As a result of an increasing number of bacteria developing resistance against antibiotics, antimicrobial peptides (AMPs) are currently attracting significant interest. However, much less focus has been placed on delivery systems for AMPs. Nanoparticles may provide opportunities, e.g., for controlling peptide release, reducing infection-related AMP degradation or increasing bioavailability. We have previously shown that mesoporous silica nanoparticles (MSNP) are interesting delivery systems for AMPs, e.g., providing protection against proteolytic degradation. We propose to extend this work by addressing the effect of particle topography on membrane interactions and antimicrobial effects of MSNPs. In this proposal we plan to compare interactions of ’virus-like’ and smooth MSNPs with negative charged POPC/POPG bilayers as bacterial membrane mimics, both in the absence and presence of AMP.