Fabrication and assessment of bifunctional electrospun poly(L-lactic acid) scaffolds with bioglass and zinc oxide nanoparticles for bone tissue engineering

Electrospun scaffolds based on poly(L-lactic acid) (PLLA) with bioglass (n-BG) and zinc oxide (n-ZnO), and mixture of both, were developed to design bifunctional biomaterials with enhanced bioactive and biocidal properties. The presence of n-BG increased the fiber diameter of the pure PLA from 1.5 ± 0.3 μm to 3.0 ± 0.8 μm for 20 wt%. ZnO and the mixed nanoparticles did not significantly affect the morphology. The mechanical properties decreased with the presence of nanoparticles. Scaffolds based on PLA/n-BG promoted hydroxyapatite (HA) formation in simulated body fluid (SBF) that was inhibited with the presence of ZnO. Notably, mixed particles produced bioactivity although at longer times. The incorporation of n-ZnO produced a biocidal capacity against S. aureus in the polymeric scaffold, reaching a viability reduction of 60 % after 6 h of exposure. When both types of nanoparticles were combined, the bacterial viability reduction was 30 %. Pure PLA scaffolds and the composites with n-BG showed good ST-2 bone marrow-derived cell line viability, scaffolds with n-BG (pure or mixture) presented lower viability. Results validated the use of both n-BG and n-ZnO fillers for the development of novel bifunctional PLA-based scaffolds with both bioactive and biocidal properties for bone tissue engineering applications.P.A. Zapata acknowledge the financial support of Direccion de Investigacion Científica y Tecnologica, Universidad de Santiago de Chile (DICYT) project: 052241ZR_DAS. D. Canales thanks the financial support of FONDECYT under postdoctoral project No. 3210810. Finally, D. Canales is immensely grateful to Katharina Schuhladen, Sonja Kuth, Lena Vogt, Irem Unalam, and Florian Ruther, members of Institute of Biomaterials of University of Erlangen-Nuremberg, for their support in the mechanical and biological analysis

Poly (lactic acid)/D-limonene/ZnO bio-nanocomposites with antimicrobial properties

Antimicrobial films of poly (lactic acid) (PLA)/D-limonene/zinc oxide (ZnO)-based bio-nanocomposites were prepared via melt compounding and subsequent thermocompression. D-limonene was incorporated at concentrations of 10 or 20 wt%, and ZnO pure nanoparticles and those organically modified with oleic acid (O-ZnO), with an average diameter of 13.5 nm, were included at concentrations of 3, 5, and 8 wt%. The plasticizing effect of D-Limonene was corroborated by a decrease in the glass transition temperature compared to pure PLA. The presence of ZnO and O-ZnO in the PLA matrix promoted a slight increase in the degree of crystallinity due to its nucleant performance. Although ZnO and O-ZnO induced lower thermal stability and slightly decreased microhardness in the composites, excellent antimicrobial performance was demonstrated. Both ZnO and O-ZnO nanocomposites reached 99.9% of effectiveness for nanoparticles content above 5 wt%, regardless of the source of irradiation, D-limonene concentration, and nanoparticle modification. Therefore, these bio-nanocomposites will allow for future advances in sustainable antimicrobial materials for the medical or food packaging fields.DICYT, Grant/Award Number: Project 022041ZR_POSTDOCT; Fondo Nacional de Desarrollo Científico y Tecnológico,Grant/Award Numbers: 1170226, 320029

Mechanical and antimicrobial properties of low-density-polyethylene/MgO nanocomposites

Low-density polyethylene (LDPE) nanocomposites containing magnesium oxide (MgO) nanoparticles are obtained by melt mixing. MgO nanoparticles ca. 29 ± 2 nm are synthesized by sol–gel and organically modified on the surface with oleic acid (Mod-MgO), whose final concentration in the polymers is 3, 5, and 10 wt%. The presence of these nanoparticles did not affect the crystallization process of LDPE. However, Young's modulus increases with 10 wt% of Mod-MgO nanoparticles, rendering higher reinforcement effects with an increase as high as 48%. This affects the elongation at break, which decreases ca. 57% compared to neat LDPE. The storage and loss modulus of the LDPE/MgO and LDPE/Mod-MgO nanocomposites increases at room temperature and low temperatures (−150 to −50°C) compared to neat LDPE. SEM analysis showed that the organic modification of MgO nanoparticles improved their dispersion within the polymer matrix. Nanocomposites present antimicrobial properties against Escherichia coli, reaching an efficiency ca. 53%.Paula A. Zapata thanks the financial support under FONDECYT Regular Project 1220093. Viviana Moreno-Serna thanks the ANID FON-DECYT Postdoctorado 3210077. Carlos Loyo and Raúl Vallejos thank Proyecto de Dirección de Investigación Científica y tecnológica (DICYT), 022141ZR_POSTDOC, USA2055, Universidad de Santiago de Chile

Circumsolar energetic particle distribution on 2011 November 3

Late on 2011 November 3, STEREO-A, STEREO-B, MESSENGER, and near-Earth spacecraft observed an energetic particle flux enhancement. Based on the analysis of in situ plasma and particle observations, their correlation with remote sensing observations, and an interplanetary transport model, we conclude that the particle increases observed at multiple locations had a common single source active region and the energetic particles filled a very broad region around the Sun. The active region was located at the solar backside (as seen from Earth) and was the source of a large flare, a fast and wide coronal mass ejection, and an EIT wave, accompanied by type II and type III radio-emission. In contrast to previous solar energetic particle events showing broad longitudinal spread, this event showed clear particle anisotropies at three widely separated observation points at 1AU, suggesting direct particle injection close to the magnetic footpoint of each spacecraft, lasting for several hours.We discuss these observations and the possible scenarios explaining the extremely broad particle spread for this event

Influence of operating parameters on the biodegradation of steroid estrogens and nonylphenolic compounds during biological wastewater treatment processes

This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Environmental Science & Technology, copyright © American Chemical Society after peer review. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/es901612v.This study investigated operational factors influencing the removal of steroid estrogens and nonylphenolic compounds in two sewage treatment works, one a nitrifying/denitrifying activated sludge plant and the other a nitrifying/denitrifying activated sludge plant with phosphorus removal. Removal efficiencies of >90% for steroid estrogens and for longer chain nonylphenol ethoxylates (NP4−12EO) were observed at both works, which had equal sludge ages of 13 days. However, the biological activity in terms of milligrams of estrogen removed per day per tonne of biomass was found to be 50−60% more efficient in the nitrifying/denitrifying activated sludge works compared to the works which additionally incorporated phosphorus removal. A temperature reduction of 6 °C had no impact on the removal of free estrogens, but removal of the conjugated estrone-3-sulfate was reduced by 20%. The apparent biomass sorption (LogKp) values were greater in the nitrifying/denitrifying works than those in the nitrifying/denitrifying works with phosphorus removal for both steroid estrogens and nonylphenolic compounds possibly indicating a different cell surface structure and therefore microbial population. The difference in biological activity (mg tonne−1 d−1) identified in this study, of up to seven times, suggests that there is the potential for enhancing the removal of estrogens and nonylphenols if more detailed knowledge of the factors responsible for these differences can be identified and maximized, thus potentially improving the quality of receiving waters.Public Utilities Board (Singapore), Anglian Water Ltd, Severn Trent Water Ltd, Thames Water Utilities Ltd, United Utilities 393 Plc and Yorkshire Water Services

Direct Polyphenol Attachment on the Surfaces of Magnetite Nanoparticles, Using Vitis vinifera, Vaccinium corymbosum, or Punica granatum

