Water/Chloroform interface

Recently, the competitive adsorption dynamics of phospholipid/protein mixed system at the chloroform/water interface was investigated by using the drop volume technique. The three proteins P-Lactoglobulin, P-Casein, and Human Serum Albumin were used in this study. To investigate the influence of the phospholipid structure at concentrations close to the CAC (critic aggregation concentration) the four lipids dipalmitoyl phosphatidyl choline (DPPC), dimyristoyl phosphatidyl choline (DMPC), dimyristoyl phosphatidyl ethanolamine (DMPE)... 

Nucleoprotein complex can be extracted from cells with N NaCl solution. If the resulting viscous solution is shaken with chloroform containing a little cetyl alcohol, the protein forms a gel at the chloroform/water interface and the sodium salts of the nucleic acids remain in the aqueous phase. Chromatography and centrifuging can then be used to isolate pure specimens (Chapter 14.3). Samples of DNA can be dissolved in water to form very viscous solutions. On adding alcohol to these, a soggy cotton wool-type of precipitate is obtained, from which semi-crystalline threads of DNA can be picked out. 

Yin et al. [73,74] prepared new microgel star amphiphiles and stndied the compression behavior at the air-water interface. Particles were prepared in a two-step process. First, the gel core was synthesized by copolymerization of styrene and divinylbenzene in diox-ane using benzoylperoxide as initiator. Microgel particles 20 run in diameter were obtained. Second, the gel core was grafted with acrylic or methacryUc acid by free radical polymerization, resulting in amphiphilic polymer particles. These particles were spread from a dimethylformamide/chloroform (1 4) solution at the air-water interface. tt-A cnrves indicated low compressibility above lOmNm and collapse pressnres larger than 40 mNm With increase of the hydrophilic component, the molecnlar area of the polymer and the collapse pressure increased. 

As a cationic polymer and a cationic amphiphile, poly(allyl amine hydrochloride) (PAA) and octadecylamine (ODA) shown in Fig. 6 were used, respectively. The stability of the monolayers of the anionic amphiphiles was increased by polyion-complexation with PAA added in the aqueous subphase in comparison with Ca2+ salt formation. Ion complexation (1 1) of each anionic amphiphile with ODA was also performed at the air-water interface by spreading a chloroform solution of a 1 1 surfactant mixture. 

This method was first reported by Vanderhoff [82] for the preparation of artificial latexes. The polymer and drug are dissolved or dispersed in a volatile water-immiscible organic solvent, such as dichloromethane, chloroform, or ethyl acetate. This is emulsified in an aqueous continuous phase containing a surfactant, such as poly(vinylalcohol), to form nanodroplets. The organic solvent diffuses out of the nanodroplets into the aqueous phase and evaporates at the air/water interface, as illustrated in Figure 6. The solvent is removed under reduced pressure. The nanodroplets solidify and can be separated, washed, and dried to form a free-flowing powder. 

The question as to the potential availability of the requisite amphiphilic precursors in the prebiotic environment has been addressed experimentally by Deamer and coworkers, [143,145] who looked into the uncontaminated Murchison chondrite for the presence of such amphiphilic constituents. Samples of the meteorite were extracted with chloroform-methanol and the extracts were fractionated by thin-layer chromatography, with the finding that some of the fractions afforded components that formed monomolecular films at air-water interfaces, and that were also able to self-assemble into membranous vesicles able to encapsulate polar solutes. These observations dearly demonstrated that amphiphiles plausibly available on the primitive Earth by meteoritic infall have the ability to self-assemble into the membranous vesides of minimum protocells. ... 

The properties of poly(D, L-lactic acid) monolayers spread at the air - water interface were also shown to be strongly dependent of the nature of the spreading solvent. In this case, the monolayers spread from acetone and tetrahydrofuran exhibited typical reversible collapse behavior in the compression - expansion cycle with a quasi - plateau at large areas followed by a steep rise in the surface pressure at small areas. Conversely, the monolayers spread from chloroform, dichloromethane,... 

Fig. 3.11 Surface pressure (Tr)-area (A) isotherms for poly(D, L-lactic acid) monolayers spread at the air/water interface 250 pg of polymer was spread from (1) acetone, (2) tetrahydrofuran, (3) ethyl acetate, (4) dichloromethane, and (5) chloroform. Arrows indicate area (125m2/g) at which Langmuir-Blodgett sampling was performed. Compression rate 34.5cm2/min, (From ref. [58])...

Hore DK, Walker DS, MacKinnon L, Richmond GL (2007) Molecular structure of the chloroform-water and dichloromethane-water interfaces. J Phys Chem C 111 8832-8842 Huang JY, Wu MH (1994) Nonlinear optical studies of binary mixtures of hydrogen bonded liquids. Phys Rev E 50 3737-3746... 

Tew and Amt [92-94] have prepared amphiphilic meta-PPEs 58 and investigated their behavior at the air-water interface where they prefer an extended conformation. These PPEs are active in the lysis of phospholipid vesicles and might find application as bactericidal substances. While the derivative 58 with R = H forms clear solutions in water, the alkoxy-substituted congeners aggregate and precipitate out upon addition of water to their solution in DMSO. The structure of 58 in the solid state is assumed to be helical rather than extended. If acrylic ester substituents are placed on 59, it is possible to capture the helical intermediates by a photochemical 2-1-2 cycloaddition (Figure 6.2) [95,96]. The presence of a fixated helical structure was evident, because addition of chloroform to the cross-linked form did not... 

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