Surfactant Vesicles Research Articles

Gene transfer to rat cerebral cortex mediated by polysorbate 80 and poloxamer 188 nonionic surfactant vesicles.

BackgroundGene therapy can be an intriguing therapeutic option in wide-ranging neurological disorders. Though nonviral gene carriers represent a safer delivery system to their viral counterparts, a thorough design of such vehicles is crucial to enhance their transfection properties.PurposeThis study evaluated the effects of combined use of two nonionic surfactants, poloxamer 188 (P) and polysorbate 80 (P80) into nanovesicles – based on 2,3-di(tetradecyloxy)propan-1-amine cationic lipid (D) – destined for gene delivery to central nervous system cells.MethodsNiosome formulations without and with poloxamer 188 (DP80 and DPP80, respectively) were prepared by the reverse-phase evaporation technique and characterized in terms of size, surface charge, and morphology. After the addition of pCMS-EGFP plasmid, the binding efficiency to the niosomes was evaluated in agarose gel electrophoresis assays. Additionally, transfection efficiency of complexes was also evaluated in in vitro and in vivo conditions.ResultsIn vitro experiments on NT2 cells revealed that the complexes based on a surfactant combination (DPP80) enhanced cellular uptake and viability when compared with the DP80 counterparts. Interestingly, DPP80 complexes showed protein expression in glial cells after administration into the cerebral cortices of rats.ConclusionThese data provide new insights for glia-centered approach for gene therapy of nervous system disorders using cationic nanovesicles, where nonionic surfactants play a pivotal role.

FORMULATION AND EVALUATION OF KETOCONAZOLE NIOSOMAL GEL

ABSTRACT
 
 In recent years, treatment of infectious disease through Novel Drug delivery system (NDDS) has undergone a revolutionary shift. Niosomes are a Novel Drug Delivery system which has potential application to treat infectious disease topically. Niosomes are non-ionic surfactant vesicles, in which medication is encapsulated in a vesicle for controlled drug release. Ketoconazole niosomes were prepared by using Cholesterol, Span 60/ Span 40 as surfactants, chloroform, and diethyl ether using rotary vacuum evaporator method. Formulation was then evaluated for particle size, drug content, entrapment efficiency, and in-vitro drug release studies. The Entrapment efficiency and drug content were calculated at 225nm using UV spectrophotometer. The drug content was found to be 70.37% for Span 40 and 72.81% for Span 60.The percentage of drug entrapment in niosomes was 60.3 % for Span 40 and 62.21 % for Span 60. FT-IR studies for niosomes containing Span 40 shows -CH stretching (Aliphatic) at 2891 cm-1and2925 cm-1 for niosomes containing Span 60. Ketoconazole niosomal gel was prepared using Carbopol 940, glycerol, Triethanolamine and distilled water. Evaluation of niosomal gel was determined by Physical appearance, pH, viscosity, drug content, entrapment efficiency and In-vitro diffusion studies.The percentage of the drug release from the niosomal gel was found to be 40.78 % for Span 40 and 33.75% for Span 60 . This delivery system is cost effective and simple to prepare as only the prepared gel of niosomes was introduced in Rotary vacuum evaporator for solvent evaporation.
 

TRANSFEROSOME: A RECENT APPROACH FOR TRANSDERMAL DRUG DELIVERY

Novel drug delivery systems are now a day is creating a new interest in development of drug deliveries. The transdermal route of drug delivery has gained great interest of pharmaceutical research, as it circumvents number of problems associated with oral route of drug administration. Transferosomes are capable of transdermal delivery of low as well as high molecular weight drugs. This offers several potential advantages over conventional routes like avoidance of first pass metabolism, predictable and extended duration of activity, minimizing undesirable side effects, utility of short half life drugs, improving physiological and pharmacological response and have been applied to increases the efficiency of the material transfer across the intact skin, by the use of penetration enhancers and non-ionic surfactant vesicles. It is suitable for controlled and targeted drug delivery and it can accommodate drug molecules with wide range of solubility. Due to its high deformability it gives better penetration of intact vesicles. Transferosome possess an infrastructure consisting of hydrophobic and hydrophilic moieties together and as a result can accommodate drug molecules with wide range of solubility. They are biocompatible and biodegradable as they are made from natural phospholipids and have high entrapment efficiency. In this review, we have focused on transferosome with discussions on novel drug delivery systems for targeted delivery of therapeutics and important issues and challenges for future clinical applications.
 Keywords: Novel drug delivery systems, Transferosomes, Transdermal drug delivery, Targeted drug delivery

