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. Author manuscript; available in PMC: 2018 Jan 11.
Published in final edited form as: ACS Appl Mater Interfaces. 2016 Dec 19;9(1):101–111. doi: 10.1021/acsami.6b11304

Figure 1.

Figure 1

Illustration of gadolinium chelated melanin nanoparticles with silica nanocoating (Gd-Mel@SiO2 NPs) in preparation and application. Dopamine molecules start polymerization in the presence of hydroxide ions and end up making spherical melanin nanoparticles (Mel NP). Paramagnetic Gd3+ ions are chelated in melanin matrices for MRI T1 contrast effect. Then, a silica layer is formed on the surfaces of Mel NP with a slow sol–gel reaction controlling a feeding of precursor to reduce self-nucleation of free silica particles. Lastly, fluorescent dye molecules are labeled for the fluorescent imaging of Gd-Mel@SiO2 NPs without significant electron quenching. Our developed fluorescent dye-labeled Gd-Mel@SiO2 NPs are applied to dual-modal contrast enhanced MRI/fluorescent image-guidance for cancer therapy.