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Since the first application of surface plasmon resonance (SPR) for biosensing almost two decades ago, SPR has made great strides in terms of both the instrumentation and the application. We used spectroscopic ellipsometry as an SPR sensor to detect the reaction of HER2 protein of SKBR3 cancer cells with its antibody. Since the Psi value of ellipsometry is related to the reflectivity of p wave, the surface plasmon signal can be measured using spectroscopic ellipsometry. A glass plate coated with 50 nm-thick gold film was dipped in HER2 antibody solution for 1 hour. The substrate was then dipped in a soup containing broken SKBR3 cells to induce HER2 antibody-antigen reaction. The pure gold film exhibited a typical SPR peak at 2.04 eV. After the adsorption of HER2 antibody, a new peak appeared at 1.99 eV. After dipping in the soup of SKBR3 cells, the peak shifted to 1.96 eV. We believe this shift is due to the change in surface plasmon caused by binding of HER2 protein and antibody. Morphology of the samples and the size of the protrusions on the surface observed by atomic force microscopy (AFM) agreed with the change expected from the sample treatment. Our result adds a successful example of utilizing spectroscopic ellipsometry and AFM for detecting cancer cells. This work was supported by the Korea Science and Engineering Foundation through NCRC program of Seoul National University. |