Single- and Two-photon Excitation Autofluorescence Spectroscopy of Diabetic Rat Artery

This paper explores the differences in autofluorescence spectroscopy characteristics of rat arterial wall between normal and diabetic animal models using single- and two-photon excitation. The system we used is mainly composed of a laser scanning confocal microscope and a femtosecond Ti: Sapphire laser. Our samples come from 3 healthy and 3 diabetic Wistar rats. Each tissue slice has a thickness of 20 mum and is excited using 488 nm CW light as well as 740 nm and 800 nm ultrashort femtosecond near infrared (NIR) light, respectively. Experimental results show that for single-photon excitation at 488 nm, the normal and diabetic rat tissue has same emission spectra with two peaks near 518 nm and 570 nm respectively, but their peak intensity ratio of the first to the second is quite different; for two-photon excitation at 740 nm and 800 nm, a shift of emission spectrum and a difference in relative normalized intensity at emission peaks are observed. Preliminary results show that autofluorescence spectroscopy using single- and two-photon excitation may have potential applications in clinics for tissue discrimination and diagnosis.