The synthesis of highly antimicrobial nanocrystalline zinc oxide and its covalent modifications is presented. In order to achieve further improvement of antimicrobial activity, surface of ZnO was effectively modified with selected silanes comprising amino-and ionic liquidfunctionalities. We demonstrate for the first time ionic liquid surface immobilization on ZnO and application of this hybrid material for antimicrobial purposes. Different microscopic and spectroscopic techniques as well as size, surface and elemental composition analysis were employed to prove these modifications. Characterisations revealed that surface and antimicrobial properties strongly depend on the modification employed. Most of the aminoand ionic liquid-functionalised nanocrystalline ZnO exhibited improved antimicrobial activity compared to commercially available silane-containing antimicrobial agent attached to nanocrystalline ZnO. Bacterial growth reduction was assessed by following optical density of bacterial growth with different concentrations of the novel antimicrobial nanomaterials. Complete bacterial inactivation was achieved for specific amino-and ionic liquidmodifications at 0.125 g L -1 , revealing synergistic effect of ZnO and its modifications, exhibiting up to 2-fold improvement compared to unmodified ZnO.

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