Organogels from lecithins

Abstract

Solutions of lecithin in organic solvents can be transformed into transparent gels by addition of a critical amount of water. The molar ratio of water to lecithin (w0) is in the range 1-12, and for each organic solvent only a well-defined w0(gel) is able to produce a gel. Solvents such as linear and cyclic alkanes, ester of fatty acids, and amines are effective for building gels. However, the phenomenon is not general (many organic solvents do not yield gels). Gels are thermoreversible, isotropic, and not birefringent. Dynamic shear viscosity measurements have been carried out, and viscosity can be as high as a few thousand poise. NMR measurements have been measured following the chemical shift of water protons: differences with bulk water are significant. Additional molecules (e.g., vitamins and dyes) can be incorporated into the gel and be studied spectroscopically. The structure and possible applications of these novel gels are discussed.

Phosphatidylcholine reverse micelles on the wrong track in molecular dynamics simulations of phospholipids in an organic solvent

“…In most cases, lecithin which is a mixture of PC lipids (exact composition depends on the source of origin) has been studied [5][6][7][8][9][10] but also organogels of single PC lipids such as 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) 10 have been examined. Regardless of the exact PC lipid composition, PC organogels are thermodynamically stable, optically clear, and isotropic solutions 11 of entangled wormlike reverse micelles (RMs) with similar viscosity characteristics. In them, water acts as the gelation agent and gelation typically occurs at a certain water-to-lipid ratio, w 0 , range that is dependent on the chemical nature of the organic media.…”

“…In them, water acts as the gelation agent and gelation typically occurs at a certain water-to-lipid ratio, w 0 , range that is dependent on the chemical nature of the organic media. 11 Increase in temperature can move the gelation range to a higher water-to-lipid ratio or prevent it altogether. [10][11][12] Furthermore, the stability region of the organogels is influenced also by modifications in the structure of the phospholipid tails.…”

Formulation and Evaluation of Lecithin Organogel for Treatment of Arthritis

“…In present work lornoxicam containing lecithin organogel was prepared by method established by Scartazzini and Luisi in 1988. [20]; with slight modification.…”

“…The topical delivery has been attempted and made successful using several lipid-based systems viz e., liposomal formulations [4][5][6], nanostructured lipid carrier [7][8], lipid microemulsions [9], solid lipid microparticles [10], elastic liposomes or transfersomes [11], ethosomes [12][13] and lipid cubic phases [14][15] etc. In recent development; phospholipids in conjunction with some other additives have been shown to provide a very promising topical drug delivery vehicle known as lecithin organogels (LOs) [16][17]. The organogels are gels based on nonaqueous liquids, which have been mentioned in various pharmacopoeias as useful topical deliveries for lipophilic drugs [18].…”

Groundnut oil based emulsion gels for passive and iontophoretic delivery of therapeutics

“…The molecular interactions can be modulated by adding appropriate amount of water. In an early report, Scartazzini et al [2] described gelation of lecithin on the addition of small quantities of water. Later, different kinds of organogels, capable of delivering therapeutics in a controlled manner were reported by various groups.…”