This study presents an alternative approach to directly synthesizing magnetite nanoparticles (MNPs) in the presence of Vitis vinifera, Vaccinium corymbosum, and Punica granatum derived from natural sources (grapes, blueberries, and pomegranates, respectively). A modified co-precipitation method that combines phytochemical techniques was developed to produce semispherical MNPs that range in size from 7.7 to 8.8 nm and are coated with a ~1.5 nm thick layer of polyphenols. The observed structure, composition, and surface properties of the MNPs@polyphenols demonstrated the dual functionality of the phenolic groups as both reducing agents and capping molecules that are bonding with Fe ions on the surfaces of the MNPs via –OH groups. Magnetic force microscopy images revealed the uniaxial orientation of single magnetic domains (SMDs) associated with the inverse spinel structure of the magnetite (Fe3O4). The samples’ inductive heating (H0 = 28.9 kA/m, f = 764 kHz), measured via the specific loss power (SLP) of the samples, yielded values of up to 187.2 W/g and showed the influence of the average particle size. A cell viability assessment was conducted via the MTT and NRu tests to estimate the metabolic and lysosomal activities of the MNPs@polyphenols in K562 (chronic myelogenous leukemia, ATCC) cells

Microsurgery in complex trauma of pelvic limb in a pediatric patient: case report

Complex trauma is defined as the condition secondary to the exchange of kinetic energy of two or more tissues in one limb. This entity is a surgical emergency that can have many sequelae and can even result in limb loss. An 11-year-old female patient presents complex pelvic limb trauma secondary to contuse injury caused by a helicopter’s rotor blades.  Pelvic limb reconstruction was performed with iliac crest bone graft, the fracture was stabilized with an external fixator and the skin defect was covered with an anterolateral microvascular thigh flap (ALT). There was an adequate integration of the bone graft with adequate skin coverage thanks to the ALT thigh flap. The patient presented discreet limb shortening as consequence.  Currently, microsurgery is the only medical option that meets the objectives of limb reconstruction. Microsurgical techniques can be used in pediatric and adult patients. The success of any recovery from complex trauma is vigorous surgical cleaning, avoiding sequential and/or multiple washes

B cell and/or autoantibody deficiency do not prevent neuropsychiatric disease in murine systemic lupus erythematosus

Background: Neuropsychiatric lupus (NPSLE) can be one of the earliest clinical manifestations in human lupus. However, its mechanisms are not fully understood. In lupus, a compromised blood-brain barrier may allow for the passage of circulating autoantibodies into the brain, where they can induce neuropsychiatric abnormalities including depression-like behavior and cognitive abnormalities. The purpose of this study was to determine the role of B cells and/or autoantibodies in the pathogenesis of murine NPSLE. Methods: We evaluated neuropsychiatric manifestations, brain pathology, and cytokine expression in constitutively (JhD/MRL/lpr) and conditionally (hCD20-DTA/MRL/lpr, inducible by tamoxifen) B cell-depleted mice as compared to MRL/lpr lupus mice. Results: We found that autoantibody levels were negligible (JhD/MRL/lpr) or significantly reduced (hCD20-DTA/MRL/lpr) in the serum and cerebrospinal fluid, respectively. Nevertheless, both JhD/MRL/lpr and hCD20-DTA/MRL/lpr mice showed profound depression-like behavior, which was no different from MRL/lpr mice. Cognitive deficits were also observed in both JhD/MRL/lpr and hCD20-DTA/MRL/lpr mice, similar to those exhibited by MRL/lpr mice. Furthermore, although some differences were dependent on the timing of depletion, central features of NPSLE in the MRL/lpr strain including increased blood-brain barrier permeability, brain cell apoptosis, and upregulated cytokine expression persisted in B cell-deficient and B cell-depleted mice. Conclusions: Our study surprisingly found that B cells and/or autoantibodies are not required for key features of neuropsychiatric disease in murine NPSLE

Lymphotropism of Merkel Cell Polyomavirus Infection, Nova Scotia, Canada

Lymphoid cells may be a site for virus persistence