Phase state of foam bilayer NBF from amniotic fluid

Phase state of Foam Bilayer (NBF) from Amniotic Fluid 

As it is well known [36,37], the natural lipid/protein mixtures (such as amniotic fluid) can undergo different phase transitions due to variation in temperature or composition. Of special importance for the natural bilayer lipid membranes is the so-called main phase transition between the lipid crystalline and gel states at which a melting of the hydrocarbon tails of the lipid molecules occurs. For example, it has been demonstrated [36] that there exists an upper limit of the gel phase content in membranes above which the membrane morphology and permeability change dramatically thus making the execution of the physiological functions of the membrane impossible. 

The phase state of AF foam bilayers has been studied from the effect which the temperature exerts on the threshold dilution (i.e. threshold concentration) for formation of foam bilayers (NBFs) from AF [38]. Samples of AF were collected during the 39th gestation week. Microscopic foam films were formed from diluted AF in the temperature range from 10°C to 30°C. The values of d, were found from the dependence probability W for observation of foam bilayer on dilution d at different temperatures. Such a dependence is shown in Fig. 11.6,a for one of the samples at 15°C. A sharp drop in W value at d, is seen in the figure. 

The equivalent dependence calculated with respect to the total concentration C of phosphatidylcholines in the AF solutions is shown in Fig. 11.6,b. This concentration is reversibly proportional to the dilution d 

The values of the threshold dilution d, for different temperatures are presented in Fig. 11.7 in Arrhenius co-ordinates for the five samples investigated. As it is seen, linear dependences of similar slope were obtained within the temperature range from 10°C to 30°C. The temperature dependences of d, were determined as concentrations higher than the critical electrolyte concentration Ceixr for formation of foam bilayers from amniotic fluid and it was found that d, is not a function of the electrolyte concentration. 

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