Magnetoplasmons for Ultrasensitive Label-Free Biosensing

Abstract

Early detection of immunoglobin G (IgG), a glycoprotein antibody produced in the serum due to various infections, is of paramount importance that will enable effective treatment, immunity assessment, and assist in monitoring outbreaks of contagious diseases. This work demonstrates the transverse magneto-optic Kerr effect (T-MOKE) based magnetoplasmons excited on a composite ferromagnetic/plasmonic grating as a highly sensitive, single wavelength, and target specific biosensing platform. The sharp T-MOKE sensitivity curve corresponding to reduced fwhm results in a two orders of magnitude enhancement in the resolving power compared to conventional propagating surface plasmon polariton (SPP), which is pivotal in identifying minute fluctuations in specific biomolecular concentrations. An order of magnitude improvement in antibody immunoglobin G (IgG) detection limit is observed compared to the SPP based sensing. A detection limit down to 10 ng/mL (66 pM) is achieved using the proposed T-MOKE technique. The results obtained provide compelling evidence of the significantly superior sensitivity and resolving power of the T-MOKE technique for the detection of Human IgG, and it is envisioned that this spectroscopy free, single wavelength measurement approach can be extended to detect biologically/chemically relevant molecules at lower concentrations for early biomedical diagnosis and therapy.