Hydrophilicity characterization

In their native state most serum proteins are quite hydrophilic. Characterization of the surface properties of the native proteins is best achieved by time dependent contact angle measurements on relatively thick protein layers or by the adsorption method. With high bulk concentrations of the coating solution the method... 

Hydrophilic sols are characterized by a high viscosity, and often set to gels on cooling it is... 

Hydrogels are water-containing polymers, hydrophilic in nature, yet insoluble. In water, these polymers swell to an equiUbrium volume and maintain thek shape. The hydrophilicity of hydrogel is a result of the presence of functional groups such as —NH2, —OH, —COOH, —CONH2, —CONH—, —SO H, etc. The insolubihty and stabiUty of hydrogels are caused by the presence of a three-dimensional network. The scope, preparation, and characterization of hydrogels has been reviewed (107). 

An off-lattice minimalist model that has been extensively studied is the 46-mer (3-barrel model, which has a native state characterized by a four-stranded (3-barrel. The first to introduce this model were Honeycutt and Thirumalai [38], who used a three-letter code to describe the residues. In this model monomers are labeled hydrophobic (H), hydrophilic (P), or neutral (N) and the sequence that was studied is (H)9(N)3(PH)4(N)3(H)9(N)3(PH)5P. That is, two strands are hydrophobic (residues 1-9 and 24-32) and the other two strands contain alternating H and P beads (residues 12-20 and 36-46). The four strands are connected by neutral three-residue bends. Figure 3 depicts the global minimum confonnation of the 46-mer (3-barrel model. This (3-barrel model was studied by several researchers [38-41], and additional off-lattice minimalist models of a-helical [42] and (3-sheet proteins [43] were also investigated. 

High-performance size exclusion chromatography is used for the characterization of copolymers, as well as for biopolymers (3). The packings for analyses of water-soluble polymers mainly consist of 5- to 10-/Am particles derived from deactivated silica or hydrophilic polymeric supports. For the investigation of organosoluble polymers, cross-linked polystyrene beads are still the column packing of choice. 

Synchropak columns are very useful for characterizing hydrophilic, anionic, and nonionic, water-soluble polymers, CATSEC columns work best for characterizing cationic polymers utilizing both light scattering and/or differential viscometry detection over a wide range of molecular weights. 

The initial studies of LSDAs were carried out with oleochemicals because of their structural similarity to soap. However, since the molecular structure of an efficient LSDA is characterized by a bulky hydrophilic polar head attached to a long hydrophobic tail, it is also possible to prepare LSDAs from petrochemicals. Sulfated sulfonamide derivatives of alkylbenzenes, such as commercially available detergent alkylates, were synthesized as follows [17] ... 

Qi, L. Colfen, H. and Antonietti, M. (2001). Synthesis and Characterization of CdS Nanoparticles Stabilised by Double Hydrophilic Block Copolymers. Nano Lett, 1, 61-65. 

Historically, after the development of oligopeptide-based vesicles, several groups developed and characterized vesicles using polypeptide hybrid systems consisting of polypeptide and synthetic polymer blocks [17-19]. Soon thereafter, vesicles formed entirely from polypeptides, such as poly(L-lysine)-h-poly(L-leucine) and poly(L-lysine)-h-poly(L-glutamate), were developed [20, 21]. This review will focus on recent developments in the formation of vesicles composed of polypeptide hybrid or polypeptide systems, as well as the potential promise of these systems as effective dmg delivery vehicles. A specific example of a polypeptide-based vesicle is shown in Fig. 1, where the hydrophobic segment is a-helical and the hydrophilic segment is a random coil. 

For the characterization of Langmuir films, Fulda and coworkers [75-77] used anionic and cationic core-shell particles prepared by emulsifier-free emulsion polymerization. These particles have several advantages over those used in early publications First, the particles do not contain any stabihzer or emulsifier, which is eventually desorbed upon spreading and disturbs the formation of a particle monolayer at the air-water interface. Second, the preparation is a one-step process leading directly to monodisperse particles 0.2-0.5 jim in diameter. Third, the nature of the shell can be easily varied by using different hydrophilic comonomers. In Table 1, the particles and their characteristic properties are hsted. Most of the studies were carried out using anionic particles with polystyrene as core material and polyacrylic acid in the shell. 

The structure of these globular aggregates is characterized by a micellar core formed by the hydrophilic heads of the surfactant molecules and a surrounding hydrophobic layer constituted by their opportunely arranged alkyl chains whereas their dynamics are characterized by conformational motions of heads and alkyl chains, frequent exchange of surfactant monomers between bulk solvent and micelle, and structural collapse of the aggregate leading to its dissolution, and vice versa [2-7]. 

C13-0080. Identify the following amino acids and characterize them as possessing hydrophilic or hydrophobic side chains ... 

The combination of hydrophilicity and hydrophobicity into a single pol5meric support can lead to interesting results. Amphiphilic materials, containing both hydrophilic and hydrophobic domains, appreciably swell in a range of solvents of quite different polarity (see for example the characterization of amphiphilic CFPs given in Ref. [82]). This concept has been elegantly applied by Uozumi and Nakao in both reduction [159] and oxidation reactions (see Section 5.2) [70] catalyzed by... 

Yang, Y.-B., Harrison, K., and Kindsvater, J., Characterization of a novel stationary phase derived from a hydrophilic polystyrene-based resin for protein cation-exchange high-performance liquid chromatography, /. Chromatogr. A, 723, 1, 1996. 

Hydroformylation and subsequent hydrogenation of C=C and -CHO groups of PBD appear to be an appropriate means whereby a pendent hydroxy group can be introduced onto the polymer backbone. A variety of partially hydroformyl ated (2-20%) and hydroxymethy-lated polymers have been synthesized by a two-step catalytic reaction and characterized by I.R. and 1H N.M.R. spectroscopy. As expected, the hydrophilic group, OH, in the polymer resulted in a greater decrease in the intrinsic viscosity as compared to the HPBD. 

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