Kinetic Analysis of Superoxide Anion Radical-Scavenging and Hydroxyl Radical-Scavenging Activities of Platinum Nanoparticles

The chloroplast contains densely stacked arrays of light‐harvesting proteins that harness solar energy with theoretical maximum glucose conversion efficiencies approaching 12%. Few studies have explored isolated chloroplasts as a renewable, abundant, and low cost source for solar energy harvesting. One impediment is that photoactive proteins within the chloroplast become photodamaged due to reactive oxygen species (ROS) generation. In vivo, chloroplasts reduce photodegradation by applying a self‐repair cycle that dynamically replaces photodamaged components; outside the cell, ROS‐induced photodegradation contributes to limited chloroplast stability. The incorporation of chloroplasts into synthetic, light‐harvesting devices will require regenerative ROS scavenging mechanisms to prolong photoactivity. Herein, we study ROS generation within isolated chloroplasts extracted from Spinacia oleracea directly interfaced with nanoparticle antioxidants, including dextran‐wrapped nanoceria (dNC) previously demonstrated as a potent ROS scavenger. We quantitatively examine the effect of dNC, along with cerium ions, fullerenol, and DNA‐wrapped single‐walled carbon nanotubes (SWCNTs), on the ROS generation of isolated chloroplasts using the oxidative dyes, 2’,7’‐ dichlorodihydrofluorescein diacetate (H2DCF‐DA) and 2,3‐bis(2‐methoxy‐4‐nitro‐5‐sulfophenyl)‐2H‐tetrazolium‐5‐carboxanilide sodium salt (XTT). Electrochemical measurements confirm that chloroplasts processed from free solution can generate power under illumination. We find dNC to be the most effective of these agents for decreasing oxidizing species and superoxide concentrations whilst preserving chloroplast photoactivity at concentrations below 5 μM, offering a promising mechanism for maintaining regenerative chloroplast photoactivity for light‐harvesting applications.

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“…[40][41][42][43][44] Nanoparticles offer several advantages over the traditional, molecular means of ROS scavenging.…”

Section: Full Papermentioning

confidence: 99%

Application of Nanoparticle Antioxidants to Enable Hyperstable Chloroplasts for Solar Energy Harvesting

Boghossian

Şen

Gibbons

et al. 2013

Advanced Energy Materials

106

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“…PtNPs are also capable of eliminating superoxide and hydroxyl radicals [21]. PtNPs size can vary from 1 to 5 nm with the smallest particles being the most reactive towards superoxide ions [22]. At a dose of 50 mg…”

Section: Study Of the Anti-oxidizing Action Of Synthetic Nps Supsensionsmentioning

confidence: 99%

Physico-Chemical, Biological and Therapeutic Characteristics of Electrolyzed Reduced Alkaline Water (ERAW)

Henry

Chambron

2013

Water

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Abstract:The consumption of alkaline reduced water produced by domestic electrolysis devices was approved in Japan in 1965 by the Ministry of Health, Labour and Welfare for the cure of gastro-intestinal disorders. Today, these devices are freely available in several countries and can be easily purchased without reserve. The commercial information included with the device recommends the consumption of 1-1.5 L of water per day, not only for gastro-intestinal disorders but also for numerous other illnesses such as diabetes, cancer, inflammation, etc. Academic research in Japan on this subject has been undergoing since 1990 only but has established that the active ingredient is dissolved dihydrogen that eliminates the free radical HO• in vivo. In addition, it was demonstrated that degradation of the electrodes during functioning of the device releases very reactive nanoparticles of platinum, the toxicity of which has not yet been clearly proven. This report recommends alerting health authorities of the uncontrolled availability of these devices used as health products, but which generate drug substances and should therefore be sold according to regulatory requirements.

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“…With nPt, the larger surface area of smaller particles can potentiate the catalytic activity of metals, and its colloidal forms contribute to a further efficient catalysis with high electron holding at the surface (Roucoux et al, 2002), allowing nPt to quench both superoxide anion and hydrogen peroxide, and the scavenging activity is durable because of its features as an SOD/catalase mimetic (Kajita et al, 2007;Hamasaki et al, 2008). In the present study, therefore, we investigated whether administration of nPt could be beneficial in the clinical setting with neuroprotection against pathology in mice after transient middle cerebral artery occlusion (tMCAO).…”

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confidence: 99%

Neurological and pathological improvements of cerebral infarction in mice with platinum nanoparticles

Takamiya

Miyamoto

Yamashita

et al. 2011

J of Neuroscience Research

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Ischemic stroke is a major, urgent neurologic disorder in which reactive oxygen species (ROS) are deeply involved in the detrimental effects. Platinum nanoparticle (nPt) species are a novel and strong scavenger of such ROS, so we examined the clinical and neuroprotective effects of nPts in mouse ischemic brain. Mice were subjected to transient middle cerebral artery occlusion (tMCAO) for 60 min. Upon reperfusion, nPt or vehicle was administered intravenously. At 48 hr after the tMCAO, motor function, infarct volume, immunohistochemistry of neurovascular components (endothelial NAGO, tight junctional occludin, and basal laminal collagen IV), and zymography for MMP-9 activity were examined. Superoxide anion generation at 2 hr after tMCAO was determined with oxidized hydroethidine. Compared with vehicle, treatment with nPts significantly improved the motor function and greatly reduced the infarct volume, especially in the cerebral cortex. Immunohistochemical analyses revealed that tMCAO resulted in a minimal decrease of NAGO and occludin but a great decrease of collagen IV and a remarkable increase of MMP-9. Treatment with nPts greatly reduced this decrease of collagen IV and activation of MMP-9 and, with large reductions of MMP-9 activation on zymography and superoxide production. The present study demonstrates that treatment with nPts ameliorates the neurological scores with a large reduction in infarct size as well as the preservation of outer components of the neurovascular unit (collagen IV) and inactivation of MMP-9. A strong reduction of superoxide anion production by nPts could account for such remarkable neurobehavioral and neuroprotective effects on ischemic stroke.

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Kinetic Analysis of Superoxide Anion Radical-Scavenging and Hydroxyl Radical-Scavenging Activities of Platinum Nanoparticles

Cited by 196 publications

References 63 publications

Application of Nanoparticle Antioxidants to Enable Hyperstable Chloroplasts for Solar Energy Harvesting

Application of Nanoparticle Antioxidants to Enable Hyperstable Chloroplasts for Solar Energy Harvesting

Physico-Chemical, Biological and Therapeutic Characteristics of Electrolyzed Reduced Alkaline Water (ERAW)

Neurological and pathological improvements of cerebral infarction in mice with platinum nanoparticles

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