Brief Effect of a Small Hydrophobic Drug (Cinnarizine) on the Physicochemical Characterisation of Niosomes Produced by Thin-Film Hydration and Microfluidic Methods.

Novel niosomal formulations containing cinnarizine were developed to enhance its drug characteristics. In this work, niosomes (non-ionic surfactant vesicles) were prepared by conventional thin-film hydration (TFH) and microfluidic (MF) methods with sorbitan monostearate (Span® 60), cholesterol, and co-surfactants (Cremophor® ELP, Cremophor® RH40 and Solutol® HS15) as key excipients. The aim was to study the effect of cinnarizine on the characteristics of different niosomal formulations manufactured by using different methods. For effective targeted oral drug delivery, the efficacy of niosomes for therapeutic applications is correlated to their physiochemical properties. Niosome vesicles prepared were characterised using dynamic light scattering technique and the morphology of niosomes dispersion was characterised using optical microscopy. Dialysis was carried out to purify niosome suspensions to determine drug loading and drug release studies was performed to study the potential use of niosomal systems for cinnarizine.

In vitro and Ex vivo Studies of Linagliptin Loaded Non-Ionic Surfactant Vesicles Using Statistical Optimization

In vitro and Ex vivo Studies of Linagliptin Loaded Non-Ionic Surfactant Vesicles Using Statistical Optimization

NIOSOMES: PRESENT SCENARIO AND FUTURE ASPECTS

Drug targeting is a kind of phenomenon in which drug gets distributed in the body in such a manner that the drug interacts with the target tissue at a cellular or subcellular level to achieve a desired therapeutic response at a desire site without undesirable interactions at other sites. This can be achieved by modern methods of targeting the drug delivery system such as niosomes. Niosomes are the type of non-ionic surfactant vesicles, which are biodegradable, non-toxic, more stable and inexpensive, a new approach to liposomes. Their structure similar to liposome and hence they can represent alternative vesicular systems with respect to liposomes. The niosomes have the tendency to load different type of drugs. This review article represents the structure of niosome, advantages, disadvantages, the methods for niosome preparation and characterization of pharmaceutical NSVs.
 Keywords: Niosome, Cholesterol, Hydrophilic and Lipophilic drugs, Surfactant, Targeted delivery Bioavailability Improvement, Factors, Applications.

Proliferation and In Vitro Wound Healing Effects of the Microniosomes Containing Narcissus tazetta L. Bulb Extract on Primary Human Fibroblasts (HDFs).

PurposeIn Traditional Persian Medicine (TPM), different natural treatments have been suggested for skin damages such as Narcissus tazetta L. bulb application. New drug delivery systems such as niosomes have shown considerable increase transdermal drug delivery through stratum corneum, the main barrier against substances transport into skin. The aim of this study is preparation of niosomal formulations from N. tazetta bulb extract and evaluation of its in vitro wound healing effect.Materials and methodsNon-ionic surfactant vesicles (NSVs or niosomes) were prepared by film hydration method from percolated extract of N. tazetta bulb. A number of 12 niosomal formulations (F1-F12) were prepared using different proportions of Span 60/Tween 60/cholesterol and 80% methanol-dissolved/aqueous PEN (percolation extract of N. tazetta) (30 and 50 mg/ml). Their morphology, particle size, physical and chemical stability and encapsulation efficiency was studied. In vitro wound healing effect of various concentrations of the best PEN niosomal formulation (F9) was evaluated in comparison to PEN on human dermal fibroblasts (HDFs).ResultsIncreasing the aqueous/methanolic PEN concentration from 3 to 5% resulted size reduction of NSVs with statistically significant difference (p < 0.05). F9 showed the most physicochemical stability and was chosen for in vitro wound healing effect. This formulation exhibited significantly effects (p < 0.05) on cell proliferation in HDF cells at 1.562 and 3.125 μg/ml compared with the untreated cells using neutral red assay.ConclusionFormulation of PEN in niosome carrier significantly decreased the gap width on human dermal fibroblasts. Graphical abstractSchematic processes of proliferation effect of narcisus tazetta bulb on fibroblast cells.

