The Development of an Optical Immunosensor Based on Ion-Exchanged Waveguides in Glass and Evanescent Excitation of Fluorescence

Zhou, Yan (1992) The Development of an Optical Immunosensor Based on Ion-Exchanged Waveguides in Glass and Evanescent Excitation of Fluorescence. PhD thesis, University of Glasgow.

Abstract

Although there are a number of optical techniques which can be used for immunosensing, optical evanescent wave immunosensors are considered to be promising because they can eliminate the washing step usually associated with conventional immunoassays. The low cost of fabrication of ion-exchanged waveguides favours the concept of a single use disposable immunosensor which will probably dominate the huge immunotesting market in the future. Consequently, the ion-exchange technique is employed to fabricate waveguides suitable for immunosensing purposes. As a result of the research, a novel disposable wash-free optical immunosensor based on potassium ion-exchanged patterned waveguides in glass has been demonstrated. The immunosensor has shown very good performance when it is applied to multichannel (or multi-analyte) and differential immunoassays. Potassium ion-exchanged surface planar waveguides have been successfully buried using a thermal sodium ion-exchange process. The idea of fabricating patterned waveguides and using them as the sensing element has been put forward and successfully implemented for the first time (to the author's knowledge). The wells etched in the superstrate of a completely buried waveguide make it possible to immobilise different antigens as well as control proteins in different individual wells. As a result, multichannel (or multi-analyte) immunoassays and differential immunoassays have been successfully conducted. Experimental results have shown that the evanescent wave immunosensor has a sensitivity (or detection limit) of about 0.3mug/ml for FITC (fluorescein isothiocyanate) labelled antibodies and this is roughly equal to that of a corresponding conventional solid phase fluorescence immunoassay. Although the sensitivity is limited by background noise and is not high enough for diagnostic testing, it is very likely that the sensitivity can be increased substantially if the method of time-resolved fluorescence immunoassay is adopted.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Electrical engineering, Materials science
• Date of Award: 1992
• Depositing User: Enlighten Team
• Unique ID: glathesis:1992-78410
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 28 Feb 2020 12:09
• Last Modified: 28 Feb 2020 12:09
• URI: https://theses.gla.ac.uk/id/eprint/78410