Topical application is the preferred administration route of the photosensitizer (PS) in antimicrobial photodynamic therapy (aPDT), e.g. for the treatment of infections in the oral cavity or skin. The drug formulation should allow for a sufficient contact time between the preparation and tissue, a rapid release of PS, and a selective uptake of PS in bacteria. The  drug formulation should not reduce the amount of incident light at the target (e.g. bacteria in a wound). In the present work nanovehicles such as micelles, cyclodextrins and liposomes containing PS have been screened on G+ and G- bacteria . The hydrophobic PS was then loaded in alginate foams with the use of selected nanovehicles. The alginate foams were suitable for topical application and gave an immediate release of the PS during foam hydration. The hydrated foams would remain intact to be removed after drug release, prior to irradiation.

Application of nanovehicles in preparations for antimicrobial photodynamic therapy (aPDT)
Tønnesen HH, Hegge AB, Bruzell E.
Applications of Nanodrugs in Photodynamic Therapy, Gothenburg April 11-12, 2013 (A)