An Overview on Niosomes: A Drug Nanocarrier

Niosome are non-ionic surfactant vesicles acquired on hydration of synthetic nonionic surfactants, with or without consolidation of cholesterol or their lipids. They are vesicular systems like liposome’s that can be utilized as transporters of amphiphilic and lipophilic medications. Niosomes are promising vehicle for drug delivery and being non-ionic; and Niosomes are biodegradable, biocompatible non immunogenic and show adaptability and flexibility in their structural characterization.

Abstract 4650: Quantitative assessment of the intracellular uptake of chlorotoxin in a U87 human glioma mouse model for the targeted drug delivery system

Abstract This study quantitatively evaluates the tumor cell-targeting capabilities and intracellular uptake pattern of chlorotoxin (CTX) when delivered intratumorally (IT) and intravenously (IV) using subcutaneous (SC) U87 human glioblastoma mouse model. CTX is a scorpion-derived polypeptide that selectively binds to tumor cells of neuroectodermal origin, such as glioma and a wide range of other tumor cells, but not normal cells. The quantification of CTX cellular uptake presented here will assist in the further development of our tumor-targeting drug delivery system (DDS) consisting of a chemotherapeutic encapsulated in nonionic surfactant vesicles embedded in a thermosensitive cross-linked chitosan hydrogel, which has affinity for MUC1 receptor overexpressed on many tumor cells, including low-differentiated glioma. CTX addition to the DDS will serve as a second tumor-targeting molecule. In this study, U87 human glioma cells were implanted SC in the flank of nude athymic/ncr/nus mice. When tumors reached approximately the volume of 0.25 cm3, mice were injected either IT or IV (tail vein) with 50 μl of 100 μg CTX or phosphate buffer saline (PBS) as a control. The tumors were harvested at 5 minutes post IT injection or 7 hours post IV injection, fixed, sectioned at 5 μm, and followed by either immunofluorescence or immunocytochemistry using anti-CTX primary antibody and AlexaFluor-594 conjugated secondary antibody or immunoperoxidase- AEC kit, and evaluated by confocal or scanning microscopy, respectively. CTX levels were compared between three different tumor regions (A, B, and C; A = injection site marked by methylene blue dye, C = most distant from injection site, B = equidistant between these two) after direct IT injection and compared to CTX levels in tumor tissues following IV injection. Quantitative evaluation of CTX levels was performed with ImageJ software, while further intracellular analysis of CTX presence utilized MATLAB system. CTX was found to be evenly distributed between cells within each region post IT injection, but decreased in intensity from the injection site (A) toward the tumor edge. With region A set at 100% CTX intensity, the levels decreased to 23.7% (in region B), and 2.1% (in region C), compared to 1.8% post IV injection. Our previous in vitro studies showed CTX localization near the nucleus in U87 glioma cells but not in normal human astrocytes. Current evaluation of tumor z-sections quantified levels of CTX inside U87 glioma cells in vivo. These results confirm the specificity of CTX uptake by U87 human glioma cells in vitro and in vivo with CTX tissue levels post IV injection, which is comparable to those post IT injection in the distant C tumor region. This proves CTX is an important second tumor-targeting molecule for our DDS system. Citation Format: Alan D. Roberts, Joseph O. Johnson, Aleksandra Karolak, Norma Alcantar, Katarzyna A. Rejniak, Marzenna Wiranowska. Quantitative assessment of the intracellular uptake of chlorotoxin in a U87 human glioma mouse model for the targeted drug delivery system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4650.

