Fiber-optic biosensor based on polyelectrolytes

• Main Author: Tan, Irene Mei Xiu.
• Other Authors: Chan Chi Chiu
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Bioengineering
• Online Access: http://hdl.handle.net/10356/53689
• Institution: Nanyang Technological University

In this project, a photonic crystal fiber (PCF) modal sensor has been proposed as a miniature, label free fiber-optic biosensor, for monitoring and providing quantitative measurements of the binding kinetics of the antibody-antigen complex. The sensor was fabricated by splicing a certain length of the PCF to a single mode fiber (SMF), and collapsing the micro air hole structure within the PCF at the spliced point, and fiber tip ending. The sensor was then subjected to a series of surface modification techniques, in order to modify and alter the surface interface of the sensor to effectively attain different intended conformations. A sol-gel layer, followed by the layer-by-layer (LbL) assembly was employed, to achieve a stable polyelectrolyte multilayer structure that could effectively optimize the orientation and loading capacity of the antibody. Next, the binding kinetics of the immunological binding activity of the antibody-antigen complex was monitored in real-time, and quantified by the immobilization of antibody immunoglobulin G (IgG), to varying concentrations of its complementary antigen species, (anti-IgG). The response signal obtained depicts the resultant phase shifts of the various binding phase occurring at the sensor surface, and was correlated to various kinetics analysis theories. The performance of the proposed biosensor was evaluated on its feasibility in deriving the corresponding association and dissociation rate constants. Finally, a minimum detection limit of 0.0855 mg/L concentration was derived. The data presented in this paper have shown that the proposal may be employed as a valuable monitoring tool with its immunosensing capability and quantitative characterization of biological samples for real-time analysis.