Protein loss quantification of abraded virgin and abraded bleached hair according to Bradford assay

This study intends to present Bradford assay as an alternative to Lowry test to quantify hair damage during combing or brushing. The protocol involves collecting hair fragments that are chipped away from hair during these abrasive treatments and quantitatively measuring the amount of protein using an analytical procedure to detect low amounts of proteins. This protein determination method involves the binding of Coomassie Brilliant Blue G-250 to hair protein (keratin). It is quite rapid and sensitive and less prone to interferences as the standard Lowry procedure. The latter is subject to interference from compounds such as lipids, cationic surfactants and EDTA, which are ingredients commonly used in hair care formulations and may lead to a false positive result. These drawbacks should be eliminated when using the so called Bradford method for hair protein quantitation. Our studies showed reproducible results for human hair protein and the developed color was stable for up to one hour. The data also show that virgin hair releases less protein than bleached hair. The amount detected for the former after combing ranges from 0.875 to 1.03 mg/g of hair and 4.85 to 5.35 mg/g of hair for the latter.