Keratin-Templated Synthesis of Metallic Oxide Nanoparticles as MRI Contrast Agents and Drug Carriers

Keratin is a family of cysteine-rich structural fibrous proteins abundantly present in skin and skin appendages. Inspired by the template synthesis strategy, in this work, keratin was utilized for the first time as a platform template to synthesize metallic oxide nanoparticles, such as MnO2 (MnNPs@Keratin) and Gd2O3 (GdNPs@Keratin), in a simple and environment-benign fashion. These nanoparticles possess good colloid stability and biocompatibility, high T-1, relaxivity (r(1) value = 6.8 mM(-1)s(-1) for MnNPs@Keratin and 7.8 mM(-1)s(-1) for GdNPs@Keratin), and superior in vivo magnetic resonance imaging performance of tumor. Moreover, these keratin-templated nanoparticles have great potential as drug carriers with the capacity of redoxresponsive drug release due to the existence of disulfide cross linking in keratin coating. These results suggest that keratin can be a promising platform template for the development of metal-based nanoparticles for cancer diagnosis and therapy.