Advances in Optical Bio-Sensing and Bio-Detection

Abstract

Optical and nano technologies such as fiber optic-based sensors and fluorescent nanoparticles have been gaining more attention in the fields such as biology, biophysics, medicine in the past few decades. One focus of the application of such technologies in bio-sensing and bio-detection have been on improving sensitivity, specificity, and limit of detection of currently available tests and assays. It is of importance, as seen during COVID-19 pandemic, that the healthcare industries have the most accurate and sensitive and specific tests available to them in order to efficiently combat such pandemics as well as other contagious diseases. In addition, the improvement in the limit of detection of biomarkers will help in earlier detection of diseases like cancer, which is paramount to the successful treatment and remission of such diseases. In this dissertation, we review the necessity of early detection of biomarkers of diseases and give a general overview of current optical technologies that show promising potential in achieving the lower limits of detection. We will further discuss the application of the optical technologies in bio-sensing and bio-detection of bio-molecules and also provide a theory for the use of lasing of fluorescent molecules used as detection tags in such assay platforms as a method ultra-sensitive method for detection low concentrations of bio-molecules. In addition, we demonstrate that using fluorescent nanoparticles in a competitive assay as fluorescent detection agent instead enzymatic enhancement used in Enzyme-Linked Immunosorbent Assay (ELISA), in tandem with confocal microscopy as detection instrument can potentially improve the antibody neutralizing assay’s limit of detection. Finally, we will discuss the surface functionalization protocol of optical microresonators for using whispering gallery modes for single molecule detection, as a sensitive optical bio-sensor.