Alginate grafted with poly(ε‐caprolactone): effect of enzymatic degradation on physicochemical properties

The paper discusses the enzymatic behaviour of a series of copolymers composed of alginate grafted with poly(ε‐caprolactone) (PCL) of various lengths and degrees of substitution. The study is focused on viscosity measurements and pyrene probe fluorescence with or without two enzymes: alginate lyase, which breaks the alginate backbone; and esterase, which breaks PCL pendent groups. Alginate lyase is inactive at pH = 3.8 and degrades quickly all copolymers at pH = 6.3. The degradation is not complete and is slowed down by the presence of PCL. Esterase degrades only copolymers with long pendent PCL groups. It has no effect on copolymers when PCL has a length of 530 g mol^?1. These systems are good candidates for controlled release of drugs using an enzymatic method. Copyright © 2012 Society of Chemical Industry     

Surface modifications of the titanium mesh for cranioplasty using selenium nanoparticles coating

The aim of this study was to made and characterized a nanostructured surface on titanium mesh for cranioplasty, by adhesion of selenium nanoparticles (SeNPs) in situ, in a hydrothermal reaction. The structural characterization of selenium nanoparticles was performed using DLS and TEM, revealing that the size and morphology of nanoparticles depends on the nature of saccharide reducing agent. In situ hydrothermal reaction revealed that selenium nanoparticles adherence on titanium mesh surface had the best result in the case of starch-derived SeNPs, as demonstrated by SEM/EDX analysis. In vitro hemolysis and RBC osmotic fragility tests suggest that nanostructured surface created upon SeNPs adhesion doesn’t induce damage to RBC membrane; the hemolysis values indicated a good biocompatibility especially in the case of titanium specimens modified with starch-derived SeNPs. Moreover, the nanostructured surface clearly offers the desired biological response of human fibroblasts cells. The proposed improvement of the surfaces in the case of titanium mesh for cranioplasty may offer important benefits in terms of osteointegration, without using additional screws for fixation and closure procedure.     

Endotoxin,extracellular polysaccharides,and β(1‐3)‐glucan concentrations in dust and their determinants in four European birth cohorts: results from the HITEA project

Early‐life exposure to microbial agents may play a protective role in asthma and allergies development. Geographical differences in the prevalence of these diseases exist, but the differences in early‐life indoor microbial agent levels and their determinants have been hardly studied. We aimed to describe the early‐life levels of endotoxin, extracellular polysaccharides (EPS), and β(1‐3)‐glucans in living room dust of four geographically spread European birth cohorts (LISA in Germany, PIAMA in the Netherlands, INMA in Spain, and LUKAS2 in Finland) and to assess their determinants. A total of 1572 dust samples from living rooms of participants were analyzed for endotoxin, Penicillium/Aspergillus EPS, and β(1‐3)‐glucans. Information on potential determinants was obtained through questionnaires. Concentrations of endotoxin, EPS, and β(1‐3)‐glucans were different across cohorts. Concentrations of endotoxin and EPS were respectively lower and higher in INMA than in other cohorts, while glucans were higher in LUKAS2. Season of sampling, dog ownership, dampness, and the number of people living at home were significantly associated with concentrations of at least one microbial agent, with heterogeneity of effect estimates of the determinants across cohorts. In conclusion, both early‐life microbial exposure levels and exposure determinants differ across cohorts derived from diverse European countries.     

Influence of the substitution degrees on the optical properties of cellulose acetates

Cellulose acetates with different substitution degrees possess a set of properties that makes them highly suitable for optical applications. This article discusses some of these properties, namely refractivity, dielectric properties, and transmittance. The contribution of the ratio between the molar refraction, which is proportional to the induced dipole moment, and the molar volume for the different atoms present in the studied polymers to the optical properties was investigated. The study illustrates the importance of such structural and compositional characteristics in tailoring some specific optical applications. Furthermore, optical transmission has been investigated in the 200–1000 nm range. To obtain the optical parameters, the approach proposed by Tauc for amorphous semiconductors has been used because of the similarity of the absorption edges. The values of pseudogap energy ranged between 3.44 and 4.70 eV, whereas those of Urbach energy were modified in the 18–37 meV range. All parameters determined have been related to the influence of the substitution degrees and of the synthesis condition. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Extraction,structure and biofunctional activities of laminarin from brown algae

