j. Cosmet. Sci., 52, 119-129 (March/April 2001) Examining cationic polysaccharide deposition onto keratin surfaces through biopolymer fluorescent labeling JAMES V. GRUBER, FRANCOISE M. WINNIK, ANDRE LAPIERRE, NEELA D. KHALOO, NIRAJ JOSHI, and PETER N. KONISH, Amerchol Corporation, 136 Talmadge Rd., Edison, NJ 08818-4051 O.V.G., N.J., P.N.K), and Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (F.M.W., A.L., N.D.K.). Accepted for publication February 28, 2001. Synopsis Fluorescein-labeled polyquaternium-10 and guar hydroxypropyltrimonium chloride were employed to study the deposition behavior of these cationic polymers onto hair from a surfactant system. The influence of the covalently attached fluorescein dye on labeled polyquaternium-10 was examined through rheological studies and comparative studies against data previously obtained from radiolabeled polyquaternium-10. A quan- titative method for analyzing the amount of cationic polymer that deposits onto hair during a standard shampooing process has been developed using the labeled cationic polymers. The technique requires digestion of the hair and analysis of the resulting solutions against known standardization curves. It has been found that the molecular weight of the cationic polymers plays the most significant role in influencing the deposition of the polymers from surfactant, a far greater role than either cationic charge or washing cycles. The technique also allows for determination of polymer deposition at various tress locations, allowing for the study of the influence of tress age (i.e., damage) on polymer deposition. The use of fluorescein-labeled polyquaternium-10 also provides a unique opportunity to visualize the deposited polymers on individual hair fibers via fluorescent or confocal microscopy. INTRODUCTION It is now widely accepted that cationic polymers form deposits onto keratin surfaces treated with polymer/surfactant systems. This was not always the case. It was only through the painstaking application of various analytical methodologies that this fact of great importance to the cosmetic industry was established beyond doubt. Qualitative indication of cationic polymer deposition was gathered, for example, from streaming potential and ESCA analysis of treated hair (1). There are still only a few methods to James v. Gruber's present address is Arch Personal Care, 70 Tyler Place, South Plainfield, NJ 07080. Francoise M. Winnik's present address is Faculte de Pharmacie, Universit6 de Montreal, C.P. 6128 Suc- cursale Centre Ville, Montreal, Quebec, Canada H3C 3J. 119

120 JOURNAL OF COSMETIC SCIENCE measure the amount of cationic polymer deposited on a keratin surface. The only truly quantitative method was developed by Goddard and coworkers nearly 30 years ago. It requires the use of radiolabeled cationic polymers (2,3). While this technology is quite powerful and accurate, it is rarely used nowadays, as most personal care research labo- ratories do not have facilities allowing them to use radioactive isotopes. Moreover, it was used mostly to investigate model systems and was only rarely applied to study cationic polymer deposition from surfactant systems (4,5). A titration technique was developed more recently. It requires the use of anionic polymers that form complexes with depos- ited cationic polymers (6). Such technique does not provide meaningful information if the cationic polymer is deposited in the presence of anionic surfactants, as in the case of body washes or shampoos studies, since the surfactant interferes with the complexation of oppositely charged polymers. Fluorescent and colored dyes have been employed to try and measure cationic polymer deposition (7). However, these dyes are usually added after treatment to the observed keratin surface, where they are expected to interact only with the cationic polymer. Thus, the potential for quantitative error can be significant. There have been several recent reports on the covalent attachment of a fluorescent dye to a biopolymer, converting a naturally spectroscopically invisible polymer into a spec- troscopically visible species. The labeling of proteins (8,9), chitosan (10), dextrans (11), guar (12), and carboxymethylcellulose (13) has been discussed in the literature, and the potential use of these fluorescent polymers in personal care studies has been considered (8,9,12). One of us reported recently the preparation and characterization of a fluores- cently labeled cationic hydroxyethyl cellulose using a triazine-modified fluorescein de- rivative (Scheme 1) (14,15). The labeled cationic polymers were employed in model studies (14). We report here the use of these polymers to study deposition from sham- poos. Aspects of this work have been addressed recently (16). Scheme 1.