Hierarchical self-assembly of 3D amphiphilic discrete organoplatinum(Ⅱ)metallacage in water

Here we described the design and synthesis of a discrete 3D amphiphilic metallacage 4,in which the tetragonal prismatic frameworks act as the hydrophobic cores and the poly(ethylene glycol)(PEG)chains as the hydrophilic tails.The structure of 4 was characterized by 1H NMR,31P NMR and electrospray ionization time-of-flight mass spectrometry(ESI-TOF-MS).Notably,4 with its Iong PEG tails was subsequently ordered into micelles at a low concentration(1.20×10^-6 mol/L)in water.As the concentration and cultivation time increased,the micelles can further self-assembly into nanofibers and nanoribbons.Considering the dynamic property of the coordination bond,these structures show reversible transformation under external stimuli.     

胶束增强型聚电解质微胶囊的制备

采用杂化碳酸钙微球作为模板, 利用LbL技术, 选择聚苯乙烯磺酸钠(PSS), 烯丙基胺的盐酸盐(PAH)和二烯丙基二甲基胺盐酸盐(PADA)聚电解质, 分别组装了PAH/PSS(弱/强)聚电解质胶囊和PADA/PSS(强/强)聚电解质微胶囊. 除去模板后得到了球形良好、分散均匀的聚电解质微胶囊. 研究结果表明, 利用杂化碳酸钙微球作为聚电解质微胶囊的模板, 得到的微胶囊的囊壁厚而致密, 同时, 由于组装采用的聚电解质的种类不同, 囊壁的微观形貌有较大差异.     

Analytical applications of organized assemblies for on-line spectrometric determinations: present and future

An amphiphile (surfactant) spread on water can lead to the formation of different aggregates: vesicles, miscelles, emulsions or microemulsions; depending on its concentration; its molecular structure and/or the experimental conditions. Such aggregates, (a) may concentrate products, reactants or analytes and so improve the analytical sensitivity and (b) may solubilize such substances and so favorably change the analytical selectivity. Bilayer membrane vesicles for instance, apart from their wide applications in cosmetic and pharmaceutical industries, have a great analytical potential due to their ability to (i) reversibly sequester metal ions avoiding matrix interference and (ii) improve cold vapor (Hg and Cd) and hydride (As, Se, Pb) chemical generation. Micellar solutions have also found wide applications in different areas of analytical chemistry, showing their capacity to concentrate and separate a significant variety of analytes. Among the numerous micelle-based separation techniques, cloud point extraction offers an excellent enrichment factor for metal ions, allowing their quantification at microgram/litre levels. Also agitating a mixture of water, oil and one or more surfactants under controlled experimental conditions, a cloudy mixture (emulsion) or a transparent solution (microemulsion) can be formed. Adequate formulation is necessary in order to obtain a stable organized media. To fulfill this requirement, a major effort is necessary in order to shorten the gap between the current knowledge on this topic and the promising field of applications that await development. Recent publications show that self-assembly structures from highly viscous samples can be accomplished on-line with the advantages of drastically reducing the time of analysis and assuring the absolute control over the stability of the aggregate. Flow systems allow effective mixing of samples with added surfactant and provide continuous pumping of the resulting mixture to sensitive detectors for the on-line determination of different analytes in complex samples.     

Pressure-induced structural transition of nonionic micelles

We report dynamic light scattering and small angle neutron scattering studies of the pressure-induced structural transition of nonionic micelles of surfactant polyoxyethylene 10 lauryl ether (C12E10) in the pressure range 0 to 2000 bar. Measurements have been performed on 1 wt% C12E10 in aqueous solution with and without the addition of KF. Micelles undergo sphere to lamellar structural transitions as the pressure is increased. On addition of KF, rod-like micelles exist at ambient pressure, which results in rod-like to lamellar structural transition at a much lower pressure in the presence of KF. Micellar structural transitions have been observed to be reversible.      

Exploring anionic emission of 2-benzoyl benzimidazole in micellar environments

In this paper, an interesting transformation of the emission of anionic conformer of 2-benzoyl bezimidazole in ionic and non-ionic micelles is reported. Deprotonation is hindered in cationic and non-ionic micelles owing to probe molecule's passage deep inside positive ion-rich Stern-layer in contrast with anionic micelle. The orientation of probe molecule in the two ionic micelles, as determined from the spectral properties is opposite in nature. Micellar environment shields the formation of mono- and di-cationic species at very low pH. Three decay times of the probe in different time domains were attributed to three possible anionic species and they are modified differently in ionic and neutral micelles. Quantum chemical calculations also predict the existence of three different possible anionic species.     

