Near-infrared-responsive, superparamagnetic Au@Co nanochains

This manuscript describes a new type of nanomaterial, namely superparamagnetic Au@Co nanochains with optical extinctions in the near infrared (NIR). The Au@Co nanochains were synthesized via a one-pot galvanic replacement route involving a redox-transmetalation process in aqueous medium, where Au salt was reduced to form Au shells on Co seed templates, affording hollow Au@Co nanochains. The Au shells serve not only as a protective coating for the Co nanochain cores, but also to give rise to the optical properties of these unique nanostructures. Importantly, these bifunctional, magneto-optical Au@Co nanochains combine the advantages of nanophotonics (extinction at ca. 900 nm) and nanomagnetism (superparamagnetism) and provide a potentially useful new nanoarchitecture for biomedical or catalytic applications that can benefit from both activation by light and manipulation using an external magnetic field.