Efficacy of Laser-Activated Gold Nanoshells in Ablating Prostate Cancer Cells in Vitro

Abstract

Nanoshells (NS) are nanoparticles consisting of a dielectric silica core covered by a thin gold shell. Nanoshells can be designed to absorb near-infrared (NIR) light strongly to generate heat and provide optically guided hyperthermic ablation. Laser-activated gold nanoshells (LAGN) may offer a minimally invasive targeted ablative treatment for prostate cancer. We studied the in-vitro effectiveness of LAGN ablation on human prostate cancer cells. Two human prostate cancer (PCa) cell lines, PC-3 and C4-2, were grown to 80% confluency in T medium with 5% fetal bovine serum. In order to determine a threshold concentration of gold nanoshells (GNS) needed to achieve full cellular ablation, dose titration was performed. In subsequent experiments, GNS were added to PCa cells in phosphate-buffered saline at concentrations above the predetermined threshold. The cells were then exposed to NIR light (810 nm, 88 W/cm2) for 5 minutes and stained immediately for viability using the Calcein AM assay. For determining long-term cell survival, the crystal violet assay was employed. The GNS could be evenly distributed across the culture plates. A ratio of 5000 GNS per PCa cell was critical for achieving cell kill. Cells treated with GNS + NIR demonstrated a laser-specific zone of cell death. The crystal violet viability assay confirmed consistent cell death rather than induction of cell dormancy. Cells treated with GNS alone or with NIR light alone demonstrated no toxicity. Laser-activated gold nanoshells can ablate human PCa cells in vitro. This nanoparticle technology is an attractive therapeutic agent for selective tumor ablation.