(700g) Multifunctional Theranostic Silica-Gold Core-Shell Nanoparticles for Breast Cancer Applications

Breast cancer (BrCa) is the second leading cause of cancer death in women, and this year about 40,000 women are predicted to die from BrCa. About 10-20% of BrCa are found to be triple negative, an even more severe type of BrCa that has lower survival rates. Triple negative BrCa (TNBC) does not express the genes for hormone epidermal growth factor receptor 2 (HER-2), estrogen receptors (ER), and progesterone receptors (PR) which means hormone therapy and drugs that target these receptors are ineffective means of treatment. Recently the use of nanoparticles has gained popularity for drug delivery uses, and this research focuses on the synthesis and characterization of multifunctional theranostic silica-gold core-shell nanoparticles (SGCSNs) which will be used for imaging and photothermal therapy of TNBC. The nanoparticles were synthesized by seeding a functionalized silica core with gold nanoparticles, and then forming a complete gold shell around the seeded nanoparticle through gold reduction onto the surface. The silica-gold core-shell nanoparticles were then functionalized with a bifunctional polyethylene glycol (PEG) molecule. One end of the PEG molecule has a thiol group attached which binds to the gold shell of the core-shell nanoparticles by a gold-sulfur bond. The other end of the PEG molecule either has folic acid attached, which binds to the over expressed folate receptor seen in TNBC, or fluorescein isothiocyanate (FITC) attached which serves as a fluorescent imaging agent. A gold shell was chosen for the synthesis of the core-shell nanoparticles because gold serves as a good agent for CT scanning because of its high Z value, making the nanoparticles ideal for imaging. In addition, because of surface plasmon resonance, gold nanoparticles can be used to destroy cells through photothermal therapy. As a result of the core-shell structure, during photothermal therapy, more heat can be generated from the nanoparticle compared to just gold nanoparticles because of the difference in dielectric constants, therefore more efficiently destroying cancerous cells. The characterized and functionalized SGCSNs will be used for applications in imaging and photothermal therapy of TNBC in vitro, using MDA-MB-231 cells. If successful SGCSNs could be useful for both imaging and photothermal therapy, and could greatly improve the quality of life of TNBC patients.