Applications of Optical Resonance to Biological Sensing and Imaging: II. Resonant Cavity Biosensors

Interrogating binding interactions between proteins, segments of DNA or RNA, and biospecific small molecules is critically important for a great number of applications in biological research and medicine. Microarray technology has emerged over the past decade to address applications that seek to measure thousands or even millions of binding interactions at once. A microarray consists of a solid support, or substrate, with multiplicity of spots on its top surface each containing a different type of fixed capturing molecule. A sample solution containing unknown target molecules, or analytes, is introduced to the microarray surface typically via a small fluid chamber or flow cell. The amount of target material bound to any feature after washing the array gives an indication of the affinity between the target and capturing agent at that spot. There are a number of important applications in biological research that benefit from microarray throughput such as gene expression profiling or antigen-antibody interaction monitoring. Aside from research applications, microarrays may play a crucial role in a new era of medical diagnostics. Biomedical research is continuing to point toward molecular biomarkers that can be used to help doctors diagnose diseases sooner, with greater accuracy, and provide information that helps doctors personalize treatment plans.