Mixed monolayers of Bauhinia monandra and Concanavalin A lectins with phospholipids, part II

Thermodynamic characterization of the prevailing molecular interactions in mixed floating monolayers of phospholipids and usnic acid

“…1 and 3, one can see that the total dipole moments of the floating molecules begin to rearrange and influence the electrical properties of the interface at mma values of 0.6 nm 2 for the pure UA film and at 0.7, 0.7, and 1.0 nm 2 for the DBPC/UA, DPPC/UA, and DOPC/UA mixed monolayers, respectively. In a recent investigation of the properties of mixed floating monolayers of these phospholipids with lectins [24], it was established that while the V -A relationships for DPPC and DBPC do not parallel those observed in the corresponding Π -A isotherms, in fact, they amplified the effect of the chain length on the interfacial behavior of these two lipids, mainly due to effects associated to the orientation of the intrinsic molecular dipole of the molecules forming the film and of the organizational structure of water molecules in the subphase. As for DOPC, the double bond present in its aliphatic chain has a direct effect on the observed V -A profile, where a noticeable surface potential can be observed even at the beginning of the compression; at both low and intermediate compression regimes, the DOPC molecules reorient themselves much more easily to a more vertical position with respect to the water plane.…”

Measuring Selective Estrogen Receptor Modulator (SERM)–Membrane Interactions with Second Harmonic Generation

“…68,69 In contrast, the limiting area per molecule of DOPC lipids at the collapse pressure (46 mN/m) was 67.5 Å 2 . 70 Thus, significantly more space between lipids is available for drug intercalation in DOPC bilayers compared to DMPC bilayers, which may account for differences in binding constants. The MMA of DPPC lipids is about 50 Å 2 , 70 which suggests that SERMs do not adsorb to DPPC because the closely packed acyl chains did not allow for small molecule penetration.…”

“…70 Thus, significantly more space between lipids is available for drug intercalation in DOPC bilayers compared to DMPC bilayers, which may account for differences in binding constants. The MMA of DPPC lipids is about 50 Å 2 , 70 which suggests that SERMs do not adsorb to DPPC because the closely packed acyl chains did not allow for small molecule penetration. The loose packing of the acyl chains of DOPC and DMPC allowed sufficient space for SERMs to intercalate.…”

“…phase DOPC lipids. The mean molecular area (MMA) of DMPC at 22 °C was measured to be 58 Å 2 at a surface pressure (Π) of 30 mN/m. , In contrast, the limiting area per molecule of DOPC lipids at the collapse pressure (46 mN/m) was 67.5 Å 2 . Thus, significantly more space between lipids is available for drug intercalation in DOPC bilayers compared to DMPC bilayers, which may account for differences in binding constants.…”

Characteristics of Phospholipid–Immunosuppressant–Antioxidant Mixed Langmuir–Blodgett Films

“…In addition, the surface coverage in molecules cm –2 , which was determined by considering the averaged molecular weight of the components, attending their molar fraction in the mixture is presented in the Supporting Information (Figure S4). For one-component monolayers, the experimental surface coverage was compared with the theoretical one calculated on the basis of a limiting area of DOPC (67 Å 2 molecule –1 ), , a molecular area in both vertical (182 Å 2 molecule –1 ) and horizontal (374 Å 2 molecule –1 ) position for CsA, and a molecular model for the vertically arranged molecule for LG (24 Å 2 molecule –1 ; Spartan 08 V 1.2.0). The theoretical molecular area ( A t ) is shown in Table .…”