Methylene blue-loaded liposomes for enhanced photodynamic therapy

Photodynamic therapy is currently presented as a promising alternative to treat various pathologies. This technique is based on the use of a non-toxic photosensitizer, which can absorb energy from a light source with specific wavelength and irradiance characteristics. This process allows the photosensitizer to reach a higher energy state, triggering photochemical reactions that, in the presence of oxygen, generate reactive oxygen species capable of eliminating microorganisms.

Methylene blue, a compound derived from phenothiazine, has demonstrated analgesic, antibacterial and antitumor properties. In addition, compared to other photosensitizers, such as aminolevulinic acid, it offers the advantage of being less expensive.

Nonetheless, this photosensitizer presents some limitations, including limited tissue penetration and low stability in biological environments. To address these challenges, one possible solution is the utilization of nanometric vesicles to encapsulate and deliver the photosensitizer.

This work focuses on the design of liposomes containing methylene blue, which were coated with a hydrophilic polymer to prolong their permanence time at the application site.