In spite of the high analytic potential of Magneto Optical Surface Plasmon Resonance (MOSPR) assays, their applicability to biosensing has been limited due to significant chip stability issues. We present novel solutions to surpass current limitations of MOSPR sensing assays, based on innovative chip structure, tailored measurements and improved data analysis methods. The structure of the chip is modified to contain a thin layer of Co-Au alloy instead of successive layers of homogenous metals with magnetic and plasmonic properties, as currently used. This new approach presents improved plasmonic and magnetic properties, yet a structural stability similar to standard Au-SPR chips, allowing for bioaffinity assays in saline solutions. Moreover, using a custom-designed measurement configuration that allows the acquisition of the SPR curve, i.e., the reflectivity measured at multiple angles of incidence, instead of the reflectivity value at a single-incidence angle, a high signal-to-noise ratio is achieved, suitable for detection of minute analyte concentrations. The proposed structure of the MOSPR sensing chip and the procedure of data analysis allow for long time assessment in liquid media, a significant advancement over existing MOSPR chips, and confirm the MOSPR increased sensitivity over standard SPR analyses.
Keywords: Affinity biosensor; Angle-resolved surface plasmon resonance; Fixed-angle surface plasmon resonance; Magnetic alloys; Magneto-optic surface plasmon resonance; Surface plasmon resonance enhancement.