Molecular Order Parameter Profiles and Diffusion Coefficients of Cationic Lipid Bilayers on a Solid Support

Abstract

The molecular order and lateral diffusion in fluid cationic bilayers of chain perdeuterated DPTAP (1,2dipalmitoyl-d62-trimethylammonium-propane) on a spherical solid support were studied by deuterium NMR and microcalorimetry. In comparison to the zwitterionic perdeuterated DPPC (1,2-dipalmitoyl-d62sn-glycero-3-phosphocholine), the molecular order parameter profile of the palmitoyl chains of DPTAP shows significantly higher molecular order toward the interface while similar values were obtained in the vicinity of the bilayer center. The lateral diffusion coefficient D of DPTAP is D ) (13.2 ( 1.5) × 10 -12 m 2 /s at 60 °C, slightly below that of DPPC at this temperature. Increasing the ionic strength caused the value of D to decrease further. The results suggest that despite the cationic charge the supported DPTAP bilayer features tighter molecular packing and a reduced lateral diffusivity of its constituents than for the zwitterionic DPPC on a solid support.

Cluster Formation of Polyphilic Molecules Solvated in a DPPC Bilayer

“…The difference in the side chain orientation and configuration is also in good agreement with the simulation results we obtained before [35]. In general, the conclusions drawn from simulations are consistent with experimentally observed effects [16,17,42]. We anticipate that these findings will be important for understanding the role of polyphilic molecules in modulating and modifying bilayer properties.…”

“…The calculated self-diffusion coefficient of pure DPPC at 335K as presented in Table 1 is in very good agreement with the experimentally determined value of 14.2 ± 1.2 ×10−123.33333ptm2/normals [42]. The diffusion coefficient of B16/10 molecules is slightly lower than the diffusion coefficient of the lipids in a pure bilayer.…”

Electrostatic effects on deposition of multiple phospholipid bilayers at oxide surfaces

“…Substrate surface chemistry, charge, and morphology affect membrane properties such as fluidity, permeability, domain formation, asymmetric molecular distribution across leaflets in mixed bilayers, and thermotropic behavior [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57]. Depending on the potential application, a need exists to investigate mechanisms of vesicle rupture and SPB formation in particle suspensions, as compared to the planar single-crystal surfaces that have predominantly been used in past studies.…”

A Phospholipid Bilayer Supported under a Polymerized Langmuir Film

“…Up to now, classical methods to prepare SPB include i), sequential Langmuir-Blodgett (LB)-Langmuir-Schaeffer (LS) transfer of two monolayers from the air-water interface to a hydrophilic support (Tamm and McConnell, 1985), and ii), adsorption, fusion, and rupture of small unilamellar vesicles (SUV) on a clean hydrophilic support (Brian and McConnell, 1984;Reviakine and Brisson, 2000;Keller et al, 2000). This later method, which results in a fluid (Tamm, 1988;Cézanne et al, 1999;Junglas et al, 2003) and rather homogeneous bilayer (Mou et al, 1994;Egawa and Furusawa, 1999;Jass et al, 2000), is ideal for the incorporation of membrane proteins in the bilayer (Watts et al, 1984;Nakanishi et al, 1985;Contino et al, 1994;Granéli et al, 2003). Some alternatives to these methods were developed later.…”