高效液相色谱法测定碳酸氢钠注射液中乙二胺四乙酸二钠

建立碳酸氢钠注射液中乙二胺四乙酸二钠的高效液相色谱测定方法。采用葡聚糖凝胶G-10色谱柱,以水为流动相,用高效液相色谱法测定碳酸氢钠注射液中乙二胺四乙酸二钠的含量。乙二胺四乙酸二钠的质量在0.1758~17.58μg的范围内与色谱峰面积线性关系良好,相关系数为0.9991,乙二胺四乙酸二钠的检出限为6.31μg/L。测定结果的相对标准偏差为0.89%(n=6),加标回收率为97.2%。该方法操作简单、准确、重现性好,可有效地控制碳酸氢钠注射液的质量。     

Chemoselective Esterification of Phenolic Acids in the Presence of Sodium Bicarbonate in Ionic Liquids

Chemoselective esterification of phenolic acids with dialkyl sulphates or alkyl halides in the presence of sodium bicarbonate in 1,3‐dialkylimidazolium ionic liquids is reported in excellent yields and less reaction time as compared to organic solvents.     

海藻酸钠-壳聚糖-桑椹红微囊的制备

以海藻酸钠-壳聚糖为复合囊材采用锐孔法制备桑椹红微囊,探讨了海藻酸钠浓度、壳聚糖浓度、Ca Cl2浓度、桑椹红浓度、针头孔径、下滴高度、温度、转速等因素对微囊包封率的影响。确定了最佳制备工艺条件为海藻酸钠浓度4.0%、壳聚糖浓度2.5%、氯化钙浓度2.0%、桑椹红浓度0.50%、针头孔径0.390mm、下滴高度4cm、温度为20℃、转速为300r·min-1。制得的微囊药物含量为11.28%,包封率为88.93%。     

Functionalization of chitosan polymer and their applications

The deacetylated derivative of chitin i.e. chitosan is an advantageous and interesting bioactive polymer. Despite its biodegradability, it consists of many reactive primary and secondary hydroxyl (–OH) and amino (–NH₂) functional groups which allow the possibilities of chemical modifications. The several chemical modifications such as alkylation, acylation, quaternization, phthaloylation, sulfation, thiolation, carboxymethylation, graft copolymerization etc. carried out. The chemical modification results various types of derivatives with modified properties for specific applications in varied area mainly of pharmaceutical, biomedical, biotechnological, cosmetic, agricultural, food and non-food industries as well as in water treatment, paper, and textile industry. The ability of chitosan to undergo versatile modifications and applications presents a great opportunity to scientific community and to industry.     

Tripolyphosphate-responsive release property of monoolein cubic phase containing sodium dodecyl sulfate and oligo chitosan

Tripolyphosphate (TPP)-responsive MO cubic phase was prepared by immobilizing oligo chitosan in the water channel through its electrostatic attraction with sodium dodecyl sulfate (SDS). The phase transition temperature (PTT) increased with increasing the content of SDS. The PTT of cubic phase whose SDS content was 0%, 0.21%, 0.42%, 0.84%, and 1.68%, determined by polarized microscopy, was about 69.5°C, 72°C, 75°C, 80.5°C, and 95°C, respectively. The PTT did not markedly deviate from that determined by differential scanning calorimetry. The release degree for 72 h of dye (i.e., amaranth and methylene blue) was dependent on the pH value of release medium (pH 3.0 and pH 7.0). Moreover, the release degree significantly increased when the TPP concentration in the release medium increased to 0.4% (w/v). Oligo chitosan was electrostatically complexed with TPP and the complexation took place extensively at the oligo chitosan/TTP mass ratio of 1:0.125 and 1:0.25 and at the oligo chitosan concentration of 1.6% (w/v), evidenced by optical spectroscopy and scanning electron microscopy. It was thought that the complexation was responsible for the TPP concentration-dependent release.     

