Metallosurfactant based synthetic liposomes as a substitute for phospholipids to safely store curcumin

Curcumin has shown remarkable therapeutic utilization for various medical conditions. Still, its limited chemical stability and rapid hydrolysis capped its applications to a certain extent. Approaches have been made in the past to surpass these shortcomings by encapsulating the drug in surfactant-based micelles or liposomes and so far, natural surfactants have been used to do this bidding. Through this report, we are presenting curcumin entrapped inside synthetic metal-based liposomal assembly (metallosomes) based on hybrid-surfactants known as metallosurfactants (MS). Three metallosomes i.e. metallosomes (a), (b), and (c) were synthesized with increasing cholesterol (Chl) ratio w.r.t MS (MS:Chl 1:0, 1:0.5, and 1:1). Firstly, the membrane properties of the metallosomes were studied in the absence of the drug. The studies confirmed the direct influence of Chl concentration on the membrane properties and the metallosomes were found to be more hydrophobic, rigid, homogenous, stable, and less fluid with Chl incorporation. These studies were proven beneficial when drug-loaded metallosomes were studied and metallosomes (c), with the highest Chl content, emerged as the maximum drug loader due to their most hydrophobic nature. However, the drug was released at the slowest rate for this metallosomal system due to its less fluid and more rigid nature. On the other hand, these metallosomes were more efficient for shielding entrapped drug from acidic and alkaline environs as lesser drug degradation was observed in the experiments compared to the free curcumin. These metallosomes also exhibited efficient interactional behavior with bacterial (MRSA) DNA.

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.

Glucose-triggered dissolution of phenylboronic acid-functionalized cholesterol-based niosomal self-assembly for tuneable drug release

Cholesterol-containing phenylboronic acid-based niosomal self-assemblies showed glucose-responsive dissolution and release of an encapsulated drug.

Effect of Indole-3-Carbinol on Dimyristoylphosphatidylcholine Multilamellar Vesicles

This study reports the interaction of indole-3-carbinol (I3C), which is a chemopreventive reagent, with an artificial model membrane {(dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLVs)}, using the intrinsic fluorescence properties of I3C, extrinsic fluorescence properties of Nile Red (NR), differential scanning calorimetry (DSC), dynamic light scattering (DLS), and confocal microscopy. The intrinsic fluorescence of I3C helps to provide information about its location, partitioning ability, and sensitivity toward the phase-transition temperature of liposomes, confirmed by cetylpyridinium chloride (CPC) quenching study, partition coefficient values {(4.60 ± 0.1) × 10⁵ (solid gel phase) and (7.29 ± 0.1) × 10⁵ M^-1 (liquid crystalline phase)} and temperature-dependent emission behavior of I3C. I3C perturbs the DMPC MLVs above 15 mol %, as observed using the fluorescence properties of NR, DSC, and DLS data. This perturbation occurs as a consequence of interfacial hydration of the DMPC MLVs, which was clearly indicated by the fluorescence properties (emission intensity, fluorescence lifetime, and nonextensive distribution analysis) of NR.

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.