A novel assessment system of toxicity and stability of CuO nanoparticles via copper super sensitive Saccharomyces cerevisiae mutants.

CuO nanoparticles (CuO-NPs) toxicity in organisms is contributed mainly through the copper uptake by both the ionic and nanoparticle form. However, the relative uptake ratio and bioavailability of the two different forms is not well known due to a lack of sensitive and effective assessment systems. We developed a series of both copper resistant and hyper sensitive Saccharomyces cerevisiae mutants to investigate and compare the effects of CuO-NPs and dissolved copper (CuCl2), on the eukaryote with the purpose of quantitating the relative contributions of nanoparticles and dissolved species for Cu uptake. We observed the toxicity of 10 mM CuO-NPs for copper sensitive strains is equal to that of 0.5 mM CuCl2 and the main toxic effect is most likely generated from oxidative stress through reactive oxygen species (ROS) production. About 95% CuO-NPs exist in nanoparticle form under neutral environmental conditions. Assessing the cellular metal content of wild type and copper transporter 1(CTR1) knock out cells showed that endocytosis is the major absorption style for CuO-NPs. This study also found a similar toxicity of Ag for both 10 mM Ag-NPs and 0.2 mM AgNO3 in the copper super sensitive strains. Our study revealed the absorption mechanism of soluble metal based nanomaterials CuO-NPs and Ag-NPs as well as provided a sensitive and delicate system to precisely evaluate the toxicity and stability of nanoparticles.

The toxicity of silver nanomaterials (NM 300K) is reduced when combined with N-Acetylcysteine: Hazard assessment on Enchytraeus crypticus.

The widespread production and use of silver nanomaterials (AgNMs) in consumer and medical products have been raising environmental concerns. Once in the environment, the soil is one of the major sinks of AgNMs due to e.g. sewage sludge applications, and invertebrates are directly exposed. In this study, we investigate the potential of N-acetylcysteine (NAC) to reduce the toxic effects of Ag NM300 K (and AgNO3) on the soil invertebrate Enchytraeus crypticus. Ag NM300 K induces mortality, reproduction impairment, and avoidance. The addition of NAC to the soil showed a remarkable reduction in the toxicity of Ag, indicating that NAC can act as a detoxifying agent for terrestrial organisms exposed to Ag materials. That the reduction in toxicity likely is caused by thiol groups, was confirmed by GSH and GSSH studies. Identifying the mechanisms and hence alternatives that allow the recovery of contaminated soils is an important mitigation measure to promote environmental safety and reduce the associated risks to human health. Further, it may inform on strategies to implement in safe-by-design industry development.

Does Sericin, as a Novel Pleurodesis Agent, Have Higher Effectiveness Compared to Talcum Powder, Doxycycline, and Silver Nitrate Pleurodesis?

INTRODUCTION: The usefulness of sericin as pleurodesis agent has previously been described. Present study aims to compare sericin pleurodesis regarding success, effectiveness, tolerability, and side-effects. METHODS: Adult, 12-week-old Wistar-albino rats (n=60), divided to five groups as sericin, talcum-powder, doxycycline, silver-nitrate and control. Agents were administrated through left thoracotomy, rats sacrificed twelve-days after. RESULTS: Highest ratio of collagen fibers was observed in sericin group, and the intensity was higher than talcum-powder group (p<0.05). Compared to silver nitrate, sericin group displayed better mesothelial reaction, and multi-layer mesothelium was also better (p<0.05). Foreign body reaction and emphysema were less frequent in sericin group (p<0.05). The presence of biological tissue in parenchyma was less prominent in sericin group (p<0.05). Foreign body reaction on thoracic wall was less common in sericin group (p<0.05). Presence of biological tissue glue in thoracic wall was less prominent in sericin group (p<0.05). Glomerular degeneration was lower in sericin group compared to the silver nitrate group (p<0.05), and tubular degeneration was less common in sericin group than talcum group (p<0.05). Pericarditis was less common in sericin group compared to the other groups (p<0.05). CONCLUSION: As an intrinsic, natural glue protein, sericin protects the lung parenchyma and tissues, and its glue-like characteristics enable pleurodesis. The success of sericin in pleurodesis was demonstrated in the present study based on investigations of the pleurae. Being cost-effective and better tolerated agent associated with a low potential of side effects, sericin is more effective, less expensive and provides more lung parenchyma protection.

Toxicity assessment of nanosilver wound dressing in Wistar rat.

Antibiotic resistance to microorganisms is one of the major problems faced in the field of wound care in burns patients. Silver nanoparticles have come up as potent antimicrobial agent and are being evaluated in diverse medical applications ranging from silver based dressings to silver coated medical devices. We aimed in present study to test the release of nanosilver from nanosilver wound dressing and compare the dermal and systemic toxicity of nanosilver dressings in a repeated dose (21 days) model. Under general anesthesia, a limited standard 2nd degree burns were provided on the back of each rat in all treatment, negative control (simple dressing) and 5% silver nitrate groups, each contained 5 male wistar rats. According to the analysis made by atomic absorption spectrometry, the wound dressings released 0.599 ± 0.083 ppm of nanosilver during first 24 hrs of study. Daily observations were recoded and wounds were covered with new dressings each 24 hrs. Burn healing was observed in nanosilver wound dressing group in shorter time periods than the control groups. In toxicity assessment, this dressing didn't cause any hematological and histopathological abnormalities in treatment group but biochemical studies showed significant rise of plasma transaminase (ALT) at the endpoint (21 days) of the study (P=0.027). Portal mononuclear lymphoid and polymorphonuclear leukocyte infiltrations in three to four adjacent foci were recognized around the central hepatic vein in treatment group. Mild hepatotoxic effects of nanosilver wound dressing in wistar rat emphasize the necessity of more studies on toxicity potentials of low dose nanosilver by dermal applications.

Assessment of nanosilver toxicity during zebrafish (Danio rerio) development.

Nanomaterials (NMs) including silver nanoparticles (AgNPs) are incorporated into an increasing number of consumer and medical products. However, the potential toxicity of AgNPs to aquatic organisms is largely unknown. This study characterizes the effects of AgNPs on zebrafish (Danio rerio) development. The effects of silver ions (Ag(+)) and AgNPs were examined at equivalent Ag concentrations, which ranged from 0.03 to 1.55 µg mL(-1) total Ag. The Ag(+) was more toxic than AgNPs but both lead to death and delayed hatching in surviving embryos. Both silver types depleted glutathione levels but generally did not affect antioxidant enzymes activities. In addition to silver some of the embryos were also exposed to cysteine, which generally reduced the toxicity of both silver types. This study demonstrates that AgNPs and Ag(+) are capable of inducing toxicity in zebrafish embryos including the induction of oxidative stress.

Assessment of silver-coated urinary catheter toxicity by cell culture.

The toxicity of silver-coated urinary catheters was assessed using a cell culture technique. The inhibitory effect of catheter extracts on the uptake of 3H-labelled thymidine by mouse fibroblasts was measured. The results show that silver-coating had no toxic effect whereas silvernitrate and silversulphate coating did have a toxic effect.