Theranostic Niosomes for Efficient siRNA/MicroRNA Delivery and Activatable Near-Infrared Fluorescent Tracking of Stem Cells.

RNA interference-mediated gene regulation in stem cells offers great potential in regenerative medicine. In this study, we developed a theranostic platform for efficient delivery of small RNAs [small interfering RNA (siRNA)/microRNA (miRNA)] to human mesenchymal stem cells (hMSCs) to promote differentiation, and meanwhile, to specifically label the transfected cells for the in vivo tracking purpose. We encapsulated indocyanine green (ICG) in a nonionic surfactant vesicle, termed "niosome", that is mainly composed of a nonionic surfactant sorbitan monooleate (Span 80) and a cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). This novel ICG-containing niosome system (iSPN) demonstrated highly efficient siRNA and miRNA delivery in hMSCs. Specific inhibition of miR-138, a negative regulator of osteoblast differentiation, was achieved by iSPN/miR-138, which significantly promoted osteogenesis of hMSCs. Furthermore, iSPN exhibited OFF/ON activatable fluorescence upon cellular internalization, resulting in efficient near-infrared labeling and the capability to dynamically monitor stem cells in mice. In addition, iSPN/siRNA achieved simultaneous long-term cell tracking and in vivo gene silencing after implantation in mice. These results indicate that our theranostic niosomes could represent a promising platform for future development of stem cell-based therapy.

An insight of in vitro transport of PEGylated non-ionic surfactant vesicles (NSVs) across the intestinal polarized enterocyte monolayers

PEGylated non-ionic surfactant-based vesicles (NSVs) are promising drug delivery systems for the local, oral and systemic administrations of therapeutics. The aim of this study was to test the cellular biocompatibility and transport of Nile Red-loaded NSVs (NR-NSVs) across the Caco-2-cell monolayers, which represent an in vitro model of human intestinal epithelium. The NR-NSVs assumed a spherical shape with a mean size of 140 nm, and a narrow size distribution. The NR-NSVs did not modify Caco-2 cell viability, which remained unaltered in vitro up to a concentration of 1 mM. The transport studies demonstrated that the NR-NSVs moved across the Caco-2 monolayers without affecting the transepithelial electrical resistance. These results were supported by flow cytometry analysis, which demonstrated that NR-NSVs were internalized inside the Caco-2 cells. Nanoparticle tracking and Transmission Electron Microscopy (TEM) analysis showed the presence of NR-NSVs in the basolateral side of the Caco-2 monolayers. TEM images also showed that NSVs were transported intact across the Caco-2 monolayers, thus demonstrating a predominant transcytosis mechanism of transport through endocytosis. The NSVs did not affect the integrity of the membrane barrier in vitro, and can potentially be used in clinics to increase the oral bioavailability and delivery of therapeutics.

Enhanced intercellular release of anticancer drug by using nano-sized catanionic vesicles of doxorubicin hydrochloride and gemini surfactants

In this study, we provide an alternative formulation to develop gemini surfactant (GSs)–drug nano-sized catanionic vesicles with multi stimuli-responsiveness, which have great potential applications in the fields of controlled release and drug delivery in chemotherapy. The main aim of this study was to investigate how catanionic vesicles could influence the encapsulation and release of the anticancer drug Doxorubicin (DOX). The DOX was self-associated in an aqueous medium according to reported studies still controversial. We present here the simple and convenient methods, surface tension, conductance and circular dichroism (CD) studies to give direct evidence that DOX was self-associated at the critical concentration about 0.841mmolL−1. The influence of micelle based on DOX-loaded (DLs) and mixed micelle (C*(αDOX+αGSs)) catanionic vesicles (DGCs) showed the highly synergistic interaction. The physicochemical properties, molecular docking, drug uptake and release of DOX in in-vitro for DL and DGC were explored. The substantial amounts of DOX could successfully encapsulate into the catanionic vesicles. The important point of DGC vesicles was they could reduce toxicity and revealed better therapeutic effects when the DOX was in high concentration. Moreover, the cell viability of DL-12 vesicles was 44%, and DL-16 vesicles was 70% at 18μmolL−1, while at 20.0μmolL−1 it was 44% in DGC-12 as αDOX was 0.6 and 56% in DGC-16 as αDOX was 0.9. The in-vitro cytotoxicity and fluorescence microscopic images of DL and DGC vesicles on MCF-7 cell lines showed the improved nuclear localization of DOX uptakes. These findings showed the high importance of catanionic vesicles to enhance the free DOX entrance mainly via endocytosis for breast cancer cell.

