Adsorption and Desorption Behaviors of Cationic Liposome-DNA Complexes upon Lipofection in Inside and Outside Biomembrane Models Using a Dynamic Quasi-Elastic Laser Scattering Method

Abstract

Biomembranes play important roles in mass transfer, molecular recognition, and energy flow on membrane surfaces. Biomembranes are composed of many kinds of phospholipids and form bilayers by stacking the hydrophobic alkyl chain parts on the inside of the membrane. The major phospholipids in the cell organelle are phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylcholine (PC), sphingomyelin (SM), and phosphatidylinositol (PI). Interestingly, the composition of these phospholipids is asymmetric on the inside and outside of the cell membrane. The composition depends on the kind of cell and on the organelles.1,2 In general, the major parts of the PE and PS are in the inner half of the lipid bilayer, while PC and SM are mainly observed in the outer half.1,2 The different constitutions induce different structures and properties of biomembranes; such structures and properties are believed to be closely related to the recognition and selective transfer of exogenous biomolecules on the cell surfaces. However, the mechanisms governing the asymmetric constitution in the inside and outside monolayers are not clearly understood. The way in which they induce different dynamic behaviors of exogenous biomolecules into cells is not clear. Thus, it is intriguing and important to investigate the differences in the dynamic behaviors of exogenous biomolecules on the inner and outer surfaces of cells in order to understand how exogenous molecules are recognized and incorporated into the bilayer of a biomembrane.Lipofection is one of the most powerful techniques of DNA transfection into living cells by the use of liposomes. Among various kinds of liposomes, cationic ones are efficient in gene transfer because they can strongly interact with DNAs and can spontaneously form cationic liposome-DNA complexes. They fuse the plasma membrane of cells and facilitate the delivery of functional DNA into the nucleus at high probability.3-11 Many studies have reported on the improvement of the transfection efficiency as a result of the development of synthetic cationic liposome.3-11 These studies were significant in the investigations of gene function 12-18 and gene therapy [19][20][21][22][23][24][25][26][27][28][29][30] in a broad range of diseases; the processes are safe, simple, and non-immunogenic.A number of studies of DNA, cationic liposomes, and their complexes at solid/liquid, air/liquid, and liquid/liquid interfaces have been conducted to investigate the structures and properties of DNA-surfactant complexes at interfaces using UV-visible spectrophotometry, The dynamic behaviors of cationic liposome-DNA complexes in inside and outside biomembrane models upon lipofection were investigated using the time-resolved quasi-elastic laser scattering (QELS) method. Inside and outside biomembrane models with similar phospholipid compositions to those in living cells were formed at a tetradecane/phosphate buffered saline (TD/PBS) interface. Cationic liposome-DNA complexes were injected into the buffer subphase, and their adsorption...

Aerosol Droplet Surface Measurement Methods

“…14,15 The technique relies on two phenomena to achieve aerosol droplet capture and surface tension analysis, the first is the use of a focused laser that acts as an optical tweezer, and the second is the use of quasi-elastic laser scattering (QELS). [32][33][34][35][36][37][38][39][40] Spontaneous spherical resonance occurs as a result of thermal fluctuations at the surface of the liquid droplet, which can be observed in the Hz range of frequencies in a QELS spectrum. Figure 6 shows the experimental setup used to immobilize aerosol droplets using an optical tweezer as well as the use of QELS to analyze the spherical resonance modes at the droplet surface.…”