1.A novel, simple method to simulate gelling process of injectable biodegradable in situ forming drug delivery system based on determination of electrical conductivity.
Wang K1, Jia Q, Yuan J, Li S. Int J Pharm. 2011 Feb 14;404(1-2):176-9. doi: 10.1016/j.ijpharm.2010.10.042. Epub 2010 Oct 30.
The purpose of the present study was to develop a novel, simple and determination-of-electrical-conductivity-based method to trace the gelling process of injectable biodegradable in situ forming organogels after administration. The electrical conductivity of pH 7.4 PBS solution with different amount of N-methyl-2-pyrrolodone (NMP) and drug-free organogel formulation contained 0.6mL NMP were determined at 37 °C, respectively. The electrical conductivity of PBS solution was linearly proportional to the amount of NMP. Organogel contained 0.6 mL NMP in PBS solution showed a descending of electrical conductivity as time runs, while the value of electrical conductivity was almost a constant at 7.58 ms/cm after 110 min, which was nearly equaled to the electrical conductivity of 0.6 mL NMP in PBS solution (7.59 ms/cm). This data indicated that the diffusion of NMP caused the descending of system electrical conductivity and NMP completely diffused from organogel after 110 min, which led to the constant electrical conductivity.
2.In situ-forming pharmaceutical organogels based on the self-assembly of L-alanine derivatives.
Couffin-Hoarau AC1, Motulsky A, Delmas P, Leroux JC. Pharm Res. 2004 Mar;21(3):454-7.
PURPOSE: To characterize novel pharmaceutical organogels based on the self-assembly of L-alanine derivatives in hydrophobic vehicles.
3.Abiogenic Syntheses of Lipoamino Acids and Lipopeptides and their Prebiotic Significance.
Sproul G1. Orig Life Evol Biosph. 2015 Dec;45(4):427-37. doi: 10.1007/s11084-015-9451-4. Epub 2015 Aug 7.
Researchers have formed peptide bonds under a variety of presumed prebiotic conditions. Here it is proposed that these same conditions would have also formed amide bonds between fatty acids and amino acids, producing phosphate-free amphipathic lipoamino acids and lipopeptides. These compounds are known to form vesicles and are ubiquitous in living organisms. They could represent molecules that provided protection by membranes as well as possibilities for proto-life metabolism . It is here demonstrated that when a fatty acid is heated with various amino acids, optimally in the presence of suitable salts or minerals, lipoamino acids are formed. Magnesium and potassium carbonates as well as iron (II) sulfide are found to be particularly useful in these reactions. In this manner N-lauroylglycine, N-lauroylalanine, N-stearoylalanine and several other lipoamino acids have been synthesized. Similarly, when glycylglycine was heated with lauric acid in the presence of magnesium carbonate, the lipopeptide N-lauroylglycylglycine was formed.
4.Physical gelation of binary mixtures of hydrocarbons mediated by n-lauroyl-L-alanine and characterization of their thermal and mechanical properties.
Bhattacharya S1, Pal A. J Phys Chem B. 2008 Apr 24;112(16):4918-27. doi: 10.1021/jp7104715. Epub 2008 Mar 29.
Fatty acid amides, such as n-lauroyl-L-alanine, gelate both aliphatic and aromatic hydrocarbon solvents efficiently. In addition this compound is found to gelate the binary solvent mixtures comprised of aromatic hydrocarbon, e.g., toluene and aliphatic hydrocarbons, e.g., n-heptane. Scanning electron microscopy and atomic force microscopy show that the fiber thickness of the gel assembly increases progressively in the binary mixture of n-heptane and toluene with increasing percentage of toluene. The self-assembly patterns of the gels in individual solvents, n-heptane and toluene, are however different. The toluene gel consists of predominantly one type of morphological species, while n-heptane gel has more than one species leading to the polymorphic nature of the gel. The n-heptane gel is thermally more stable than the toluene gel as evident from the measurement using differential scanning calorimetry. The thermal stability of the gels prepared in the binary mixture of n-heptane and toluene is dependent on the composition of solvent mixture.