Accumulation Of Silver In Tissues Research Articles

Kinetics of Silver Accumulation in Tissues of Laboratory Mice after Long-Term Oral Administration of Silver Nanoparticles.

Since ancient times, silver has been known for its pronounced bactericidal, antiviral and fungicidal properties. Currently, nanoparticles of this metal are widely used in the food, light and pharmaceutical industries, as well as in medicine. Silver in any form can have a toxic effect not only on pathogens, but also on healthy cells. The biological activity and bioavailability of silver preparations depend on the degree of their solubility in water. In addition, the maximum permissible concentration of soluble forms of silver is an order of magnitude lower than that of insoluble forms. This makes nanoparticles of silver with a hydrophilic coating that form stable colloidal solutions in aqueous media potentially unsafe objects. In this work, we studied the kinetics of the accumulation of silver nanoparticles with an average size of 34 ± 5 nm stabilized with polyvinylpyrrolidone in the organs of laboratory C57Bl/6 mice. The administration of nanoparticles was carried out orally for 30, 60, 120 and 180 days at the dose of 50 µg/day/animal. All the mice developed and gained weight normally during the experiment. No adverse effects were observed. Determination of the silver content in biological tissues of mammals was accomplished by neutron activation analysis. The masses and concentrations of silver in the brain and its different sections (hippocampus, cerebellum, cortex and remnants), as well as in the lungs, testes, liver, blood, kidneys, spleen and heart, were determined. The injection times at which the accumulation curves reached saturation were established. An extremely high accumulation of silver in the testes was shown at 120 days of administration, and a significant accumulation of silver in the lungs and brain was observed. The accumulation of silver in all parts of the brain except the cortex was significant, and its trend was similar to that in the whole brain.

Integrative assessment of silver nanoparticles toxicity in Prochilodus lineatus fish

The aim of this study was to evaluate simultaneously a battery of biomarkers in Prochilodus lineatus fish in order to obtain a holistic overview of silver nanoparticles (AgNP) toxicity. Juveniles were exposed to 2.5 and 25.0 µgAgNP L−1 for 5 and 15 days. We analyzed silver accumulation in tissues (liver, intestine and brain), morphometric and hematological parameters, oxidative stress markers (antioxidant enzymes, lipid peroxidation, and antioxidant capacity against peroxyl radicals-ACAP-), and metabolic responses in plasma (glucose, proteins, triglycerides and cholesterol), liver and muscle (glycogen, proteins, and lipids). Additionally, after 15-day exposure, the number of colony forming units (CFU) of bacteria living at the skin mucus secretion was analyzed to corroborate the AgNP biocide properties. Tissue Ag accumulation was concentration- and time-dependent: liver > intestine > brain. The hepatosomatic index increased at both periods of exposure at 25.0 µgAgNP L−1. Hematological and plasma biochemical parameters increased after 5 days of exposure to the highest concentration. When fish were exposed for 15 days to 25.0 µgAgNP L−1, many changes were observed: glycogen content increased in liver and muscle, muscle protein concentration decreased, all antioxidant enzymes activities were enhanced and ACAP decreased in liver. The CFU decreased in the mucus of fish exposed to both AgNP treatments when compared to the control group. The multivariate analysis revealed a clear difference in physiological profiles of individuals exposed to the different treatments. Our results showed that AgNP in short and subchronic exposures threaten the health of fish.

The effect of administration of silver nanoparticles on silver accumulation in tissues and the immune and antioxidant status of chickens

The effect of administration of silver nanoparticles on silver accumulation in tissues and the immune and antioxidant status of chickens

Silver nanoparticles at sublethal concentrations disrupt cytoskeleton and neurite dynamics in cultured adult neural stem cells

Silver nanoparticles (AgNPs) have potent antimicrobial properties at concentrations far below those that cause cytotoxic and genotoxic effects in eukaryotic cells. This property has resulted in the widespread use of AgNPs in consumer products, leading to environmental exposures at sub-lethal levels through ingestion and inhalation. Although the toxicity of AgNPs has been well characterized, effects of environmentally relevant exposures have not been extensively investigated in spite of studies that suggest accumulation of silver in tissues, including brain. To assess the sublethal effects of AgNPs on neural cell function, we used cultured SVZ-NSCs, a model of neurogenesis and neural cells. Throughout life, neural stem cells (NSCs) in the subventricular zone (SVZ) of the lateral ventricles proliferate and migrate via the rostral migratory stream to the olfactory bulb. Once there, they complete differentiation into neurons and glia and integrate into existing circuits. This process of neurogenesis is tightly regulated, and is considered a part of healthy brain function. We found that 1.0μg/mL AgNP exposure in cultured differentiating NSCs induced the formation of f-actin inclusions, indicating a disruption of actin function. These inclusions did not co-localize with AgNPs, and therefore do not represent sequestered nanoparticles. Further, AgNP exposure led to a reduction in neurite extension and branching in live cells, cytoskeleton-mediated processes vital to neurogenesis. We conclude that AgNPs at sublethal concentrations disrupt actin dynamics in SVZ-NSCs, and that an associated disruption in neurogenesis may contribute to documented deficits in brain function following AgNP exposure.

Short-term silver accumulation in tissues of three marine invertebrates: Shrimp Penaeus duorarum, sea hare Aplysia californica, and sea urchin Diadema antillarum

The present study was carried out to examine possible differential silver distribution among several tissues of three marine invertebrate species: the shrimp Penaeus duorarum, the sea hare Aplysia californica, and the sea urchin Diadema antillarum. Animals were exposed to sub-lethal concentrations of silver (1 or 10 μg/L) in seawater for 48 h. In gill-breathing species (shrimp and sea hare), higher silver accumulation in gills were associated with higher hemolymph silver levels. Furthermore, sea urchin showed lower hemolymph silver concentrations than shrimp and sea hare. These findings suggest that gills are an important route for silver uptake in marine invertebrates. In both sea hare and shrimp, hepatopancreas silver accumulation was concentration-dependent and this organ accumulated the most silver after 48 h of exposure, suggesting a possible involvement of the hepatopancreas in both silver accumulation and detoxification in marine invertebrates. In shrimp and sea hare, substantial silver accumulation in nervous tissues was detected, suggesting the need for further studies on possible behavioral effects of silver in these invertebrate species. In sea urchin, egg mass accumulated more silver than other tissues analyzed, indicating the need for future studies on possible reproductive effects of silver in sea urchin. In all three species, the lowest silver concentrations were observed in muscle, suggesting a low potential of this tissue for trophic transfer of silver.