A method of making a multi-layer biocidal structure includes providing a support and locating a first curable layer on the support, the first curable layer including dispersed multiple biocidal particles. A second curable layer is located on the first curable layer; the multiple biocidal particles are dispersed within only the first 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.