Reactive oxygen species-related activities of nano-iron metal and nano-iron oxides

Abstract

Nano-iron metal and nano-iron oxides are among the most widely used engineered and naturally occurring nanostructures, and the increasing incidence of biological exposure to these nanostructures has raised concerns about their biotoxicity. Reactive oxygen species (ROS)-induced oxidative stress is one of the most accepted toxic mechanisms and, in the past decades, considerable efforts have been made to investigate the ROS-related activities of iron nanostructures. In this review, we summarize activities of nano-iron metal and nano-iron oxides in ROS-related redox processes, addressing in detail the known homogeneous and heterogeneous redox mechanisms involved in these processes, intrinsic ROS-related properties of iron nanostructures (chemical composition, particle size, and crystalline phase), and ROS-related bio-microenvironmental factors, including physiological pH and buffers, biogenic reducing agents, and other organic substances.

Is nano safe in foods? Establishing the factors impacting the gastrointestinal fate and toxicity of organic and inorganic food-grade nanoparticles

“…Iron oxide (Fe 2 O 3 ) nanoparticles may be utilized in foods as colorants or sources of bioavailable iron. [47][48][49][50] The range of applications of iron oxide as a food colorant in the United States are highly limited, i.e., up to 0.1 wt% in sausages as part of casings. 51 It was estimated that the mean intake of iron oxide from consumers of these products was around 450 μg/ day.…”

“…53 It has been proposed that the ability of iron oxide nanoparticles to generate ROS is the most likely mechanism for their potential toxicity. 49 A study where iron oxide nanoparticles were orally administered at about 3 mg/kg body weight to rats over a 13-week period reported that they did not accumulate in tissues or produce toxicity. 54 Another rat feeding study with much higher oral dose (250-1000 mg/kg body weight) of iron oxide nanoparticles for 13-week also did not find their tissue accumulation or toxicity in both male or female rats.…”

“…12 One of the most important factors contributing to the toxicity of inorganic nanoparticles is their ability to generate ROS, such as singlet oxygen, superoxide, hydrogen peroxide and hydroxyl radicals. 49 These ROS may then cause damage to cell membranes, organelles, and the nucleus by interacting with lipids, proteins, or nucleic acids. 15,33,49 As a result, many biochemical functions required to maintain cell viability, such as ATP production, DNA replication, and gene expression, may be adversely affected.…”

“…49 These ROS may then cause damage to cell membranes, organelles, and the nucleus by interacting with lipids, proteins, or nucleic acids. 15,33,49 As a result, many biochemical functions required to maintain cell viability, such as ATP production, DNA replication, and gene expression, may be adversely affected. 33 A number of studies have reported the ability of inorganic nanoparticles to increase the generation of ROS in cells and to produce cytotoxicity, including silicon dioxide nanoparticles, 81 ZnO nanoparticles, 36,126,127 and silver nanoparticles.…”

Nanotoxicology of Metal Oxide Nanoparticles

“…Most papers have described the in vitro and in vivo toxicity of chemically and/or physically synthesized iron oxide nanoparticles [32,87,90,91]. The toxicity of iron oxide nanoparticles can be attributed to the ROS induction of oxidative stress [92], and it is dependent on the particle surface, size distribution, zeta potential, and the chemical nature of the surface coating [32,87].…”