Thermodynamic Characteristics And Direct AFM Observation Of Binary Mixtures Of Lipid Molecules With Amphotericin B

A Study found that the half permeability of biological film and the boundary nature are closely linked to many life functions, biological film researching has related to materials,medical and other fields, and increasingly become one of active forefront subject in the bio-medical and biological physics.this article use phosphatidylcholine, phosphatidylethanolamine and cholesterol as basic framework of biological film, and Langmuir-Blodgett (LB) films were used to prepared amphotericin B and lipid molecules mixed monolayer. Studing thermodynamic properties of amphotericin B and lipid molecules mixed monolayer at water/air interface by surface pressure-mean molecular area (Ï€-A) curves. According to data, we have calculated elastic modulus (CS-1), excess molecular area (Aex) and surface excess Gibbs free energy (AGex) and other thermodynamic parameters.based on molecular fusion level, we quantificational analysed dynamics and thermodynamic properties that between mixed monolayers. surface detection of biological film by atomic force microscopy(AFM),further indicated the theory of molecular dynamics and thermodynamic properties.Binary mixtures isotherms between amphotericin B,cholesterol and phosphatidyl ethanolamine with different proportion are showed regular arrangement, as amphotericin B content increaseing, the compressibility of mixed monolayers reduceing and terminal membrane pressure presents decreaseing gradually. At amphotericin B/cholesterol monolayers, the changing of excess molecular area and excess Gibbs free energy has related with surface film pressure and amphotericin B levels. At amphotericin B/phosphatidylethanolamine mixed monolayer, the excess Gibbs free energy and excess molecular size took on redular deviation, near XAmB=0.6, monolayer film has better mix property and stability.Ternary hybrid systems isotherms among amphotericin B, cholesterol and phosphatidyl ethanolamine with different proportion are showed regular arrangement. In amphotericin B/ phosphatidylcholine/cholesterol mixed monolayer film, when surface pressure 5,10 and 15mN, deviation level of the thermodynamic parameters would increaing as surface pressure increasing, At surface 20mN,appeared reverse deviation.In the amphotericin B/phosphatidylethanolamine/ cholesterol ternary mixed monolayer film, when the concentration of amphotericin B that XAmB= 0.2,0.6, an deviation occurred minimum;deviation of excess Gibbs free energy would enhance along with surface pressure increasing,near XAmB=0.6, we found minimum deviation.Under fixed surface pressure, binary and ternary mixed monolayer system between AmB and lipid molecules with different molar ratio, AFM images reflected the height information of monolayer. We can see the structure,which has mixed monolayer cohesion, sheet, rod, mesh, chain, particles and LB film defects from the images, though analysed the structural change of AmB mixed monolayer with different molar ratio, further indicated the theory of molecular film thermodynamic properties and mutual action.