported patients with either progressive external ophthalmoplegia (PEO) or clear hypertrophic cardiomyopathy with exercise intolerance and/or muscle weakness carrying recessive mutations leading to a complete absence of the SLC25A4 protein. Most likely in our patient, although severely reduced, SLC25A4 is still partially present and functional.
Publication
Journal: Polymers
April/9/2019
Abstract
Solid polymer electrolytes (SPEs) have attracted considerable attention due to the rapid development of the need for more safety and powerful lithium ion batteries. The prime requirements of solid polymer electrolytes are high ion conductivity, low glass transition temperature, excellent solubility to the conductive lithium salt, and good interface stability against Li anode, which makes PEO and its derivatives potential candidate polymer matrixes. This review mainly encompasses on the synthetic development of PEO-based SPEs (PSPEs), and the potential application of the resulting PSPEs for high performance, all-solid-state lithium ion batteries.
Publication
Journal: Biomedical Materials (Bristol)
May/27/2008
Abstract
We examined the effects of cross-linking molecular weights on the properties of a hyaluronic acid (HA)-poly(ethylene oxide) (PEO) hydrogel. Swelling behaviors, mechanical strength and rheological behaviors of the HA-PEO hydrogel were evaluated by employing different cross-linking molecular weights (100 kDa and 1.63 mDa) of the HAs in the hydrogel networks. The low molecular weight of HA was obtained in advance by treating high molecular weight HA with a hydrogen chloride solution. Methacrylation of HA was obtained by grafting aminopropylmethacrylate to its caroboxylic acid functional groups. While reduction of the HA molecular weights was confirmed by gel permeation chromatography, the degree of methacrylate grafting to the HA was measured by (1)H-nuclear magnetic resonance. Synthesis of the HA-PEO hydrogel was successfully achieved via the Michael-type addition reaction between the methacrylate arm groups in the HA and the six thiol groups in PEO. The hydrogel formation was not dependent upon the HA molecular weights and its gelation behaviors were markedly different. Compared to the properties of the high molecular weight HA-based PEO one, the low molecular weight HA-based hydrogel induced quicker hydrogelation, as observed from the behaviors of the elastic and viscous modulus. Furthermore, the low molecular weight HA-based hydrogel demonstrated stronger mechanical properties as measured with a texture analyzer, lower water absorption as measured with a microbalance and smaller pore sizes on its surface and cross section as observed with scanning electron microscopy. The information about the effects of the cross-linking molecular weights of the gel network on the properties of the HA-based PEO hydrogel may lead to better design of hydrogels, especially in tissue engineering applications.
Publication
Journal: Nature Communications
January/12/2019
Abstract
The features of well-conjugated and planar aromatic structures make π-conjugated luminescent materials suffer from aggregation caused quenching (ACQ) effect when used in solid or aggregated states, which greatly impedes their applications in optoelectronic devices and biological applications. Herein, we reduce the ACQ effect by demonstrating a facile and low cost method to co-assemble polycyclic aromatic hydrocarbon (PAH) chromophores and octafluoronaphthalene together. Significantly, the solid photoluminescence quantum yield (PLQYs) for the as-resulted four micro/nanococrystals are enhanced by 254%, 235%, 474 and 582%, respectively. Protection from hydrophilic polymer chains (P123 (PEO20-PPO70-PEO20)) endows the cocrystals with superb dispersibility in water. More importantly, profiting from the above-mentioned highly improved properties, nano-cocrystals present good biocompatibility and considerable cell imaging performance. This research provides a simple method to enhance the emission, biocompatibility and cellular permeability of common chromophores, which may open more avenues for the applications of originally non- or poor fluorescent PAHs.
