Analysis of keratin films as screening tools for predicting the efficacy of potential hair dyes

Abstract

The technology for generating high quality keratin films has recently advanced and led to their implementation in a variety of applications. As an initial step toward investigating the films as a screening tool for predicting the efficacy of potential hair dyes, CI Acid Orange 7 was applied to a set of opaque and translucent films. Overlaid time‐of‐flight secondary ion mass spectrometry images arising from protein and dye fragments revealed that dye uniformly penetrated both film types. Results also showed that the relative concentration of dye in each film complemented outcomes from ultraviolet‐visible analysis and revealed that the translucent film contained a higher dye concentration. Scanning electron microscopy analysis of film morphology suggested that the observed difference was due to the higher porosity of the opaque film, which facilitated dye desorption during the rinsing step. Consequently, the translucent film was judged to be a better substrate for screening potential new hair dyes.

Evaluation of the Toxicological and Color Properties of Anionic Hydrophobic Monoazo Dyes for Sustainable Human Hair Coloration

“…The color of the fibers washed 1× was quantified using various coloristic parameters derived from reflectance spectroscopy. Indeed, reflectance spectroscopy is suitable for measuring the color of opaque materials such as textile fabrics and human hair keratin films . Dye uptake was assessed using the summation of K / S values observed from 360 to 750 nm (i.e., Σ K / S ) as a parameter, and Σ K / S values for dyed hair fibers increased on the order of RC12 < RC4 < RC8, indicating both the advantage of an extended alkyl chain and the disadvantage of chain lengths reaching double digits.…”

“…Indeed, reflectance spectroscopy is suitable for measuring the color of opaque materials such as textile fabrics 34 and human hair keratin films. 51 Dye uptake was assessed using the summation of K/S values observed from 360 to 750 nm (i.e., ΣK/S) as a parameter, and ΣK/S values for dyed hair fibers increased on the order of RC12 < RC4 < RC8, indicating both the advantage of an extended alkyl chain and the disadvantage of chain lengths reaching double digits. A ΣK/S value of 44.33 represents a medium shade depth for dye RC8 on hair and is about 20% better than the two other dyes.…”

In situ Chelation of Monoazo Dyes in Human Hair Keratin Fibers Using Environmentally Benign Metal Ions

“…The color of unwashed (0×) fibers and washed three times (3×) fibers was evaluated using UV−vis reflectance spectroscopy, which is a method suitable for measuring the color of opaque materials such as textile fabrics, plastics, paint films, 32 and even films prepared from extracted human hair keratin. 36 The coloristic data acquired is shown in Table 1, where L* represents the lightness/darkness, a* represents greenness (−) to redness (+), and b* represents blueness (−) to yellowness (+) of the substrate. The overall color difference (ΔE) of the substrate before and after washing was calculated using these parameters.…”

A review of developments in industrial hair colorant actives for oxidative dyes

“…For example, nanoscale mass spectrometry was used to image the penetration and distribution of oxidative coloration produced by PPD and 2M5AP within the hair cuticle 184 . Techniques based on keratin film have been explored as a means of screening colorants to discover those with the potential to diffuse most readily into hair, although the work reported so far does not extend to oxidative actives 185 . Based on limited results from another study comparing the performance of metallisable sulphonamide‐substituted acid dyes with oxidative coloration produced by a combination of AHP and MAP, the conclusion was drawn that “use of oxidative dye is not ideal for screening studies involving the films” 186 .…”