Synthesis and characterization of gold nanostructured Chorin e6 for Photodynamic Therapy.

Photodynamic therapy is an alternative treatment for cancer based on cellular uptake of a photosensitizer, illuminated with an appropriate wavelength in the presence of oxygen. A cascade of reactions generates reactive oxygen species leading to cell death. Using carbodiimide chemistry, chlorin e6 (Ce6) was covalently bonded to thiourea, and (via the sulphur end group) to gold nanoparticles (AuNPs), forming the Ce6-AuNP complex. Ce6 absorbs in the range 650-680nm, where the coefficient of biological tissue absorption is low (part of the therapeutic window), which is ideal for biological application. Transmission Electron Microscopy, UV-vis spectroscopy, Fourier transform Infrared Spectroscopy and Zeta potential measurements were completed to characterize the Ce6-AuNP complex. The bare AuNPs have an average diameter of 18±4nm. A line of human breast carcinoma cells (MDA-MB-468) was used to determine whether Ce6 functionalization to AuNPs potentiate its activity. Trypan blue assays were used to assess cell viability. In the absence of light, Ce6 either alone or bounded to AuNPs was not cytotoxic. When irradiated at 660nm, the cytotoxicity of Ce6-AuNP was higher than Ce6 alone for MDA-MB-468 cells using 4h incubation. AuNPs without Ce6 showed no cytotoxic.

Apoptosis-associated genes related to photodynamic therapy in breast carcinomas.

The aim of this study was to find the apoptosis molecular markers involved in the cell death that might be related to photodynamic therapy (PDT) mechanisms in breast cancer. The mammary tumors were induced in 25 Sprague-Dawley female rats by a single, oral gavage of 7,12-dimethylbenz(a)anthracene (DMBA; 70 mg/kg body weight). Animals were divided into four groups: G1 (normal, without DMBA), G2 (control, without PDT treatment), G3 (euthanized 48 h after PDT), and G4 (euthanized 24 h after PDT). For PDT experiments, the photosensitizer used was Photodithazine, and 100 J/cm of light at a fluence rate of 100 mW/cm was delivered to treat lesions. A sample of each animal was investigated by quantitative real-time PCR using Rat Apoptosis RT2 Profiler™ PCR Array platform. The results showed 20 genes with differential expression between PDT and control groups. A significant upregulation was observed for pro-apoptotic genes CASP4, CASP12, CIDEA, GADD45A, and FAS and downregulation of anti-apoptotic genes MAPK8IP1, TNFRSF11B, and NAIP2 in PDT-treated tumors. These results indicate that these genes are more directly involved in cell apoptosis induced by PDT.