Does Shape Matter? Bioeffects of Gold Nanomaterials in a Human Skin Cell Model
Nicole M. Schaeublin, Laura K. Braydich-Stolle, Elizabeth I. Maurer, Kyoungweon Park, Robert I. MacCuspie, A R M N. Afrooz, Navid B. Saleh, R.A. Vaia, Saber Hussain
Gold nanomaterials (AuNMs) have distinctive electronic and optical properties, making them ideal candidates for biological, medical, and defense applications. Therefore, it is imperative to evaluate the potential biological impact of AuNMs before employing them in any application. This study investigates the role of shape of the AuNMs, i.e., aspect ratio (AR), on mediation of biological responses in the human keratinocyte cell line (HaCaT) through evaluation of cell viability, ROS generation, alteration in gene and protein expression, and inflammatory response. The highly uniform 16.7 nm diameter and 43.8 nm long pegylated gold nanorods (AuNR-PEGs) with low fractal dimension (Df = 1.28 ± 0.08) (i.e., loose packing density) are found to be cytotoxic to the HaCaT cells, with a significant decrease in cell viability occurring at 25 µg/mL and higher. The uniform 20 nm gold nanospheres coated with mercaptopropane sulfonate (AuNS-MPS) with higher fractal dimension (Df = 2.57 ± 0.4) (i.e., dense packing density) are found to be non-toxic even at the highest dose of 100 µg/mL. Moreover, AuNR-PEG caused significant ROS production and up-regulated several genes involved in cellular stress and toxicity. These results combined with increased levels of several inflammatory and apoptotic proteins demonstrate that the AuNR-PEGs are damaging the cells via apoptosis. Exposure to AuNS-MPS however, did not show any of the detrimental effects observed from the AuNR-PEG. Therefore we conclude that shape and agglomeration pattern appears to play a key role in mediating the cellular response to AuNMs.