Direct synthesis of highly reactive polyisobutylenes via cationic polymerization of isobutylene co‐initiated with TiCl4 in nonpolar hydrocarbon media

Living cationic polymerization of isobutylene (IB) with 1‐chlorine‐2,4,4‐trimethyl pentane (TMPCl)/TiCl₄/isopropanol (iPrOH) or isoamylol (iAmOH) has been achieved in the presence of 2,6‐di‐tert‐butylpyridine (DtBP) at ?80°C. Polyisobutylenes with nearly theoretical M_n based on TMPCl molecules and more than 90% of tert‐chlorine‐end groups could be obtained at high [TMPCl]. The β‐proton elimination from ? CH₃ in growing chain ends increased with increasing polymerization temperature and decreasing solvent polarity. A chain‐transfer‐dominated cationic polymerization process with H₂O/TiCl₄/iAmOH could be achieved in n‐hexane at ?30°C. The monomer conversion and content of exo‐olefin end groups increased while molecular weight decreased with increasing [iAmOH]. To the best of our knowledge, this is the first example to achieve the direct synthesis of highly reactive polyisobutylene with low M_n of 1200～1600, carrying more than 80% of exo‐olefin terminals by a single‐step process via cationic polymerization co‐initiated by TiCl₄ in nonpolar hydrocarbon. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42232.     

阳离子明胶蛋白助剂在涤纶碱减量中的应用研究

将自制的阳离子明胶蛋白助剂应用于涤纶碱减量处理工艺中,探讨阳离子明胶蛋白助剂对涤纶减量率的影响以及对涤纶吸湿性的影响,同时与促进剂1227的作用效果进行比较,评价阳离子明胶蛋白助剂的处理效果。结果表明:阳离子明胶蛋白助剂对涤纶碱减量有一定促进作用,同时对涤纶有一定改性作用,能进一步改善碱减量涤纶织物的服用性能。虽然阳离子明胶蛋白助剂对涤纶碱减量的促进效果低于促进剂1227,但其对改善涤纶吸湿性、透气性、抗静电性和白度效果优于1227。     

阳离子瓜儿胶季铵盐的制备及应用

通过对阳离子瓜尔胶的制备方法、影响因素及其在洗发香波中应用的研究,得到有机溶剂法制备阳离子瓜尔胶的最佳工艺条件如下:以异丙醇作溶剂,瓜尔胶用量10g,CTA用量2.5g,氢氧化钠用量0.8g,在80℃下,持续反应9h,所得阳离子瓜尔胶的取代度为0.075,反应效率为73%。1.0%的阳离子瓜尔胶可以使洗发香波的粘度由1650mPa·s增至8150mPa·s,洗发后使毛发显著变得柔软光滑。     

Reduction‐Sensitive Dextran Nanogels Aimed for Intracellular Delivery of Antigens

Targeting of antigens to dendritic cells (DCs) to induce strong cellular immune response can be established by loading in a nano‐sized carrier and keeping the antigen associated with the particles until they are internalized by DCs. In the present study, a model antigen (ovalbumin, OVA) is immobilized in cationic dextran nanogels via disulfide bonds. These bonds are stable in the extracellular environment but are reduced in the cytosol of DCs due to the presence of glutathione. Reversible immobilization of OVA in the nanogels is demonstrated by the fact that hardly any release of the protein occurred at pH 7 in the absence of glutathione, whereas rapid release of OVA occurs once the nanogels are incubated in buffer with glutathione. Furthermore, these OVA conjugated nanogels show intracellular release of the antigen in DCs and boost the MHC class I antigen presentation, demonstrating the feasibility of this concept for the aimed intracellular antigen delivery.     

Preparation and evaluation of Baicalin-loaded cationic solid lipid nanoparticles conjugated with OX26 for improved delivery across the BBB

Purpose: A novel brain targeting drug delivery system based on OX26 antibody conjugation on PEGylated cationic solid lipid nanoparticles (OX26-PEG-CSLN) was prepared.

Methods: The Baicalin-loaded PEGylated cationic solid lipid nanoparticles modified by OX26 antibody (OX26-PEG-CSLN) were prepared by emulsion evaporation–solidification at low temperature method. The immune-gold labeled OX26-PEG-CSLN was visualized by transmission electron microscopy. The mean diameter and zeta potential of OX26-PEG-CSLN, PEG-CSLN and CSLN were determined using a Zetasizer. The entrapment efficiency of OX26-PEG-CSLN, PEG-CSLN and CSLN was determined by ultrafiltration centrifugation method. And the solid-state characterization of OX26-PEG-CSLN and CSLN were analyzed by X-ray. Pharmacokinetics studies were conducted by in vivo microdialysis in rat cerebrospinal fluid.

