Application of Nanonized Melanin to Protecting Cells from Acute Oxidative Stress
Yi-Cheng Liu1,4*, Jhong-Han Liu2, Sih-Min Chen3, Hsiang-Wei Hsu2, Hoang-Yan Lin1, Szu-yuan Chen2,3,4
1Graduate Institute of Photonics and Optoelectronics, and Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan
2Department of Physics, National Central University, Jhongli, Taiwan
3Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan
4Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
* presenting author:Yi-Cheng Liu,
Melanin is one of the most ubiquitous heterogeneous biological polymer widespread in our body tissue and it has been shown that melanin has potential medical functions against free radicals, reactive oxygen species (ROS), tumor, venin, virus, and heavy metal ions. However, its insolubility drastically reduces its efficacy. We have shown previously that melanin can be processed to become nanometer-sized and water-dispersible in simple ways. In principle, the nanonized melanin could be ingested by cells at a rate and a proportion much larger than micrometer-sized aggregates, and the exposed surface is increased by many orders of magnitude, dramatically increasing the efficiency of chemical and biological interactions. In this work, we explored the utilization of the nanonized melanin as medication against acute oxidative stress. The viabilities of cultured retinal pigment epithelium (RPE) cells exposed to exogenous H2O2 stress and treated with various conditions of melanin and irradiation were compared. It was found that nanonized melanin exhibited a much stronger effect than unprocessed melanin on protecting cultured RPE cells from acute ROS stress. The effect was even more prominent without simultaneous light irradiation, compatible with the constraint of in vivo application.

Keywords: melanin, nano-medicine, water-dispersible, reactive oxygen species, antioxidant