Mixed amino acid surfactants

Amino acid-based surfactants are derived from simple amino acids or mixed amino acids from synthesis or protein hydrolysates. They are composed of amino acid as the hydrophilic part and a long hydrocarbon chain as the hydrophobic part. The hydrophobic chain can be introduced through acyl, ester, amide, or alkyl linkage. Interest in amino acid surfactants is not new, as shown by early work in the area. In 1909, Bondi performed the first research on the introduction of a hydrophobic group to obtain A-acylgiycine and A-acyla-lamine [18], Subsequent work in this area focused on A-acylamino acids, as reported by Funk [19], Izar [20], Karrer [21], Staudinger and Becker [22],... 

Most commercial amino acid surfactants are produced from mixed amino acids that are readily obtained from protein hydrolysates due to a cost advantage. A number of readily available and inexpensive sources of raw materials offer interesting prospects for the preparation of hydrolysates. Various plant proteins (e.g., derived from cereal, vegetable, or oilseed) or animal proteins (e.g., derived from milk, whey, blood) or waste proteins could be converted to hydrolysate hence they are a source of amino acid pool. 

The yield of the purified mixed amino acids as Na salts from waste proteins was 60-75%, that of amino acid ester from glutamic acid was higher (85-92%) [99], The active matter contents of most of the synthesized amino acid surfactants were more than 95%. The structural representation of amino acid surfactants from Ci2Na-SR spectra was identified and confirmed by IR and NMR as follows ... 

In order to clarify whether the influence of the A-substituent group in an amino acid surfactant on micellization is present in a mixture of A-acyl amino acid surfactants, Miyagishi et al. [120] determined the cmc values of mixtures of sodium salts of A-lauroyl amino acid derived from glycine, valine, and phenylalanine. The results indicate that the steric hindrance of A-substituent is not always significant in the formation of mixed micelle. The interaction between the surfactants with and without a substituent group was very small. The interaction parameter was zero for lauroyl phenylalanine/SDS. A strong interaction was observed in a mixture of C12EO6 and A-lauroyl valinate. 

The use of mixed micelles for chiral recognition was discussed in Section 5.3.3, using cyclodextrins. In addition to cyclodextrins, however, metal-amino acid complexes can also be used in a mixed mode arrangement. Bile salts are naturally occurring chiral surfactants that can be used as alternatives to, or in addition to, SDS for chiral recognition. In the presence of SDS, the migration times are faster. Table 5.5 shows initial operating conditions that can be used in chiral CE as a start to methods development.40... 

H -tetramethylbenzidine in anionic-cationic mixed micelles has been studied in detail by ESR . The photochemistry of the semi-oxidised forms of eosin Y and rose bengal have been investigated in colloidal solutions. Relevant to the fluorescence of proteins is a study of fluorescence quenching of indolic compounds by amino-acids in SOS, CTAB, and CTAC micelles O Rate constants for proton transfer of several hydroxyaromatic compounds have been measured in a variety of surfactant solutions. Photoprotolytic dissociation does not require exit of the reactant molecules from the micelles. Micellar solutions can be used to improve the fluorescence determination of 2-naphthol by inhibiting proton transfer or proton inducing reactions z2. jpe decay of the radical pair composed of diphenylphosphonyl and 2,4,6-trimethyl benzoyl radicals in SDS is affected by magnetic... 

Enzyme synthesis and fluorescence measurement of enzyme activity in the microdroplets were performed on a microfluidic platform composed of an inverted microscope (Nikon TE-200U), a thermoplate to heat the microfluidic chip to 37 °C, and four syringe pumps that delivered different reagents (oil, amino acid mix, nucleic acid mix, enzyme substrate) into the PDMS chip. The oil phase was composed of fluorinated oil (Novec 7500) mixed with 2 % Pico-Surf-surfactant from Dolomite [2]. 

Radley and co-workers [133] reported that when chiral dopants—decyl esters of amino acids, serine, alanine, leucine, and methionine—were added to an aqueous solution of alkyl methyl ammonium bromides, mixed with decanol, amphiphilic cholesteric crystals were formed. They found that the sense and magnitude of the induced helix by decyl ester of amino acid hydrochlorides except decyl ester of alanine are dependent on the achiral cationic surfactant, alkyl methyl ammonium bromides. The formation of amphiphilic cholesteric crystals was interpreted in terms of the trans and cis ro-tamers of the chiral ester of amino acid, associated with the ester linkage. Also, they reported [134] that in the case of the ester hydrochloride of proline as a chiral dopant, a concentration-dependent reversal in helical twist was observed. 

Brito, R. O., Marques, E. F., Gomes, P. et al. (2006) Self-assembly in a catanionic mixture with an amino acid-derived surfactant from mixed micelles to spontaneons vesicles. J. Phys. Chem. B, 110, 18158-18165. 

Three different ways have been developed to produce nanoparticle of PE-surfs. The most simple one is the mixing of polyelectrolytes and surfactants in non-stoichiometric quantities. An example for this is the complexation of poly(ethylene imine) with dodecanoic acid (PEI-C12). It forms a solid-state complex that is water-insoluble when the number of complexable amino functions is equal to the number of carboxylic acid groups [128]. Its structure is smectic A-like. The same complex forms nanoparticles when the polymer is used in an excess of 50% [129]. The particles exhibit hydrodynamic diameters in the range of 80-150 nm, which depend on the preparation conditions, i.e., the particle formation is kinetically controlled. Each particle consists of a relatively compact core surrounded by a diffuse corona. PEI-C12 forms the core, while non-complexed PEI acts as a cationic-active dispersing agent. It was found that the nanoparticles show high zeta potentials (approximate to +40 mV) and are stable in NaCl solutions at concentrations of up to 0.3 mol l-1. The stabilization of the nanoparticles results from a combination of ionic and steric contributions. A variation of the pH value was used to activate the dissolution of the particles. 

---