(1972) was the first to report niosomes as a cosmetic industry feature. Niosomes, or non-ionic surfactant vesicular systems, were formed when a mixture of cholesterol and a single alkyl chain was hydrated, according to a 1979 study by Handjanivila et al. certain systems are now a practical method for enhancing results and delivering payload to certain locations. Applications for lipid vesicles have been discovered in the fields of genetic engineering, immunology, and membrane biology. Vesicles can also be employed to target and deliver API, as well as to imitate biological membranes.
All cells and organelles are surrounded and divided into sections by biological membranes, which act as universal delimiting structures. The sole organizational characteristic that all bio These are only one kind of experimental bio membrane models that provide insight into the motional dynamics and static structures of some isolated compartments of biological membranes and lipid vesicles. Although these models were created for fundamental study, their applications have led to several technical innovations, and lipid vesicles have successfully developed into appropriate vehicles for controlled distribution. Due to considerable "off-target" accumulation of the API and restricted payload cellular penetration, conventional chemotherapy is ineffective for treating intracellular infections. The application of vesicular drug delivery methods could get around this. It is possible for payload encapsulation in a vesicular structure to decrease "off-target" accumulation and become available in systemic circulation. Phagocytic absorption after systemic distribution of vesicular biological membranes has in common is the bilayer configuration of lipids.

fig: 1 structure of niosome

preparation of niosome:

surfactant: cholesterol in chloroform

(Thin film) citric acid (300 mm PH 4.0)

Free and thaw (3 time)

                                                                                                                                           sonicate

Drug in aqueous phase

vortex

Disodium phosphate

Heat 60 ⁰ c for 10 min

Niosome

fig: systematic representation of preparation of Niosome

It is possible to estimate the physicochemical stability and biological fate of niosome by identifying certain characteristics. Particle size (PS), Zeta potential (ZP), polydispersity index (PDI), particle shape, surface morphology, lamellarity, encapsulation efficiency, phase behavior/polymorphism, in vitro drug release, and in vivo performance are generally used to describe niosome.
3.1. Polydispersity Index (PDI) and Particle Size (PS):

Since niosome are thought to be spherical, laser light scattering can be used to calculate their mean diameter. The diameter of niosome can also be measured using TEM. The size of niosome has also been measured using optical microscopy, photon correlation microscopy, ultracentrifugation, and molecular sieve chromatography PS is a measure of noisome' capacity to cross biological barriers like the BBB, or blood-brain barrier. The BBB can be crossed by small particles, which is crucial for specific drug delivery to the brain or for macrophage phagocytosis in cases of illnesses like HIV/AIDS and tuberculosis. A modest PDI is typically recommended in order to allow accurate assessment of particle behavior. The PDI of a formulation is a measure of the particle size distribution of the niosome in the formulation.
Particle size and polydispersity analysis's most popular method, dynamic light scattering (DLS), photon correlation spectroscopy (PCS), or quasi-elastic light scattering, is used to evaluate a dispersion's PDI. DLS is used to track the particles' Brownian motion as a result of the Particle aggregations and individual particles cannot be distinguished by DLS, and the data cannot be cleansed of the impact of particle solubility. Particle size analysis with DLS is extremely sensitive to particle contamination, and the size determined by DLS is regarded as a hydrodynamic diameter.

3.2 Zeta Potential (ZP)

The ZP of niosome dispersions is determined by the formulation's constituents and is equivalent to the total of the surface charges. To evaluate the long-term stability of the technology, as well as the in vivo performance and the biological fate of the carriers, it is essential to analyse the surface charge of the niosome. Comparing big negative or positive charged noisome to neutral and mildly charged niosome, the former show minimal aggregation in a dispersion. The absence of electrostatic repulsive forces in neutral dispersions is the reason behind this.
When measuring ZP, DLS is utilized to calculate variations in scattered light intensity brought on by niosome mobility as a result of the applied electric field. on the charges of particles. The mobility of niosome is controlled by their surface charge, which modifies the scattered light's intensity.

3.3. The Efficiency of Encapsulation (EE)

The degree to which a payload has been successfully encapsulated by the noisome is measured by encapsulation efficiency, or EE. Quantitating the EE is essential since it affects the payload release rate and determines the dosage of the formulation that will ultimately be given.
Centrifugation of dialysis is used to remove any API that has not been encapsulated after a niosome dispersion has been made. After disrupting the vesicle with 50% v/v n-propanol or 0.1% w/v Triton X-100 solution, the payload of the noisome is calculated. A approved test approach for the payload is used to analyse the resulting.

4. Phase Conduct

Polymorphism is a crucial factor to take into account while assessing a system's stability and making API release predictions. When compared to amorphous niosome, crystalline niosome are more stable and show sustained drug release characteristics. The most popular methods for examining the phase behavior of nanosomic are crystallographic methods like X-ray diffraction (XRD) and thermal methods like thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Utilizing these methods to examine the temperature behavior and crystallinity of such a system, useful supplementary data can be produced for the characterization and quality assurance of niosome formulations.

3.5. Drug Release in Vitro

One of the most important parameters to control is the in vitro payload release behavior from niosome. This behavior involves the drug concentration, the bilayer's state, hydration volume, and rigidity. Dialysis membrane techniques are typically employed to study the release of drug compounds from niosome. A dialysis bag containing purified niosome suspension is closed on both ends and placed within a beaker filled with simulated body fluids or phosphate-buffered saline. The beaker is then kept at 37 °C with agitation. At prearranged intervals, samples are obtained and replaced with an equal volume of fresh medium. The concentration of payload delivered over time is then ascertained by analysing these samples using suitable quantitation techniques. Similar broad processes are followed by other alternative approaches that have been claimed to use Franz diffusion cells.

3.6. Elements of Surface Composition
In order to determine if the payload is adsorbed on the niosome surface, which may be a predictor of burst release and encapsulation efficiency, surface composition of the niosome is a crucial metric.
For this, elemental dispersive spectroscopy (EDX), a method combined with SEM, has been employed extensively. Although not frequently applied to niosome, the method has been successfully applied to liposomes to ascertain whether effective drug loading took place.
Another method that might be helpful for figuring out the surface elemental composition of noisome is X-ray photoelectron spectroscopy, or XPS. Although its usage in liposomes has been documented and can be extrapolated to niosome, its use in niosome has not been recorded.

3.7. Formation of Bilayers

Using light polarization microscopy, the assembly of non-ionic surfactants to create bilayered vesicles is identified by the creation of an X-cross It is also possible to demonstrate the development of bilayers using stained transmission electron microscopy (TEM).

3.8. Lamelae Number

TEM, small angle X-ray scattering, and nuclear magnetic resonance (NMR) spectroscopy are used to determine the number of lamellae.

3.9. Stiffness of Membranes  

The mobility of a fluorescent probe as a function of temperature can be used to determine the stiffness of a membrane. Regarding drug release, the niosome bilayer's stiffness directly affects both in vitro and in vivo performance.

Factor affecting on niosome: