Studies on the interactions between bovine β-lactoglobulin and chitosan at the solid-liquid interface

Chitosan ultrathin films have been formed on polycrystalline Au substrates using the LbL technique with the purpose of studying its interaction with bovine β-lactoglobulin (β-LG) at the solid-liquid interface. The immobilization of chitosan was followed by Quartz Crystal Microbalance with energy dissipation (QCM-D), Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). The behavior of the chitosan films in the presence of β-LG solutions with different bulk concentrations ([β-LG]), ionic strength (I), and pH has been investigated using the same techniques plus Atomic Force Microscopy (AFM). The results showed that for pHs lower than protein's pI, weak intermolecular forces (H bonding, Van der Waals, hydrophobic, etc.) are established between β-LG and chitosan (especially close to the pI) leading to low coverage nonspecific adsorption. On the contrary when pH > pI, strong ionic bonding through attractive electrostatic interactions lead to high coverage adsorbed phases composed of large β-LG aggregates. The adsorption process was shown to consist of a relatively fast step (in which these interactions are predominant) which is followed, once the β-LG monolayer is exceeded, by the slow formation of thicker and increasingly viscoelastic films through β-LG self-aggregation. QCM-D and AFM experiments unveiled the role of [β-LG] and I on the formation of these aggregates. The adsorption isotherm built from impedance data in the medium-low [β-LG] range (0.001-0.3 mg mL⁻¹), showed good fitting to the Langmuir model confirming that the formation of one β-LG monolayer is achieved in this concentration range.     

Core-shell structured nanoassemblies based on β-cyclodextrin containing block copolymer and poly(β-benzyl L-aspartate) via host-guest complexation

Double hydrophilic copolymers (PEG-b-PCDs) with one PEG block and another block containing β-cyclodextrin (β-CD) units were synthesized by macromolecular substitution reaction. Via a dialysis procedure, complex assemblies with a core-shell structure were prepared using PEG-b-PCDs in the presence of a hydrophobic homopolymer poly(β-benzyl l-aspartate) (PBLA). The hydrophobic PBLA resided preferably in the cores of assemblies, while the extending PEG chains acted as the outer shell. Host-guest interaction between β-CD and hydrophobic benzyl group was found to mediate the formation of the assemblies, where PEG-b-PCD and PBLA served as the host and guest macromolecules, respectively. The particle size of the assemblies could be modulated by the composition of the host PEG-b-PCD copolymer. The molecular weight of the guest polymer also had a significant effect on the size of the assemblies. The assemblies prepared from the host and guest polymer pair were stable during a long-term storage. These assemblies could also be successfully reconstituted after freeze-drying. The assemblies may therefore be used as novel nanocarriers for the delivery of hydrophobic drugs.     

N,N′-二硫双(N-苄基-β-丙氨酸)二乙酯的合成

介绍了以苄胺、丙烯酸乙酯、一氯化硫等为原料合成新型杀虫剂棉铃威的重要中间体N ,N′ 二硫双 (N 苄基 β 丙氨酸 )二乙酯的方法 ,研究了溶剂种类、投料比、反应时间、反应温度对收率的影响 ,确定了较佳的合成条件 ,以丙烯酸乙酯计收率达 90 3%。     

Carbon nanotube–polyaniline composites

The last decade has seen a growing interest in hybrid electrically conducting nanocomposites. This article aims to provide a detailed overview of the present status of research in carbon nanotube–polyaniline (CNT/PANI) composites, from processing to structural and property evaluations. CNT/PANI are synthesized by electrochemical and chemical processing. When chemical methods are used, the main challenge is to obtain processable CNT/PANI in the emeraldine salt (ES) form composites. Stable dispersions of ES–CNT in organic media are prepared using the post doping method, inverse emulsion polymerization, or ex situ polymerizations. On the contrary, stable water dispersions of CNT/ES are prepared using hydrophilization of a preformed CNT/ES composite, direct synthesis of micelle–CNT hybrid templates, interfacial polymerization, covalent functionalization of CNT with a water soluble polymer, or using electrostatic interactions between two oppositely charged ES and CNT aqueous colloids. Moreover, the strategies for the synthesis of ternary CNT/PANI composites incorporating noble metal nanoparticles, metal oxide, or graphene sheets are also presented and analyzed in depth. Finally, we give a review of potential applications, including chemical sensors, capacitors, fuel cells and electronic devices.     

Activated PPARβ/δ Protects Pancreatic β Cells in Type 2 Diabetic Goto–Kakizaki Rats from Lipoapoptosis via GPR40

GW501516-activated peroxisome proliferator-activated receptor (PPAR) β/δ and G-protein-coupled receptor (GPR) 40 were shown to protect pancreatic β cells against lipoapoptosis. Therefore, this study aimed to investigate whether activated PPARβ/δ could protect type 2 diabetic rats from lipoapoptosis through regulation of GPR40 and to compare the protective effects of activated PPARβ/δ and PPARγ. We made an animal model of type 2 diabetic lipoapoptosis by feeding spontaneously type 2 diabetic Goto–Kakizaki (GK) rats with a high-fat diet (HFD) to evaluate the effects of PPARβ/δ on islet β cell apoptosis. And, treated INS-1 cells with 0.5 mM palmitate (PAM) in the absence/presence of GW501516 (a specific agonist of PPAR β/δ) and with/without transfection of GPR40 siRNA to explore the underlying molecular mechanism. HFD aggravated GK rats' poorer INSR30, lower mass, greater apoptosis of β cells, lower mass, and lower expression of GPR40, which were similarly improved by GW501516 at 3 or 6 mg/kg day and pioglitazone. Compared with pioglitazone, GW501516 caused more weight loss and had no effect on insulin resistance. GW501516 protected INS-1 cells from PAM-induced apoptosis by upregulating GPR40 and activating Akt/Bcl-2/caspase-3. Activated extracellular regulated protein kinases (ERK) was relevant to the lipoapoptosis in INS-1 cells, but was not involved in the antilipoapoptotic effect of GW501516. These results showed that the PPARβ/δ agonist GW501516 protected β cells from lipoapoptosis and improved β cell mass by upregulating GPR40 and activating the Akt/Bcl-2/caspase-3 pathway, but not the ERK-signaling pathway.     

β-取代卟啉及卟啉锰对氧化破坏的稳定性

在假一级条件下,以亚碘酰苯为氧化剂,通过测定β-未取代的四苯基卟啉(TPP),以及不同β-取代的β-Cl8TPP、β-Br8TPP、β-Br4TPP、β-NO2TPP、β-(CH3)8TPP及其金属锰配合物的氧化破坏反应的表观动力学常数,获得了卟啉配体的稳定性顺序为TPP>β-(CH3)8TPP>β-Br8TPP>β-Cl8TPP>β-Br4TPP>β-NO2TPP,β位位阻越大相应的卟啉配体越稳定,并由此推导PhIO由β位进攻卟啉配体。β-取代锰卟啉的稳定性顺序为:Mn(β-Cl8TPP)Cl>Mn(β-Br8TPP)Cl>Mn(β-Br4TPP)Cl>Mn(β-NO2TPP)Cl>Mn(TPP)Cl>Mn[β-(CH3)8TPP]Cl,并与在催化氧化环己烷反应中的稳定性一致,β位吸电子作用越大相应的锰卟啉越稳定,并推导由氧化能力更强的高价金属-氧中间体以位阻较小的面对面方式进攻β-取代锰卟啉。     

四氯化锡催化合成β-萘甲醚

四氯化锡催化下,β 萘酚与无水甲醇反应合成β 萘甲醚,考察了甲醇用量、催化剂用量、反应时间等对产率的影响。当β 萘酚取1.8g,甲醇1.5mL,SnCl4·5H2O取0.33g时,80℃反应10h,β 萘甲醚产率可达75.3%。     

改性β环糊精絮凝剂的制备及性能研究

以环氧氯丙烷（EPI）为交联剂,在碱性介质中合成了β-环糊精（-βCD）水溶性交联聚合物,并以其为基体,以硝酸铈铵（CAN）为引发剂,在弱酸性条件下,合成出了新型的水溶性交联-βCD接枝聚丙烯酰胺（PAM）的共聚物絮凝剂（WCDP）.对产物的红外光谱分析（FTIR）表明WCDP的合成是成功的.研究了WCDP的制备条件（交联剂用量、引发剂用量、温度、时间等）对吸附有机污染物和除浊性能的影响,结果表明：在最佳合成条件下,WCDP能同时去除水中的浊度和小分子有机污染物,并能形成絮体从水中分离.以高岭土和对硝基苯酚（p-NP）为研究对象,WCDP对浊度和p-NP的去除率分别为96.7%和60.6%.     

HPLC手性流动相添加剂法拆分巴氯芬对映体

建立了以羧甲基-β-环糊精为手性流动相添加剂,在反相液谱条件下拆分巴氯芬对映体的方法。研究了手性添加剂的种类及浓度、流动相组成、pH值及流速等尉崇对拆分的影响。流动千H为甲醇、乙腈、水,体积比为90：5：5,其中含2．00g／LCM-β-CD,pH值5．95,流速0．60mL／min,检测波长231nm,分离度为1．31。该方法简便、快速、相对偏差小。     

不同时间尺度的慢变量引起的簇放电研究

本文基于两个重要的慢负反馈机制给出了一个组合型的胰腺β-细胞模型.在这个模型中,不同簇放电模式对快、中、慢的振荡周期具有鲁棒性,这样可以通过快振荡周期簇放电模式的快慢动力学分析得到所有簇放电的动力学机理和拓扑类型.对于快振荡周期的簇放电,较慢的慢变量α几乎为常数,较快的慢变量Cer对快子系统没有影响,因此只要考虑慢变量...