Disclosed herein are engineered constructs that have keratin-binding functionality, and uses thereof for hair treatment, e.g., engineered keratin-binding constructs comprising at least one keratin-binding molecule are disclosed. In some embodiments, the engineered keratin-binding construct comprises one or more of each of two or more types of keratin-binding molecule. In some aspects, the keratin-binding constructs disclosed herein comprise a site for bioconjugation to a lipid. Disclosed herein are compositions comprising one or more of the keratin-binding constructs disclosed herein, in combination with one or more cosmetic ingredients. Disclosed herein are kits for hair repair, hair treatment, or hair coloring comprising the compositions disclosed herein.
