The selectivity of antimicrobial photodynamic therapy (PDT) can be enhanced by coupling the photosensitizer (PS)to a targeting ligand. Nanoplatforms provide a medium for designing delivery vehicles that incorporate both functionalattributes. We report here the photodynamic inactivation of a pathogenic bacterium, Staphylococcus aureus, usingtargeted nanoplatforms conjugated to a photosensitizer (PS). Both electrostatic and complementary biological interactionswere used to mediate targeting. Genetic constructs of a protein cage architecture allowed site-specific chemicalfunctionalization with the PS and facilitated dual functionalization with the PS and the targeting ligand. These resultsdemonstrate that protein cage architectures can serve as versatile templates for engineering nanoplatforms for targetedantimicrobial PDT.