Effect of cholesterol on the formation and hydration behavior of solid-supported niosomal membranes

Niosome as a promising tool for increasing the effectiveness of anti-inflammatory compounds

Niosomes are drug delivery systems with widespread applications in pharmaceutical research and the cosmetic industry. Niosomes are vesicles of one or more bilayers made of non-ionic surfactants, cholesterol, and charge inducers. Because of their bilayer characteristics, similar to liposomes, niosomes can be loaded with lipophilic and hydrophilic cargos. Therefore, they are more stable and cheaper in preparation than liposomes. They can be classified into four categories according to their sizes and structures, namely small unilamellar vesicles (SUVs), large unilamellar vesicles (LUVs,), multilamellar vesicles (MLVs), and multivesicular vesicles (MVVs). There are many methods for niosome preparation, such as thin-film hydration, solvent injection, and heating method. The current study focuses on the preparation methods and pharmacological effects of niosomes loaded with natural and chemical anti-inflammatory compounds in kinds of literature during the past decade. We found that most research was carried out to load anti-inflammatory agents like non-steroidal anti-inflammatory drugs (NSAIDs) into niosome vesicles. The studies revealed that niosomes could improve anti-inflammatory agents' physicochemical properties, including solubility, cellular uptake, stability, encapsulation, drug release and liberation, efficiency, and oral bioavailability or topical absorption. See also the graphical abstract(Fig. 1).

Hyaluronic Acid Derivative Effect on Niosomal Coating and Interaction with Cellular Mimetic Membranes

Hyaluronic acid (HA) is one of the most used biopolymers in the development of drug delivery systems, due to its biocompatibility, biodegradability, non-immunogenicity and intrinsic-targeting properties. HA specifically binds to CD44; this property combined to the EPR effect could provide an option for reinforced active tumor targeting by nanocarriers, improving drug uptake by the cancer cells via the HA-CD44 receptor-mediated endocytosis pathway. Moreover, HA can be easily chemically modified to tailor its physico-chemical properties in view of specific applications. The derivatization with cholesterol confers to HA an amphiphilic character, and then the ability of anchoring to niosomes. HA-Chol was then used to coat Span^® or Tween^® niosomes providing them with an intrinsic targeting shell. The nanocarrier physico-chemical properties were analyzed in terms of hydrodynamic diameter, ζ-potential, and bilayer structural features to evaluate the difference between naked and HA-coated niosomes. Niosomes stability was evaluated over time and in bovine serum. Moreover, interaction properties of HA-coated nanovesicles with model membranes, namely liposomes, were studied, to obtain insights on their interaction behavior with biological membranes in future experiments. The obtained coated systems showed good chemical physical features and represent a good opportunity to carry out active targeting strategies.

Introducing Tween-curcumin niosomes: preparation, characterization and microenvironment study

In this work, we report unusual niosomes (non-ionic surfactant based vesicles), prepared using non-ionic surfactant Tween 80 (T80) as well as Tween 20 (T20) and curcumin. Conventional niosomes consist of non-ionic surfactant and cholesterol. We found that, despite being a probiotic, curcumin plays a similar role to cholesterol in the formation and stabilization of niosomes. The prepared Tween-curcumin niosomes were characterised using Dynamic Light Scattering (DLS), zeta potential, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and Transmission Electron Microscopy (TEM) techniques. The curcumin-induced micelle to vesicle transition in the Tween surfactants was investigated by DLS, zeta potential, fluorescence anisotropy, and fluorescence lifetime studies. At room temperature (298 K), the prepared niosomes were found to be stable; however, at a higher temperature (333 K), the niosomes degrade gradually and irreversibly to form micelles. The temperature-dependent vesicle to micelle degradation was monitored using fluorescence anisotropy, absorption, DLS and Differential Scanning Calorimetry (DSC) measurements. Further, the Tween-curcumin niosomes show a controlled release of curcumin, which could open up the possibility of multidrug therapy.

Significant bile salt induced perturbation of niosome membrane: A molecular level interaction study using 1-Naphthol fluorescence

This study demonstrates that significant perturbation of tween20:cholesterol(1:1) niosome membrane takes place even at premicellar concentration of bile salts. Here, 1-naphthol (1-NpOH), a known and sensitive excited state proton transfer (ESPT) probe, was used to understand the nature of perturbation of the membrane in an unbuffered medium. The significant decrease in 1-NpOH fluorescence intensity in niosome-bile salt mixed system at both lower (10 °C) and higher (50 °C) temperatures indicates the bile salts [sodium cholate (NaC) and sodium deoxycholate (NaDC)] induce perturbation of niosome membranes. Variations in the fluorescence lifetime values of both the prototropic emissions (neutral and anionic species) along with the proton transfer rate of 1-NpOH confirm the bile salts perturb up to the hydrophobic core domain of the niosomal membranes. Bile salts induce size change of the niosomal membrane is confirmed through dynamic light scattering study.

