Characterization and Photophysical Properties of Phthalocyanine-Cytidine-Single Walled Carbon Nanotube Anti-Cancer Complex

Abstract

Background: The mortality rate of cancer, one of the leading causes of death globally is continuously increasing. Despite the progress in preparing and approving conventional chemotherapeutic drugs, new forms of the diseases are evolving. Hence, an urgent need for alternative therapy .  Objectives: To prepare combinatory drugs composed of nucleoside-metallophthalocyanine and a single-walled carbon complex as a potential anti-cancer agent.The complex is a major key player in photodynamic therapy. Cytidine, a nucleoside which is a major component of ribonucleic acid was chemically linked to zinc tetra-phenoxycarboxy phthalocyanine (1), a photoactive compound represented as ZnTCPC-cytidine (2). Complex 2 was adsorbed on single-walled carbon nanotube (SWCNT) represented as ZnTCPC-cytidine-SWCNT (3). Methods: Complexes 1, 2 and 3 were characterized using UV-visible and Fourier transform infrared (FTIR) spectroscopy. The photophysical properties such as fluorescence quantum and triplet quantum yield were studied using fluorescence emission and laser flash spectroscopy respectively. Results: The absorption spectra show that complex 1, 2 and 3 have the characteristics Q-band of metallophthalocyanine compounds, the FTIR spectra also confirmed that the cytidine was chemically linked to ZnTCPC, while ZnTCPC-cytidine was successfully adsorbed on SWCNT through π-π stacking. The fluorescence quantum yields were 0.10, 0.098 and 0.130, while the triplet quantum yield was 0.49, 0.76 and 0.78 for complex 1, 2 and 3 respectively. Conclusions: The triplet quantum yield result showed that complexes 2 and 3 can generate high singlet oxygen, the cytotoxic agent responsible for the irreversible destruction of cancerous cells. Hence, these complexes would find application as potential anticancer drugs for photodynamic therapy.

Keywords: Zinc tetra-phenoxycarboxy phthalocyanine, Single-walled carbon nanotubes, cytidine, fluorescence and triplet quantum yields