Two−dimensional protein crystals as patterning elements in molecular nanotechnology

Two‐dimensional crystalline bacterial cell surface layers (S‐layers) are unique self assembly systems. They are composed of single (glyco)protein species with the inherent ability to recrystallise in suspension and on solid supports such as silica, mica, metals or synthetic polymers. Since S‐layers are composed of identical subunits functional groups are located on the lattice in an identical position and orientation. S‐layers are anisotropic structures with regard to their surface topography and distribution of charged groups. Pores in the lattice have identical size, morphology and physicochemical properties. In contrast to conventional solid supports where the functional groups are randomly distributed and oriented, crystalline bacterial surface layers allow for the first time the controlled immobilisation of (macro)molecules, leading to the formation of a monomolecular lattice. This potential is the basis for a broad spectrum of applications of S‐layers as patterning elements and immobilisation matrices in molecular nanotechnology.