异相法制备磺酸基取代壳聚糖衍生物

用3-氯-2-羟基丙磺酸钠与壳聚糖在较低温度下进行非均相反应制备了一系列取代度,结构新颖的改性壳聚糖.实验表明化学改性能极大的提高壳聚糖在水溶液中的溶解性能.研究了不同的反应条件对壳聚糖取代度的影响并用核磁共振表征了它们的结构.反应可在中性、较为温和的条件下进行,通过改变反应时间和反应物比例能有效的控制改性壳聚糖的取代度.改性后的壳聚糖能溶解于中性的水溶液中,浊度实验表明产物具有明显的两性聚电解质特征,其等电点约在pH=5.7.该方法为制备化学改性壳聚糖的一种有效的方法.     

Copper passivity and its breakdown in sodium bicarbonate solutions: A scanning electron microscopy and x-ray photoelectron and auger spectroscopy study

Effect of bicarbonate ions on the copper passivity and its local breakdown is studied by cyclic voltammetry, Auger spectroscopy, x-ray photoelectron spectroscopy, and scanning electron microscopy. Comparing data for solutions with various sodium bicarbonate concentrations shows copper to undergo pitting in 0.02 M NaHCO₃, whereas it remains stably passive in 0.10 M NaHCO₃. Independent studies suggest that carbonates play a protective role in stabilization of the oxide-hydroxide passive film on copper.     

Towards a bio-based industry: benign catalytic esterifications of succinic acid in the presence of water

The biorefinery of the future will need to integrate bioconversion and appropriate low environmental impact chemical technologies (Green Chemistry) so as to produce a wide range of products from biomass in an economically effective and environmentally acceptable manner. The challenge for chemists is to develop chemistry that works with fermentation-derived dilute, aqueous mixtures of oxygenated chemicals (platform molecules) rather than the petroleum-derived non-aqueous, non-oxygenated feedstocks we have been working with for 50+ years and to avoid energy intensive and wasteful concentration and purification steps. Here we show that a new family of tuneable mesoporous carbonaceous catalysts derived from starch can be used to accomplish efficient chemistry in aqueous solution. Our new aqueous catalytic chemistry relies on the ability to adjust the surface properties including the hydrophobicity-hydrophilicity balance of mesoporous Starbons by carbonisation at different temperatures (250-750 degrees C). Simple treatment of these materials with sulfuric acid then provides a series of porous solid acids that can function under a range of conditions including dilute aqueous solution. The reactions of succinic acid (platform molecule) in aqueous alcohol demonstrate the outstanding activities of these new catalysts.     

Effect of sodium bicarbonate and sodium chloride on protein conformation and gel properties of pork myofibrillar protein

To explore the potential of using sodium bicarbonate to take the place of sodium chloride, the changes in endogenous fluorescence, ultraviolet absorption spectrum, water holding capacity, gel properties and water distribution of pork myofibrillar protein were investigated. Because of the increase in pH and the exposure of more tryptophan and tyrosine residues with increasing sodium bicarbonate, the cooking yield and gel strength of pork myofibrillar protein significantly increased (P < 0.05), and centrifugal loss significantly decreased (P < 0.05). Meanwhile, the colour of the cooked pork myofibrillar protein was darker with increasing sodium bicarbonate, the bound water and immobile water were bound more tightly to the protein matrix, and the mobility of the water was lower, except for in the sample with 0.4 % sodium bicarbonate. Moreover, free water significantly increased (P < 0.05) when 0.4 % sodium bicarbonate was added, indicating that the mobility of the water was enhanced. Overall, the use of sodium bicarbonate could induce the protein conformation change, and improve the bond water content and texture properties of reduced-salt pork myofibrillar protein.     

A novel green biosorbent from chitosan modified by sodium phytate for copper (II) ion removal

A novel kind of adsorbent bead was prepared from chitosan (CS) by ionic‐linked with sodium phytate (SP) and then covalent cross‐linked with epichlorohydrin (ECH) by nonsolvent‐induced phase separation. The structure of the beads was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. The adsorption properties of the beads for Cu(II) ions under different adsorption conditions were investigated. The maximum adsorption capacity of Cu(II) ions was 177.1 mg g⁻¹ at the conditions of pH of 5.2, temperature of 50°C, and initial Cu(II) ion concentration of 728.3 mg L⁻¹. The adsorption isotherm of Cu(II) ions on the CS/SP/ECH beads was well correlated with the Langmuir isotherm model, and the whole adsorption process could be better followed the pseudo‐second‐order kinetic model. Moreover, the CS/SP/ECH beads still exhibited good adsorption capacity even after the 15th regeneration cycles.     

