乙酰化对壳聚糖-明胶海绵结构和性能的影响

用乙酸酐对壳聚糖与明胶共混物进行乙酰化,然后冷冻干燥制备乙酰化壳聚糖-明胶海绵,并研究乙酰化对海绵结构与性能的影响。用盐酸环丙沙星作模型药物,探讨载药海绵的抑菌效果。结果表明:制得的海绵具有多孔结构,随壳聚糖在混合物中含量的增加,海绵的吸水率和保水率先增后减;随着乙酰化程度的提高,海绵的吸水率先减后增,而保水率与吸水率的变化规律相反。酶对海绵的降解率不受壳聚糖和明胶混合比例的影响,但随海绵乙酰化程度的增加而增加。载药海绵的抑菌效果与海绵中壳聚糖含量有关。     

Gas chromatography with mass spectrometry for the quantification of ethylene glycol ethers in different household cleaning products

A rapid and simple procedure is reported for the determination of six ethylene glycol ethers in cleaning products and detergents using gas chromatography with mass spectrometry. The analytes were extracted from 2.0 g samples in acetonitrile (3 mL) and the extract was submitted to a clean‐up step by QuEChERS method, using a mixture containing 0.3 g magnesium sulfate, 0.15 g primary/secondary amine, and 0.05 g C₁₈. The clean acetonitrile extract (1 μL) was injected into the chromatographic system. No matrix effect was observed, so the quantification of the samples was carried out against external standards. Detection limits were in the range 3.0–27 ng/g for the six ethylene glycol ethers. The recoveries obtained, using the optimized procedure, were in the 89.4–118% range, with relative standard deviations lower than 14%. Twenty‐three different household cleaning products, including glass cleaner, degreaser, floor, softeners, and clothes and dishwashing detergents, were analyzed. Large interindividual variations were observed between samples and compounds.     

Characterization of chitosan microparticles reinforced cellulose biocomposite sponges regenerated from ionic liquid

The chitosan-microparticles reinforced cellulose biocomposite sponges regenerated from ionic liquid were prepared and characterized. Fourier transform infrared (FTIR) spectroscopy confirmed that the cellulose dissolved in 1-allyl-3-methylimidazolium chloride without derivatization. Chitosan particles as reinforcement were incorporated into the cellulose matrix. FTIR spectra indicated hydrogen bonding between hydroxyl groups of cellulose and chitosan. The biocomposite sponges showed uniform three-dimensional interconnected porous structures. The breaking strength of the sponges increased significantly, from 0.09 to 0.32 MPa with the addition of 1.0 wt% chitosan. The sponges also demonstrated excellent antibacterial activity against S. aureus and E. coli with the average inhibition zone diameters >2 mm and the inhibition rate higher than 80 %. Furthermore, the biocomposite sponges exhibited good moisture penetrability and high porosity. The water uptake ability of the sponge was >25 times of its weight in water with a fast swelling. The chitosan/cellulose composite sponge is expected to be a promising material for potential applications as wound dressing.     

式根岛海绵宏基因组文库的抗菌吲哚三聚体

构建了式根岛海绵的宏基因组文库,对其进行双层琼脂抗菌活性功能筛选,得到1株抗菌活性克隆pDC111. 以抗菌活性为指导,对pDC111的化学成分进行分析和分离,得到化合物1,并通过1D NMR（¹H NMR和 ¹³C NMR）及2D NMR（¹H-¹H COSY,HMQC和HMBC）结合HR-TOFMS数据,确定其结构为吲哚三聚体. 抗菌活性实验结果表明,化合物1在10 μg/paper（id=6 mm）时,对蜡状芽孢杆菌的抑菌圈达到12 mm. 本文利用功能宏基因组方法,从蕴藏大量不可培养微生物的海绵中寻找到活性物,并具有通过分子生物学技术获得其功能基因的潜能.     

