Properties Of Reactive Oxygen Species Research Articles

Mesoporous Cerium Oxide Nanoparticles with High Scavenging Properties of Reactive Oxygen Species for Treating Age‐Related Macular Degeneration

Mesoporous Cerium Oxide Nanoparticles with High Scavenging Properties of Reactive Oxygen Species for Treating Age‐Related Macular Degeneration

Mesoporous Cerium Oxide Nanoparticles with High Scavenging Properties of Reactive Oxygen Species for Treating Age‐Related Macular Degeneration

Age‐related macular degeneration (AMD), the leading cause of vision loss among older individuals, is characterized by damage to photoreceptors and retinal pigment epithelial cells (RPEs). Oxidative stress and chronic inflammation in the retina play notable roles in AMD pathogenesis, rendering them attractive therapeutic targets. Cerium oxide nanoparticles (CeNPs) have shown promise in scavenging reactive oxygen species (ROS) by mimicking antioxidant enzymes, whereas mesoporous materials have emerged as versatile drug carriers. Herein, mesoporous CeNPs (mCeNPs) that integrate the advantages of CeNPs and mesoporous materials are presented. The mCeNPs can be synthesized using 1,1′‐carbonyldiimidazole and imidazole in acetone without heating and pressurization. The resulting mCeNPs exhibit mesoporous structures comprising assembled small CeNPs, exerting excellent ROS‐scavenging capabilities, biocompatibility, and cytoprotective and anti‐inflammatory effects against H2O2‐induced damage in RPEs. Using a sodium iodate‐induced AMD mouse model, it is demonstrated that intravitreal mCeNP administration can exhibit disease‐preventive effects. These findings indicate the therapeutic potential of mCeNPs against AMD.

Reactive oxygen species- and nitric oxide-dependent regulation of ion and metal homeostasis in plants.

Deterioration and impoverishment of soil, caused by environmental pollution and climate change, result in reduced crop productivity. To adapt to hostile soils, plants have developed a complex network of factors involved in stress sensing, signal transduction, and adaptive responses. The chemical properties of reactive oxygen species (ROS) and reactive nitrogen species (RNS) allow them to participate in integrating the perception of external signals by fine-tuning protein redox regulation and signal transduction, triggering specific gene expression. Here, we update and summarize progress in understanding the mechanistic basis of ROS and RNS production at the subcellular level in plants and their role in the regulation of ion channels/transporters at both transcriptional and post-translational levels. We have also carried out an in silico analysis of different redox-dependent modifications of ion channels/transporters and identified cysteine and tyrosine targets of nitric oxide in metal transporters. Further, we summarize possible ROS- and RNS-dependent sensors involved in metal stress sensing, such as kinases and phosphatases, as well as some ROS/RNS-regulated transcription factors that could be involved in metal homeostasis. Understanding ROS- and RNS-dependent signaling events is crucial to designing new strategies to fortify crops and improve plant tolerance of nutritional imbalance and metal toxicity.

Extracellular-matrix-mimicked 3D nanofiber and hydrogel interpenetrated wound dressing with a dynamic autoimmune-derived healing regulation ability based on wound exudate

Dynamic regulation of wound physiological signals is the basis of wound healing. Conventional biomaterials delivering growth factors to drive wound healing leads to the passive repair of soft tissues because of the mismatch of wound healing stages. Meanwhile, the bioactivity of wound exudate is often restricted by oxidation and bacterial contamination. Herein, an extracellular matrix mimicked nanofiber/hydrogel interpenetrated network (NFHIN) was constructed with a 3D nanofibrous framework for cell immigration, and interfiled aerogel containing cross-linked hyaluronic acid and hyperbranched polyamidoamine to balance the wound microenvironment. The aerogel can collect wound exudate and transform into a polycationic hydrogel with contact-killing effects even against intracellular pathogens (bactericidal rate > 99.9% in 30 min) and real-time scavenging property of reactive oxygen species. After co-culturing with the NFHIN, the bioactivity of fibroblast in the ex vivo blister fluid was improved by 389.69%. The NFHIN showed sustainable exudate management with moisture–vapor transferring rate (6000 g m−2 ×24 h), equilibrium liquid content (75.3%), Young’s modulus (115.1 ± 7 kPa), and anti-tearing behavior similar to human skin. The NFHIN can collect and activate wound exudate, turning it from a clinical problem to an autoimmune-derived wound regulation system, showing potential for wound care in critical skin diseases.