Regioselective synthesis and biological activity of oxidized chitosan derivatives

Oxidized chitosan derivatives with various degrees of oxidation (DS, 0.1–1.0) were prepared by the treatment of chitosan with CrO₃/aq HClO₄ or by the oxidation of ­3‐O‐ and N‐protected chitosan with 30% aq H₂O₂/Na₂WO₄ followed by 3‐O‐ and N‐deprotection. The oxidized products were then N‐acetylated with Ac₂O in order to improve their water‐solubility. Although the oxidized chitosan derivative of DS 0.28 and the degree of N‐acetylation of chitosan (DA) 38% was insoluble in the pH 3–8 region, that of DS 0.26 and DA 76% was soluble in the neutral pH range. The newly‐prepared acetylated and oxidized chitosan derivatives were found to suppress the chemiluminescence response of inflammatory cells such as canine polymorphonuclear cells (PMNs). Analysis by the surface plasmon resonance method revealed that the bind and release behavior of PMNs to acetylated oxidized chitosan derivatives was similar to that against carboxymethylated chitosan derivatives. The amount of water‐soluble chitosan derivative bound to cytokine IL‐8 was found to be affected by the structural and electronic features of the chitosan substituents in the chitosan chain. Copyright © 2003 John Wiley & Sons, Ltd.     

Facile preparation of monodisperse hollow cross‐linked chitosan microspheres

We have successfully prepared biocompatible and biodegradable hollow microspheres using carboxyl‐functionalized polystyrene particles as core template and the chitosan cross‐linked with glutaraldehyde as the shell. The monodisperse carboxyl‐functionalized polystyrene particles were made by emulsifier‐free emulsion polymerization. The structure, morphology, and constitution of the carboxyl‐functionalized polystyrene particles were characterized by FTIR, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X‐ray photoelectron spectroscopy (XPS). The structure, morphology, and formation process of the hollow cross‐linked chitosan microspheres were characterized by FTIR, SEM, and TEM. The results revealed that the latex particles were removed by exposed to solvent and the microspheres exhibited the hollow structure. This work confirmed that the hollow microspheres were accomplished by fabricating on the basis of chemical cross‐linking on the surface of the carboxyl‐functionalized polystyrene particles and then removing off the cores of particles. Moreover, with the increase of carboxyl‐functionalization degree at the surface of latexes and the increase of cross‐linking period, the thicker and firmer monodisperse hollow microspheres were obtained. In addition, a water‐soluble drug, salicylic acid, encapsulated in the microcapsules slowly released at pH 1.2. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 228–237, 2008     

Study of the solid-state hydrolysis of chitosan in presence of HCl

Chemical depolymerization of chitosan was obtained in the solid state by means of gaseous HCl. This new method allowed us to simultaneously form the hydrochloric salt and saturate the hydration water with acid. The depolymerization was carried out by keeping the product at a given temperature for the desired time. The measurements of the molecular weight distributions demonstrated the ability to control the reaction and produce oligomers with chosen dimensions. This solid-state hydrolysis favors the presence of a four-fold distribution that can be related to the original morphology and crystallinity of the initial material. The effects of the hydrolysis on the crystallinity, the crystalline structure, and the supramolecular order of the obtained chitosans were also studied. Finally, the washing of the hydrolyzed products in concentrated alkaline or acidic media allowed us to eliminate the lowest DPs and thus to narrow the molecular weight distribution. In this case, the crystallinity was also increased up to values beyond 70%. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3181–3191, 1997     

Esterification activity and stability of Candida rugosa lipase immobilized into chitosan

