Preparation of Naturally Active Melanin Nano-Platforms Chelated with Barium Ions as a Potential X-Ray-Computed Tomography Contrast Agent

Facile preparation of biocompatible nano-platforms for computed tomography (CT) is demanding. In this work, PEGylated melanin nanoparticles (MNPs) are prepared and reacted with barium ions as CT imaging contrast agent (Ba-MNPs-mPEG). It is found that the hydrodynamic size of MNPs is in accordance with size of MNPs measured by electron microscopy (4 +/- 1 nm). The zeta potential of MNPs reduces by PEGylation and chelating with Ba2+ ions. Fourier transformed infrared (FTIR) analysis proposed that OH and NH groups of MNPs are possible binding sites for Ba2+ ions. The prepared Ba-MNPs-mPEG shows no significant cytotoxicity at concentration up to 100 ppm of barium concentration after 24 h. Finally, our results indicated that the X-ray attenuation of Ba-MNPs-mPEG is similar and slightly higher than Iohexol as the commercially available iodinated contrasting agent at the same concentrations.