A method of making a multi-layer biocidal structure includes providing a support and locating a first curable layer on the support. A second curable layer is located on the first curable layer, the second curable layer having multiple biocidal particles dispersed within the second curable layer. The first curable layer and the second curable layer are imprinted in a single step with an imprinting stamp having a structure with a depth greater than the thickness of the second curable layer. The first curable layer and the second curable layer are cured in a single step to form a first cured layer and a second cured layer. The imprinting stamp is removed.