The massive production and use of silver nanoparticles (Ag NPs) have led to their increasing release into the environment. Even though the antimicrobial and cytotoxic effects of native nanoparticles have been well studied, the environmental impacts of transformation products such as silver sulfide nanoparticles (Ag2S NPs) have not been elucidated. In the present study, we assessed the toxicity of Ag2S NPs and silver nitrate (AgNO3), as a source of Ag, to the earthworm Eisenia andrei using a nominal concentration of 5 mg Ag kg-1 soil. We used the OECD guidelines to assess effects on weight loss and mortality for 14 days. After exposure, we also extracted the immune effector cells (coelomocytes) and conducted a battery of biomarker tests. To ensure the quality of the toxicological results, the structural changes of NPs during the experiment and the uptake of silver by the earthworms were monitored. During the experiment, mortality effects were not detected, but a weight loss was observed in the earthworms exposed to Ag2S NPs. Altough Ag2S NPs were engulfed by E. andrei cells, neither phenoloxidase activity nor lipid peroxidation differed from the untreated control group. Cells from earthworms treated with Ag2S NPs exerted very broad value range of nitric oxide (NO) generation, suggesting an imbalance in the NO metabolism. Overall, this study suggests minimal risks associated with Ag2S NPs exposure to earthworms. However, further studies are needed to assure no immunotoxicological or chronic effects on a wider range of terrestrial organisms.
- MeSH
- dusičnan stříbrný toxicita MeSH
- hmotnostní úbytek MeSH
- kovové nanočástice * chemie toxicita MeSH
- látky znečišťující půdu * toxicita MeSH
- Oligochaeta * MeSH
- půda chemie MeSH
- sloučeniny stříbra MeSH
- stříbro metabolismus toxicita MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Enterococcus faecalis is a Gram-positive facultative anaerobe involved in many fatal or refractory infections of humans. Silver, often used as silver ions (Ag+) or nanoparticles (AgNPs), is a strong and broad-spectrum antibacterial agent, but E. faecalis shows resistance against it. Despite this, the knowledge about the resistance of E. faecalis against silver is still lacking. In this study, the silver-resistant E. faecalis strains (AgR and ANR E. faecalis) were established through a serial selection method. Their biological and silver-resistant features as well as the Gene Ontology (GO) in comparison with the original E. faecalis were evaluated. The results showed that the silver-resistant E. faecalis could proliferate as original bacteria and had strong resistance against both Ag+ and AgNPs. The minimum bactericidal concentrations (MBCs) of AgNO3 on original, AgR, and ANR E. faecalis were 400 mg/L, 600 mg/L, and 500 mg/L, and the MBCs of AgNPs on these strains were 80 mg/L, 110 mg/L, and 130 mg/L, respectively. GO analysis revealed significant difference (P < 0.05) in gene expressions of biological process (BP), cellular component (CC), and molecular function (MF) among original, AgR, and ANR E. faecalis. These findings provided a significant basis for further understanding and managing the silver-resistance of E. faecalis in infection-control environments. The mechanism behind Ag+/AgNPs resistance of E. faecalis needs to be further investigated.
- MeSH
- antibakteriální látky chemie farmakologie MeSH
- bakteriální léková rezistence účinky léků genetika MeSH
- bakteriální proteiny genetika MeSH
- dusičnan stříbrný metabolismus farmakologie MeSH
- Enterococcus faecalis účinky léků genetika růst a vývoj fyziologie MeSH
- kovové nanočástice chemie MeSH
- lidé MeSH
- mikrobiální testy citlivosti MeSH
- regulace genové exprese u bakterií MeSH
- stříbro chemie farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
In the present work, non-woven, non-regenerated cellulose wound dressing was subjected to in situ silver (Ag) deposition in the form of silver chloride (AgCl) under various reaction conditions. The studied reaction parameters were as follows: time, temperature, and reactants´ concentration. AgCl was bound on the cellulose via two-step process. Firstly, the silver ions (Ag+) were attracted to cellulose in the solution of silver nitrate (AgNO3). Secondly, Ag+ were precipitated directly on the cellulose by immersing the samples into the solution of sodium chloride (NaCl). The prepared samples were examined on the amount of bound and released Ag, and the release was studied both in water and in simulated body fluids. The reaction parameters significantly affected the amount of bound and released Ag, the difference of released Ag was as high as 75%. The key parameter in the process was reactants´ concentration. Non-regenerated cellulose modified with AgCl was antibacterially active.
