Novel AS1411-gallium(III) phthalocyanine conjugates for targeted photodynamic therapy

In this study, peripheral tetra, non-peripheral tetra and peripheral octa gallium (III) phthalocyanines bearing 4mercaptopyridin groups (Pc1, Pc2 and Pc3) and the quaternized derivatives (Pc1Q, Pc2Q and Pc3Q) of these compounds were synthesized. The structures of all compounds were confirmed by UV-Vis., FT-IR, 1H NMR, MALDI-TOF mass spectra and elemental analysis. The interaction of Pc1Q, Pc2Q and Pc3Q with AS1411 aptamer was investigated by UV-Vis. and CD spectroscopies. The binding constants and interaction stoichiometry values were found spectrophotometrically. The effects of the compounds on AS1411 structure were determined by CD spectroscopy. The stability of AS1411-Pc conjugates was investigated by 1-month long CD spectroscopic monitoring. The interaction of Pc1Q, Pc2Q and Pc3Q with AS1411 was also examined through electrochemical impedance spectroscopy (EIS) technique. The impact of doxorubicin (Dox) on the binding affinity of each phthalocyanine to AS1411 was examined to validate the specificity of our assay within complex biological environments. The cytotoxic activities of AS1411, individual phthalocyanines and AS1411-Pc complexes were also studied in both MCF-7 and Dox-Res-MCF-7 cell lines in the presence and absence of Dox. The findings suggest that phthalocyanines conjugated with aptamers, particularly Pc2Q, enhance apoptosis and cytotoxicity, making them promising candidates for selective cancer treatment.