Simultaneous determination of DTPA,EDTA, and NTA by UV–visible spectrometry and HPLC

In this study, UV–visible spectrophotometry (UV–Vis) and high-performance liquid chromatography (HPLC) were used for simultaneous analysis of chelating agents diethylenetriamine pentaacetic acid (DTPA), ethylenediamine tetraacetic acid (EDTA), and nitrilotriacetic acid (NTA), as their metal chelates in dishwashing detergents, natural waters, and pulp mill water. The total amounts of the chelating agents in dishwashing detergents were verified by potentiometric titration with Fe(III) solution. Nickel(II) chelates were determined by UV–Vis and iron(III)chelates by HPLC and titration. Recoveries of DTPA, EDTA, and NTA from a standard mixture of analytes by UV–Vis were 107±7, 101±12 and 94±13%, respectively, and the recovery of the total amount of complexing agents was 99±4%. The limits of detection for DTPA, EDTA, and NTA were 667, 324, and 739 mol L^–1, respectively. In HPLC measurements the optimized mobile phase contained 0.03 mol L^–1 sodium acetate, 0.002 mol L^–1 tetrabutylammonium bromide, and 5% methanol at pH 3.15 and the detection was by UV–Vis detection at 254 nm. All three complexing agents could be separated from each other in a simultaneous analysis in less than 5 min. The limits of detection were 0.34, 0.27, and 0.62 mol L^–1 for DTPA, EDTA, and NTA, respectively. The total amounts of the analytes measured in the dishwashing detergents by the three techniques were found to be highly comparable (ANOVA: F=0.04, P=0.96). R² values were 0.99 for EDTA, 0.99 for NTA, and 0.99 for all the results when UV–Vis and HPLC determinations were compared using regression lines. The UV–Vis and HPLC methods were proved to be viable also for analyses of natural and pulp mill waters. The absence of matrix interferences was verified by the standard addition technique.     

Effect of ionizing radiation on monument deteriorating microorganisms

The effect of⁶⁰Co -rays and detergents on bacteria isolated from monuments has been studied. Most of the heterotrophic bacteria examined were found to be resistant to radiation, whereas nitrifiers are moderately radio-resistant. The most effective growth supression of microorganisms was observed with the simultaneons application of ionizing radiation and detergents.     

Evaluation of differential protein expression in Haliclona aquarius and sponge-associated microorganisms under cadmium stress

A comparative proteomic approach was used to assess differentially expressed proteins in marine sponges after 36 h of exposure to cadmium (Cd). After separation performed by 2-D polyacrylamide gel electrophoresis, 46 protein spots indicated differential expression, and 17 of these proteins were identified by electrospray ionization quadrupole time-of-flight mass spectrometry. From the proteins identified, 76 % were attributed to sponge-associated microorganisms (fungi and bacteria), and 24 % were attributed to Haliclona aquarius. Some of the proteins that were identified may be related to cell proliferation and differentiation or processes of oxidative stress repair and energy procurement. An integrated evaluation based on spot expression levels and the postulated functions of these proteins allowed a more accurate evaluation of the stress caused to the sponge holobiont system by cadmium exposure. This study could provide new insights into the use of a proteomic approach in the marine sponge to assess the effects of Cd pollution in a marine environment.     

Preparation and morphology control of three‐dimensional interconnected microporous PDMS for oil sorption

This study described an approach to impart controlled morphology and improved pore interconnectivity to poly(dimethylsiloxane) (PDMS) sponges for oil sorption by partially fusing the sugar particles together prior to creation of a continuous PDMS matrix. PDMS sponges with high absorption capacity, low water pickup, and remarkable reusability were fabricated by the polymerization of the PDMS prepolymer and a curing agent in cyclohexane. The PDMS sponge showed oil absorbency in the range from 790% to 4000% for various oils solvents, with the maximum absorption capacity reaching up to 23 times of its weight. Compressive modulus of PDMS subjected to sugar fusion for 24 hr was significantly increased to 1900 Mpa. The sponge also exhibited excellent repellency to corrosive strong acid and alkali. Besides, oil can be quickly adsorbed in tens of seconds and maintained for several months. Furthermore, PDMS sponges showed little loss of their absorption capacities and owned weights after 20 absorbing/recovering cycles. Copyright © 2015 John Wiley & Sons, Ltd.     

