Reactive oxygen species creation by laser-irradiated indocyanine green as photodynamic therapy modality: an in vitro study

Abstract

Applications of lasers in phototherapy have been the trend for the last few decades. The photodynamic therapy process normally depends on photosensitizers and laser beams. Through this study, indocyanine green has been used as a photosensitizer, which is normally activated using laser lines between 750 and 805 nm. The activity of the indocyanine green to do fluorescence by other pulsed laser sources has been tested by fluorescence technique, and it has been proven that the laser lines at 810, 940, and 980nm are able to excite the indocyanine green with different extents. The indocyanine green activation has been tested by several laser lines (810, 940, and 980 nm) commonly used as surgical lasers. The generated oxygen has been measured after irradiating the indocyanine green with the different laser lines. A comparison has been made between laser irradiation as a pinpoint and a broad beam. It is found that the wide beam is more effective in activating oxygen production. In the end, it is concluded that lines 810 and 940nm were effective in activating the used dye, while the 980nm activity did not show enough efficiency.

Keywords: Indocyanine green; Laser ablation; Laser spectroscopy; Photodynamic therapy; Photosensitizers.

Fig. 1

The excitation spectra of the used ICG powder

Fig. 2

The absorption spectra of ICG as it is stated in the spectra the maximum coordinates was (926, 0.77), the full with at half maximum (FWHM) in between 624 nm and 952 nm, and the double FWHM was in between 588 nm and 981nm

Fig. 3

The emission spectra of ICG after excited by pulsed laser with wavelength a 840nm, b 940 nm, and c 980 nm

Fig. 4

The amount of the TDO in the bi-distilled water before (red line) and after (black line) exposed to pinpoint different lasers with wavelengths 810, 940, and 980 nm

Fig. 5

The amount of the TDO in the ICG before (black bar) and after (red bar) exposed to a broad and b pinpoint different lasers with wavelengths 810, 940, and 980 nm