Osmotic Pressure beyond Concentration Restrictions

Abstract

Osmosis is a fundamental physical process that involves the transit of solvent molecules across a membrane separating two liquid solutions. Osmosis plays a role in many biological processes such as fluid exchange in animal cells (Cell Biochem. Biophys. 2005, 42, 277-345;1 J. Periodontol. 2007, 78, 757-7632) and water transport in plants. It is also involved in many technological applications such as drug delivery systems (Crit. Rev. Ther. Drug. 2004, 21, 477-520;3 J. Micro-Electromech. Syst. 2004, 13, 75-824) and water purification. Extensive attention has been dedicated in the past to the modeling of osmosis, starting with the classical theories of van't Hoff and Morse. These are predictive, in the sense that they do not involve adjustable parameters; however, they are directly applicable only to limited regimes of dilute solute concentrations. Extensions beyond the domains of validity of these classical theories have required recourse to fitting parameters, transitioning therefore to semiempirical, or nonpredictive models. A novel approach was presented by Granik et al., which is not a priori restricted in concentration domains, presents no adjustable parameters, and is mechanistic, in the sense that it is based on a coupled diffusion model. In this work, we examine the validity of predictive theories of osmosis, by comparison with our new experimental results, and a meta-analysis of literature data.

Experimental Estimation of Membrane Tension Induced by Osmotic Pressure

“…When we transfer the GUV into a hypotonic solution where the glucose concentration is C out (< C in 0 ) (i.e., DC 0 ¼ C in 0 À C out ) (where the units of all the concentrations are mol/m 3 (mM)), P is applied to the GUV due to the difference in the chemical potential of water inside and outside of the GUV. It is reported that when the concentrations, C, of sucrose and glucose are low (i.e., C < 100 mM) the linearity between P and C holds, and thus, the ideal equation (van't Hoff's law) for P can be used (31,32). We also measured osmolarity (mOsm/L) of sucrose and glucose solutions of <98 mM and obtained the linear relationship between the osmolarity and the molar concentration (Fig.…”

Influence of osmosis on the diffusion from concentrated solutions through composite/asymmetric membranes: Theoretical analysis

“…However, below it is shown that, for example, for the membrane used in [12] and a 1 M (1:1) electrolyte solution, F can be as large as ca. 180.…”

“…In [12], the osmotic pressure in concentrated solutions of sucrose was studied by using a specially designed membrane osmometer. To avoid the deformation and eventual rupture of the membrane, the latter was supported by a porous metal disk.…”

“…To avoid the deformation and eventual rupture of the membrane, the latter was supported by a porous metal disk. To check the possible diffusion leaks through the membrane, the authors of [12] studied (in a separate diffusion cell) the diffusion of concentrated solutions of sucrose through the membrane used in the osmometer, and no noticeable diffusion fluxes were detected in 12 h [13]. The diffusion "checks" were carried out without a supporting disk.…”

A novel subcutaneous infusion delivery system based on osmotic pump:in vitroandin vivoevaluation

“…Therefore, the T i and T e values may be affected not only by osmotic pressure but also by hydrophilicity of osmotic agents. According to Van't Hoff equation (Grattoni et al, 2007), the same amount of mannitol created the lowest osmotic pressure in tablet resulted in the longest Te. The same amount of lactose created relatively high osmotic pressure, but the rate of water hydration of tablet core with lactose as the osmotic agent was lower than that of tablet core with mannitol as the osmotic agent.…”