George Lewis Brode

Cationic Polysaccharides for Cosmetics and Therapeutics

Chitosan salts, covalent chitosan derivatives and quaternary ammonium salts of cellulose ethers are examples of cationic polysaccharides with significant potential in cosmetic and/or therapeutic applications. Film forming properties, moisture retention, viscosifying properties and substantivity are features that make this class of materials of special interest. The substantivity of cationic polymers to hair and skin has been demonstrated by several methods. More recently, substantivity from fully formulated products has been studied in vitro and in vivo using a combination of tape stripping and Electron Spectroscopy for Chemical Analysis (ESCA). The definitive assignment of substantivity from a fully formulated product is particularly noteworthy in view of the step change in the complexity of the systems. Details of these experimental results will be presented.

Interpolymer Complexes between Hyaluronan and Cationic Cellulose Polymers

The past decade has marked a rapidly growing interest in topical applications of both hyaluronan and cationic cellulose polymers. Because of their polyelectrolyte character and opposite charge, they can form strong interpolymer complexes with novel properties and significantly enhanced utility. This paper will describe the physiochemical properties and applications of complexes formed between hylan (a modified hyaluronan) and cationic cellulose polymers. The effect of charge density and hydrophobe content of the cellulosics on water solubility and stability of the complexes will be outlined. For stable water soluble complexes, the rheological properties of their solutions will be described, and conditions for optimizing their viscoelastic properties will be defined. The utility of the interpolymer complexes between hylan and cationic cellulosics will be demonstrated in terms of their rheological synergy and their enhanced substantivity to keratinous substrates. The latter has been determined by ESCA analysis and radiotracer studies.

Polysaccharides: “Naturals” for Cosmetics ad Pharmaceuticals

Certain polysaccharides and polysaccharide derivatives are “natural” products for use in cosmetic and therapeutic applications. Polysaccharides are ubiquitous in nature, found extensively in both plants and animals. Largely of carbohydrate structure, this class of polymers is essentially derived from sugar-type molecules by cyclodehydration/addition reactions. Polymer properties and the resulting formulations containing them depend on several key structural parameters, including: (1) molecular weight and molecular weight distribution; (2) conformation and stereochemistry in the monomeric and oligomeric repeat units; (3) type of functional group(s); (4) derivatization - both the type and distribution; (5) charge density and distribution in ionic polymers; (6) hydrophile/lipophile ratios and distribution patterns, etc. These factors are discussed with a view to capitalizing on those features important for cosmetic and therapeutic applications. Emphasis is placed on cellulose derivatives, chitin/chitosan, and hyaluronic acid.