Methods of producing an effector molecule that links keratin, to apply dermocosmeticamente effector molecule active to the skin, hair, and / or the fingernails and toenails and to increase the residence time of a dermocosmeticamente active ingredient on the skin, hair and nails of the hands and / or Toenails, effector molecule that binds to keratin, the use of effector molecules that bind keratin.Compounds and dermocosmetic