Background and objective: The mechanism of tumor tissues selectively uptake the photosensitizer in photodynamic therapy (PDT) is still unclear. This study was to investigate the affinity of tumor cells to the photosensitizer photofrin-II.
Methods: Ultraviolet spectrophotometer was applied to measure the absorption spectra of various cell culture media. The fluorescence spectrum of photofrin-II was determined by spectrofluorometer. The absorption and elimination condition of photofrin-II were detected in immortalized human esophageal epithelial cell line SHEE and its malignant transformation cell line SHEEC.
Results: The maximum excitation wavelength of fluorescence for photofrin-II was (395.0+/-0.5) nm, and the maximum emission wavelength of that was (634.1+/-0.5) nm. The laser at the wavelength of 630 nm used in this experiment could permeate various types of cell culture media. There was no significant difference in the absorption and elimination of photofrin-II between SHEE and SHEEC at the same concentration and time. The absorption of photofrin-II in SHEE and SHEEC increased with the increase in photofrin-II concentration and duration, and reached the platform at the concentration of 30 microg/mL and a time point of 150 min, respectively. The photofrin-II contents of SHEE and SHEEC showed a slight change after 15-30 min, and diminished rapidly after 30 min.
Conclusion: High photosensitizer concentration in tumor tissues may be not correlated with the affinity of tumor cells.