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 T1 relaxivity (r1 value = 6.8 mM−1s−1 for MnNPs@Keratin and 7.8 mM−1s−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 redox-responsive 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.