Light absorption measurements for explaining tumor cell killing efficiency in photodynamic therapy

M.E. ETCHEVERRY; M.A. PASQUALE; M. GARAVAGLIA

Villa Carlos Paz

Congreso; XLII Reunión Anual de la Sociedad Argentina de Biofísica; 2013

Sociedad Argentina de Biofísica

In this contribution we present results from a LED lamp at 637 nm and with an average width of 8 nm, used for PDT in our previous works. The efficiency of light absorption for solutions with different photosensitizer concentrations (Themoporfin) and light intensity was evaluated with and spectrophotometer (Ocean Optics HR2000 + ES) coupled to an optical fiber and from photometric data employing an electronic eye mounted in an optical bench. Results were consistent with the improve in PDT efficiency obtained from HeLa cells (human cervical carcinoma) cultures treated with increasing photosensitizer concentrations (0.05 μg/ml, 0.25 μg/ml and 1μg/ml) and illuminating times (3min, 6min and 12 min) times. The absorption spectrum for temoporfirin exhibited a characteristic peak centered at 650nm. Spectrophotometric measurements at the employed conditions in theses work, showed that near the region of the absorption peak, the signal exhibited significant differences when using two concentrations and four light intensities, the latter obtained varying the distance of the lamp to the detector. Indeed, the higher the drug concentration the lower the spectrophotometric record, which would correspond to a greater number of photons absorbed by HeLa cells.