Mill Creek Biotin Deep Conditioning Gel This special conditioning treatment features Biotin and Cystine, one of the most important amino acids for healthy hair growth, and Elastin to help improve tensile strength. Cystine, a precursor to Keratin protein, has the ability to penetrate the hair shaft bringing with it nourishing and conditioning benefits. MillCreek's unique gel base provides a deep penetrating treatment to help replenish important nutrients necessary for healthy scalp and hair. Order Biotin Gel by MillCreek Today!