Na2S2O4@Co-metal organic framework (ZIF-67) @glucose oxidase for biofilm-infecting wound healing with immune activation

In recent years, photodynamic therapy (PDT) or chemodynamic therapy (CDT) based on the antimicrobial property or anti-biofilm property of reactive oxygen species (ROS) have been widely recognized for their low susceptibility to microbial resistance. However, due to the complication of the three-dimensional structure of the biofilm at the wound site and the high quenching rate of common ROS, the treatment with traditional ROS could not achieve satisfactory wound healing effects. Here, Na2S2O8@ZIF-67/GOx nanoparticles (NZG NPs) were prepared as a new high-toxic ROS nanogenerator for application of biofilm-infecting wound healing with the assistance of glucose oxidase (GOx) for amplified CDT and immune activation. When the NZG NPs entered the biofilm, Co-based metal organic frame (ZIF-67) ruptured in the acidic microenvironment, which induced the release of GOx and the production of gluconic acid and H2O2, further promoting the decrease of pH of the biofilm microenvironment and in turn accelerating the cleavage of ZIF-67 and the release of Na2S2O8. Then, S2O82− could gradually transformed into high-toxic sulfate radical (SO4−), part of which further produced OH in situ with H2O, thereby inhibiting the proliferation of bacteria and biofilms. Interestingly, these two types of ROS not only caused direct damage to the biofilm, but also activated the immune system of the wound site as well as the body more effectively, which also played an indirect role in promoting biofilm destruction and wound healing. In vitro and in vivo results showed that, as a new high-toxic ROS nanogenerator, the NZG NPs supply amplified chemodynamic therapy and immune activation to destroy biofilms, but also achieve effective wound healing without causing bacterial tolerance, which provides a new strategy for the development of biofilm-infecting wound healing.

Hydrogen Sulfide: A Therapeutic Option in Systemic Sclerosis.

Systemic sclerosis (SSc) is a lethal disease that is characterized by auto-immunity, vascular injury, and progressive fibrosis of multiple organ systems. Despite the fact that the exact etiology of SSc remains unknown, oxidative stress has been associated with a large range of SSc-related complications. In addition to the well-known detrimental properties of reactive oxygen species (ROS), gasotransmitters (e.g., nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S)) are also thought to play an important role in SSc. Accordingly, the diverse physiologic actions of NO and CO and their role in SSc have been previously studied. Recently, multiple studies have also shown the importance of the third gasotransmitter H2S in both vascular physiology and pathophysiology. Interestingly, homocysteine (which is converted into H2S through the transsulfuration pathway) is often found to be elevated in SSc patients; suggesting defects in the transsulfuration pathway. Hydrogen sulfide, which is known to have several effects, including a strong antioxidant and vasodilator effect, could potentially play a prominent role in the initiation and progression of vasculopathy. A better understanding of the actions of gasotransmitters, like H2S, in the development of SSc-related vasculopathy, could help to create early interventions to attenuate the disease course. This paper will review the role of H2S in vascular (patho-)physiology and potential disturbances in SSc. Moreover, current data from experimental animal studies will be reviewed. Lastly, we will evaluate potential interventional strategies.

