Flash 4.0 lt

A commercial microscope system (Olympus, IX83) was customized to achieve automated polarized light imaging. A circular polarizer with a wavelength range of 400–700nm (Edmund Optics, #88-099) and an interference bandpass filter centered at 535nm with a pass-band of 64.4nm (Olympus, IF550) were placed in the illumination path to achieve circularly polarized light illumination. In the image acquisition path, four linear polarizers (Chroma, 21003b) were placed into a motorized filter wheel (Prior Scientific Inc., HF108SIX3) to perform serial image acquisition at 4 polarization angles. The images were acquired with a 16bit CMOS camera (Hamamatsu, Flash 4.0 LT).

The fluorescence spectra of aptamer–QD@MNP and antibody–QD@MNP nanosensors were measured in a solution to characterize cortisol detection using a spectrofluorometer (FluoroMax-4c, Horiba) with 380 nm wavelength excitation. Steroid hormone-induced QD fluorescence quenching was performed on a glass substrate and analyzed using an inverted fluorescence microscope (Olympus IX73) through a 40× objective lens under UV excitation with a spectral range from 350 to 400 nm produced by a light-emitting diode (LED) excitation (X-Cite 120) and a filter set (DAPI-50LP). The fluorescence signals were characterized by a monochromic sCMOS camera (Hamamatsu Flash 4.0 LT) on the microscope. The color fluorescent images were captured by a color charge-coupled device (CCD) camera (Lumenera Infinity3–3UR). The fluorescent images were taken with background subtraction, and the same setting was used throughout the experiment. Fluorescence lifetime measurements were accomplished using a time-correlated single-photon counting (TCSPC) system (Picoharp 300, PicoQuant) and 375 nm UV pulsed laser excitation.