Publication
Journal: Biomacromolecules
December/29/2009
Abstract
Molecular dynamics (MD) simulation was used to study the roles of nonpolar and polar intermolecular interactions in the improvement of the drug loading capacity of poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL) with increasing PCL content for two water insoluble anticancer drugs: Cucurbitacin B (CuB) and Cucurbitacin I (CuI). In particular, random binary mixture models containing 10-12 wt % drug and remaining PEO-b-PCL with three different PCL/PEO (w/w) ratios (0.5, 1, and 2) were used to calculate their Flory-Huggins interaction parameters (chi). The MD simulation results show that, for both CuB and CuI, the computed chi decreases (i.e., affinity increases) with increasing PCL/PEO ratio. Such results are consistent with our experimental observation that increasing the PCL/PEO (w/w) ratio from 1 to 4.8 significantly increases the drug loading capacity of micelles formed by PEO-b-PCL for both drugs. Analysis of the energy data shows that increasing affinity (loading) at higher PCL/PEO ratio is attributed to the increase in favorable polar interactions and to the formation of additional hydrogen bonds (H-bonds) between the drugs and the PCL block rather than to the increase in the hydrophobic characteristics of the diblock copolymer as one would normally expect. In fact, the nonpolar intermolecular interactions became more unfavorable at higher PCL/PEO ratio. Analysis of the radial distribution functions of the model mixtures indicates that at high PCL/PEO ratio, multiple H-bond sites on the PCL block interacted with single H-bond sites on the drug molecules. However, at low PCL/PEO ratio, only single H-bonds formed between various H-bond sites on the drug molecules and those of the PCL and PEO blocks. It seems that formation of H-bonds between multiple H-bond sites on the PCL block and single H-bond sites on the drug molecules is responsible for inducing drug/PEO-b-PCL affinity. The finding also explains the experimental observation that release rates of both drugs decrease with increasing PCL/PEO ratio and that the decrease in the release rate of CuB is more pronounced than that of CuI. Our simulation results show that the number of H-bonds formed between CuB and the PCL block is much higher than that of CuI at high PCL/PEO ratio.
Publication
Journal: European Journal of Pharmaceutical Sciences
June/28/2018
Abstract
The increased prevalence of chronic wounds requires novel treatment options. The aim of this study was to develop a beta-glucan (βG)-loaded nanofiber wound dressing. Nanofibers were prepared using the needle-free Nanospider™ technology, an electrospinning method which enables the production of nanofibers at an industrial scale. The βG was selected as active ingredient based on its confirmed wound healing potential in both animals and humans. Hydroxypropyl methylcellulose (HPMC) and polyethylene oxide (PEO) were included as copolymers. Rheological profiles of spinning solutions containing HPMC, PEO, βG, ethanol and water, were optimized. The nanofiber formation was confirmed by Field Emission Scanning Electron Microscopy (FE-SEM), and both nanofibers with (βG-nanofibers) or without βG (NoβG-nanofibers) were evaluated by their swelling index and FT-IR spectroscopy. The formulations, active ingredient and excipients were tested for their possible in vitro toxicity in keratinocytes. Finally, the wound healing potential of the nanofibers was tested in externally induced excisional wounds in male diabetic db/db mice. Three different doses of βG-nanofibers and the βG-free, NoβG-nanofibers, were evaluated for their in vivo wound healing efficacy. All nanofiber-treatments provided improved wound healing as compared to the negative control (water). All βG-nanofiber treated groups exhibited significantly improved wound healing as compared to the NoβG-nanofiber treated group, indicating the potential of βG-nanofibers as wound dressing.
Publication
Journal: Langmuir
August/21/2014
Abstract
Understanding nanoparticle diffusion within non-Newtonian biological and synthetic fluids is essential in designing novel formulations (e.g., nanomedicines for drug delivery, shampoos, lotions, coatings, paints, etc.), but is presently poorly defined. This study reports the diffusion of thiolated and PEGylated silica nanoparticles, characterized by small-angle neutron scattering, in solutions of various water-soluble polymers such as poly(acrylic acid) (PAA), poly(N-vinylpyrrolidone) (PVP), poly(ethylene oxide) (PEO), and hydroxyethylcellulose (HEC) probed using NanoSight nanoparticle tracking analysis. Results show that the diffusivity of nanoparticles is affected by their dimensions, medium viscosity, and, in particular, the specific interactions between nanoparticles and the macromolecules in solution; strong attractive interactions such as hydrogen bonding hamper diffusion. The water-soluble polymers retarded the diffusion of thiolated particles in the order PEO>> PVP>> PAA>> HEC whereas for PEGylated silica particles retardation followed the order PAA>> PVP = HEC>> PEO. In the absence of specific interactions with the medium, PEGylated nanoparticles exhibit enhanced mobility compared to their thiolated counterparts despite some increase in their dimensions.
