6 research outputs found
Lateral Heterogeneity of Dipalmitoylphosphatidylethanolamine−Cholesterol Langmuir−Blodgett Films Investigated with Imaging Time-of-Flight Secondary Ion Mass Spectrometry and Atomic Force Microscopy
Influence of Molecular Environment on the Analysis of Phospholipids by Time-of-Flight Secondary Ion Mass Spectrometry
Investigating lipid interactions and the process of raft formation in cellular membranes using ToF-SIMS
Gel Formulation Containing Mixed Surfactant and Lipids Associating with Carboplatin
The interaction of amphiphilic molecules such as lipids and surfactants with the hydrophilic drug carboplatin was investigated to identify suitable self-assembling components for a potential gel-based delivery formulation. 1H-NMR Studies in sodium bis(2-ethylhexyl) sulfosuccinate (aerosol-OT, AOT)-based reverse micelles show that carboplatin associates and at least partially penetrates the surfactant interface. Langmuir monolayers formed by dipalmitoyl(phosphatidyl)choline are penetrated by carboplatin. Carboplatin was found to also penetrate the more rigid monolayers containing cholesterol. A combined mixed surfactant gel formulation containing carboplatin and cholesterol for lymphatic tissue targeting was investigated for the intracavitary treatment of cancer. This formulation consists of a blend of the surfactants lecithin and AOT (1?:?3 ratio), an oil phase of isopropyl myristate, and an aqueous component. The phases of the system were defined within a pseudo-ternary phase diagram. At low oil content, this formulation produces a gel-like system over a wide range of H2O content. The carboplatin release from the formulation displays a prolonged discharge with a rate three to five times slower than that of the control. Rheological properties of the formulation exhibit pseudoplastic behavior. Microemulsion and Langmuir monolayer studies support the interactions between carboplatin and amphiphilic components used in this formulation. To target delivery of carboplatin, two formulations containing cholesterol were characterized. These two formulations with cholesterol showed that, although cholesterol does little to alter the phases in the pseudo-ternary system or to increase the initial release of the drug, it contributes significantly to the structure of the formulation under physiological temperature, as well as increases the rate of steady-state discharge of carboplatin
Structure Dependence of Pyridine and Benzene Derivatives on Interactions with Model Membranes
Pyridine-based
small-molecule drugs, vitamins, and cofactors are
vital for many cellular processes, but little is known about their
interactions with membrane interfaces. These specific membrane interactions
of these small molecules or ions can assist in diffusion across membranes
or reach a membrane-bound target. This study explores how minor differences
in small molecules (isoniazid, benzhydrazide, isonicotinamide, nicotinamide,
picolinamide, and benzamide) can affect their interactions with model
membranes. Langmuir monolayer studies of dipalmitoylphosphatidylcholine
(DPPC) or dipalmitoylphosphatidylethanolamine (DPPE), in the presence
of the molecules listed, show that isoniazid and isonicotinamide affect
the DPPE monolayer at lower concentrations than the DPPC monolayer,
demonstrating a preference for one phospholipid over the other. The
Langmuir monolayer studies also suggest that nitrogen content and
stereochemistry of the small molecule can affect the phospholipid
monolayers differently. To determine the molecular interactions of
the simple N-containing aromatic pyridines with a membrane-like interface, <sup>1</sup>H one-dimensional NMR and <sup>1</sup>H–<sup>1</sup>H two-dimensional NMR techniques were utilized to obtain information
about the position and orientation of the molecules of interest within
aerosol-OT (AOT) reverse micelles. These studies show that all six
of the molecules reside near the AOT sulfonate headgroups and ester
linkages in similar positions, but nicotinamide and picolinamide tilt
at the water–AOT interface to varying degrees. Combined, these
studies demonstrate that small structural changes of small N-containing
molecules can affect their specific interactions with membrane-like
interfaces and specificity toward different membrane components