Niosomes as Novel Drug Delivery System: Review Article

Niosome are non-ionic surfactant vesicles obtained by hydrating mixture of cholesterol and nonionic surfactants. It can be used as carriers of amphiphilic and lipophilic drug. In niosomes drug delivery system, the medication is encapsulated in a vesicle. Niosomes are biodegradable, biocompatible non-immunogenic and exhibit flexibility in their structural characterization. The main object of this review the application of niosome technology is used to treat a number of diseases, niosome have good opportunity in research and beneficial for researcher and pharma industries. Niosome appears to be a well preferred drug delivery system over liposome as niosome being stable and economic. Also niosomes have great drug delivery potential for targeted delivery of anti-cancer, anti-infective agents. Drug delivery potential of niosome can enhances by using novel drug delivery concepts like proniosomes, discomes and aspasome. Niosomes also serve better aid in diagnostic imaging and as a vaccine adjuvant. Thus these areas need further exploration and research so as to bring out or to make for commercially available niosomal preparation.

Characterization of DDAB/Cholesterol Vesicles and Its Comparison with Lipid/Cholesterol Vesicles.

Vesicles prepared by synthetic surfactant, DDAB (dilauryldimethylammonium bromide), were modified with cholesterol and their membrane surface properties of the vesicle were characterized through the analyses of fluorescent probes, such as Laurdan (6-lauroyl-2-dimethylaminonaphthalene) and DPH (1,6-diphenyl-1,3,5-hexatriene). The self-assembly of DDAB with cholesterol showed stable vesicle structure with a mean diameter of 127 nm through the dynamic light scattering analysis. While the DDAB vesicle showed high polarity and high fluidity, the modification of the DDAB vesicle with cholesterol lead to the formation of "heterogeneous phase" on the vesicle membrane. DDAB:cholesterol = 70:30 vesicle showed unique characteristics that represents polar environment but lower fluidity. A novel platform for the chemical process in aqueous media can be expected by using the artificial surfactant vesicles modified with cholesterol.

Sorbitane Monostearate and Cholesterol based Niosomes for Oral Delivery of Telmisartan.

Niosomes are non-ionic surfactant vesicles used as drug carriers for encapsulating both hydrophobic and hydrophilic drugs. The aim of the present study was to prepare and characterize niosomes formulations for oral delivery of telmisartan and evaluated for its antihypertensive activity. Telmisartan loaded niosomes were prepared using thin film hydration method by varying the Span 60 and cholesterol at several molar ratios and characterized for vesicles size, polydispersity index, zeta potential, entrapment efficiency. The in vivo antihypertensive study of optimized formulation and molecular impact of angiotensin II type-1 receptor (AT1R) messenger Ribonucleic acid (mRNA) and protein expression on smooth vascular muscles of aorta was determined by real-time polymerase chain reaction (RT-PCR) and western blot analysis in Wistar albino rats. The optimized niosomes formulation NS6 presented vesicles size of 618.47 nm, polydispersity index of 0.86, with entrapment efficiency of 83.83% and possesses negative charge. In vivo study showed that the optimized formulation could reduce the systolic blood pressure in methyl prednisolone acetate induced hypertensive rats in close proximity to normal range of systolic blood pressure and maintain it over an extended period. In addition, telmisartan loaded niosomes treatment to hypertensive rats significantly attenuates the raised mRNA level and protein level of AT1R gene in comparison to hypertensive rats. Results of present study confer the potential of developed niosomes as suitable carriers for improved oral delivery of telmisartan.

