Studies on effect of stabilizers, chelators and inherent periodicity on nanoparticle antioxidant activity

Graduation date: 2015Access restricted to the OSU Community, at author's request, from May 13, 2015 - May 13, 2017The level of reactive oxygen species (ROS) is tightly regulated in biological systems as overproduction can lead to oxidative stress and result in a number of diseases. Due to its negative effects, antioxidants are studied and used against ROS in medicine, pharmaceuticals and therapeutics. Because of issues with the uptake and delivery of natural antioxidants, nanoparticle (NP) antioxidants are promising due to their higher bioavailability, solubility and stability. Given the importance of oxidative stress and the potential for certain NPs to modify redox balance, it is important to build a rapid, reproducible, robust assay for analysis of NP chemical behaviors. Many studies have addressed the impact of surface chemistry on single NP antioxidant capacity (AOC), yet few have compared different NP AOCs in relation to their intrinsic properties. In this study, we investigated the AOC of silver, gold and eight lanthanide metal oxide NPs (AgNP, AuNP and LnOxNPs) using Trolox equivalent antioxidant capacity assay. We found that all of the NPs tested exhibited AOC, and AuNP AOC was more pronounced than AgNP when ions were not accounted for in the reaction. When ions released from the surface were removed by the addition of chelators into the dispersion, the AOC of AgNP was higher than AuNP. For the LnOxNPs, the AOC exhibited periodicity based on their elemental properties. LnOxNPs AOC was negatively correlated to the amount of unpaired electrons in 4f orbital and lanthanum crystal ionic radius. This study supports that we can predict AOC of various NPs based on their intrinsic atomic properties. Moreover, it provides a potential mechanism to simulate and explain the effect of surface chemistry on AOC of NPs, which will be valuable for nanomedicine and the nanoscience industry