AbstractBiosensors, as defined by Biosensors and Bioelectronics, are analytical devices “incorporating a biological material, a biologically derived material or biomimetic intimately associated with or integrated within a physicochemical transducer or transducing microsystem”. Fluorescence‐based biosensors are those devices that derive an analytical signal from the fluorescence emission process. Such biosensors may be used for a wide variety of tasks, including: detection of compounds of biomedical,1environmental2or defense interest,3on‐line monitoring for process control,4monitoring of foodstuffs,5selective detection of compounds undergoing a chemical separation,6and screening of drug compounds.7Advantages of such devices include:8high selectivity; rapid response times; reusability; amenability to remote analysis; and immunity from electrical interferences. The selective nature of the complexation between the biomolecule and the analyte, combined with the small size of the device and the advantages of total internal reflection (TIR)‐based spectroscopy,9also results in an ability to measure analytes in complex matrixes. Such samples may include highly scattering systems such as milk or whole blood,10or relatively inaccessible locations such as groundwater wells, or even intracellular environments.11The key limitation of such devices mainly centers around the poor stability of biological compounds, which can lead to a substantial drift in instrument response over time. There is also the potential for interferences related to biological autofluorescence, and the analyte‐dependent sensitivity and limit of detection (LOD) for sensors, which rely on the nature of both the protein and the fluorescent probe utilized. Finally, in cases where immunological reagents are used, the devices can show a lack of reversibility, and may operate only as a “one‐shot” screen, without the potential for continuous, quantitative analysis.
