Co-delivery of docetaxel and doxorubicin using biodegradable PEG-PLA micelles for treatment of breast cancer with synergistic anti-tumour effects

Poly(ethylene glycol)-poly(lactic acid) copolymer, prepared by ring opening polymerization, was used as a single platform to co-deliver both hydrophilic doxorubicin and hydrophobic docetaxel (DTX) in a simulated physiological environment. The average size of the negatively charged drug loaded polymeric micelles were found to be 293 nm. The drug loading (%) and encapsulation efficiency (%) were calculated to be 1.21 and 59.0, respectively. The in vitro cytotoxicity test using MCF7 breast cancer cells was conducted using 1 × 10⁴ cells in 10% FBS and 1% antibiotic, and the absorbance of formazan was evaluated at 570 nm. Cell growth inhibition by MTT assay showed viability of 33% of the MCF7 cells after treatment with drug-loaded micelles for 48 h. Controlled release of drugs from the polymeric micelles indicated a burst release effect initially; whereas, 98% of drug could be released at pH 7.4 within a time period of 96 h. Time period for drug release shorten to 48 h only in simulated mild acidic pH (5.4) condition. The in vitro drug release study from micelles indicated synergistic cytotoxicity effect in human metastatic breast cancer MCF7 cell.     

Self-assembly of synthetic glycolipid/water systems

Glycolipids (amphiphiles that bear oligosaccharides as their hydrophilic headgroups) are of importance both scientifically and technically. This review describes recent advances in our understanding of the molecular correlations in phase behavior in aqueous glycolipids over the past several years. In the first part, we discuss how headgroup stereochemistry affects the phase behavior of glycolipids both in two- and three-dimensional systems. In the second part, we discuss the effects of alkyl chain structure and phase behavior of phytanyl-chained glycolipid/water systems. The physical properties of glycolipid/water systems depend strongly on the inter-headgroup interactions that are related to such factors as stereochemistry (conformation) and size of headgroups, type of sugar residues involved, alkyl chain structure, etc. Thus, apart from the conventional concept like ‘hydrophilic/lipophilic balance', explicit accounts of headgroup interactions are crucial to control the particular glycolipid/water system concerned. This is in marked contrast to the conventional amphiphile/water systems where the inter-headgroup interactions are in most cases simply repulsive.     

Cascade reaction-based fluorescent probe for detection of H2S with the assistance of CTAB micelles

We report a turn-on fluorescent probe for H₂S through a cascade reaction using a new trap group 4-(bromomethyl)benzoate, based on excited-state intramolecular proton transfer (ESIPT) sensing mechanism. The probe showed good selectivity and high sensitivity towards H₂S and it was capable of detecting and imaging H₂S in living HeLa cells, indicating its potential biological applications.     

双重敏感的磺酸甜菜碱-姜黄素药物载体的合成和表征

合成了聚姜黄素-二硫键-聚甲基丙烯酸二乙胺基乙酯-聚磺酸甜菜碱(Cur-DA-ss-PDEA-PS,或简写为Cur-ss-PDEA-PS),采用核磁、红外对聚合物结构进行了表征,用示差扫描量热法测试了聚合物热性能.用溶剂挥发法制备聚合物胶束,形成了聚磺酸甜菜碱为亲水壳层、聚姜黄素为疏水核、二硫键作为还原敏感基团和聚甲基丙烯酸二乙氨基乙酯为p H敏感基团的胶束.用荧光分光光度计测定了临界胶束浓度,动态光散射以及扫描电镜对胶束结构及性质进行了表征.结果显示,胶束稳定性良好,粒径分布较窄,且具有p H敏感性和还原敏感性.胶束载药量及包封率测试结果显示,相比于聚己内酯为内核的聚合物胶束,聚姜黄素的引入提高了胶束对药物的封装效果.     

胶束对酸碱指示剂离解平衡和变色点及变色范围的影响

探讨了十六烷基三甲基溴化铵(CTMAB),十二烷基硫酸钠(SDS)和TritonX-1003种胶束对酸套指示剂百里香酚蓝和溴百里香酚蓝离解反庆的离解常数的影响,进行了研究了以上3种胶束对指示剂变色点的变以范围的影响,实验结果表明,选择适当的胶束溶液作为滴定介质,不仅可以扩大酸碱指示剂的应用范围,而且还大大提高了测量的准确度.     

