Poster/3. Biomedical Photonics

ShenZhen University;ShenZhen University

Two-photon excitation fluorescence imaging (TPEFI) is a nonlinear optical imaging technique. Compared with the traditional single-photon imaging technology, it has many advantages such as little light damage, small bleaching area, high spatial resolution, high fluorescence collection efficiency, and high image contrast. Especially, two-photon microscopy is more suitable for the observation of thick specimen, and real-time three-dimensional or four-dimensional observations of living cells and even living tissue. However, some probes used to label living cells are toxic and will have an adverse effect on the living cells imaging. Squaraine dye is an organic dye with strong fluorescence and low cytotoxicity. In this study, we synthesized a squaraine organic dye with a significant fluorescent effect. OVCAR-3 ovarian cancer cells were labelled with the squaraine dye and detected by confocal laser scanning microscope Leica TCS SP8 for single-photon and two-photon imaging. The OVCAR-3 cells were co-incubated with the squaraine dye at 1 μmol L-1 for 0.5 h, washed with PBS 7.4 three times, and then detected with Leica TCS SP8. The excitation wavelength was 600 nm for single-photon imaging and 1000 nm for two-photon imaging. The results showed that two-photon imaging has better resolution and deeper imaging depth, suggesting its potential application in imaging of thick samples. In conclusion, two-photon imaging using squaraine dye is a potential imaging technique that may be widely applied in cancer diagnosis in the future.