Self-cleaning antimicrobial surfaces by bio-enabled growth of SnO ₂ coatings on glass

Conventional vapor-deposition techniques for coatings require sophisticated equipment and/or high-temperature resistant substrates. Therefore bio-inspired techniques for the fabrication of inorganic coatings have been developed in recent years. Inspired by the biology behind the formation of the intricate skeletons of diatoms orchestrated by a class of cationic polyamines (silaffins) we have used surface-bound spermine, a naturally occurring polyamine, to promote the fast deposition of homogeneous, thin and transparent biomimetic SnO ₂ coatings on glass surfaces. The bio-enabled SnO₂ film is highly photoactive, i.e. it generates superoxide radicals (O₂ ^-) upon sunlight exposure resulting in a strong degradation of organic contaminants and a strong antimicrobial activity. Upon illumination the biomimetic SnO₂ coating exhibits a switchable amphiphilic behavior, which-in combination with its photoactivity-creates a self-cleaning surface. The intrinsic self-cleaning properties could lead to the development of new protective, antifouling coatings on various substrates.