Antibacterial properties of reactive oxygen species in carbon supported silica

Antibacterial properties of reactive oxygen species in carbon supported silica

Antioxidant Properties of Plastoquinone and Prospects of its Practical Application

This review describes the properties of reactive oxygen species that determine their destructive impact on the tissues of animals and plants and also presents the mechanisms of formation of reactive oxygen species in these tissues. The importance of antioxidant protection of hydrophobic zones, first of all, lipid membranes, in living organisms is underlined. Pathological states initiated by violation of the membrane structure and composition, in particular, due to the toxic effect of cholesterol oxidation products are described; data on such states arising from oxidative processes in low-density lipoproteins are provided. The results of application of ubiquinone and plastoquinone derivatives as membrane antioxidants and regulators of the level of reactive oxygen species in tissues are presented. The advantages of natural plastoquinone as a lipid-soluble compound that protects cell components from oxidation are discussed.

Reactive oxygen species in photodynamic therapy

Photosensitizer-mediated production of reactive oxygen species (ROS) plays a key role in photodynamic therapy (PDT). Reactive oxygen species mainly includes singlet oxygen, hydrogen peroxide, hydroxyl radical, superoxide anion radical and so on, among which singlet oxygen is the most important reactive oxygen species. In this paper, we firstly introduce the basic property of reactive oxygen species, generation and elimination of endogenous reactive oxygen species and generation mechanism of exogenous reactive oxygen species based on light, oxygen and photosensitizer. Next, we focus on the photosensitizers used to generate reactive oxygen species, factors that affect the yield of reactive oxygen species, and methods to increase the reactive oxygen species concentration at the tumor site. There are many factors that can affect the reactive oxygen species concentration at the tumor site, mainly among which are the singlet oxygen yield of the photosensitizer, the targeting of the photosensitizer, the oxygen concentration, and the illumination frequency. To achieve a good PDT effect, many photosensitizers or their nanoparticles with high singlet oxygen generation and good targeting ability are synthesized. Perfluorocarbon is used to deliver oxygen to overcome oxygen deficiency. Upconversion nanoparticles and two-photon absorption are very useful to solve the problem of weak penetration of short-wavelength light. New PDT methods are also introduced in the text, such as PDT combined photothermal therapy or chemotherapy. Then, we summarized various methods and technologies for reactive oxygen species detection, including direct detection of phosphorescence spectrophotometry, fluorescent probes and chemical probes for indirect detection, electron spin resonance, and positron emission tomography. The direct phosphorescence method mainly detects singlet oxygen based on the 1270 nm phosphorescence emission when singlet oxygen returns to the ground state. The first method to enhance the 1270 nm phosphor signal is to use a NIR photomultiplier tube (PMT) or an InGaAs linear array in combination with scanning of the excitation laser beam, and the second one is based on the use of a NIR camera with a filter. Because the lifetime of singlet oxygen is very short, time resolution is especially important. There are basically three main photon counting techniques: gated photon counting (GPC), multichannel scaling (MCS), and time-correlated single photon counting (TCSPC). In addition, singlet oxygen-sensitized delayed fluorescence (SOSDF) can also be used to detect singlet oxygen. Various new types of probes can specifically detect different types of reactive oxygen species, for example, 9, 10-anthracenedipropionic acid and MitoSOX can be used to detect singlet oxygen and superoxide anion in living cells respectively. The fluorescent probe itself does not have fluorescence, but reacts with reactive oxygen species to form an inner oxide, and emits strong fluorescence under the excitation of a certain wavelength of light. The difference of chemical probe is that it does not require light excitation because it can emit light spontaneously after reacted with reactive oxygen species. Electrons spin resonance (ESR) and positron emission tomography (PET) are also available to detect reactive oxygen species by using a probe. Finally, we discussed the mechanism of reactive oxygen species killing tumor cells, mainly in the following three aspects: (1) direct toxicity to tumor cells and induce their necrosis, apoptosis or autophagy; (2) damage on the tumor capillary endothelial cells and destruction of the microvasculature; (3) activation of an acute inflammatory response in host defense mechanisms. The effect of reactive oxygen species on the immune system and the apoptotic pathway of tumor cells from genes, proteins to the cell level were described in detail.