Organogels from ABA triblock copolymers

ABA triblock copolymers with two polystyrene endblocks connected by a poly(ethylene/butylene) midblock form highly elastic gels in a solvent which is incompatible for the endblocks but a good solvent for the midblock, for example, paraffin oil. In this situation the polystyrene endblocks aggregate into micelles. The midblocks can either form loops or build up bridges between different micelles; thus, domains and networks of interconnected micelles are produced. We have studied organogels of this kind consisting of a polymer with a molar mass of 90,000 and a styrene content of 31% per weight (Kraton G 1650) in paraffin oil. Rheological, calorimetric (differential scanning calorimetry) and small-angle X-ray scattering experiments were performed on these systems. An interesting result of our work which was not described previously is that the size (r˜ 6.8 nm) and the separation (d˜ 36 nm) of the micellar aggregates does not seem to be influenced by the block copolymer content in the concentration range investigated. Received: 12 March 2001 Accepted: 5 April 2001     

In Memoriam of Ernő Pungor 1923–2007

This review aims to present recent accomplishments in flow injection analysis by the use of surfactants, micellar systems, and cloud point extractions. The analysis of metals, pharmaceuticals, environmental samples, and samples of biological interest, as well as, surfactants themselves is covered. General considerations of micellar systems and cloud point extractions are briefly reviewed along with references to works that cover these fundamentals in greater detail. Highlights of the current work in these areas are given to stress the advantages of employing surfactants as an analytical tool to facilitate the experimental uses of these reagents and their future possibilities in green chemistry and automated laboratory techniques.     

Light Scattering Probes of Viscoelastic Fluids and Solids

In this article, we discuss recent advances in static and dynamic light scattering applied to soft materials. Special emphasis is given to light scattering methods that allow access to turbid and solid‐like systems, such as colloidal suspensions, emulsions, glasses, or gels. Based on a combination of single‐ and multispeckle detection schemes, it is now possible to cover an extended range of relaxation times from a few nanoseconds to minutes or hours and length scales below 1 nm up to several microns. The corresponding elastic properties of viscoelastic fluids or solid materials range roughly from below 1 Pa to several 100 kPa. Different applications are discussed such as light scattering from suspensions of highly charged colloidal particles, colloid and protein gels, as well as dense surfactant solutions.     

Spectrophotometric Flow Injection Analysis of Sulfite and Formaldehyde In Aqueous Micellar Medium Using 5,5′-Dithiobis(2-Nitrobenzoic Acid)

Abstract

Aqueous sulfite and formaldehyde were quantitated in the nanomole range using the reaction of 5,5′-dithiobis(2-nitrobenzoic acid), DTNB, with sulfite. Cationic micelles were used and found to greatly increase the sensitivity, bathochromically shifting the absorption spectra as well as lowering the pK of the reaction. the method was adapted to flow injection analysis, allowing more than 100 samples to be analyzed per hour with a relative standard deviation of less than 1.5% in all cases studied. the method is simple, fast and more sensitive than any available methods. the great flexibility of the choice of pH, surfactant concentration and buffer concentration contributes much to the high precision that could be achieved.     

Interfacially Cross‐Linked Reverse Micelles as Soluble Support for Palladium Nanoparticle Catalysts

Reverse micelles (RM) were formed in heptane/CHCl₃ with a surfactant carrying the triallylammonium (=triprop‐2‐en‐1‐ylammonium) head group (Scheme). Photo‐cross‐linking with dithiothreitol (=rel‐(2R,3R)‐1,4‐dimercaptobutane‐2,3‐diol; DTT) captured the RMs and afforded organic, soluble nanoparticles in a one‐step reaction. Similar to dendrimers, the cross‐linked reverse micelles could encapsulate palladium nanoparticles within their hydrophilic cores and protect them in catalytic reactions. Good to excellent yields were obtained in the Heck coupling of a range of alkyl acrylates (=alkyl prop‐2‐enoates) and iodobenzenes (Tables 1 and 2). The catalytic activity of the palladium nanoparticles was maintained in several repeated runs.