Publication
Journal: Nano Letters
May/9/2017
Abstract
Replacing flammable organic liquid electrolytes with solid Li-ion conductors is a promising approach to realize safe rechargeable batteries with high energy density. Composite solid electrolytes, which are comprised of a polymer matrix with ceramic Li-ion conductors dispersed inside, are attractive, since they combine the flexibility of polymer electrolytes and high ionic conductivities of ceramic electrolytes. However, the high conductivity of ceramic fillers is largely compromised by the low conductivity of the matrix, especially when nanoparticles (NPs) are used. Therefore, optimizations of the geometry of ceramic fillers are critical to further enhance the conductivity of composite electrolytes. Here we report the vertically aligned and connected Li1+xAlxTi2-x(PO4)3 (LATP) NPs in the poly(ethylene oxide) (PEO) matrix to maximize the ionic conduction, while maintaining the flexibility of the composite. This vertically aligned structure can be fabricated by an ice-templating-based method, and its conductivity reaches 0.52 × 10-4 S/cm, which is 3.6 times that of the composite electrolyte with randomly dispersed LATP NPs. The composite electrolyte also shows enhanced thermal and electrochemical stability compared to the pure PEO electrolyte. This method opens a new approach to optimize ion conduction in composite solid electrolytes for next-generation rechargeable batteries.
Publication
Journal: Bioconjugate Chemistry
September/7/2005
Abstract
A facile, one-step synthesis of cationic block copolymers of poly(2-N-(dimethylaminoethyl) methacrylate) (pDMAEMA) and copolymers of poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO) has been developed. The PEO-PPO-PEO-pDMAEMA (L92-pDMAEMA) and PEO-pDMAEMA copolymers were obtained via free radical polymerization of DMAEMA initiated by polyether radicals generated by cerium(IV). Over 95% of the copolymer fraction was of molecular mass ranging from 6.9 to 7.1 kDa in size, indicating the prevalence of the polyether-monoradical initiation mechanism. The L92-pDMAEMA copolymers possess parent surfactant-like surface activity. In contrast, the PEO-pDMAEMA copolymers lack significant surface activity. Both copolymers can complex with DNA. Hydrodynamic radii of the complexes of the L92-pDMAEMA and PEO-pDMAEMA with plasmid DNA ranged in size from 60 to 400 nm, depending on the copolymer/DNA ratio. Addition of Pluronic P123 to the L92-pDMAEMA complexes with DNA masked charges and decreased the tendency of the complex to aggregate, even at stoichiometric polycation/DNA ratios. The transfection efficiency of the L92-pDMAEMA copolymer was by far greater than that of the PEO-pDMAEMA copolymer. An extra added Pluronic P123 further increased the transfecton efficacy of L92-pDMAEMA, but did not affect that of PEO-pDMAEMA.
Publication
Journal: Journal of Cellular Biochemistry
October/3/2007
Abstract
Recovery of bone loss is one of the active research issues in bone medicine due to the need for efficient measures for bone gain. We examined here a novel drug delivery system using a nanogel of cholesterol-bearing pullulan (CHP) in combination with prostaglandin E2 (PGE2). PGE2 or PGE2/CHP, vehicle (saline containing 0.06% ethanol and 0.02% Tween 80) or CHP were injected on to the calvariae of mice once every day for 5 days per week for 4 weeks. Low dosage of PGE2 (0.6 microg) alone or CHP alone did not induce new bone formation in this system. In contrast, PGE2 (0.6 microg)/CHP induced new bone formation. Bone formation activities of PGE2 was enhanced by CHP nanogels only at the site of injection (calvaria) but not in the distant sites of the skeleton, showing that PGE2/CHP could avoid systemic effects. In spite of the fact that previously reported animal models of bone formation by PGE2 were associated with loss of body weight, bone formation based on PGE2/CHP did not associate with loss of body weight. Furthermore, only a single application of PGE2 in combination with nanogel cross-linking hydrogel sphere (PGE2/CHP-PEO) induced new bone formation. Thus, nanogel-based delivery system is an efficient delivery system of bone anabolic agent, PGE2.
