256 research outputs found

    Synthesis and Solution Properties of Hydrophobically Modified Polysaccharides

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    Hydrophobically modified polymers are amphiphilic macromolecules mainly constituted of a hydrophilic backbone and hydrophobic side groups. In aqueous solutions these polymers undergo inter- or intra-molecular hydrophobic association, which results in unusual properties useful for a number of practical applications. The areas of application of these polymers include associative thickeners for enhanced oil recovery, pharmaceuticals, personal care formulations, coatings, adhesives, surfactants, emulsifiers, etc. This review presents the analysis of a literature data on preparation of hydrophobically modified polysaccharides (HMP) and their properties in aqueous solutions. Some of the synthetic methods used for hydrophobic modification of non-ionic (cellulose ethers, starch, dextran, pullulan, etc.), anionic (carboxymethylcellulose, hyaluronic acid, pectic acid, alginic acid, heparin) and cationicВ  olysaccharides (chitosan) are presented. The methodology used for the investigation of solution properties of hydrophobically modified polysaccharides is discussed. Special attention is paid to aggregate and micelle formation in solutions of hydrophobically modified polysaccharides, solubilization of hydrophobic compounds, their rheological properties and surface activity. The effects of polymer architecture (level of hydrophobic substitution, nature of hydrophobic groups, molecular weight of a hydrophilic backbone, etc.), concentration, temperature, presence of inorganic salts and organic solvents on solution properties of hydrophobically modified polysaccharides are discussed. Some applications of hydrophobically modified polysaccharides are briefly highlighted

    Mucoadhesion and mucosa-mimetic materials - a mini-review

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    Mucoadhesion describes an attractive interaction between dosage form and mucosal membrane. The evaluation of mucoadhesive excipients often requires the use of ex vivo mucosal tissues taken from laboratory animals. These can be difficult to source, highly heterogeneous, and require the use of animal products. Thus, from both a user-convenience and ethical point-of-view, it is desirable to produce a synthetic alternative to these tissues - a mucosa-mimetic material. In this mini-review, the use of alternative materials to test the performance of mucoadhesives is reviewed and discussed. There is a surprising prevalence of the use of mucosa-mimics in the literature, which hitherto has not been compiled and compared.Peer reviewe

    Investigation of Physicochemical Properties of PVA-GANT Mucoadhesive Hydrogels

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    The aim of this work was the manufacture and characterisation of novel chemically cross-linked mucoadhesive PVA-GANT hydrogels prepared by using autoclaving. Particularly, the study was focused on the physicochemical and pharmaceutical properties of these hydrogels with regards to potential applications for drug delivery and wound dressing. PVA-GANT hydrogels with different molar ratios and total concentrations of polymers in solution were prepared using a standard sterilisation autoclave. The physico-chemical properties were characterised by various techniques including IR spectroscopy, Texture Analysis and SEM and thermo-analytical techniques (DSC and TGA). Pharmaceutical characteristics were obtained in drug loading/release tests and microbiological assays. The results have shown that the properties of hydrogels (swelling degree, mechanical properties, internal structure, drug loading/release and antimicrobial properties) are very dependent on the polymer composition
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