Novel nanofibers mats were fabricated by electrospinning of polyvinyl alcohol/hyaluronan (PVA/HA) solutions in the presence of silver nanoparticles (AgNPs). The AgNPs were synthesized by in-situ chemical reduction of silver ions (Ag+) using HA as a reducing and stabilizing agent. Narrow size distribution and spherical shape of AgNPs were achieved by optimizing the initial silver nitrate concentration (0.01 to 1 M) and reaction time (10-60 min). HA-AgNPs nanocomposite and PVA/HA-AgNPs nanofibrous mats were fabricated by electrospinning technique from aqueous solution containing a different mass ratio of PVA and HA-AgNPs and characterized by UV/Vis spectroscopy, SEM, TEM, DLS, XRD, TGA, and ATR-FTIR. Mechanical and rheological properties were also investigated and discussed. The novel nanofibrous mats show great potential in skin regeneration and drug carrier applications.
- MeSH
- dusičnan stříbrný chemie MeSH
- elektrochemie MeSH
- ionty MeSH
- kovové nanočástice chemie MeSH
- kyselina hyaluronová chemie MeSH
- nanokompozity chemie MeSH
- nanovlákna MeSH
- nosiče léků MeSH
- obvazy MeSH
- polyvinylalkohol chemie MeSH
- povrchové vlastnosti MeSH
- reologie MeSH
- rozpouštědla MeSH
- spektroskopie infračervená s Fourierovou transformací MeSH
- stříbro chemie MeSH
- technologie zelené chemie * MeSH
- velikost částic MeSH
- Publikační typ
- časopisecké články MeSH
OBJECTIVES: The aim of this study was to establish and evaluate the mortality rate, hatching rate and observe the presence of sublethal changes in zebrafish embryos after exposure to silver ions and nanoparticles. METHODS: Tests were conducted on newly fertilized zebrafish embryos, according to the modified OECD guideline 236, using a semistatic method and 96 hour incubation time. Silver nitrate and two different silver nanoparticles, stabilized with 0.01% solution of maltose and gelatine in the first case, and stabilized with polyvinylpyrrolidone, in the latter, were tested. RESULTS: Significant differences in toxicity of tested substances were recorded. The value of 96hLC50 for silver nitrate was 58.44 μg/L. The value of 96hLC50, calculated for silver nanoparticles stabilized with 0.01% solution of maltose and gelatine, was nearly 100 times higher, 4.31 mg/L. The value 96hLC50 for silver nanoparticles stabilized with polyvinylpyrrolidone exceeded 100mg/L, occurrence of sublethal effects caused by silver nanoparticles stabilized with polyvinylpyrrolidone was insignificant in most of the exposition groups, but only in this substance caused decreased hatching rate. CONCLUSION: Properties of different silver nanoparticles play an important role in levels of their toxicity and predominant mechanisms of action. In general, silver nanoparticles are less toxic for Danio rerio embryos than silver ions.
- MeSH
- dánio pruhované MeSH
- dusičnan stříbrný toxicita MeSH
- embryo nesavčí účinky léků MeSH
- LD50 MeSH
- maltosa MeSH
- nanočástice * MeSH
- povidon MeSH
- stříbro toxicita MeSH
- želatina MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- argyrie * etiologie patologie MeSH
- diferenciální diagnóza MeSH
- dusičnan stříbrný MeSH
- lidé MeSH
- mladý dospělý MeSH
- noha (od hlezna dolů) MeSH
- pigmentace MeSH
- Check Tag
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
The increased content of isoflavonoids in dry cell suspension and nutrient medium was observed after application of electric current and AgNO3 on Genista tinctoria L. cultures in vitro. The highest content of genistin (1.7 mg g(- 1) DW - dry weight) was measured in the dry cell suspension culture after 30 min elicitation of 10 V and 6 h cultivation and daidzein content (3.5 mg g(- 1) DW) was measured after 60 min elicitation of 5 V and 24 h cultivation. In the case of AgNO3 elicitation, the content of genistin in dry cell suspension culture (0.5 mg g(- 1) DW) was highest after 48 h of AgNO3 treatment and concentration of 5.9 × 10(- 4) mol/L. The AgNO3 concentration of 5.9 × 10(- 4) mol/L was also the most effective combination for daidzein production (0.9 mg g(- 1) DW) after 168 h. The results of this study show that the secondary metabolites could also be released from G. tinctoria L. cells into the nutrient medium.