Probing the temperature-dependent changes of the interfacial hydration and viscosity of Tween20 : cholesterol (1 : 1) niosome membrane using fisetin as a fluorescent molecular probe

A detailed photophysical study of fisetin in a Tween20 : cholesterol (1 : 1) niosome membrane has been carried out. Fisetin is found to partition well into the Tween20 : cholesterol (1 : 1) niosome membrane at low temperature (Kp = 2.7 × 104 M-1 at 10 °C). Cetylpyridinium chloride quenching study confirms the location of fisetin molecules in the interfacial domain of Tween20 : cholesterol (1 : 1) niosome membrane. The emission from the prototropic forms of fisetin (neutral form, excited state anion, ground state anion and phototautomer form) is found to sensitively reflect the local heterogeneities in Tween20 : cholesterol (1 : 1) niosome membrane. The shift in anionic emission maximum with variation in temperature shows the sensitivity of fisetin towards water accessibility at the interfacial domain of Tween20 : cholesterol (1 : 1) niosome membrane. Zeta potential value confirms that there is no role of surface charge in the multiple prototropism of fisetin in Tween20 : cholesterol (1 : 1) niosome membrane. The microviscosity changes with temperature, as reflected in fluorescence anisotropy values of fisetin phototautomeric species FT*, give information about the temperature-induced changes in the motional resistance offered by the interfacial domain of the niosomal membrane to small molecules. A temperature-dependent fluorescence lifetime study confirms the distribution of FT* in the two different sites of niosomal interfacial domain, i.e. water-deficient inner site and water-accessible outer site. This heterogeneity in distribution of FT* is further confirmed through time-resolved fluorescence anisotropy decay resulting in two different rotational time constants (faster component of ∼1.04 ns originates from water-accessible outer site and slower component of ∼16.50 ns originates from water-deficient inner site). The interfacial location of fisetin in Tween20 : cholesterol (1 : 1) niosome membrane has an important implication with regards to antioxidant activity as confirmed from a DPPH radical scavenging study.

Establishing Structure Property Relationship in Drug Partitioning into and Release from Niosomes: Physical Chemistry Insights with Anti-Inflammatory Drugs

Understanding the physical chemistry underlying interactions of drugs with delivery formulations is extremely important in devising effective drug delivery systems. The partitioning and release kinetics of diclofenac sodium and naproxen from Brij 30 and Triton X-100 niosomal formulations have been addressed based on structural characterization, partitioning energetics, and release kinetics, thus establishing a relationship between structures and observed properties. Both the drugs partition in nonpolar regions of TX-100 niosomes via stacking of aromatic rings. The combined effects of interactions of the drugs with polar head groups and the rigidity of the niosome vesicles determine entry and partitioning of drugs into niosomes. The observed slower rate of release of the drugs from the drug encapsulated niosomes of TX-100 than those of Brij 30, suggest stable complexation of drugs in the nonpolar interior of the former. No release of drugs from the niosomes was observed until 24 h even upon varying pH conditions without SDS. However, SDS in drug loaded niosomes led to release of drugs in as early as 6 h. The sustained pattern of in vitro release kinetics of the drugs thus observed from our niosomal preparations suggest these vesicular systems to be promising for pharamaceutical applications as potential drug delivery vehicles.

pH-sensitive niosomes: Effects on cytotoxicity and on inflammation and pain in murine models

pH-sensitive nonionic surfactant vesicles (niosomes) by polysorbate-20 (Tween-20) or polysorbate-20 derivatized by glycine (added as pH sensitive agent), were developed to deliver Ibuprofen (IBU) and Lidocaine (LID). For the physical-chemical characterization of vesicles (mean size, size distribution, zeta potential, vesicle morphology, bilayer properties and stability) dynamic light scattering (DLS), small angle X-ray scattering and fluorescence studies were performed. Potential cytotoxicity was evaluated on immortalized human keratinocyte cells (HaCaT) and on immortalized mouse fibroblasts Balb/3T3. In vivo antinociceptive activity (formalin test) and anti-inflammatory activity tests (paw edema induced by zymosan) in murine models were performed on drug-loaded niosomes. pH-sensitive niosomes were stable in the presence of 0 and 10% fetal bovine serum, non-cytotoxic and able to modify IBU or LID pharmacological activity in vivo. The synthesis of stimuli responsive surfactant, as an alternative to add pH-sensitive molecules to niosomes, could represent a promising delivery strategy for anesthetic and anti-inflammatory drugs.

