Effects of mono- and di-valent metal cations on the morphology of lipid vesicles.

Lipid vesicles are an attractive model membrane experimental platform that is widely used in a biological context. The stability of vesicles can affect their performance and depends on various experimental conditions. How bio-related ions affect vesicle morphology is poorly understood in some cases. Herein, we investigated changes in vesicle morphology influenced by cation in the static and flowing environments. The effects of different mono- and di-valent metal cations on the morphology of lipid vesicles were systematically studied using the various techniques. The results showed that divalent cations caused significant aggregation or fusion of lipid vesicles, but monovalent cations had little effect on the vesicle morphology. Cation binding increased the net surface potential of vesicles, leading to changes in the zeta potential. The same qualitative kinetics were observed for cations that had the same valence at the same ionic strength. However, different types of cations gave different quantitative effects. The order of the ability to destroy the vesicle morphology was Cu2+ > Mg2+ > Ca2+ > Na+ > K+. These results are of practical value in the use of lipid vesicles as a bionic model, and help to shed light on the role of ions at membrane surfaces and interfaces.

Preparation of a beta-tricalcium phosphate nanocoating and its protein adsorption behaviour by quartz crystal microbalance with dissipation technique.

Beta-tricalcium phosphate (ß-TCP) nanocoatings, which can be analysed using a quartz crystal microbalance with dissipation technique (QCM-D), were fabricated on a gold surface by electrophoretic deposition. The influences of electric field intensity and electrophoresis time were investigated. The adsorption behaviours of bovine serum albumin (BSA) and lysozyme (LSZ) on Au and ß-TCP surfaces were observed in real time by QCM-D. The homogeneous ß-TCP nanocoating with moderately sized particles on gold surface was fabricated at 25V/cm for 5min, and it met the requirements for the QCM-D experiment. The adsorption behaviour of BSA was different from that of LSZ, which was caused by the differences of protein properties. The adsorption quantity of BSA on a ß-TCP surface was higher than that on a gold surface. However, the adsorption amount of LSZ on a ß-TCP surface was lower than that on a gold surface. The electrostatic force was the major factor affecting the adsorption quantities of BSA and LSZ on Au and ß-TCP surfaces based on the investigation of various factors. The findings reported here will be useful for understanding the mechanism of the interaction between biomaterials and proteins.