Brown algae are rich sources of bioactive compounds such as polysaccharides, peptides, omega‐3 fatty acids, carotenoids, phenolics, vitamins and minerals. Laminarin is low‐molecular‐weight polysaccharide and bioactive compound present in brown algae. Laminarin is found in the fronds of Laminaria and Saccharina species. Laminarin, a storage β‐glucan, is composed of (1,3)‐β‐d ‐glucan and some β‐(1,6)‐intrachain links. The reported content of laminarin from brown algae is up to levels of 35% on dry basis, which varies depending on species, harvesting season, habitat and method of extraction. Laminarin has many reported biofunctional activities including antitumour, anti‐apoptotic, anti‐inflammatory, anticoagulant and antioxidant activity. Biofunctional activities of laminarin can be enhanced after suitable chemical modifications, sulphation and novel processing techniques. Studies on feeding of laminarin‐rich extracts to animals indicate it's suitability as functional ingredient for food applications. This paper reviews the main sources, structure and extraction of laminarin with its biofunctional activities.     

Silver/selenium/chitosan co-substituted bioceramic coatings of Ni–Ti alloy: Antibacterial efficiency and cell viability

The effects of silver (Ag), selenium (Se), and chitosan (Cht) additives on the antibacterial activity and cell viability of NiTi were investigated. Three different hydroxyapatite (HA)-based bioceramic coatings to improve the antibacterial activity and cell viability of NiTi; HA, HA/Ag, and HA/Se–Cht were applied to NiTi substrates by a sol–gel method. The coated samples were characterized by scanning electron microscopy–electron-dispersive spectroscopy and X-ray diffraction and surface hardnesses were measured. The antimicrobial efficiency of the coatings and uncoated surfaces were tested against Escherichia coli-JM 103 and Staphylococcus aureus-ATCC29293. In vitro cell–material interactions using Saos-2 osteoblast cells were characterized by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (mitochondrial activity test) assay for cell viability. A homogeneous, crack-free, and porous surface morphology is achieved in coatings. It has been shown that the Se–Cht additives did not have a significant effect on the surface hardness of the HA coating, but the Ag additive increased the hardness. Through in vitro antibacterial activity and cell viability tests, it was shown that Ag additive to bioceramic coatings significantly increased (p < .05) antibacterial properties but caused a decrease in cell viability. However, although Se–Cht additives did not have a significant effect on antibacterial properties (p < .05), it was observed that they increased cell viability.     

超声法提取枸杞多糖的工艺研究

通过单因素和正交实验研究了超声波法在枸杞多糖提取中的应用。结果表明,影响枸杞多糖提取因素的主次顺序为超声时间超声温度料液比,最佳工艺为超声温度70℃,超声时间50 min,料液比1∶30,在该条件下多糖提取率为5.02%。超声波法与热水浸提法比较,耗能少,提取率更高。     

微波消解－ICP－MS测定土壤及植物中硒的含量

建立微波消解电感耦合等离子体质谱（ ICP－MS）测定土壤及植物中硒的分析方法。对土壤样采用硝酸－氢氟酸、植物样采用硝酸作为消解液进行微波消解,用ICP－MS 测定样品中的硒含量。该方法对菠菜GSB－6（ GBW10015）和土壤ESS－3（ GSBZ50013－88）标准参考物质中硒进行分析结果与标准值相符合,相对误差分别为7．6％和10．5％。用于实际土壤样品和植物样品中硒的测定,该方法的检出限为0．20μg／L,其相对标准偏差RSD＜10％,加标回收率介于92％～108％之间。为土壤和植物样品中硒的分析测试提供了一种简便、快速、准确、可靠的方法。