Non-Ionic Surfactant Vesicles (Niosomes) as New Drug Delivery Systems

Lipid vesicular systems composed of hydrated amphihiles with or without bilayer inducing agents such as cholesterol. On the basis of used amphiphilic molecule different nomenclature are used as liposomes, ufasomes and niosomes. Nonionic surfactants with mono-, di- or trialkyl chains form niosomes which are lipid vesicles with more chemical stability in comparison with phospholipids of liposomes. Both hydrophobic and hydrophilic chemicals can be encapsulated in niosomes as a new drug delivery system. This drug carrier system could have administered via injection, oral, pulmonary, vaginal, rectal, ophthalmic, nasal or transdermal routes with penetration enhancing potential. This chapter presents a detailed explain about niosome forming components, methods of preparation and routes of administration. Many examples for drug delivery potential of niosomes are also available in this review. Vaccine adjuvant and genetic substances vector capabilities are not given here.

Non-Ionic Surfactant Vesicles (Niosomes) as New Drug Delivery Systems

Lipid vesicular systems composed of hydrated amphihiles with or without bilayer inducing agents such as cholesterol. On the basis of used amphiphilic molecule different nomenclature are used as liposomes, ufasomes and niosomes. Nonionic surfactants with mono-, di- or trialkyl chains form niosomes which are lipid vesicles with more chemical stability in comparison with phospholipids of liposomes. Both hydrophobic and hydrophilic chemicals can be encapsulated in niosomes as a new drug delivery system. This drug carrier system could have administered via injection, oral, pulmonary, vaginal, rectal, ophthalmic, nasal or transdermal routes with penetration enhancing potential. This chapter presents a detailed explain about niosome forming components, methods of preparation and routes of administration. Many examples for drug delivery potential of niosomes are also available in this review. Vaccine adjuvant and genetic substances vector capabilities are not given here.

Temperature-dependent water penetration in Tween20:cholesterol niosome membrane: a study using excited state prototropism of 1-naphthol

The niosomal core region remains unaffected, whereas interfacial hydration occurs with an increase in temperature.

Unraveling the impact of hydroxylation on interactions of bile acid cationic lipids with model membranes by in-depth calorimetry studies

We used eight bile acid cationic lipids differing in the number of hydroxyl groups and performed in-depth differential scanning calorimetry studies on model membranes doped with different percentages of these cationic bile acids. These studies revealed that the number and positioning of free hydroxyl groups on bile acids modulate the phase transition and co-operativity of membranes. Lithocholic acid based cationic lipids having no free hydroxyl groups gel well with dipalmitoylphosphatidylcholine (DPPC) membranes. Chenodeoxycholic acid lipids having one free hydroxyl group at the 7'-carbon position disrupt the membranes and lower their co-operativity. Deoxycholic acid and cholic acid based cationic lipids have free hydroxyl groups at the 12'-carbon position, and at 7'- and 12'-carbon positions respectively. Doping of these lipids at high concentrations increases the co-operativity of membranes suggesting that these lipids might induce self-assembly in DPPC membranes. These different modes of interactions between cationic lipids and model membranes would help in future for exploring their use in DNA/drug delivery.

Niosomes from 80s to present: the state of the art

Efficient and safe drug delivery has always been a challenge in medicine. The use of nanotechnology, such as the development of nanocarriers for drug delivery, has received great attention owing to the potential that nanocarriers can theoretically act as "magic bullets" and selectively target affected organs and cells while sparing normal tissues. During the last decades the formulation of surfactant vesicles, as a tool to improve drug delivery, brought an ever increasing interest among the scientists working in the area of drug delivery systems. Niosomes are self assembled vesicular nanocarriers obtained by hydration of synthetic surfactants and appropriate amounts of cholesterol or other amphiphilic molecules. Just like liposomes, niosomes can be unilamellar or multilamellar, are suitable as carriers of both hydrophilic and lipophilic drugs and are able to deliver drugs to the target site. Furthermore, niosomal vesicles, that are usually non-toxic, require less production costs and are stable over a longer period of time in different conditions, so overcoming some drawbacks of liposomes. The niosome properties are specifically dictated by size, shape, and surface chemistry which are able to modify the drug's intrinsic pharmacokinetics and eventual drug targeting to the areas of pathology. This up-to-date review deals with composition, preparation, characterization/evaluation, advantages, disadvantages and application of niosomes.