On a carrier surface, a layer of S-layer proteins is produced as a carrier of functional molecules. A solution containing S-layer proteins in the form of monomers or oligomers is brought into contact with the carrier surface. Electrochemical conditions are produced in the solution such that the S-layer proteins (SU) have an electrical net charge by establishing an electrochemical potential difference between the solution and the carrier surface such that the S-layer proteins accumulate on the carrier surface. A two-dimensional crystalline structure is formed in the layer, and this can occur at a time separate from the deposition of the S-layer proteins, and under different electrochemical conditions.