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The influence of cholesterol fraction in the membranes of giant unilamellar vesicles (GUVs) on their size distributions and bending moduli has been investigated. The membranes of GUVs were synthesized by a mixture of two elements: electrically neutral lipid 1, 2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cholesterol and also a mixture of three elements: electrically charged lipid 1,2-dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (DOPG), DOPC and cholesterol. The size distributions of GUVs have been presented by a set of histograms. The classical lognormal distribution is well fitted to the histograms, from where the average size of vesicle is obtained. The increase of cholesterol content in the membranes of GUVs increases the average size of vesicles in the population. Using the framework of Helmholtz free energy of the system, the theory developed by us is extended to explain the experimental results. The theory determines the influence of cholesterol on the bending modulus of membranes from the fitting of the proper histograms. The increase of cholesterol in GUVs increases both the average size of vesicles in population and the bending modulus of membranes.

Irreversible electroporation (IRE) is a nonthermal tumor/cell ablation technique in which a series of high-voltage short pulses are used. As a new approach, we aimed to investigate the rupture of giant unilamellar vesicles (GUVs) using the IRE technique under different osmotic pressures (Π), and estimated the membrane tension due to Π. Two categories of GUVs were used in this study. One was prepared with a mixture of dioleoylphosphatidylglycerol (DOPG), dioleoylphosphatidylcholine (DOPC) and cholesterol (chol) for obtaining more biological relevance while other with a mixture of DOPG and DOPC, with specific molar ratios. We determined the rate constant (kp) of rupture of DOPG/DOPC/chol (46/39/15)-GUVs and DOPG/DOPC (40/60)-GUVs induced by constant electric tension (σc) under different Π. The σc dependent kp values were fitted with a theoretical equation, and the corresponding membrane tension (σoseq) at swelling equilibrium under Π was estimated. The estimated membrane tension agreed well with the theoretical calculation within the experimental error. Interestingly, the values of σoseq were almost same for both types of synthesized GUVs under same osmotic pressure. We also examined the sucrose leakage, due to large osmotic pressure-induced pore formation, from the inside of DOPG/DOPC/chol(46/39/15)-GUVs. The estimated membrane tension due to large Π at which sucrose leaked out was very similar to the electric tension at which GUVs were ruptured without Π. We explained the σc and Π induced pore formation in the lipid membranes of GUVs.

Spinel magnetite (Fe3O4) nanoparticles (MNPs) were successfully synthesized from the reduction of stoichiometric ratio of aqueous solutions of Fe2+ and Fe3+ with NaOH solution. Then naturally available Ipomoea aquatica leaf aqueous extract (IA extract) was used for the surface modification of MNPs where biomolecules of leaf extract were acted as stabilizer. Gas chromatography‐mass spectrometry (GC‐MS), Fourier transform infrared (FT‐IR), and energy dispersive X‐ray (EDX) analyses evidence the proper incorporation of the biomolecules of leaf extract in MNPs. X‐ray diffraction (XRD) confirms the synthesis of MNPs where the uniform size distribution with spherical shape was approved by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses. Thermal analysis was performed using differential scanning caloremetry (DSC) and thermogravimetric analysis (TGA) and a phase transition from Fe3O4 to maghemite (γ‐Fe2O3) was detected at 650 °C. The superparamagnetic nature of the studied materials at room temperature was confirmed by vibrating sample magnetometer (VSM) study and the correlation among saturation magnetization (Ms), crystallite size (D), particle size (d), dislocation density (δ), and microstrain (ϵ) were described. The antibacterial activity of the synthesized MNPs was confirmed by investigating the zones of inhibition which were 19 mm for Gram‐negative bacteria Escherichia coli and 14 mm for Gram‐positive bacteria Bacillus subtilis.