Insight into pathways of methylene blue degradation with H2O2 over mono and bimetallic Nb, Zn oxides

The aim of this work was to investigate the influence of surface properties of metal oxides (Nb2O5, ZnO and ZnNb2O6) on the type of reactive oxygen species (ROS) formed in contact with hydrogen peroxide, and to determine the effect of zinc addition to niobium pentoxide on the type of ROS formed and its activity in methylene blue degradation. The structure and surface properties of materials synthesized were characterized by nitrogen adsorption, XRD, XPS, SEM, SEM-EDX, DR UV–vis and FTIR techniques. The ability of metal oxides to generate superoxo and peroxo species upon treatment with H2O2 was documented and discussed in respect to the type of metal oxide used. It was found that the distortion of NbO6 species in bimetallic oxide influenced the interaction of this mixed oxide with hydrogen peroxide. The oxidative properties of reactive oxygen species formed on the surface of metal oxides were tested in degradation of methylene blue. The activity of niobium(V) oxide in this process was much higher than that of mixed oxide and ZnO. In order to identify the reaction pathways on the basis of determination of the reaction intermediates, the reaction mixtures were analyzed by ESI–MS. On the basis of the results obtained the mechanism of the dye degradation was discussed.

Imaging short-lived reactive oxygen species (ROS) with endogenous contrast MRI.

To characterize the relaxation properties of reactive oxygen species (ROS) for the development of endogenous ROS contrast magnetic resonance imaging (MRI). ROS-producing phantoms and animal models were imaged at 9.4T MRI to obtain T1 and T2 maps. Egg white samples treated with varied concentrations of hydrogen peroxide (H2 O2 ) were used to evaluate the effect of produced ROS in T1 and T2 for up to 4 hours. pH and temperature changes due to H2 O2 treatment in egg white were also monitored. The influences from H2 O2 itself and oxygen were evaluated in bovine serum albumin (BSA) solution producing no ROS. In addition, dynamic temporal changes of T1 in H2 O2 -treated egg white samples were used to estimate ROS concentration over time and hence the detection sensitivity of relaxation-based endogenous ROS MRI. The relaxivity of ROS was compared with that of Gd-DTPA as a reference. Finally, the feasibility of in vivo ROS MRI with T1 mapping acquired using an inversion recovery sequence was demonstrated with a well-established rotenone-treated mouse model (n = 6). pH and temperature changes in treated egg white samples were insignificant (<0.1 unit and <1°C, respectively). T1 relaxation time in the H2 O2 -treated egg white was reduced significantly (P < 0.05), while there was only small reduction in T2 (<10%). In the H2 O2 -treated BSA solution that produce no ROS, there was a small change in T1 due to H2 O2 itself (±1%), although a significant T2 -shortening effect was observed (>10%, P < 0.05). Also, there was a small reduction in T1 (13 ± 1%) and T2 (1 ± 2%) from molecular oxygen. The detection sensitivity of ROS MRI was estimated around 10 pM. The T1 relaxivity of ROS was found to be much higher than that of Gd-DTPA (3.4 × 107 vs. 0.9 s-1 ·mM-1 ). Finally, significantly reduced T1 was observed in rotenone-treated mouse brain (5.1 ± 2.5%, P < 0.05). We demonstrated in the study that endogenous ROS MRI based on the paramagnetic effect has sensitivity for in vitro and in vivo applications. 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2018;47:222-229.

