A nanoparticle comprising a keratin polypeptide and at least one lipophilic active ingredient, wherein the at least one lipophilic active ingredient is non-covalently bound to the keratin polypeptide and can be e.g. a therapeutic or diagnostic agent, a nutraceutical, a cosmetic ingredients, a dye or a cosmeceutical, the keratin polypeptide being water-soluble； optionally, the nanoparticle further comprises at least one hydrophilic active ingredient non-covalently bound to the keratin polypeptide, which can be e.g. a therapeutic or diagnostic agent, a nutraceutical, a cosmetic ingredients, a dye or a cosmeceutical.
