High Throughput Screening for Oxidative Stress Potential By Nanomaterials in a Biological System

| June 4, 2013

NSF Grant Number: EEC-0425826
PI(s): Eugene J. Rogers and Dhimiter Bello
Student Researchers: Shu-Feng Hsieh and Nikhil Organti.
Institution: University of Massachusetts Lowell

Figure 1. The antioxidant capacity of NM-exposed and unexposed human serum in Trolox Equivalent Units (TEU’s). The bars represent the mean and 1.96 standard error of the mean (SEM) for each material assayed in triplicate in 5 runs on different days (n=15 total). *statistically significant different from unexposed control serum (p <0.05); †statistically significantly different from nCb550 and nCb990 (p <0.05); ‡statistically significantly different from refined mix and purified fullerene (p <0.05); ╫statistically significantly different (p <0.05) form 5µm size TiO2.

Figure 1. The antioxidant capacity of NM-exposed and unexposed human serum in Trolox Equivalent Units (TEU’s). The bars represent the mean and 1.96 standard error of the mean (SEM) for each material assayed in triplicate in 5 runs on different days (n=15 total). *statistically significant different from unexposed control serum (p <0.05); †statistically significantly different from nCb550 and nCb990 (p <0.05); ‡statistically significantly different from refined mix and purified fullerene (p <0.05); ╫statistically significantly different (p <0.05) form 5µm size TiO2.

Objectives: Limited studies have shown that selected nanomaterials (NMs) impart various forms of toxicity in cell culture or animals, however, these approaches are complex and expensive; a common and simple metric to screen for potential toxicity is needed. Oxidative stress exerted by NMs in biological systems has been suggested as a key metric to screen for potential adverse effects on human health and the environment. Our laboratories developed and optimized a ‘Ferric Reducing Ability of Serum (FRAS)’ assay as a screening tool to quantify the degree of oxidative damage induced by NMs in a biologically relevant medium; human blood serum. Antioxidants in blood protect against damage caused by free radicals via chemical quenching and decrease when exposed to oxidatively stressful materials.

Significant Results: Using this approach, the antioxidant capacity of NM treated serum was significantly decreased by nano-silver, a series of nano-carbon blacks, fullerene soot, and nano-TiO2 (anatase, p <0.05), but not with nano-alumina, fullerite, purified fullerene, fine TiO2 (rutile) and Min-U-Sil 5 (Figure 1). Of great interest is that both positive and negative results observed here match reports using more complex toxicity assays. This approach appears responsive to multiple determinants of oxidative damage, including particle chemistry, surface area and impurities and is a valid screening method to determine oxidative damage imparted by nanomaterials.

Broader Impact: A simple laboratory tool has been developed to screen for potential toxicity of NM’s by evaluating the degree of oxidative stress exerted by these materials in blood serum in vitro. The FRAS approach may be useful as a surrogate tool to elucidate relationships between potential biological toxicity and specific physico-chemical parameters of engineered nanomaterials and can be used early in manufacturing design with the goal of producing functional but safer materials in with regard to human health and the environment.