Immunosensing using a metal clad leaky waveguide biosensor for clinical diagnosis

The optical detection technologies have been used in biosensors for the highly sensitive, real-time and label-free detection of biomolecules. In this report, a metal clad leaky waveguide (MCLW) was used as an immunosensing tools. We optimized the structure of the sensor chip for highly sensitive detection, followed by fabrication of the MCLW sensor chips and construction of a detection system for immunosensing. Titanium and SiO2 films were deposited onto a BK7 substrate using an E-beam evaporator and the thickness of the films was 9 nm and 347 nm, respectively. The sensing response of the system to the bulk refractive index was calibrated using various concentrations of a glycerol solution. As a result, the MCLW sensor system was able to detect a change of ∼3.8 × 10−6 RIU in the refractive index of the ambient solution. In addition, immunosensing was achieved using the MCLW sensor for an antigen–antibody reaction in real time. The biotin-labeled antibody of human interleukin 5 (hIL5) was immobilized on the sensor surface containing modified with streptavidin. The hIL5 in a bio-solution was quantitatively analyzed in real time using the MCLW sensor system.