45.    Improvement of hair properties by treatment with hydrophobic recognition domains. 
Carla Joana Silva, Andreia Vasconcelos, Artur Cavaco-Paulo, Department of Textile Engineering, Minho University, Guimarães, Portugal.

Introduction: The exposure of the hair to sun, wind and modern hair styling products and techniques (e.g. shampooing, bleaching, dyeing and shaping of hair with wave preparations) imparts significant and unwanted damage to the cuticle and cortex of the hair shaft. This damage results in a loss in body, lustre, and smooth texture as well in increased electrostatic charging, reduced maximum tensile strength, breaking of the hair and in the poor appearance of hair styles. The use of proteins for cosmetic purposes began more that 50 years ago. The efficacy and substantivity of proteins have been documented by many different methods – both scientific and subjective. In this study, a new methodology of hair treatment is presented by using hydrophobic recognition domains (HRD) that are capable of increasing hair elongation, tensile strength and body, while preventing its damage. Materials and Methods: The hair samples were treated with HRD in buffer. The tensile strength measurements were done with an Instron 4505 with a load cell of maximum capacity of 2,5 N. Hair cross-sections were analysed by a transmission optic microscope (Olympus BH2) with a magnification of 40X. Also, a panel of 5 technicians evaluated the handle and appearance of the hair. Results: Tensile strength resistance increased about 2% for hair that was not chemically treated and about 55% for hair that was previously treated chemically. Interestingly, there was also an increase in the elongation properties of hair (of 6% for non treated hair and of 15% for chemically treated hair). Also, by means of transversal cuts, the penetration of the HRD was analysed. It was seen, by fluorescence microscopy, that different HRD were penetrating completely inside hair cortex, while others were retained at the surface of hair, in the cuticle layer. This last set of HRD had a higher protecting effect on hair. Conclusions: The results revealed that hydrophobic recognition domains can enhance the elasticity and tensile strength of hair, especially chemically treated hair. In addition, HRD were found to extend the gloss, brightness and the body of the hair.