Investigation of Shape Transformations of Vesicles, Induced by Their Adhesion to Flat Substrates Characterized by Different Adhesion Strength

The adhesion of lipid vesicles to a rigid flat surface is investigated. We examine the influence of the membrane spontaneous curvature, adhesion strength, and the reduced volume on the stability and shape transformations of adhered vesicles. The minimal strength of the adhesion necessary to stabilize the shapes of adhered vesicles belonging to different shape classes is determined. It is shown that the budding of an adhered vesicle may be induced by the change of the adhesion strength. The importance of the free vesicle shape for its susceptibility to adhesion is discussed.

Vesicle shape transformations driven by confined active filaments

In active matter systems, deformable boundaries provide a mechanism to organize internal active stresses. To study a minimal model of such a system, we perform particle-based simulations of an elastic vesicle containing a collection of polar active filaments. The interplay between the active stress organization due to interparticle interactions and that due to the deformability of the confinement leads to a variety of filament spatiotemporal organizations that have not been observed in bulk systems or under rigid confinement, including highly-aligned rings and caps. In turn, these filament assemblies drive dramatic and tunable transformations of the vesicle shape and its dynamics. We present simple scaling models that reveal the mechanisms underlying these emergent behaviors and yield design principles for engineering active materials with targeted shape dynamics.

Formulation and Evaluation of Lignocaine Hydrochloride Proniosomes Loaded Orabase for Dental Anaesthesia

The aim of this research is to prepare and evaluate lignocaine HCl Proniosomal orabase for enhanced permeation and prolonged dental anaesthesia effect. Objective: Various lignocaine proniosomal gels were formulated employing various surfactants. Methods: The formulations were scrutinized for entrapment efficiency, optical microscopy, in-vitro diffusion and release studies, mucoadhesive strength, ex-vivo permeation studies and drug – excipient interactions were determined by FTIR spectroscopy. Results: span 80 was found to be superior and significant for loading in to orabase. Considering the best entrapment efficiency with span 80 (91.60%) and optimum vesicle shape, along with prolonged drug permeation (33.6% for 24 h) the formulation F4 was selected and optimized for loading into orabase. The formulation F4 loaded orabase exhibited significant prolonged release over 10 h, and permeation profiles exhibited nearly two – fold increased flux in comparison with control. Good mucoadhesive strength was observed for proniosomal orabase 6273dynes/cm2, No evidence of incompatibility amongst formulation components from FTIR studies. SEM images revealed the particle size range from 50 μmt to 100 μmt for proniosomal orabase. Conclusion: Orabase can be an effective carrier for proniosomes with enhanced retention time at the site of application and provide prolonged release for oro-dental conditions. Keywords: lignocaine Hcl, Oro-dental anaesthesia, Proniosomal gel, Orabase, Entrapment efficiency, prolonged release.

The effect of polydispersity, shape fluctuations and curvature on small unilamellar vesicle small-angle X-ray scattering curves

Small unilamellar vesicles (20–100 nm diameter) are model systems for strongly curved lipid membranes, in particular for cell organelles. Routinely, small-angle X-ray scattering (SAXS) is employed to study their size and electron-density profile (EDP). Current SAXS analysis of small unilamellar vesicles (SUVs) often employs a factorization into the structure factor (vesicle shape) and the form factor (lipid bilayer electron-density profile) and invokes additional idealizations: (i) an effective polydispersity distribution of vesicle radii, (ii) a spherical vesicle shape and (iii) an approximate account of membrane asymmetry, a feature particularly relevant for strongly curved membranes. These idealizations do not account for thermal shape fluctuations and also break down for strong salt- or protein-induced deformations, as well as vesicle adhesion and fusion, which complicate the analysis of the lipid bilayer structure. Presented here are simulations of SAXS curves of SUVs with experimentally relevant size, shape and EDPs of the curved bilayer, inferred from coarse-grained simulations and elasticity considerations, to quantify the effects of size polydispersity, thermal fluctuations of the SUV shape and membrane asymmetry. It is observed that the factorization approximation of the scattering intensity holds even for small vesicle radii (∼30 nm). However, the simulations show that, for very small vesicles, a curvature-induced asymmetry arises in the EDP, with sizeable effects on the SAXS curve. It is also demonstrated that thermal fluctuations in shape and the size polydispersity have distinguishable signatures in the SAXS intensity. Polydispersity gives rise to low-q features, whereas thermal fluctuations predominantly affect the scattering at larger q, related to membrane bending rigidity. Finally, it is shown that simulation of fluctuating vesicle ensembles can be used for analysis of experimental SAXS curves.

Formulation optimisation and characterisation of azithromycin proniosome

The research was featured to formulate, characterise and optimise the Azithromycin Proniosome using the three-factor three-level Box Behnken scheme. The independent variables chosen were span 20 (X1), span 80 (X2) and phospholipids (X3) to assess their individual and shared response on entrapment efficiency (Y1) and % drug released at six h (Y2). Based on Box Behnken design, 15 formulations were prepared and optimised using Design Expert Version 12.0.10.0. The entrapment efficiency and in-vitro drug release were exposed to different regressions to setup a polynomial equation. The counterplots understood the connections between the independent and dependent factors. The congruity of the polynomial equations was tested by fixing three checkpoint groups. The optimised formulation was determined by point prediction method using the various constraints. The optimised batch was subjected to multiple parameters such as vesicle shape, viscosity, spread ability, drug content, entrapment efficiency, in-vitro drug diffusion and stability studies. The optimised formulation shows better physical and chemical stability which is confirmed by the results of various parameters. The in-vitro drug diffusion has observed to be 98.53% at 24th h obeying zero-order drug release with diffusion mediated non-fickian type of drug release kinetics. The formulation preserved at both refrigerated and room temperature shows better stability. This approach might be an additional finding in enhancing the adherence of patient and improves compliance.

Active shape oscillations of giant vesicles with cyclic closure and opening of membrane necks

During each active oscillation cycle, the vesicle shape undergoes a symmetry-breaking transformation from an up-down symmetric to an up-down asymmetric dumbbell followed by the reverse symmetry-restoring transformation.

DMPC vesicle structure and dynamics in the presence of low amounts of the saponin aescin

Vesicle shape and bilayer parameters are studied by small-angle X-ray (SAXS) and small-angle neutron (SANS) scattering in the presence of the saponin aescin. Bilayer dynamics is studied by neutron spin-echo (NSE) spectroscopy.

Nanoparticle wrapping at small non-spherical vesicles: curvatures at play

Wrapping of nanoparticles that enter and exit vesicles depends on several important parameters, such as particle size and shape, vesicle size and reduced volume, and membrane spontaneous curvature. This implies complex wrapping behavior where particle wrapping transitions and vesicle shape transitions are intimately coupled.