Results: The results showed that the OX26-PEG-CSLN, PEG-CSLN and CSLN had average diameters of 47.68?±?1.65, 27.20?±?1.70 and 33.89?±?5.74?nm, Zeta potentials of ?0.533?±?0.115?mV, 11.200?±?0.500?mV and 11.080?±?1.170?mV and entrapment efficiencies of 83.03?±?0.01%, 92.90?±?3.50% and 97.83?±?0.19%, respectively. In the pharmacokinetics studies, the AUC value of OX26-PEG-CSLN was11.08-fold higher than that of the Baicalin solution (SOL) (p?p?>?0.05); the C_max value of OX26-PEG-CSLN was 7.88-fold higher than that of SOL (p?p?Conclusion: These results demonstrated OX26-PEG-CSLN could be a promising carrier to deliver drugs across the BBB for the treatment of brain diseases.     

Double-Headed Cationic Lipopeptides: An Emerging Class of Antimicrobials

Antimicrobial peptides (AMPs) constitute a promising tool in the development of novel therapeutic agents useful in a wide range of bacterial and fungal infections. Among the modifications improving pharmacokinetic and pharmacodynamic characteristics of natural AMPs, an important role is played by lipidation. This study focuses on the newly designed and synthesized lipopeptides containing multiple Lys residues or their shorter homologues with palmitic acid (C₁₆) attached to the side chain of a residue located in the center of the peptide sequence. The approach resulted in the development of lipopeptides representing a model of surfactants with two polar headgroups. The aim of this study is to explain how variations in the length of the peptide chain or the hydrocarbon side chain of an amino acid residue modified with C₁₆, affect biological functions of lipopeptides, their self-assembling propensity, and their mode of action.     

Selective separation and characterisation of dual ACE and DPP-IV inhibitory peptides from rainbow trout (Oncorhynchus mykiss) protein hydrolysates

Microwave pretreatment and hydrolysis were applied to rainbow trout (Oncorhynchus mykiss) by-products to produce bioactive peptides with dual in vitro angiotensin-I converting enzyme (ACE) and dipeptidyl-peptidase IV (DPP-IV) inhibitory activities. Peptides were fractionated using the single step electrodialysis with ultrafiltration membrane (EDUF). Concentration of cationic peptides (CP) increased in the recovery solution, reaching 125 μg mL⁻¹ after a 4-h treatment with migration rate of 15.68 ± 2.98 g m⁻² h. CP fractions displayed ACE and DPP-IV I inhibitory properties, with IC₅₀ values of 0.0036 mg mL⁻¹ and 1.23 mg mL⁻¹ respectively. The bioactivity was attributed to the low molecular weight peptides (300–500 Da) recovered. CP exhibited non-competitive inhibition patterns for ACE and DPP-IV, which were dose dependent. These results showed that bioactive peptides can successfully be separated from complex hydrolysate mixtures by EDUF. The fractionated peptides can serve as potential functional food ingredients or nutraceuticals for the management of hypertension and diabetes.     

Synthesis and properties of bromide‐ functionalized poly(isobutylene‐co‐p‐ methylstyrene) random copolymer

Poly(isobutylene‐co‐p‐methylstyrene) (IB/p‐MS) random copolymer is a new generation of polyisobutylene‐based elastomers. The cationic copolymerization of IB with p‐MS was thoroughly examined by using 2‐chloro‐2,4,4‐trimethylpentane/ethylaluminiumsesquichloride/electron donor as initiating system. IB/p‐MS random copolymers with high molecular weight were obtained at elevated temperature through the addition of ethyl acetate; the reaction proceeded in a mildly exothermic manner. Although the reactivity ratios of comonomer pairs differ by close to an order of magnitude, p‐MS was uniformly distributed in the chains. IB/p‐MS random copolymer can be brominated by adding molecular bromine into the copolymer solution, thereby yielding a completely saturated polymer backbone with a chemically reactive site. The types and selection of appropriate vulcanization systems for bromide‐functionalized IB/p‐MS random copolymers are also discussed. © 2016 Society of Chemical Industry     

疏水缔合型阳离子聚丙烯酰胺的合成及絮凝性能

以甲基丙烯酸三氟乙酯(TFEMA)为疏水单体、丙烯酰胺(AM)为主单体、甲基丙烯酰氧乙基三甲基氯化铵(DMC)为阳离子单体,以过硫酸铵和亚硫酸氢钠为复合引发剂,采用自由基胶束聚合法合成了共聚物P(AM-DMC-TFEMA)。分别考察了反应温度、引发剂用量、单体总质量分数及反应时间对P(AM-DMC-TFEMA)的产率及阳离子度的影响。确定较佳工艺条件为:反应温度65℃,引发剂用量占单体总质量的2%,单体总质量分数26%,反应时间3 h。采用红外光谱(FT-IR)、核磁共振氢谱(~1H NMR)和环境扫描电镜(ESEM)对其结构进行了表征。同时考察了P(AM-DMCTFEMA)对硅藻土悬浮液的絮凝效果,结果表明,其对硅藻土具有良好的絮凝效果,絮凝时间仅为20 s,合成的共聚物上清液透过率为97.31%。