Examining cationic polysaccharide deposition onto keratin surfaces through biopolymer fluorescent labeling

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 quantitative 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.