ASSIGNMENT代写

密歇根代写Assignment:亲水性分子的能力

2019-03-22 05:53

近年来,由于立方相纳米体系具有溶解亲水性、疏水性和亲水性分子的能力,因此在药物控释研究中被广泛应用。在这方面,单油酸甘油酯(GMO)是一种经美国食品和药物管理局批准的合成脂质两亲性分子,已知会根据含水量形成不同的溶性液晶相。转基因生物形成的立方相是由错综复杂的同等水渠网络分离的弯曲脂质双分子层的三维网络,目前已被用于以CPNPs的形式控制不同水溶性和不溶性药物的给药[7,8]。表面活性剂的应用可以通过控制纳米粒子的形状和大小来调节相行为,而纳米粒子的形状和大小是跨越不同生理屏障的重要参数。在目前的临床研究中,常用的表面活性剂如聚乙烯醇(PVA)、吐温80、Pluronic F-127、Pluronic F-68、聚山梨醇酯80、维生素e TPGS等作为稳定剂,提高药物在肿瘤部位的治疗效果。在这方面,Barauskas等人已经证明,使用Pluronic F-127作为稳定剂,可以从转基因[9]的立方相中获得稳定的水纳米颗粒分散体。同时表明,Pluronic F-127通过被动靶向抑制药物外排转运体[10],可以增强药物向癌组织的转运。同样,一种众所周知的天然聚合物维生素e TPGS由于其生物相容性和纳米技术中的优良乳化剂,被用于基于脂质的药物传递配方。此外,它还可以作为吸收增强剂和生物利用度促进剂,促进纳米颗粒携带药物通过胃肠道屏障。除了上述特性外,最近有报道称维生素e TPGS能有效抑制p-gp泵
密歇根代写Assignment:亲水性分子的能力
Recently, due to the capability to solubilise the hydrophilic, hydrophobic and amphiphilic molecules, cubic phase nanoparticulate systems are used as attractive vehicle in controlled drug delivery research [6]. In this regard, glyceryl monooleate (GMO) a synthetic lipid amphiphilic molecule approved by food and drug administration is known to form different lyotropic liquid crystalline phases depending upon water content. The cubic phase formed from GMO is a three dimensional network of curved lipid bilayers separated by intricate network of congruent water channels, now has been used for controlled drug delivery of different water soluble and insoluble drugs in the form of CPNPs [7, 8]. The use of surfactants may modulate the phase behaviour by controlling the shape and size of the nanoparticles which is an important parameter to cross different physiological barriers. In this current scenario, usually the surfactants like poly vinyl alcohol (PVA), tween 80, Pluronic F-127, Pluronic F-68, polysorbate 80 and vitamin-E TPGS etc are used as stabilisers in clinical studies to increase the therapeutic efficacy of the drug at the tumor site. In this regard, Barauskas et al have demonstrated that using Pluronic F-127 as a stabilising agent, stable aqueous nanoparticle dispersions may be obtained from the cubic phase of GMO [9]. Also it is shown that Pluronic F-127 through passive targeting can enhance the transportation of the drug towards cancerous tissues by inhibiting the drug efflux transporters [10]. Similarly, a well known natural polymer vitamin-E TPGS due to its biocompatible nature and excellent emulsifier in nanotechnology, is used for lipid-based drug delivery formulations. Moreover, also it can be used as an absorption enhancer and bioavailability promoter and facilitates the nanoparticles for carrying the drugs through gastrointestinal barrier. Apart from the above properties, recently vitamin-E TPGS is reported to inhibit p-gp pump effectively