Examples herein include prosthetic valves, valve leaflets and related methods. In an example, a prosthetic valve is included having a plurality of leaflets. The leaflets can each have a root portion and an edge portion substantially opposite the root portion and movable relative to the root portion. The leaflets can include a fibrous matrix including polymeric fibers having an average diameter of about 10 nanometers to about 10 micrometers. A coating can surround the polymeric fibers within the fibrous matrix. The coating can have a thickness of about 3 to about 30 nanometers. The coating can be formed of a material selected from the group consisting of a metal oxide, a nitride, a carbide, a sulfide, or fluoride. In an example, a method of making a valve is included. Other examples are also included herein.