Unlike conventionally used Ni(2+) - or Co(2+) -mediated immobilization, the resulting Co(3+) -mediated immobilization is resistant toward strong ligands, such as imidazole and ethylenediaminetetraacetic acid (EDTA), and washing off over time because of the high thermodynamic and kinetic stability of the Co(3+) complex.  Furthermore, once the cobalt center has been oxidized, it becomes inert toward reducing agents, specific and unspecific interactions, so that it can be used to orthogonally functionalize surfaces with multiple proteins. 
THERM