Hydrophilic macromolecules

In addition to theoretical considerations, some experimental studies were carried out to clarify the structures of adsorbed layers of hydrophilic macromolecules. 

The above results proved the potential viability of the adsorbed hydrophilic macromolecules as bonded phases in chromatography of biopolymers but it must be admitted that additional crosslinking of previously adsorbed macromolecules is usually needed in order to obtain stable composites. The cross-linked bonded polymeric phases, however, may suffer from the restricted flexibility of the chain segment and their steric repellency may be diminished. Moreover, the conformational adaptivity of cross-linked chains for binding with solutes is poorer than that of grafted or chemically bound macromolecules. 

As a result of their size and of specific interactions, hydrophilic macromolecules or solid nanoparticles cause strong changes in micellar size and dynamics, and their structural and dynamic properties are strongly affected. In these cases, the distribution among reversed micelles can be only described by ad hoc models [13,123]. 

The core of reversed micelles can be transformed to a highly viscous domain (nanogel) by entrapping appropriate species, such as viscous solvents and hydrophilic macromolecules, or by performing in situ appropriate polymerization reactions or intramolecular cross-linking of water-soluble polymer chains [232-234]. 

Table IIL Absorption Half-lives (Minutes) of Some Lipid Insoluble Compounds Alongside Some Hydrophilic Macromolecules a...

A study on the process of the uncatalyzed polymerization was made. The conclusion was as follows (1) The hydrophilic macromolecules form hydrophobic areas (HA) in the water phase (2) Into the HA, vinyl monomers are incorporated (3) Then, the radical polymerization starts in the HA. A new concept was proposed ... 

The blood-CSF barrier is relatively permeable to hydrophilic macromolecules, (i.e., ai-macroglobulin and IgM). In addition, the passage of smaller molecules, which are larger than 500 Da, is facilitated by lipophilicity (i.e., by antibiotics and cytostatic drugs). The composition of the extracellular fluid of the brain parenchyma is unknown. It resembles CSF only in a narrow margin of a few millimeters adjacent to the free CSF space, a zone where a limited diffusion of water-soluble molecules is possible (F2). The composition of CSF is well known because the subarachnoid space can be tapped at its lowest point. Despite the great distance from the site of production, the choroid plexus, it shows all of the characteristics of a filtrate, even in the lumbar sac. 

Gregonis et al. have shown that PEO bound to quartz surfaces greatly minimizes the adsorption of proteins from plasma and from singly component protein solutions 122). Bell and coworkers at Los Alamos have developed a theory of cell-cell adhesion based on the steric repulsion characteristics of the hydrophilic macromolecules present on cell surfaces 124). 

Bernkop-Schnurch, A., C.E. Kast, and D. Guggi. 2003. Permeation enhancing polymers in oral delivery of hydrophilic macromolecules Thiomer/GSH systems. J Control Release 93 95. 

Application of an electric field to lipid bilayers such as those found in cellular membranes causes short-term depolarization of the membrane and formation of pores and other structural changes [17]. These so-called electropores allow the uptake of hydrophilic macromolecules such as plasmid DNA, siRNA, or proteins that are otherwise unable to diffuse passively through this highly regulated barrier. The use of high-voltage electrical pulses to permeabilize cell membranes was first described as a tool to deliver DNA into mammalian cells in 1982 (Wong and Neumann 1982 Neumann et al. 1982). In cuvette-based methods, cells are... 

There are many kinds of polymerizing monomers used to make up copolymers. These differ in physical and chemical properties. One of the most important differences (essential features) is their solubility, that is, how much they like or dislike a solvent, e.g., water. Hence the chemical and atomistic details of different monomeric units may not be necessary to understand the properties of many two-letter copolymers. In what follows, we will mainly use the so-called HP model [31]. This two-letter model of a linear hydrophobic/hydrophilic macromolecule reflects the spirit of minimalist models, in that it is simple yet based on a physical principle. 

Bernkop-Schnurch A, Gockel NC (1997) Development and analysis of a polymer protecting from luminal enzymatic degradation caused by a-chymotrypsin. Drug Dev Ind Pharm 23 733-740 Bernkop-Schnurch A, Kast CE, Guggi D (2003) Permeation enhancing polymers in oral delivery of hydrophilic macromolecules thiomer / GSH systems. J Control Release. 2003 Dec 5 93(2) 95-103. 

Permeation of macromolecules through the GI epithelial cells after oral administration has been reported by several research groups. We have also confirmed the permeation of the hydrophilic macromolecules by using Caco-2 cells (Nagata et al. 2006). However, there are no data clearly showing the actual absorption of macromolecular drugs into the GI tract after oral administration. 

Garcia-Fuentes, M., Torres, D., and Alonso, M. J. (2002), Design of lipid nanoparticles for the oral delivery of hydrophilic macromolecules, Coll. Surf. B Biointerf., 27,... 

Ohtake, K. Maeno, T. Ueda, H. Natsume, H. Morimoto, Y. Poly-L-arginine predominantly increases the paracellular permeability of hydrophilic macromolecules across rabbit nasal epithelium in vitro. Pharm. Res. 2003,20 (2), 153-160. 

Gradient-forming materials which provide the densities required for the separation of subcellular particles include salts of alkali metals (e.g. caesium and rubidium chloride), small neutral hydrophilic organic molecules (e.g. sucrose), hydrophilic macromolecules (e.g. proteins and polysaccharides), and a number of miscellaneous compounds more recently introduced and not included in the above group, such as colloidal silica (e.g. Percoll) and non-ionic iodinated aromatic compounds (e.g. Metrizamide, Nycodenz and Renograffin). 

The oral bioavailability of crystalline nifedipine, a potent calcium-channel antagonist, is very low because of its poor solubility and its slow dissolution rate in water. Various hydrophilic macromolecules such as poly(vinylpyrrolidone)... 

Williamson, M.R., Chang, H.I., Coombes, A.G.A., 2004. Gravity spun polycaprolactone fibres controlling release of hydrophilic macromolecule (ovalbuntin) and a lipophilic drug (progesterone). Biomaterials 24, 5053—5060. 

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