用于压力传感的还原氧化石墨烯/丝蛋白基多孔复合材料

利用丝蛋白能够在还原氧化石墨烯片层上发生选择性聚集的特性,制备了还原氧化石墨烯片层上富集有丝蛋白微纤且分散性良好的还原氧化石墨烯片和丝蛋白混合溶液,并通过冷冻以及低温乙醇处理的方法得到一系列不同比例的还原氧化石墨烯/丝蛋白基多孔复合材料.随后,采用溶液浸泡的方法在多孔材料表面再次沉积还原氧化石墨烯,以进一步提高还原氧化石墨烯/丝蛋白基多孔复合材料的压敏导电性.系统观察和测试结果表明,还原氧化石墨烯的引入,不仅使得多孔材料内部出现了相应的微纳结构,同时也提高了多孔材料的力学性能.还原氧化石墨烯/丝蛋白基多孔复合材料在完全湿态下兼具较好的强度和弹性,可以在0%~80%的压缩应变之间实现良好的压缩回复效果和压力传感性能.其中,最佳比例下的还原氧化石墨烯/丝蛋白基多孔复合材料在低压力下的灵敏度可达0.15 kPa?1,在0~17.3 kPa范围内能够高效工作并且具有优异的电学稳定性和耐疲劳性.因此,还原氧化石墨烯/丝蛋白基多孔复合材料因其高灵敏度、宽工作范围、结构可调以及可塑性好等诸多优点,有望在柔性压力传感方面获得较好的应用.     

A novel chitosan-based sponge coated with self-assembled thrombin/tannic acid multilayer films as a hemostatic dressing

In order to prepare a novel hemostatic dressing for uncontrolled hemorrhage, a porous chitosan sponge was coated with self-assembled(thrombin/tannic acid)n films, which were based on hydrogen bonding interactions between thrombin and tannic acid at physiologic p H. According to the whole blood clotting test, the coated chitosan sponges showed a significantly high rate of blood clotting due to the addition of thrombin. On the other hand, the storable half-life of immobilized thrombin is extended to 66.9 days at room temperature, which is 8.5 times longer than unfixed thrombin. It is because of the immobilization effect of, not only the porous structure of chitosan sponge but also the interactions between thrombin and tannic acid. In addition, the tannic acid has similar antibacterial effect to chitosan. Therefore, it is an excellent combination of chitosan, thrombin and tannic acid. Besides, all of materials in this research have been approved by the United States Food and Drug Administration(FDA). So the chitosan-based sponge is a promising candidate dressing for uncontrolled hemorrhage due to its storable, bio-safe and highly effective hemostatic properties.     

Zeolite‐Supported One‐Pot Synthesis of Bis‐azetidinones under Microwave Irradiation

In an attempt to synthesize antibacterial agents effective against gram‐positive and gram‐negative bacteria, the efficient synthesis of novel bis‐azetidinones ( 3a–j ) has been established. Thus, cycloaddition reaction of substituted bis‐imines with chloroacetylchloride under microwave irradiation in the presence of zeolite yielded bis‐azetidinones ( 3a–j ). Structures of the synthesized compounds have been elucidated on the basis of their elemental analysis and spectral data (IR, ¹H‐NMR, ¹³C‐NMR, and mass spectra). The synthesized bis‐azetidinones were screened for their antibacterial activity against five microorganisms: Bacillus subtilis, Proteus vulgaris, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli. They were found to exhibit good to moderate antibacterial activity.     

Highly Efficient Reusable Sponge‐Type Catalyst Carriers Based on Short Electrospun Fibers

This study reports on gold nanoparticles (AuNPs) immobilized in a sponge made of short electrospun fibers (Au‐sponge), which show surprisingly high reaction rates at extremely low gold amount. Au‐sponges are made by freeze‐drying of dispersions of short electrospun fibers with preimmobilization of AuNPs. The resulting Au‐sponges show very low densities around 7 mg cm⁻³ corresponding to a pore volume of about 150 mL g⁻¹, but low surface area and very low amount of AuNPs in the range of 0.29–3.56 wt%. In general, catalysts with immobilized AuNPs show much low reaction rates compared to systems with dispersed AuNPs. By contrast, the Au‐sponge catalyst with immobilized AuNPs is discerned here as an extremely efficient catalyst even superior to other systems with dispersed AuNPs. The fidelity of the Au‐sponges after reactions is good enough for manifold use and thereby provides a sustainable catalyst design as well.

