Preparation of Hollow Polypyrrole Nanospheres in Niosome System

Hollow polypyrrole nanospheres were successfully prepared in a Span80/PEG400/H₂O(PEG=polyethy-lene glycol) niosome system. The formation and morphology of the nanospheres vary with the concentrations of pyrrole monomer, salt and Span80. The shell thickness of the nanospheres increases gradually with monomer content. NaCl can promote the formation of the nanospheres. The formation mechanism of the nanospheres was discussed.     

Preparation and evaluation of physicochemical properties and anti-leishmanial activity of zirconium/tioxolone niosomes against Leishmania major

Due to the limitations of current chemotherapy for the treatment of leishmaniasis, there is an urgent requirement to search for new anti-leishmanial compounds and nano-drug delivery systems including niosomes. Therefore, the aim of this study was to prepare zirconium/tioxolone niosomes using the film hydration method and evaluate the physicochemical properties of the produced niosomes including morphology, size distribution, stability, and encapsulation efficiency. The best formulation was chosen as Span/Tween 40 (NZT₁) due to its physicochemical properties, and leishmanicidal activity against promastigotes and amastigotes was measured using both 3-(4,5-dimethylthiazol2yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry methods. In addition, to assess the mechanism of action of the prepared niosomes, apoptosis, levels of gene expression, reactive oxygen species (ROS) generation, superoxide dismutase (SOD) activity, and nitrite production were evaluated. The prepared formulation indicated log-normal particle size distribution curves, high encapsulation efficiency (more than 95.72 %), and good physical stability after one week, three months, and six months. Our findings demonstrated that amphotericin B was more effective than Zr/tioxolone niosomes (NZTs) due to the selectivity index (SI). However, the niosomal formulation of Zr/tioxolone showed no cytotoxic effect within the range of our experimental concentrations (CC₅₀ of 308.21 μg/mL). Moreover, the prepared niosomes increased the expression level of interleukin (IL)-12 and inducible nitric oxide synthase (iNOS) and significantly decreased the expression level of the IL-10 gene, which confirms the immunomodulatory role of NZTs. According to our findings in this study, the niosomal form of this combination can be considered for further therapeutic approaches against L. major in future planning.     

非离子表面活性剂囊泡包封药物头孢唑啉钠的研究

实验通过超声波法制备了吐温类非离子表面活性剂囊泡，研究了它们对药物质奖励不孢唑啉钠（CEZ）的包封作用以及被包封的CEZ在模拟胃液及模拟肠液中的释放情况。实验表明，吐温40与胆固醇体积比为1：1时形成的非离子表面活性剂囊泡对1mg/mL的CEZ的包封率是20％，而且在模拟胃液和模拟肠液中，对包封的药物都有一定的缓释作用，因此有可能作为临床上的药物缓释剂。     

Investigation of PEG 6000/Tween 80/Span 80/H<Subscript>2</Subscript>O niosome microstructure

A stable niosome is prepared from Poly(ethylene glycol) [PEG] 6000/Tween 80/Span 80/H₂O lamellar liquid crystal. The niosome structures and properties are studied by the methods of negative-staining transmission electron microscopy and small angle X-ray diffraction. A new calculating method is first put forward to obtain the microstructure and layer number of the niosome membrane. The membrane thickness and layer number of the niosome are 8–22 nm and 1–3.5 in PEG 6000/Tween 80/Span 80/H₂O system.     

血红蛋白在Span 80/PEG 400/H2O囊泡体系中的结构性质

通过紫外-可见吸收光谱、荧光光谱、动态光散射、圆二色谱、负染-透射电镜(NS-TEM)和冷冻蚀刻-透射电镜(FE-TEM)等实验方法研究了血红蛋白(Hb)与Span 80/PEG 400/H₂O囊泡间的相互作用及其结构特性. 结果表明: Hb易于吸附在囊泡表面, 使得囊泡的表观半径稍有增大; Hb的肽链在囊泡表面能够逐渐伸开, 特征荧光峰强度显著增强, 部分氨基酸残基进一步暴露, α-螺旋结构含量减少, β-折叠和β-转角结构含量增加, 无规卷曲结构含量基本不变. 囊泡体系中Hb的稳定性与囊泡的稳定性有关.     