Publication
Journal: Nutrition Journal
August/29/2020
Abstract
Background: Poor diet quality is associated with obesity-related morbidity and mortality. Psychological stress can increase unhealthy dietary choices, but evidence pertinent to women of reproductive age remains unclear. This paper systematically reviewed the literature to determine the association between psychological stress and diet quality in women of reproductive age.
Methods: Medline, CINAHL, Scopus, Cochrane Library, Web of Science, and Sciencedirect were searched. Data extraction was determined by the PEO. Inclusion criteria consisted of: English language, stress (exposure) measured in combination with diet quality (outcome), healthy women of reproductive age (18-49 years old (population)). Observational studies, due to the nature of the PEO, were included. Quality assessment used the Risk of Bias in Non-randomised Studies from the Cochrane Handbook of Systematic Reviews of Interventions. Meta-analysis was conducted using random-effect model to estimate the Fisher's z transformed correlation between stress and diet quality with 95% confidence interval (CI).
Results: From 139,552 hits, 471 papers were screened; 24 studies met the inclusion criteria and were conducted in different countries: 8 studies on diet quality and 16 on food intake and frequency of consumption. Studies of diet quality consisted of six cross-sectional and two longitudinal designs with a total of 3982 participants. Diet quality was measured with diverse indices; Alternate Healthy Eating Index (n = 2), Healthy Eating Index (n = 2), Dietary Approach to Stop Hypertension (DASH) Diet Index (n = 2), Dietary Quality Index- Pregnancy (n = 2), and Dietary Guideline Adherence Index (n = 1). Most studies used Cohen's perceived stress scale and no study measured biological stress response. After sensitivity analysis, only 5 studies (3471 participants) were included in the meta-analysis. Meta-analysis revealed a significant negative association between stress and diet quality with substantial heterogeneity between studies (r = - 0.35, 95% CI [- 0.56; - 0.15], p value < 0.001, Cochran Q test P < 0.0001, I2 = 93%). The 16 studies of food intake and frequency of consumption were very heterogeneous in the outcome measure and were not included in the meta-analysis. These studies showed that stress was significantly associated with unhealthy dietary patterns (high in fat, sweets, salt, and fast food and low in fruits, vegetables, fish, and unsaturated fats).
Conclusion: Future studies that explore diet quality/patterns should include both diet indices and factor analysis and measure biological markers of stress and dietary patterns simultaneously.
Keywords: Diet; Diet quality; Meta-analysis; Reproductive age; Stress; Systematic review; Women.
Publication
Journal: Journal of the American Chemical Society
April/2/2007
Abstract
Highly ordered mesoporous carbons and silicas with ultralarge accessible pores have been successfully synthesized by using laboratory-made poly(ethylene oxide)-b-polystyrene (<em>PEO</em>-b-PS) diblock copolymers as templates via the evaporation-induced self-assembly (EISA) approach. Resols and tetraethyl orthosilicate (TEOS) serve as carbon and silica precursors, respectively. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) measurements show that the mesoporous carbons (denoted as C-FDU-18) possess face centered cubic closed-packing (fcc) mesostructure (Fm3m) with large-domain ordering. N2 sorption isotherms reveal a large mesopore at the mean value of 22.6 nm with a narrow pore-size distribution. Mesoporous silicas (Si-FDU-18) also display a highly ordered fcc closed-packing mesostructure with an ultralarge unit cell (a = 54.6 nm). A hydrothermal recrystallization was introduced for the first time to produce micropores in thick silica walls (approximately 7.7 nm) and thus to generate ultralarge accessible mesopores (30.8 nm). Notably, the amphiphilic diblock copolymer with high molecular weight (<em>PEO</em>125-PS230, 29700 g mol-1) in this report was prepared via a simple method of atom transfer radical polymerization (ATRP). It can be easily available for chemists even without any experience in polymer synthesis.