SMOG: Causes, Effects and Preventions

&lt;p&gt;Dear Editor,&lt;/p&gt;&lt;p&gt;Recently many cities of Pakistan have been struck by the havoc of smog. Smog is formed when pollutants like nitrogen oxide, carbon monoxide and volatile organic compounds that are released from automobiles, industries and burning of fossil fuels interact with sunlight. These photochemical reactions usually occur in summers and leads to the development of ground level ozone or bad ozone (O&lt;sup&gt;3&lt;/sup&gt;) which is an important smog causing pollutant. This ozone adversely affects human health specially respiratory and cardiovascular system and is among the cause of premature deaths.&lt;sup&gt;1&lt;/sup&gt; Fine particulates of 2.5 micrometer or less are also among the pollutants found in smog and haze.&lt;sup&gt;2&lt;/sup&gt;&lt;/p&gt;&lt;p&gt; Mechanism behind the damaging effect of ozone on cardiopulmonary system is explained to be due to high oxidizing power of ozone that forms free radicals exposing body to oxidative stress. Also, ozone and fine particulate air pollution are found to cause acute arterial vasoconstriction normally.&lt;sup&gt;2&lt;/sup&gt; Moreover, Ozone causes reduction in vital capacity and forced expiratory volume in 1s, increase in lung resistance along with worsening of asthma in summers. It increases the release of allergens from pollens leading to respiratory allergy symptoms&lt;sup&gt;3&lt;/sup&gt; and making the respiratory problems even worse. Reactive oxygen species like hydroxyl and superoxide anion radicals produced in body by ozone and other pollutants increases the susceptibility of cancer in a person due to mutagenic properties of reactive oxygen species and their damaging effect on body cells.&lt;sup&gt;3&lt;/sup&gt;&lt;/p&gt;&lt;p&gt; Knowledge about Secondary preventive measures that one should take during smog must be spread as it will help people to cope up from the situation in a better way next time. These measures are minimal exposure to outdoor air but if exposure is inescapable than a facemask should be worn. Elderly and people experiencing any cardiac or respiratory illness are more prone to harmful effects of smog. These patients should increase the dosage of medication on their physician’s advice to prevent worsening of disease. Supplements and food containing antioxidants like omega 3 fatty acids when added to diet may help against oxidative stress caused by pollutants.&lt;sup&gt;4&lt;/sup&gt;&lt;/p&gt;&lt;p&gt; Steps should be taken to avoid the recurrence of this calamity. Media campaign for public awareness regarding the sources of pollutants causing smog should be launched. Banning deforestation and promotion of tree implantation is required nationwide as trees transpire and decreases temperature by cooling effect which indirectly prevents photochemical reactions to occur and minimizing the formation of air pollutants.&lt;sup&gt;3&lt;/sup&gt; Recycling of solid waste is a good alternative to open burning of waste and garbage. Using low emission, low carbon fuels and combustion free power sources like wind and solar powerare important for primary prevention as these are safer for health and are also low cost and energy efficient.&lt;sup&gt;1&lt;/sup&gt;&lt;/p&gt;

Nano-shape varied cerium oxide nanomaterials rescue human dental stem cells from oxidative insult through intracellular or extracellular actions.

Oxidative stress governs many stem cell functions like self-renewal and lineage differentiation, and the biological conditions involving tissue repair and disease cure where stem cell therapy is often needed. Here we demonstrate the unique role of cerium oxide nanomaterials (CeNMs) in rescuing stem cell survivability, migration ability, and intracellular components from oxidative stress. In particular, we deliver a novel finding that nano-morphologically varied CeNMs show different mechanisms in their scavenging reactive oxygen species either intracellularly or extracellularly, and this is related with their different cellular internalizations. We used human dental pulp stem cells for the model study and proved the CeNMs were effective in controlling ROS level by means of scavenging intracellularly or extracellularly, which ultimately led to improving the intact therapeutic potential of stem cells. This work touches an important biological issue of nanomaterial interactions with stem cells under the conditions related with oxidative stress and the resultant damage. The correlation of shape factor in therapeutic nanomaterials with stem cell interaction and the oxidative stress-related functions will provide informative ideas in the design of CeNMs for cellular therapy.

Reactive Oxygen Species: Physical, Chemical, and Biological Structures based on ROS-Sensitive Moieties that are Able to Respond to Oxidative Microenvironments (Adv. Mater. 27/2016).

