Confocal Raman imaging study of uptake and distribution of antitumor agent Teraftal in living A549 cancer cells

Abstract

Teraftal (TF), a cobalt octacarboxyphthalocyanine, belongs to the new class of cytostatics — binary catalytic systems developed for the therapy of malignant tumors [1]. Its cytotoxic action occurs via free radical formation mechanism and requires the presence of its catalytic pair — ascorbic acid. TF absorbs strongly in the red region (λ_max= 675 run, ε₆₇₅=1×10⁵ M^-1 cm^-1) but does not fluoresce. Thus its detection inside cells is rather complicated. In order to reveal subcellular distribution and states of TF as well as features of agent uptake we employ here a resonance Raman (RR) confocal spectral imaging (CSI) technique [2, 3]. This method is based on recording RR spectra from within cell in confocal mode. Then experimental spectrum from every point of the cell is decomposed as a sum of reference spectra with appropriate coefficients. The reference spectra originate from in vitro model measurements and describe different states and/or complexes of the drug. Integral intensity of reference spectrum multiplied by decomposition coefficient for each point produces 2D map (spectral image) which reflects relative distribution of states and complexes of antitumor drug.