     

小儿尿路感染的微生物病原菌分布及解决对策

目的探讨小儿尿路感染的病原菌分布以及解决对策。方法选择90例小儿尿路感染患者为分析对象,分析其尿路感染病原微生物分布以及抗菌药物药敏情况。结果革兰阴性杆菌所占的比例达到了83.65%,其中大肠埃希菌占到71.26%。大肠埃希菌对头孢呱酮、头孢美蛙、亚胺培南、阿米卡星、氨曲南这些药物的敏感性较高。结论导致小儿尿路感染的主要病原微生物为大肠埃希菌,临床应依据病原菌分布以及抗菌药物药敏情况,合理选择和使用抗菌药物,有效控制感染,减少耐药菌株出现。     

Simultaneous determination of DTPA,EDTA, and NTA by capillary electrophoresis after complexation with copper

We present a method for simultaneous determination of the aminopolycarboxylic acids DTPA, EDTA and NTA in dishwashing detergents, paper mill waters, and natural waters by capillary electrophoresis (CE). The complexing agents were examined as their copper(II) complexes and separated by conventional CE with reversed polarity of the applied voltage. The optimum separation conditions were established by varying the pH and phosphate and tetradecyltrimethylammonium bromide (TTAB) concentrations in the run buffer. The separations were carried out in a fused-silica capillary (61 cm×75 m i.d.) filled with phosphate buffer (80 mmol L^–1, TTAB concentration 0.5 mmol L^–1, pH 7.1, voltage –20 kV) using direct UV detection at 191 and 254 nm. With this CE method all the peaks in the electropherograms were properly separated, the calibration plots gave good correlation coefficients and all three complexing agents could be detected in less than 4 min. Linear calibration plots were obtained for CuDTPA, CuEDTA and CuNTA; limits of detection were 0.03 mmol L^–1 for all complexing agents and recoveries for all tested samples were within the range 104±7%. Results obtained from dishwashing detergent samples were found to be reliable and comparable with those from HPLC (R²=0.989) and UV–Vis (R²=0.985) methods.     

A Layered Chitosan/Graphene Oxide Sponge as Reusable Adsorbent for Removal of Heavy Metal Ions

Along with the growing severity of environment problem and energy crisis, it is inevitable to develop novel materials, which are contributed to the removal of hazardous pollutants from contaminated water. Herein, we reported a fhcile method for the preparation of free-standing chitosan/graphene oxide(CS/GO) composite sponges with low density, where CS/GO mixtures were first synthesized by tlie homogeneous reaction of chitosan and graphene oxide in aqueous acetic acid solution;then CS/GO sponges were obtained by lyophilizing the suspension, which were prefrozen at -20 ℃ and in liquid nitrogen successively. The obtained layered sponge showed good water- driven shape memory effect and was a good adsorbent of Co^2+ and Ni^2+ witli a large adsorption capacity of 224.8 and 423.7 mg/g, respectively. Importantly, the successive adsorption-desorption studies employing CS/GO sponge indicated that the composite could be regenerated by HC1 solution and reused in more than five cycles with regeneration efficiency beyond 80%. Also, the resultant sponge was explored as an exceptionally adsorbent for the removal of organic dye(e.g., methylene blue, MB).     

Facile synthesis of microfibrillated cellulose/organosilicon/polydopamine composite sponges with flame retardant properties

Cellulose composite sponges with good mechanical, heat-insulating and flame retardant properties were constructed by a facile method. Simultaneous polymerization of dopamine and hydrolysis of organosilicon in the suspension of microfibrillated cellulose could provide the stiffness and flame ratardancy of the composite sponges. The hybrid sponges had low density (15.1–28.5 mg/cm³) and desirable compression strength (76.6–135.8 kPa). Scanning electron microscopy (SEM) and thermal conductivity tests revealed that the sponges are composed of a three-dimensional cellulosic network and the porous structure endowed them low thermal conductivity [~0.046 W/(m K)]. With the addition of organosilicon (45 wt%) and polydopamine (PDA) (10 wt%), a 456% improvement in BET surface area of the sponge could be achieved. The limiting oxygen index (LOI) of the composite sponge could be as high as 29.5 with 15 wt% PDA and could self-extinguish at once when it was removed from torch. That was owing to the promoted materials carbonization ability of silicon and radical scavenging activity of dopamine.     

