We propose to investigate antimicrobial peptides that self-assemble into well-defined nanostructures. Previous SAXS results have shown that the peptides form rather robust platelets/fibers (“nanosheets”) with well-defined dimension of about 100x6x3 nm3 which persist with the attachment of poly(ethylene glycol) (“PEGylation”). Recent investigations have shown that the peptides that form nanosheets exhibit low cytotoxicity but significant antimicrobial action, while unstructured peptides were significantly more toxic and also prone to enzymatic degradation. In order to understand the biological behaviour, the basic physico-chemical characterizations are needed, in particular at surfaces that might provide insight to their cell interactions.