Protective effect of melanin nanoparticles created from squid ink against irradiation on human keratinocytes

Because the skin is the first organ to be impacted by radiation, keratinocytes (HaCaT cells) are frequently used as an in vitro model for testing potential radioprotective agents. Melanin extracted from squid ink was considered an antioxidant compound and a possible radioprotector. In this study, nanomelanin was prepared at a size of 100–200 nm from isolated squid melanin. The zeta potential of melanin nanoparticles and the functional groups on their surface were investigated. The antioxidant activity of nanomelanin was examined by the DPPH method. Keratinocyte cells were incubated with or without melanin particles for 24 h before being irradiated in various doses. The radioprotective properties of nanomelanin after 3 days post-radiation were examined by cell survival rates. Treatment with nanomelanin enhances the percentage of cell viability by 10%, depending on the dose of radiation. At 2 days post-radiation, cell groups treated with nanomelanin were reduced to the transcription levels of gene coding BAX, TNF-α, and Caspase 3 for the cellular apoptosis process at various doses (3–5 Gy) of radiotherapy in comparison with control and eliminated the apoptotic cell rate as analyzed by flow cytometry methods. Furthermore, at 3 Gy, melanin nanoparticles promoted the transcription level gene coding SOD1 enzyme by 3.4 folds compared to control.