Stability and characterization of phospholipid Langmuir-Blodgett films

Influence of Pyrene-Based Fluorescent Probes on the Characteristics of DMPA/DMPC Langmuir−Blodgett Films

“…The presence of DPPC in the monolayer helps keep the value of the transfer ratio at the downstroke close to 1, whereas when the pyrene moiety is linked to the end of the sn -2 acyl chain of DPPC, the transfer ratio at the downstroke is lower than 1. As previously shown in Table , the transfer of the DMPA/DMPC monolayer, at 40 mN·m -1 gives YZ-type multilayers; to obtain Y-type multilayers (Table ), it is necessary either to add DPPC to the monolayer in a sufficient amount or to increase the transfer pressure (the latter possibility is in agreement with the results reported by Matuoka et al . with DPPA).…”

Direct Influence of the Interaction between the First Layer and a Hydrophilic Substrate on the Transition from Y- to Z-Type Transfer during Deposition of Phospholipid Langmuir−Blodgett Films

“…The inefficient transfer of the first layer onto the silanized glass surface is probably the reason which explains the difference in results obtained with the two types of glass surface. The necessity to increase the transfer surface pressure to enhance the transfer effectiveness corroborates the results reported by Matuoka et al 7 for the transfer of a DPPA monolayer onto a glass substrate in the presence of calcium ions. Indeed, these authors have obtained a transfer ratio lower than 0.5 on the down trip when the transfer surface pressure was less than 30 mN‚m -1 ; by increasing the surface pressure to 40 mN‚m -1 , they obtained an improvement of the transfer ratio to 0.9-1.1 for the down trips.…”

Thermodynamic characteristics and Langmuir–Blodgett deposition behavior of mixed DPPA/DPPC monolayers at air/liquid interfaces

“…However, the collapse pressures of DPPA and mixed DPPA/DPPC monolayers increased slightly. This effect can be attributed to the coupling of negatively charged DPPA molecules with Ca 2+ ions [23,25,27]. Because each Ca 2+ ion can associate with two DPPA molecules or even more to form the polymeric arrangement, the DPPA molecules in the monolayer may be tighter packed and thus become more stable at higher surface pressures.…”

“…The effects of CaCl 2 on the stabilization of a DPPA monolayer may be attributed to the association of Ca 2+ ions with negatively charged DPPA molecules. The electrostatic repulsion between head groups of DPPA molecules could be reduced by the adsorption of Ca 2+ ions, and besides, DPPA molecules could be tightly associated with each other by the bridging of Ca 2+ ions [23,25]. Both effects are supposed to stabilize the monolayer at the air/liquid interface.…”

“…One possible strategy to enhance the poor LB transfer characteristic of a DPPC monolayer is to incorporate a transfer promoter as a mixed monolayer during deposition. Since dipalmitoylphosphatic acid (DPPA) is a compound that is possible to form Y-type multilayer LB films [18,[22][23][24], it may be utilized as a transfer promoter for deposition of DPPC LB films. Such strategy has been successfully adopted by Girard-Egrot et al [18] to fabricate multilayer LB films for a mixed DPPA/DPPC monolayer with the presence of Ca 2+ ions in a buffer subphase.…”