On page 5553, C. Tapeinos and A. Pandit review the properties of reactive oxygen species (ROS)-sensitive moieties which can respond to oxidative conditions inside cells. ROS-sensitive chemical structures, shown in the background of the image, are currently used in the biomedical field as drug-delivery systems, imaging probes, prochelators, and prodrugs for imaging and treatment of various diseases.

Properties of reactive oxygen species by quantum Monte Carlo.

The electronic properties of the oxygen molecule, in its singlet and triplet states, and of many small oxygen-containing radicals and anions have important roles in different fields of chemistry, biology, and atmospheric science. Nevertheless, the electronic structure of such species is a challenge for ab initio computational approaches because of the difficulties to correctly describe the statical and dynamical correlation effects in presence of one or more unpaired electrons. Only the highest-level quantum chemical approaches can yield reliable characterizations of their molecular properties, such as binding energies, equilibrium structures, molecular vibrations, charge distribution, and polarizabilities. In this work we use the variational Monte Carlo (VMC) and the lattice regularized Monte Carlo (LRDMC) methods to investigate the equilibrium geometries and molecular properties of oxygen and oxygen reactive species. Quantum Monte Carlo methods are used in combination with the Jastrow Antisymmetrized Geminal Power (JAGP) wave function ansatz, which has been recently shown to effectively describe the statical and dynamical correlation of different molecular systems. In particular, we have studied the oxygen molecule, the superoxide anion, the nitric oxide radical and anion, the hydroxyl and hydroperoxyl radicals and their corresponding anions, and the hydrotrioxyl radical. Overall, the methodology was able to correctly describe the geometrical and electronic properties of these systems, through compact but fully-optimised basis sets and with a computational cost which scales as N(3) - N(4), where N is the number of electrons. This work is therefore opening the way to the accurate study of the energetics and of the reactivity of large and complex oxygen species by first principles.

ROS and Brain Diseases: The Good, the Bad, and the Ugly

The brain is a major metabolizer of oxygen and yet has relatively feeble protective antioxidant mechanisms. This paper reviews the Janus-faced properties of reactive oxygen species. It will describe the positive aspects of moderately induced ROS but it will also outline recent research findings concerning the impact of oxidative and nitrooxidative stress on neuronal structure and function in neuropsychiatric diseases, including major depression. A common denominator of all neuropsychiatric diseases including schizophrenia and ADHD is an increased inflammatory response of the brain caused either by an exposure to proinflammatory agents during development or an accumulation of degenerated neurons, oxidized proteins, glycated products, or lipid peroxidation in the adult brain. Therefore, modulation of the prooxidant-antioxidant balance provides a therapeutic option which can be used to improve neuroprotection in response to oxidative stress. We also discuss the neuroprotective role of the nuclear factor erythroid 2-related factor (Nrf2) in the aged brain in response to oxidative stressors and nanoparticle-mediated delivery of ROS-scavenging drugs. The antioxidant therapy is a novel therapeutic strategy. However, the available drugs have pleiotropic actions and are not fully characterized in the clinic. Additional clinical trials are needed to assess the risks and benefits of antioxidant therapies for neuropsychiatric disorders.

Reactive oxygen species and their role in plant defence and cell wall metabolism

Harnessing the toxic properties of reactive oxygen species (ROS) to fight off invading pathogens can be considered a major evolutionary success story. All aerobic organisms have evolved the ability to regulate the levels of these toxic intermediates, whereas some have evolved elaborate signalling pathways to dramatically increase the levels of ROS and use them as weapons in mounting a defence response, a process commonly referred to as the oxidative burst. The balance between steady state levels of ROS and the exponential increase in these levels during the oxidative burst has begun to shed light on complex signalling networks mediated by these molecules. Here, we discuss the different sources of ROS that are present in plant cells and review their role in the oxidative burst. We further describe two well-studied ROS generating systems, the NADPH oxidase and apoplastic peroxidase proteins, and their role as the primary producers of ROS during pathogen invasion. We then discuss what is known about the metabolic and proteomic fluxes that occur in plant cells during the oxidative burst and after pathogen recognition, and try to highlight underlying biochemical processes that may provide more insight on the complex regulation of ROS in plants.