Nonionic Surfactant Vesicles as a Carrier for Transdermal Delivery of Frusemide

The aim of the present study was to formulate and evaluate the nonionic surfactant vesicles of frusemide in order to enhance its skin permeation. The process variables which could affect the preparation and properties of the niosome formulation studied included type of spans, ratio of span and cholesterol, ratio of cholesterol and dicetylphosphate (DCP), concentration of drug, type of solvent, hydration media and time of hydration. The formulated niosomes thus were characterized for various parameters such as surface morphology, size, entrapment efficiency, skin permeation, etc. Stability of the niosomes in terms of drug holding capacity was assessed for a period of 30 days on storage under defined conditions. The maximum entrapment efficiency of 77.73±2.36% was obtained with niosomes formulated from Span 60∶Cholesterol∶DCP (47.5∶47.5∶5) using chloroform:methanol (4∶1) as the solvent system at the hydration time of 1 hr. A direct relationship was observed between the percentage leaching of the drug out of the vesicles and temperature. Higher transdermal flux was obtained with niosomal gel (9.2±0.5 μg/cm²/hour) in comparison to conventional gel (6.4±0.3 μg/cm²/hour).     

Copper nanoparticles in membrane mimicking vesicles-synthesis and catalytic activity

Copper nanoparticle (CuNPs) were successfully synthesized within the confined volume of niosomal vesicles. Metallic copper nanoparticles have been prepared in niosomal vesicles. The nanoparticle characteristics are guided by the specific properties of the niosomes. It has been found that the hydrophile: lipophile balance (HLB), area per molecule and gel-fluid transition temperature of the surfactants forming the niosome are important factors affecting nanoparticle characteristics. Entrapment ability, hydration volume, vesicle size and “leakiness” are the niosomal parameters that need to be optimized for nanoparticle formation. The synthesized nanoparticles function as very effective catalysts for reduction of Methylene Blue (MB) dye. This report gives a first hand account of how the particle characteristics of the CuNPs synthesized in niosomal vesicles can be related to their efficiency as catalysts. Since use of, niosomes for drug delivery and in cosmetic formations is well documented, the present work indicates the potential for prospective delivery of CuNPs via niosomes for various applications in future.     

Synthesis and application of poly(ethylene glycol)-cholesterol (Chol-PEGm) conjugates in physicochemical characterization of nonionic surfactant vesicles

Vesicles possessing poly(ethylene glycol) (PEG) chains on their surface have been described as a blood-persistent drug delivery system with potential applications for intravenous drug administration. In this research with different molecular weights (400–10,000 g/mol) of PEG, a series of Chol–PEG^m conjugates were generated by the DCC (N,N′-dicyclohexylcarbodiimide, DCC)/(4-dimethylaminopyridine, 4-DMAP) esterification method, and confirmed by FT-IR and ¹H NMR spectrum. Then their properties in aqueous solution were studied by electron microscopy images, associative behavioral and systematic tensiometric studies over a wide concentration range. In order to elucidate the application of this Chol–PEG^m in vesicles, conventional nonionic surfactant vesicles (niosomes) composed of span 60 and cholesterol were prepared and the influence of various hydrophilic chains of the Chol–PEG^m conjugates was investigated. Results indicated that all the niosomes prepared, with or without Chol–PEG^m composition were similar in micrograph with diameter between 120 nm and 180 nm. The fixed aqueous layer thickness (FALT) around niosomes increased as Chol–PEG^m chain length increase, particularly in the Chol–PEG^10,000 modified niosomes with 9.33 ± 0.67 nm. In vitro release experiments indicated that release rate of nimodipine from Chol–PEG^m modified niosomes was enhanced. Chol–PEG^m modified niosomes showed greater accumulative release than that of plain niosomes over a period of 24 h. These studies have shed some light on the suitability of Chol–PEG^m containing niosome preparation.