Microbial lipase from Candida rugosa immobilized into porous chitosan beads was tested for esterification selectivity with butanol and different organic acids (C2–C12), and butyric acid and different aliphatic alcohols (C2–C10). After 24 h, the acids tested achieved conversions of about 40–45%. Acetic acid was the only exception, and in this case butanol was not consumed. Different alcohols led to butyric acid conversions >40%, except for ethanol, in which case butyric acid was converted only 26%. The system’s butanol and butyric acid were selected for a detailed study by employing an experimental design. The influence of temperature, initial catalyst concentration, and acid:alcohol molar ratio on the formation of butyl butyrate was simultaneously investigated, employing a 2³ full factorial design. The range studied was 37–50°C for temperature (X₁), 1.25–2.5% (w/v) for the catalyst concentration (X₂), and 1 and 2 for the acid:alcohol molar ratio (X₃). Catalyst concentration (X₂) was found to be the most significant factor and its influence was positive. Maximum ester yield (83%) could be obtained when working at the lowest level for temperature (37°C), highest level for lipase concentration (2.5% [w/v]), and center level of acid:alcohol molar ratio (1.5). The immobilized lipase was also used repeatedly in batch esterification reactions of butanol with butyric acid, revealing a half-life of 86 h.     

均匀共沉淀-水热法制备纤维状羟基磷酸钙/壳聚糖复合粉体

以尿素沉淀剂，运用溶液均匀共沉淀法制得纤维状羟基磷灰石(HAP)和无定形颗粒状守壳聚糖(CS)的复合粉体，通过水势处理调整纤维状HAP晶粒尺寸的大小，对粉体进行了XRD、TEM、IR及化学组成(Ca／P)表征。均匀一水热共沉淀过程中，pH值对粉体Ca／P、XRD、TEM、IR有很大影响。     

钾霞石固体碱催化豆油酯化反应制备生物柴油

采用共沉淀法制备了钾霞石,用于催化豆油和甲醇酯化反应,在煅烧温度1 200℃,得到单一的钾霞石物相.钾霞石表面多孔,孔径分布为0.2到1.0 μm,有利于反应物分子的内扩散和接触活性位;同时对反应温度、反应时间、催化剂用量以及催化剂Li含量进行了系统研究.反应温度120 ℃,醇油摩尔比12:1,反应时间2 min,催化...     

Plasma surface modification of chitosan membranes: characterization and preliminary cell response studies

Surface modification of biomaterials is a way to tailor cell responses whilst retaining the bulk properties. In this work, chitosan membranes were prepared by solvent casting and treated with nitrogen or argon plasma at 20 W for 10-40 min. AFM indicated an increase in the surface roughness as a result of the ongoing etching process. XPS and contact angle measurements showed different surface elemental compositions and higher surface free energy. The MTS test and direct contact assays with an L929 fibroblast cell line indicated that the plasma treatment improved the cell adhesion and proliferation. Overall, the results demonstrated that such plasma treatments could significantly improve the biocompatibility of chitosan membranes and thus improve their potential in wound dressings and tissue engineering applications.     

Solvent-Free Esterification of Carboxylic Acids and Alcohols in the Presence of Silphos [PCl3-n(SiO2)n] as a Heterogeneous Phosphine Reagent

An efficient solvent-free method for the preparation of esters from various aromatic and aliphatic acids with primary, secondary, and tertiary alcohols using a heterogeneous phosphine reagent, silphos [PCl_3-n(SiO₂)_n], in good yields is reported.     

Enhanced radiation crosslinking of carboxymethylated chitosan in the presence of acids or polyfunctional monomers

Carboxymethylated chitosan (CMCt) hydrogels were synthesized by γ-ray radiation-induced crosslinking in the presence of acids or polyfunctional monomers. Compared with that of CMCt hydrogels synthesized without additives, the gel fraction was improved and the gelation dose was decreased obviously after incorporating acids or polyfunctional monomers into CMCt hydrogels. The diffusion behavior of water in the CMCt gels prepared at different conditions was Fickian diffusion, and the swelling of the CMCt gels displayed characteristic pH sensitivity, which was analyzed by fluorescence molecular probes. Preliminary mechanism of radiation-induced crosslinking of CMCt in the presence of acids or polyfunctional monomers was discussed based on the FTIR and sol-gel analysis. Furthermore, it was found that CMCt hydrogels were hydrodegradable with high temperature (>60 °C), and incorporating polyfunctional monomers into the CMCt hydrogels also could improve the thermal stability of the CMCt hydrogels obviously.