Nanoparticles of methylene blue enhance photodynamic therapy.

Breast cancer is the most commonly diagnosed cancer and the second leading cause of death related to cancer among women worldwide. Screening and advancements in treatment have improved survival rate of women suffering from this ailment. Novel therapeutic techniques may further reduce cancer related mortality. One of several emerging therapeutic options is Photodynamic Therapy (PDT) that uses light activated photosensitizer (PS) inducing cell death by apoptosis and/or necrosis. Nanotechnology has made contribution to improve photosensitizer for PDT, increasing the efficiency of therapy using gold and silver nanoparticles. Efforts have been done to develop better mechanism to improve PS and consequently PDT effects. In this study, we investigate the efficacy of the PDT using gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) when mixed to methylene blue (MB) in the treatment of the human breast adenocarcinoma cell line (MDA-MB-468). The MDA-MB-468 was treated in the presence of different MB concentrations with/without AuNPs or AgNPs. The colloidal solution of AgNPs showed a plasmon resonance band at 411 nm in UV-visible range and a bimodal size distribution. The results of viability analysis showed that cells treated with nanoparticles exhibited higher cytotoxicity than cells treated with only MB, improving the efficiency of the treatment in the tumor cells. The cytotoxicity effect of MB associated with AgNPs on MDA-MB-468 cell line could be related to increased reactive oxygen species production due to the release of Ag+ ions from nanoparticles surface, suggesting that the association between FS and AgNPs has potential as a PDT agent.

FTIR study of secondary structure changes in Epidermal Growth Factor by gold nanoparticle conjugation.

Conformation of protein is vital to its function, but may get affected when processing to manufacture products. It is therefore important to understand structural changes during each step of production. In this study, we investigate secondary structure changes in the targeting protein Epidermal Growth Factor (EGF) during synthesis of theranostic bifunctional nanoparticle, devised for Photodynamic therapy of breast cancer. We acquired FTIR spectra of EGF; unconjugated, post treatment with α-lipoic acid, attached to gold nanoparticle, and bound to the bifunctional nanoprobe. We observed decreasing disordered structures and turns, and increasing loops, as the synthesis process progressed. There was an overall increase in ß-sheets in final product compared to pure EGF, but this increase was not linear and fluctuated. Previous crystal structure studies on EGF-EGFR complex have shown loops and ß-sheets to be important in the binding interaction. Since our study found increase in these structures in the final product, no adverse effect on binding function of EGF was expected. This was confirmed by functional assays. Such studies may help modify synthesis procedures, and thus secondary structures of proteins, enabling increased functionality and optimum results.