Improved peroxidase-mimic property: Sustainable, high-efficiency interfacial catalysis with H2O2 on the surface of vesicles of hexavanadate-organic hybrid surfactants

An emerging method for effectively improving the catalytic activity of metal oxide hybrids involves the creation of metal oxide interfaces for facilitating the activation of reagents. Here, we demonstrate that bilayer vesicles formed from a hexavanadate cluster functionalized with two alkyl chains are highly efficient catalysts for the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) with H2O2 at room temperature, a widely used model reaction mimicking the activity of peroxidase in biological catalytic oxidation processes. Driven by hydrophobic interactions, the double-tailed hexavanadate-headed amphiphiles can self-assemble into bilayer vesicles and create hydrophobic domains that segregate the TMB chromogenic substrate. The reaction of TMB with H2O2 takes place at the interface of the hydrophilic and hydrophobic domains, where the reagents also make contact with the catalytic hexavanadate clusters, and it is approximately two times more efficient compared with the reactions carried out with the corresponding unassembled systems. Moreover, the assembled vesicular system possesses affinity for TMB comparable to that of reported noble metal mimic nanomaterials, as well as a higher maximum reaction rate.

Catanionic Surfactant Vesicles as a New Platform for probing Glycan-Protein Interactions.

Glycomics lags substantially behind proteomics and genomics in its ability to decipher and synthesize complex glycans. The slow progress in deciphering glycan interactions at a molecular level is in large part due to the absence of a functional system to express, on a large scale, carbohydrates of known structure, in the context of a biologically relevant assay system. Here we describe the characterization of a glycan-functionalized catanionic surfactant vesicles (CVs) as a platform for glycan synthesis, and to demonstrate that the resulting glycan-functionalized CVs can serve as a scaffold for the interrogation of protein-glycan interactions. We demonstrate that N. gonorrhoeae lipooligosaccharide (LOS) glycosyltransferase LgtE, an enzyme that catalyzes the addition of galactose onto a terminal glucose found on LOS can be used to biochemically modify LOS or glucose functionalized CVs. CVs were characterized by differential lectin binding using flow cytometry. LgtE activity was measured on whole cells and LOS functionalized vesicles and found to have approximately the same biochemical properties. We further demonstrate that CVs can be ink-jet printed. This paper presents proof-of-concept that glycan-functionalized catanionic vesicles can be used to create a high-specificity and high-throughput glycan array that will allow for the investigation of a variety of protein-glycan interactions.

Plasmid DNA vaccine coding eight repeats of gonadotrophin-releasing hormone induced atrophy of prostate in male mice.

BackgroundProstate hyperplasia and neoplasia are major illness of men and elderly dogs. Treatment of prostate cancer requires androgen deprivation surgery or therapy to prevent metastases and alleviate pain. Recently, six DNA vaccines have entered clinical trials against prostate cancer in humans with limited success. There is a need for new therapies that delay the establishment of malignancy and prolong survival.Materials and methodsA plasmid DNA vaccine coding for eight gonadotrophin-releasing hormone (GnRH-I) interspersed in eight T-helper epitopes was used. Sexually mature male mice were immunized with the vaccine in hemagglutinating virus of Japanese envelope vector and boosted in nonionized surfactant vesicles in study weeks 0, 3, 6, 9, and 12. Plasma anti-GnRH-I antibody response, serum testosterone concentration, and effect on prostate were evaluated.ResultsResults of an indirect enzyme linked immunosorbent assay (ELISA) showed anti-GnRH-I antibody response (OD value) detected in the study week 3 (0.613 ± 0.179) with a highest response in the week 12 (1.205 ± 0.219). Serum testosterone concentration (ng/ml) in vaccinated mice was significantly reduced (P > 0.000, 0.761 ± 0.531) in the study week 24 in contrast to control serum (7.583 ± 1.251). Group average gross combined weight of prostate and seminal vesicles of vaccinated mice was significantly (P < 0.000) reduced in the study week 24 (319.75 ± 89.19 mg) in contrast to control weight (563.25 ± 108.60 mg). Sections of prostate stained with Goldner's trichrome showed profuse pink color secretion in control tubules, which however was absent in the vaccinated prostate. The lining epithelium of the vaccinated prostate was atrophied and did not enfold in its lumen.ConclusionsImmunization strategy designed with the plasmid DNA vaccine in hemagglutinating virus of Japanese envelope and nonionized surfactant vesicles can be the genetic immunization platform. This vaccine bears potentials in terms of reducing serum testosterone concentration and induction of atrophy of prostate. Targeted ablation of native GnRH-I by genetic immunization could offer leverage to vaccinologists, seeking therapeutic target to control and prevent malignancy of prostate.