Publication
Journal: Scientific Reports
May/4/2017
Abstract
Non-invasive assessment of the biodistribution is of great importance during the development of new pharmaceutical compounds. In this contribution, the applicability of in ovo MRI for monitoring the biodistribution of MR contrast agent-labelled compounds was investigated in mamaria carcinomas xentotransplanted on the chorioallantoic membrane (CAM) exemplarily for Gd-DOTA and cHSA-PEO (2000)16-Gd after systemic injection of the compounds into a chorioallantoic capillary vein. MRI was performed directly prior and 30 min, 3 h, 5 h, 20 h, and 40 h after injection of the compound. The biodistribution of injected compounds could be assessed by MRI in different organs of the chicken embryo as well as in xenotransplanted tumors at all time points. A clearly prolonged enhancement of the tumor substrate could be shown for cHSA-PEO (2000)16-Gd. In conclusion, high-resolution in ovo MR imaging can be used for assessment of the in vivo biodistribution of labelled compounds, thus enabling efficient non-invasive initial testing.
Publication
Journal: Molecular Pharmaceutics
October/30/2017
Abstract
It is hypothesized that thiolated chitosan (TCS) core/shell nanofibers (NFs) can enhance the drug loading of tenofovir, a model low molecular weight and highly water-soluble drug molecule, and improve its mucoadhesivity and in vivo safety. To test this hypothesis, poly(ethylene oxide) (PEO) core with TCS and polylactic acid (PLA) shell NFs are fabricated by a coaxial electrospinning technique. The morphology, drug loading, drug release profiles, cytotoxicity and mucoadhesion of the NFs are analyzed using scanning and transmission electron microscopies, liquid chromatography, cytotoxicity assays on VK2/E6E7 and End1/E6E7 cell lines and Lactobacilli crispatus, fluorescence imaging and periodic acid colorimetric method, respectively. In vivo safety studies are performed in C57BL/6 mice followed by H&E and immunohistochemical (CD45) staining analysis of genital tract. The mean diameters of PEO, PEO/TCS, and PEO/TCS-PLA NFs are 118.56, 9.95, and 99.53 nm, respectively. The NFs exhibit smooth surface. The drug loading (13%-25%, w/w) increased by 10-fold compared to a nanoparticle formulation due to the application of the electrospinning technique. The NFs are noncytotoxic at the concentration of 1 mg/mL. The PEO/TCS-PLA core/shell NFs mostly exhibit a release kinetic following Weibull model (r2 = 0.9914), indicating the drug release from a matrix system. The core/shell NFs are 40-60-fold more bioadhesive than the pure PEO based NFs. The NFs are nontoxic and noninflammatory in vivo after daily treatment for up to 7 days. Owing to their enhanced drug loading and preliminary safety profile, the TCS core/shell NFs are promising candidates for the topical delivery of HIV/AIDS microbicides such as tenofovir.
Publication
Journal: The Journal of bone and joint surgery. British volume
June/18/1998
Abstract
We studied peridural fibrosis in 16 dogs after laminectomies at the L2, L4 and L6 levels. They received either a free fat graft, a biodegradable mechanical barrier (polyethylene oxide (PEO)/polybutylene terephthalate (PBT) copolymer), or no treatment. The animals were killed after 4, 12, 26 and 52 weeks. Histomorphometry showed extensive and consistent peridural fibrosis in control and PEO/PBT groups. Fat grafts produced significantly less fibrous tissue, but the presence of the fat graft in the bony defect prevented closure. Degradation of the PEO/PBT barrier resulted in the formation of more fibrous tissue. We conclude that up to one year a free fat graft is effective in reducing the amount of peridural scarring.
Publication
Journal: Physical Review Letters
May/31/2012
Abstract
We develop a theory for the thermodynamics of ion-containing polymer blends and diblock copolymers, taking polyethylene oxide (PEO), polystyrene and lithium salts as an example. We account for the tight binding of Li^{+} ions to the PEO, the preferential solvation energy of anions in the PEO domain, the translational entropy of anions, and the ion-pair equilibrium between EO-complexed Li^{+} and anion. Our theory is able to predict many features observed in experiments, particularly the systematic dependence in the effective χ parameter on the size of the anions. Furthermore, comparison with the observed linear dependence in the effective χ on salt concentration yields an upper limit for the binding constant of the ion pair.
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