Artificial pheomelanin nanoparticles and their photo-sensitization properties

• Pheomelanin-type nanoparticles (PMNPs) were successfully synthesized.
• The synthesized PMNPs had a spherical shape of approximately 100 nm size.
• The synthesized PMNPs exhibited high dispersion stability in various culture media.
• PMNPs showed significant phototoxicity to HeLa cells under UV light.

Pheomelanin-type nanoparticles (PMNPs) were synthesized through a simple oxidative polymerization of 3,4-dihydroxyphenylalanine (DOPA) in the presence of cysteine by KMnO4. The synthesized PMNPs had a diameter of approximately 100 nm, exhibited high dispersion stability in neutral water and various culture media and possessed similar morphology to naturally occurring pheomelanins. The efficiency of photoinduced generation of hydroxyl radicals from PMNPs was determined and related in vitro cell experiments that were carried out, with data being compared to those from eumelanin-type nanoparticles (EMNPs) and natural sepia melanin nanoparticles. Endocytosed PMNPs showed the highest phototoxicity (~ 50% viability) to UV-irradiated HeLa cells, confirming the direct relationship between phototoxic efficiency and the generation of hydroxyl radicals through the complex processes of the O2 sensitization.

Graphical AbstractWater dispersible pheomelanin-type nanoparticles (PMNPs) were synthesized through a simple oxidative polymerization of 3,4-dihydroxyphenylalanine (DOPA) in the presence of cysteine and exhibited phototoxic efficiency compared to eumelanin-type nanoparticles (EMNPs).Figure optionsDownload as PowerPoint slide