NOVELTY - Film comprises a permeable polymer matrix provided with one or more functional groups, and embedded within the polymer matrix, one or more nanoparticles of an inorganic substance(s).    USE - The film is useful as a coating on the surface of a suitable substrate (claimed) with inorganic compounds such as arsenic trioxide (e.g. for coating arsenide semiconductors or in the treatment of acute myeloid leukemia), boric acid (e.g. antiseptic or insecticidal surfaces), magnesium sulfate or magnesium oxide (e.g. for a range of medical applications), silicon dioxide (e.g. for use in microelectronics as an electric insulator), zinc oxide (e.g. use in chemical and biosensors, in semiconductors or as a medicinal nutritional supplement), and selenate for use as a nutritional supplement. The film is useful for forming antimicrobial surfaces or coatings (e.g. for medical devices including implantable and non-implantable devices such as replacement joints, urinary catheters, percutaneous access catheters, stents, and other prostheses as well as non-implantable devices such as bandages, wound dressings, contact lenses and masks and apparatus for breathing medical air and oxygen) or in coating semiconductors and microprocessors; coating solar cells or for use as a nutritional supplement, and non-metals (e.g. fluoride for coating dental prostheses). Tests details are described but no results given.    ADVANTAGE - The method provides sustained release coatings for a bioactive inorganic substance(s) (e.g. an antimicrobial agent) or simply provides a means to affix an inorganic substance(s) to a surface.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for applying the film onto a surface of a suitable substrate, comprising: (i) depositing and polymerizing a monomer(s) comprising one or more functional groups by plasma polymerization to form a permeable polymer matrix on the surface; (ii) complexing an inorganic substance(s) to the functional groups, and (iii) reducing the inorganic substance(s) to form one or more nanoparticles of the inorganic substance(s), where the nanoparticles of the inorganic substance(s) is embedded within the polymer matrix.