Homogeneous biosensor based on optical detection of the rotational dynamics of anisotropic nanoparticles

We introduce a novel biosensor concept, which employs hybrid nanoparticles consisting of magnetic nanorods encapsulated by noble metal shells. These nanoparticles have the potential to directly signal the presence of analyte molecules in the sample solution via inducing a change in their rotational dynamics on analyte binding, thus circumventing the need of extensive sample preparation. While the nanoparticles’ magnetic cores enable rotation in an external magnetic field, their shells are used to monitor their rotational dynamics through the excitation and observation of longitudinal plasmon resonances. We present model calculations on the aspired properties of suitable core-shell nanorods and first experimental results proofing the principle of this measurement method for plain Co-nanorods excited by a rotating magnetic field.