(The) application of dome reflectors for improvement in the light collection efficiency of fluorescence detection systems

Abstract

Fluorescent immunochemical assay with specific antigen-antibody binding is frequently used to detect various biomolecules, and can be applied to determine, for example, the existence of toxic materials and the contagion of diseases. To implement portable biochemical monitoring systems for on-site diagnosis, fluorescence detection systems should be simple yet sensitive. In this work, A novel fluorescence detection system based on non-imaging optics with a cost/energy-efficient LED (Light Emitting Diode) light source was developed for point-of-care test (POCT). Instead of using refractive lenses with limited numerical apertures, our reflector-based fluorescence detection system consists of spherical dome mirrors surrounding the target sample to efficiently redirect the isotropic fluorescent light toward the photodetector. The combination of the dome reflectors coated with a metallic (silver) thin film can potentially provide more than 90% of fluorescent light collection efficiency by extending the solid angle for fluorescence collection to nearly 4π steradian. Coumarin-derived dendrimer, whose peak absorption and emission wavelength are 455 nm, and 590 nm, respectively, is used as an example of target biomolecules, and its detection limit is measured to be ~5 nM (~10 ng/mL).