A nontoxic antimicrobial chemical trap that comprises a film comprising an antimicrobial layer that comprises nanocrystalline cellulose (NCC) and an antimicrobial substance selected from the group consisting of MgO and Mg(OH)2. In some embodiments, the antimicrobial trap comprises at least one additional layer of NCC above or below said antimicrobial layer. Methods of preparation of the antimicrobial chemical trap and of articles coated thereby are disclosed, as well as methods of controlling microbial population by use of the antimicrobial chemical trap, are disclosed as well.