A facile synthesis of formazan dyes conjugated with plasmonic nanoparticles as photosensitizers in photodynamic therapy against leukemia cell line

A series of 1,5-bis(4-aryl/heteryl)-3-cyanoformazan derivatives was synthesized and characterized by spectral analysis. The synthesis strategy involved an easy and practical diazo coupling of different aryl (heteryl) diazonium salts with cyanoacetic acid. The synthesized compounds were electrostatically conjugated to gold and/or silver nanoparticles in dimethylsulfoxide and were examined as photosensitizers for photodynamic therapy (PDT). The PDT activity of the formazan derivatives alone and conjugated with metal nanoparticles was investigated against HL-60 cells under dark and light conditions. Formazan derivatives and their conjugates showed variable promising anticancer activity in dark and light conditions related to their structures. The interaction of synthesized formazan derivatives with metal nanoparticles enhanced the light absorption of the dyes and thus showed remarkable increase in PDT against cancer cells. Graphical abstract: .