Investigation of in vitro PDT activities of zinc phthalocyanine immobilised TiO2 nanoparticles

Abstract

Phthalocyanines (Pcs) are commonly used as Photosensors (PSs) in Photodynamic Therapy (PDT) applications due to their intense absorption in the far red-near IR spectral region with a high extinction coefficient and high ability for generating singlet oxygen. Pcs targetspecifically tumors, and do not show any considerable toxic effects under the absence of light. In particular, their chemical versatility has allowed the introducion a number of substituent at the periferal or axial positions which provide modulating photophysical properties, increases the solubility of these compounds in organic solvents. Nanoparticles increase the bioavailability, stability, and transport of PSs to target tissue. TiO2 nanoparticles are prefered in these applications because of their non toxic, low cost and high chemical stability properties. In our study, a Zinc Phthalocyanine (ZnPc) was used as a photosensor. The design of ZnPc integrated TiO2 nanoparticles is intended to make PSs a more effective PDT agent. With the aim to examine the nuclear imaging/treatment potentials of ZnPc and ZnPc-TiO2 in hepatocellular carcinoma (HepG2), colorectal adenocarcinoma (HT29) tumor and human healthy lung (WI38) cell lines in vitro study ZnPc and TiO2-ZnPc were also labeled with 131I. It is determined that 131I-ZnPc-TiO2 nanoparticle show a potential as an agent for the imaging/treatment of hepatocellular cancer by in vitro. The toxicity studies revealed that TiO2 nanoparticle decreases the toxicity of ZnPc. In vitro PDT results show that TiO2-ZnPc has a potential as a PDT agent in colon tumor treatment. Consequently, synthesized ZnPc and ZnPc-TiO2 could be promising candidates as theranostic agents.