Emulsion biomolecules

Surfactants employed for w/o-ME formation, listed in Table 1, are more lipophilic than those employed in aqueous systems, e.g., for micelles or oil-in-water emulsions, having a hydrophilic-lipophilic balance (HLB) value of around 8-11 [4-40]. The most commonly employed surfactant for w/o-ME formation is Aerosol-OT, or AOT [sodium bis(2-ethylhexyl) sulfosuccinate], containing an anionic sulfonate headgroup and two hydrocarbon tails. Common cationic surfactants, such as cetyl trimethyl ammonium bromide (CTAB) and trioctylmethyl ammonium bromide (TOMAC), have also fulfilled this purpose however, cosurfactants (e.g., fatty alcohols, such as 1-butanol or 1-octanol) must be added for a monophasic w/o-ME (Winsor IV) system to occur. Nonionic and mixed ionic-nonionic surfactant systems have received a great deal of attention recently because they are more biocompatible and they promote less inactivation of biomolecules compared to ionic surfactants. Surfactants with two or more hydrophobic tail groups of different lengths frequently form w/o-MEs more readily than one-tailed surfactants without the requirement of cosurfactant, perhaps because of their wedge-shaped molecular structure [17,41]. 

All the novel separation techniques discussed in this chapter offer some advantages over conventional solvent extraction for particular types of feed, such as dilute solutions and the separation of biomolecules. Some of them, such as the emulsion liquid membrane and nondispersive solvent extraction, have been investigated at pilot plant scale and have shown good potential for industrial application. However, despite their advantages, many industries are slow to take up novel approaches to solvent extraction unless substantial economic advantages can be gained. Nevertheless, in the future it is probable that some of these techniques will be taken up at full scale in industry. 

The most often investigated enzymes in micro emulsions are lipases, because these enzymes are very stable and active in this medium [ 14]. Until now, most of the relevant interactions between the biomolecules and the reaction medium have been investigated. Many enzymes which are well investigated in aqueous reaction media can be solubilised in w/o-microemulsion, retaining their activity and stability, as shown in Table 1. 

Although supercritical CO2 is an effective solvent for oils, fats, and similar substances, it is a poor one for nonvolatile hydrophilic (water-loving) substances such as proteins or metallic salts. Adding water as such to the supercritical CO2 is of little help, as the solubility of water in it is limited. Johnson and co-workers216 overcame the latter limitation by forming water-in-C02 emulsions with the aid of an added nontoxic perfluoropolyether surfactant that forms reverse micelles around the water microdroplets, in effect combining the special properties of supercritical CO2 with the solvent power of water. These emulsions can dissolve a variety of biomolecules at near-ambient temperatures, without loss of their biological activity. 

The implication of such stimuli-responsive particles as a solid polymer support of biomolecules in the biomedical field is probably due to various factors (1) easiest to prepare via precipitation polymerization (hydrogel particles) or a combination of emulsion and precipitation polymerizations (core-shell particles), (2) the colloidal properties are related to the temperature and to the medium composition (i.e., pH, salinity, surfactant etc.), (3) the adsorption and the desorption of antibodies and proteins are principally related to the incubation temperature, (4) the covalent binding of proteins onto such hydrophilic and stimuli-responsive particles can be controlled easily by temperature, and, finally, (5) the hydrophilic character of the microgel particles is an undeniably suitable environment for immobilized biomolecules. 

Sekkat Z et al (eds) (2002) Photoreactive organic thin films. Academic Press, New York Sideris M (1998) Monitoring diagnosing efficiency catalytic converters. Elsevier, Amsterdam Simmonds RJ (2001) Chemistry of biomolecules - an introduction. Elsevier, Amsterdam Sjoblom J (2006) Emulsions and emulsion stability, 2nd edn. CRC Press, Boca Raton, FL Skotheim TA, Reynolds JR (2007) Conjugated polymers - theory synthesis properties and characterization. CRC Press, Boca Raton, FL... 

Emulsion electrospinning and mainly coaxial electrospinning have been widely employed to produce this kind of scaffold in order to promote a better control of release kinetics (Figure 7.5). In emulsion electrospinning, the biomolecule is solubilized in an aqueous solution normally containing a protein, such as albumin. 

Polymer colloids have received an increasing interest in various applications and also biomedical areas in which they are mainly used as solid-phase supports of biomolecules. This is due to the versatility of the many heterophase elaboration processes (emulsion, dispersion, precipitation, physical processes) for making well-defined microspheres of appropriate particle sizes and surface reactive groups. In this direction, special attention has been dedicated to the preparation of smart colloids. The principal interest carried to colloidal particles based on alkyl(metha)acrylamide derivative is mainly related to their thermally sensitive colloidal properties. 

Typical rejected species include biomolecules, polymers and colloidal particles, as well as emulsions and micelles. Hydrostatic pressures are required to decrease with increasing MWCO and are generally between 0.1 and 0.5 MPa. In both MF and UF processes the filtration rate can be expressed by ... 

Colloidal particles are largely used in biomedical applications and they are principally used as solid-phase supports of biomolecules or basically as carriers in various technological aspects. The reactive particles needed are elaborated using many heterophase processes (emulsion, dispersion, precipitation, self-assembly, and physical processes). In this direction, various polymer-based colloids (well adapted for automated systems, nanobiotechnologies, and microsystems) have been prepared for in vitro biomedical applications. ... 

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