Synthesis of a novel amphiphilic GdPCTA-[12] derivative as a potential micellar MRI contrast agent

A novel amphiphilic contrast agent, a GdPCTA-[12] derivative containing a dodecyl chain as lipophilic moiety, has been prepared. A convergent synthetic route from commercially available diethylene triamine and 3-hydroxypyridine is described. The target amphiphilic gadolinium complex was obtained in nine steps in 22% overall yield. Physicochemical properties and relaxivity measurements of this new contrast agent are described.     

Micellization of a cationic gemini surfactant in aqueous solutions with different alkanols and alkanediols as additives: Effect of nonpolar chain and position of hydroxyl groups

The gemini surfactant N-N′bis(dimethyldodecyl)-1,4-butanediammonium dibromide (12-4-12) was synthesized and its critical micelle concentrations (CMCs) and degree of counterion dissociation (α) in aqueous solutions in the presence of alkanols viz ethanol, isomeric butyl alcohols, 1-hexanol and alkanediols (ethanediol, 1,4-butanediol, 1,2-hexanediol, 2,5-hexanediol 1,6-hexanediol, and 1,8-octanediol) determined from electrical conductivity are reported. While ethanol, ethanediol, 1,4-butanediol showed an increase in CMC, a decrease was seen for isomeric butyl alcohols, 1-hexanol, isomeric hexanediols and 1,8-octanediol. For butyl alcohols the CMC decrease showed the trend 1° >2° > 3°; in C₆ diols, 1,2-hexanediol exerted more decrease as compared to 2,5-hexanediol and 1,6-hexanediol.The results are explained on the basis of the structure and hydrophobicity of alcohols that determine their effect as cosolvent or cosurfactant (partitioning in micelles). Two-dimensional nuclear overhauser enhancement spectroscopy (2D-NOESY) was used to examine the location for 1-butanol and 1,4-butanediol in micellar systems as representative additives from alkanols and alkanediols showing CMC decreasing and increasing effect respectively.     

The research and preparation of a novel nano biodegradable polymer external reinforcement

The use of current drug-loaded vascular scaffolds is limited in sustained drug release and stability studies in clinical and preclinical trials. We found that poly(l-glutamic acid)-b-poly(propylene oxide)-b-poly(l-glutamic acid) (PLGA-b-PPO-b-PLGA) triblock copolymers can deliver multiple poorly water-soluble drugs (e.g., Paclitaxel) at clinically relevant doses. In this study, we synthesized a new drug-loaded vascular external graft with electrospun nanofibrous scaffolds [poly(l-lactide-co-?-caprolactone) (PLCL):fibrinogen; 2:1 (w/w)] and drug-loaded PLGA-b-PPO-b-PLGA micelles. Cell proliferation and viability assay results showed that beagle smooth muscle cells grew well on the surface of vascular graft-coated micelles at a percentages of 10% (w/w) GPG:PLCL-fibrinogen. This study demonstrates that micelle-coated electrospun PLCL-fibrinogen vascular scaffolds have potential applications in vascular tissue engineering.     

Use of Micelles in the TLC Separation of Polynuclear Aromatic Compounds and Amino Acids

Abstract

The polynuclear aromatic compounds (PNA): anthracene, napthalene, phenanthrene, pyrene, pyrenecarboxaldehyde, benzo (a) pyrene, benzo (e) pyrene, perylene and fluorene can be chromatographed on polyamide TLC sheets using an aqueous micellar solution cf sodium dodecylsulfate (SDS) as the mobile phase. Reversed micellar solutions (of sodium dioctylsulfosuccinate) were used in a reverse phase chromatographic separation of amino acids. Some amino acids tended to streak slightly rather than move as discrete spots. Conditions could be adjusted, however, so that most of the amino acids and all PNA's would move as spots.     

Self-assembled micelles based on hydrophobically modified quaternized cellulose for drug delivery

Novel amphiphilic cationic cellulose (HMQC) derivatives carrying long chain alkyl groups as hydrophobic moieties and quaternary ammonium groups as hydrophilic moieties were synthesized. Structure and properties of the amphiphilic cellulose derivatives were characterized by elemental analysis, FT-IR, (1)H NMR, ζ-potential measurement, dynamic light scattering (DLS), fluorescence spectroscopy and transmission electron microscopy (TEM). The results revealed that HMQCs can be self-assembled into cationic micelles in distilled water with the average hydrodynamic radius of 320-430 nm. The cytotoxicity study showed that the HMQC exhibited low cytotoxicity. Prednisone acetate, a water insoluble anti-inflammation drug, was chosen as a model drug to investigate the utilization of self-assembled HMQC micelles as a delivery carrier for poorly water-soluble drugs. The study indicated that the prednisone acetate could be incorporated effectively in the self-assembled HMQC micelles and be controlled released.