AIMS: Silver stainable nucleolar organizer regions (AgNORs) have received a great deal of attention recently as their frequency within the nuclei is significantly higher in malignant cells than in normal, reactive or benign neoplastic cells. The objective of this study was to carry out a quantitative assessment of large and small AgNORs in oral normal mucosa, precancerous lesions and infiltrating squamous cell carcinomas. METHODS: The study comprised 110 formalin-fixed, paraffin-embedded oral mucosal biopsies consisting of 30 oral dysplasia, 60 oral squamous cell carcinomas and 20 normal oral mucosa. AgNORs were counted in each nucleus, categorized as small, large and total number of AgNORs in each cell and their means were calculated. RESULTS: The mean value of small AgNORs, large AgNORs and total AgNORs increased gradually from normal mucosa to dysplastic lesions to squamous cell carcinomas. The study clearly indicates that in oral squamous cell carcinomas, AgNORs diminish in size as they increase in number. Further, AgNOR counts increase as the degree of malignant potential of the cell increases. CONCLUSIONS: By combining both the enumeration of AgNORs and their size, good distinction can be made between normal, dysplastic and infiltrating squamous cell carcinomas. This could help in the early diagnosis and prognosis of dysplastic mucosal lesions and their malignant transformation.
- MeSH
- barvicí látky diagnostické užití MeSH
- dospělí MeSH
- dusičnan stříbrný diagnostické užití MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- nádory úst patologie MeSH
- organizátor jadérka patologie MeSH
- prekancerózy patologie MeSH
- senioři MeSH
- spinocelulární karcinom patologie MeSH
- ústní sliznice patologie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Klíčová slova
- popáleniny,
- MeSH
- antiinfekční látky lokální dějiny terapeutické užití MeSH
- aplikace lokální MeSH
- dějiny 19. století MeSH
- dějiny 20. století MeSH
- dusičnan stříbrný dějiny terapeutické užití MeSH
- hojení ran * účinky léků MeSH
- lidé MeSH
- popálení * dějiny farmakoterapie mikrobiologie MeSH
- stříbrná sůl sulfadiazinu dějiny terapeutické užití MeSH
- stříbro * terapeutické užití MeSH
- Check Tag
- dějiny 19. století MeSH
- dějiny 20. století MeSH
- lidé MeSH
- Publikační typ
- historické články MeSH
The polyaniline (PANI) base was ball-milled with silver nitrate in the solid state. Samples were prepared at various mole ratios of silver nitrate to PANI constitutional units ranging from 0 to 1.5 for three processing times, 0, 5, and 10 min. The emeraldine form of PANI was oxidized to pernigraniline, and the silver nitrate was reduced to metallic silver. Nitric acid is a byproduct, which may protonate the residual emeraldine and pernigraniline. The changes occurring in the structure of PANI are discussed on the basis of Fourier transform IR and Raman spectroscopies. Raman spectra revealed the formation of pernigraniline salt. The reaction between the two nonconducting components, emeraldine base and silver nitrate, produced a mixture of two conducting components, emeraldine or pernigraniline nitrate and metallic silver. The accompanying conductivity changes were determined. The increase in the conductivity of the original base, 10(-9) S cm(-1), up to 10(-2) S cm(-1) was found to depend on the mole ratio of silver nitrate to PANI base and on the processing time of the components in the ball mill.
- MeSH
- aniliny chemie MeSH
- časové faktory MeSH
- chemické modely MeSH
- chemie organická metody MeSH
- dusičnan stříbrný chemie MeSH
- elektrická vodivost MeSH
- kyslík chemie MeSH
- polymery chemie MeSH
- Ramanova spektroskopie metody MeSH
- spektroskopie infračervená s Fourierovou transformací metody MeSH
- stříbro chemie MeSH
- testování materiálů MeSH
- transmisní elektronová mikroskopie metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
