Liposome and polymeric micelle-based delivery systems for chlorophylls: Photodamage effects on Staphylococcus aureus

[Display omitted] •S. aureus was killed by photodynamic inactivation using chlorophylls (Chls) as photosensitizer.•Photodynamic properties were dependent of the drug delivery system, micelles or liposome.•The photodynamic inactivation was related to Chls uptake to bacterial cells and Chls photophysical.•Phorbide derivatives in liposomes are indicated as promising photosensitizers for photodynamic therapy. Chlorophyll derivatives (Chls), loaded in F-127 polymeric micelles and DPPC liposomes as drug delivery systems (DDS), have been shown to be remarkable photosensitizers for photodynamic inactivation (PDI). Assays of photoinactivation of Staphylococcus aureus bacteria (as biological models) showed that the effectiveness of Chls in these nanocarriers is dependent on photobleaching processes, photosensitizer locations in DDS, singlet oxygen quantum yields, and Chl uptake to bacteria. These are factors related to changes in Chl structure, such as the presence of metals, charge, and the phytyl chain. The photodynamic activity was significantly greater for Chls without the phytyl chain, i.e., phorbides derivatives. Furthermore, the inactivation of S. aureus was increased by the use of liposomes compared to micelles. Therefore, this research details and shows the high significance of the Chl structure and delivery system to enhance the photodynamic activity. It also highlights the chlorophylls (particularly phorbides) in liposomes as promising photosensitizers for PDI.