Speciation and biosynthetic variation in four dictyoceratid sponges and their cyanobacterial symbiont, Oscillatoria spongeliae

Four species of marine sponges (Phylum Porifera, Order Dictyoceratida), which contain the filamentous cyanobacterial symbiont Oscillatoria spongeliae, were collected from four locations in Palau. The halogenated natural products associated with the symbiont were characterized from each sample, revealing that each species contained either chlorinated peptides, brominated diphenyl ethers, or no halogenated compounds. Analysis of the host sponges and the symbionts indicated that each species of sponge contained a distinct strain of morphologically similar cyanobacteria. Although cospeciation may be present in this group, we have identified that at least one host switching event has occurred in this symbiosis. Only the strain of O. spongeliae in the sponge containing the chlorinated compounds possessed genes involved in the biosynthesis of chlorinated leucine precursors, indicating that the chemical variation observed in these animals has a genetic foundation.     

Validation and evaluation of an HPLC methodology for the quantification of the potent antimitotic compound (+)‐discodermolide in the Caribbean marine sponge Discodermia dissoluta

The sponge Discodermia dissoluta is the source of the potent antimitotic compound (+)‐discodermolide. The relatively abundant and shallow populations of this sponge in Santa Marta, Colombia, allow for studies to evaluate the natural and biotechnological supply options of (+)‐discodermolide. In this work, an RP‐HPLC‐UV methodology for the quantification of (+)‐discodermolide from sponge samples was tested and validated. Our protocol for extracting this compound from the sponge included lyophilization, exhaustive methanol extraction, partitioning using water and dichloromethane, purification of the organic fraction in RP‐18 cartridges and then finally retrieving the (+)‐discodermolide in the methanol–water (80:20 v/v) fraction. This fraction was injected into an HPLC system with an Xterra RP‐18 column and a detection wavelength of 235 nm. The calibration curve was linear, making it possible to calculate the LODs and quantification in these experiments. The intra‐day and inter‐day precision showed relative standard deviations lower than 5%. The accuracy, determined as the percentage recovery, was 99.4%. Nine samples of the sponge from the Bahamas, Bonaire, Curaçao and Santa Marta had concentrations of (+)‐discodermolide ranging from 5.3 to 29.3 μg/g^?1 of wet sponge. This methodology is quick and simple, allowing for the quantification in sponges from natural environments, in situ cultures or dissociated cells.     

Preparation of active antibacterial LDPE surface through multistep physicochemical approach: I. Allylamine grafting, attachment of antibacterial agent and antibacterial activity assessment

Low-density polyethylene (LDPE) samples were treated in air plasma discharge, coated by polyallyamine brush thought copolymeric grafting surface-from reaction and deposited four common antibacterial agents (benzalkonium chloride, bronopol, chlorhexidine and triclosan) to gain material with active antibacterial properties. Surface characteristics were evaluated by static contact angle measurement with surface energy evaluation ATR-FTIR, X-ray Photoelectron Spectroscopy (XPS) and SEM analysis. Inhibition zone on agar was used as in vitro test of antibacterial properties on two representative gram positive Staphylococcus aureus (S. aureus) and gram negative Escherichia coli (E. coli) strains. It was confirmed, that after grafting of polyallyamine, more antibacterial agent is immobilized on the surface. The highest increase of antibacterial activity was observed by the sample containing triclosan. Samples covered by bronopol did not show significant antibacterial activity.     

Synthesis and antibacterial activity of some imidazo[1,2-a]pyrimidine derivatives.

A series of 75 imidazo[1,2-a]pyrimidine derivatives were synthesized. The "in vitro" antibacterial activity of these compounds and their corresponding alpha-bromoketones against a variety of gram (+), gram (-) bacteria and Mycobacterium species is reported. Some of the prepared derivatives exhibited potent antimicrobial activity.