NADPH Phagocyte Oxidase Knockout Mice Control Trypanosoma cruzi Proliferation, but Develop Circulatory Collapse and Succumb to Infection

•NO is considered to be a key macrophage-derived cytotoxic effector during Trypanosoma cruzi infection. On the other hand, the microbicidal properties of reactive oxygen species (ROS) are well recognized, but little importance has been attributed to them during in vivo infection with T. cruzi. In order to investigate the role of ROS in T. cruzi infection, mice deficient in NADPH phagocyte oxidase (gp91phox −/− or phox KO) were infected with Y strain of T. cruzi and the course of infection was followed. phox KO mice had similar parasitemia, similar tissue parasitism and similar levels of IFN-γ and TNF in serum and spleen cell culture supernatants, when compared to wild-type controls. However, all phox KO mice succumbed to infection between day 15 and 21 after inoculation with the parasite, while 60% of wild-type mice were alive 50 days after infection. Further investigation demonstrated increased serum levels of nitrite and nitrate (NOx) at day 15 of infection in phox KO animals, associated with a drop in blood pressure. Treatment with a NOS2 inhibitor corrected the blood pressure, implicating NOS2 in this phenomenon. We postulate that superoxide reacts with •NO in vivo, preventing blood pressure drops in wild type mice. Hence, whilst superoxide from phagocytes did not play a critical role in parasite control in the phox KO animals, its production would have an important protective effect against blood pressure decline during infection with T. cruzi.

Comparing the toxic mechanism of synthesized zinc oxide nanomaterials by physicochemical characterization and reactive oxygen species properties

We studied the toxicity of ZnO nanomaterials in terms of physicochemical characteristics and reactive oxygen species (ROS) properties. ZnO nanorods [synthesized at room temperature (ZnO-RT, length; 18.0±4.2nm) and at 60°C (ZnO-60, length; 80.5±6.8nm)] were used to evaluate the potential toxicity upon growth velocity-related particle size. The cytotoxicity of ZnO-60 was higher than that of ZnO-RT. We observed that the toxicity of ZnO-RT and ZnO-60 was related with ROS formation by using antioxidant N-acetylcysteine and electron spin resonance. Also, we found that the source of toxicity was not related to Zn2+ ions released from ZnO in 24h treatment. Our results indicate that toxicity of ZnO nanorods is caused by the amounts of ROS. Our study strongly suggests that size of nanomaterial is not the sole factor to be considered, thus, the development of appropriate criteria based on morphological/physicochemical characteristics as well as synthesis procedures is needed to evaluate the precise toxicity.

The Involvement of Metallothioneins in Mitochondrial Function and Disease

Mitochondrial oxidative phosphorylation deficiency is accompanied by various down-stream, adaptive responses which play a key role in the varied phenotypes observed when mitochondrial dysfunction occurs. These responses are often accompanied by the induction of genes involved in defense mechanisms against oxidative stress. Among these responses, metallothioneins (MTs) has been identified to be responsive to mitochondrial dysfunction. MTs, which are expressed in four different isoforms, are small, cysteine rich, metal binding proteins that have been associated with a protective effect in cells under numerous diseased and stressed states. Their diverse functionality and protective roles can be ascribed to their three basic abilities or primary functions which are metal homeostasis, heavy metal detoxification and free radical scavenging. The involvement of MTs with numerous cellular processes, organelles and cells has received much attention while notice of their involvement with the function of mitochondria has been lacking. It is believed that MTs promote the survival of mitochondrial dysfunctional cells by acting as highly efficient reducing elements against the damaging properties of reactive oxygen species (ROS) and by limiting apoptosis. In addition to their role in mitochondrial disease, convincing evidence exist, albeit with conflicting results, of its involvement in some key functions of the mitochondrion, including redox modulation, metal homeostasis and enzyme and transcription factor regulation.