Magneto-Plasmonic Co@Pt@Au Nanocrystals for Biosensing and Therapeutics

Multifunctional nanoparticles (NPs) exhibiting high magnetic property and plasmonic resonance are expected to be advanced nanomaterials which enable therapy, detection, and diagnosis simultaneously for medical applications. To achieve the practical performance of the multifunctional NPs, the precise design and synthesis are both required. In this work, considering the chemical stability and controllability, Co–Pt@Au core–shell NPs, which exhibit high magnetic property and plasmonic resonance, were theoretically designed based on calculation and then experimentally synthesized using an alcohol reduction method. Co–Pt NPs were uniformly synthesized using a technique which enables reduction control of Pt through the formation of a Pt–oleylamine complex. Moreover, depending on the Co/Pt ratio, the distribution of Co and Pt in a nanoparticle was precisely controlled, and as a result, Co–Pt alloy and Co@Pt core–shell NPs were individually prepared. In particular, Co@Pt NPs exhibit a high magnetic property and are suitable for Au coating due to a small lattice mismatch. In fact, Au coating onto Co@Pt NPs was successfully performed via inhomogeneous nucleation, which results in Co@Pt@Au NPs exhibiting plasmonic response of Au with high magnetic property and being dispersed in water by ligand exchange for in vivo use. The developed synthetic method enables designed synthesis of complicated multicomponent nanoparticles through tunable reduction reaction and provides highly potential NPs for transport and sensing applications.