Investigation of the pH Dependent Cytotoxicity of Paclitaxel Conjugated Gold Nanoparticles.

Background: Breast cancer, apart from skin cancer, is the most common cancer among women accounting for nearly 1 in 3 cancers and the second leading cause of cancer-related death among women after lung cancer. Finding new approaches to treat such cancers is critically important.

Objective: This work investigated the ability of a simple system based on paclitaxel conjugated gold nanoparticles (AuNP) to induce efficient cytotoxicity against T47D breast cancerous cells at different pH values.

Methods: The synthesis and characterization of nanoparticles using two approaches are presented. In one case, the AuNP capping agent is exchanged for a long chained thiol with a terminal carboxylic acid which can then be connected to paclitaxel (termed the Chemical Modification approach) while in the other case, the thiol capping agent is chemically modified with the paclitaxel first and then exchanged onto the AuNP (termed the Ligand Exchange approach). Cytotoxicity of conjugates based on gold nanoparticles at pH 7.4 (normal physiological pH) and 6.5 (more acidic pH found near tumors) against the T47D breast cancer cell line was assessed using the 3-(4, 5 dimethylthiazol-2-yl)-2, 5- diphenyltetrazolium (MTT) viability assay.

Results: T47D viability decreased significantly after treatment with the chemical modification conjugate at pH 6.5 compared to that at pH 7.4. The ligand exchange conjugate also decreased cell viability with a gap of 10 % between the two pHs.

Conclusion: These nanoparticles are promising conjugates for the treatment of breast cancer using small amounts of the active chemotherapy agents which will lead to fewer side effects.