Enhanced Physical Stability of Mixed Ion Pair Amphiphile/Double-chained Cationic Surfactant Vesicles in the Presence of Cholesterol

In this study, a pseudodouble-chained ion pair amphiphile (IPA), hexadecyltrimethylammoniumdodecylsulfate (HTMA-DS), and dialkyldimethylammonium bromide (DXDAB) with different chain lengths were used as the main materials to fabricate positively charged catanionic vesicles with various mole fractions of cholesterol. The effects of cholesterol and DXDAB alkyl chain length on physical stability of the catanionic vesicles were then investigated by size, zeta potential, and Fourier transform infrared analyses. With the presence of cholesterol in the mixed HTMA-DS/DXDAB vesicles or with increasing the DXDAB content in the presence of a proper amount of cholesterol, the physical stability of the catanionic vesicles could be enhanced. The spacing effect of cholesterol would reduce the counterion binding tendency at the charged vesicle surfaces, resulting in a more pronounced charge character of the catanionic vesicles. Furthermore, cholesterol-induced disordered structure contributed to the flexibility of the vesicular bilayers. Thus the physical stability of the vesicles was improved by adding cholesterol. With increasing the hydrocarbon chain length of DXDAB, cholesterol located toward the middle of the bilayers, enhancing the effects of cholesterol on charge and molecular packing characteristics of the vesicles. This led to a more pronounced stability enhancement effect on the vesicles with a longer alkyl chain length of DXDAB. The results suggested that the presence of cholesterol in the HTMA-DS/DXDAB catanionic vesicles could enhance vesicle stability through adjusting intra-vesicle and/or inter-vesicle interactions. In addition, the stability enhancement effect was more pronounced in the systems with a long DXDAB alkyl chain. The findings will be useful for developing new formulas of catanionic vesicles as drug delivery carriers.

Niosomes: A Vesicular Drug Delivery System

Niosomes or Non ionic surfactant vesicles are microscopic lamellar structures formed on admixture of non ionic surfactant of the alkyl or dialkylpolyglycerol ether class and cholesterol with subsequent hydration in aqueous media. Niosomes are unilamellar or multi lamellar structures that are microscopic in size. They are vesicular systems similar to liposomes that can be used as carriers of amphiphilic and lipophilic drugs[1]. The basic process of preparation is hydration by aqueous phase of the lipid phase which may be either a pure surfactant or a mixture of surfactant with cholesterol. Later preparing niosomal dispersion, by dialysis centrifugation or gel filtration the un entrapped drug is separated. The use of dialysis tubing is also included in Invitro rate release. Niosomes have been widely evaluated for controlled release and targeted delivery for treatment of cancer, viral infections and other microbial diseases. Circulation of the entrapped drug in body prolong as niosomes can entrap both hydrophilic and lipophilic drugs. Stable noisome dispersion must exhibit a constant particle size and a constant level of entrapped drug. Niosomes also serve better aid in diagnostic imaging and as a vaccine adjuvant. Niosomes are promising vehicle for drug delivery and being non ionic, it is less toxic and improves the therapeutic index of drug by restricting its action to target cells. They have all the advantages of liposomes but their low cost, greater stability and resultant ease of storage has lead to the exploitation of non ionic surfactants as alternative to phospholipids. This article gives information about the advantages, disadvantages, preparation methods, factors affecting, characterization, Invitro methods, and niosomal applications.[2]