A novel dual-color total internal reflection fluorescence detecting platform using compact optical structure and silicon-based photodetector.

A novel dual-color total internal reflection fluorescence detecting platform (DTP) was developed for the simultaneous detection of two fluorescence dyes. The DTP employed a simple and compact optical system and a Si-based photodetector SOP-1000 assembly to improve the optical efficiency and detection sensitivity. In the optical system, a single-multimode fiber optic coupler was applied for the transmission of two wavelength excitation lights and the collection and transmission of two wavelength fluorescence signals, and a fiber optical switch controlled two wavelength excited lights to alternatively enter into the combined tapered fiber optic probe and two wavelength fluorescence dyes were alternatively excited. The simultaneous and sensitive detection of two wavelength fluorescence signals was achieved by one photodetector SOP-1000 based on the time-resolved effect of the fiber optical switch. The DTP demonstrated its sensitivity of 50 fW light intensity, and the limit of detection of Cy5.5 and Pacific Blue dye (PB) were 0.05 nM and 2.1 nM, respectively. This miniaturized and integrated DTP with high sensitivity, simple optical structure, negligible cross-talk, and cost-effectiveness could be a potential alternative to the conventional dual-color fluorescence detecting systems. It could also be a powerful component of a μ-TAS system for highly sensitive dual-color fluorescence detection.