Conformation changes in human hair keratin observed using confocal Raman spectroscopy after active ingredient...

Area of Science:

• Hair Science
• Spectroscopy
• Cosmetic Chemistry

Background:

• Traditional hair care product evaluation relies on visual assessment, lacking molecular detail.
• Existing analytical methods for hair fibers offer limited surface or structural information.
• Confocal Raman spectroscopy provides in situ molecular analysis of keratin in human hair.

Purpose of the Study:

• To assess confocal Raman spectroscopy's potential for evaluating cosmetic ingredient efficacy on keratin structure.
• To analyze molecular changes in hair fibers treated with a smoothing shampoo.

Main Methods:

• Pilot study using confocal Raman spectroscopy on natural human hair treated with a smoothing shampoo.
• Analysis of alpha-helix and beta-sheet spectral markers in the Amide I band.
• Detection of spectral markers specific to cystine sulfur content.

Main Results:

• An effective active ingredient decreased alpha-helix and increased beta-sheet keratin conformation.
• Treatment reduced the intensity of disulfide (S-S) cross-linking bands of cysteine.
• These changes indicate an effect on the tertiary structure of keratin.

Conclusions:

• The tested active ingredient smooths hair by modifying keratin conformation and tertiary structure.
• Confocal Raman spectroscopy is a powerful, non-destructive, label-free technique for analyzing cosmetic ingredient effects on hair keratin.
• This method requires no sample extraction or purification and is suitable for routine cosmetic laboratory use.