Serum albumins are efficient delivery systems for the photosensitizer hypericin in photosensitization-based treatments against Staphylococcus aureus

The naturally occurring photosensitizer hypericin can be effectively delivered to bacterial cells using serum albumins as biocompatible carriers. Using a combination of spectroscopic methods we demonstrate that the photophysics of hypericin is fully preserved when bound to these proteins. Thanks to the excellent transport capabilities of serum albumins, that deliver hypericin to Gram-positive S. aureus, an efficient antibacterial action was observed, with a reduction of up to 8 log in the number of colony-forming units. The photoactive material is fully compatible with the use in food processing environments, and may be exploited as a viable method for decontamination from S. aureus and other Gram-positive bacteria.