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Porównanie oddziaływania nanocząstek i jonów srebra na aktywność mikroorganizmów epifitycznych nasion i wczesne etapy rozwoju kukurydzy cukrowej

Michałek S., Święciło A., Molas J.

Przemysł Chemiczny

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2018

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T. 97, nr 10

1654--1658

PL

Badano oddziaływanie nanocząstek srebra (nAg) i srebra w formie jonowej (AgNO3) na liczebność mikroorganizmów występujących na nasionach dwóch odmian kukurydzy cukrowej (‘Anawa F1’ i ‘Candle F1’) oraz na dynamikę kiełkowania nasion, wzrost i jakość biologiczną uzyskanych z nich siewek. Zarówno preparat nAg, jak i AgNO3 stosowano w postaci wodnych roztworów o stężeniach 0,1, 0,5 i 1,0%. Oba preparaty po 2 h powodowały istotne zmniejszenie liczebności mikroorganizmów epifitycznych, zarówno grzybów, jak i bakterii zasiedlających nasiona obu odmian kukurydzy. Roztwory nAg wykazywały jednak słabszy niż AgNO3 efekt dezynfekcyjny. Wyniki badań fizjologicznych wykazały, że kondycjonowanie nasion w AgNO3 na ogół zwiększało dynamikę kiełkowania nasion, lecz niekorzystnie wpływało na wzrost i biomasę siewek obu odmian kukurydzy. Kondycjonowanie nasion w roztworze nAg zwiększało dynamikę ich kiełkowania i wzrostu siewek. Wpływało również korzystnie na jakość biologiczną siewek. Szczególnie korzystny wpływ kondycjonowania nasion w roztworze nAg odnotowano przy wyższych jego stężeniach (0,5 i 1,0%) oraz dla odmiany ‘Candle F1’.

EN

Sweetcorn seeds of 2 cultivars were conditioned with Ag nanoparticles (nAg) and aq. AgNO3 solns., and studied for activity of epiphytic microorganisms present on the seeds, germination rates as well as growth and biol. quality of the seedlings. Ag in ionic form significantly reduced the no. of epiphytic microorganisms on the seeds of both sweetcorn cultivars and increased the germination rate, but adversely affected the growth and biomass of seedlings of both cultivars. nAg showed weaker seed-surface disinfection effect, increased the germination rate of the seeds, but in contrast to ionic form improve parameters of the seedlings quality and growth.

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Analiza zawartości fosfonianów w materiale roślinnym

Kłosińska T., Archanowicz E., Antczak A., Radomski A., Zielenkiewicz T., Oszako T., Nowakowska J. A., Kubiak K. A., Tkaczyk M.

Przemysł Chemiczny

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2015

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T. 94, nr 6

894-899

PL

Opracowano metodę ilościowego oznaczania fosfonianów w tkankach roślinnych. Zaproponowana procedura oparta jest na reakcji tych jonów z jonami srebra w środowisku kwaśnym, w wyniku której strąca się osad metalicznego srebra. Ilość wolnego srebra, powstałego w wyniku działania fosfonianów, została oznaczona metodami spektrometrii fluorescencji rentgenowskiej XRF i spektrofotometrii UV-VIS. Metoda XRF jest mniej pracochłonna, lecz jej czułość to ok. 0,1 mg srebra, co nie stanowi wyniku zadowalającego w przypadku śladowych ilości fosfonianów w tkankach roślinnych. W przypadku spektrofotometrii UV-VIS, po roztworzeniu srebra w stężonym HNO₃, skompleksowaniu jonów Ag⁺ ditizonem, ekstrakcji chloroformem i bezpośrednim oznaczeniu spektrofotometrycznym bez usuwania wolnego ditizonu, uzyskano znacznie większą czułość, wynoszącą 0,03 μM srebra. Na podstawie ilościowej reakcji fosfonianów, srebra i ditizonu można oszacować zawartość fosfonianów w tkankach roślinnych.

EN

Concn. of PHO₃²⁻ ions in plant tissues was detd. by using reaction with Ag⁺ in acidic soln. to metallic Ag ppt. The amt. of Ag was detd. by X-ray fluorescence spectrometry (XRF) and UV-VIS spectrophotometry. The XRF method was less laborious, but its accuracy was lower. Its sensitivity was insufficient to det. very low concns. of phosphonates. The UV-VIS spectrophotometry, after Ag dissoln. in concd. HNO₃, complexation of Ag⁺ with dithizone, extn. with CHCl₃ and detn. without removal of free dithizone, showed a significantly higher sensitivity.

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On the nature of silver ions in complex media

Loza K., Diendorf J., Sengstock C., Koller M., Epple M.

Engineering of Biomaterials

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2014

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Vol. 17, no. 128-129

80

EN

Antimicrobial biocides are commonly used to present the growth of bacteria on surfaces and within materials. They are typically added in small quantities to many applications to prevent bacterial growth on the treated object. Silver is increasingly used in many applications due to the aim to replace organic chemical agents by inorganic additives. Examples of applications are bacteriostatic water filters for household use or swimming pool algaecides and numerous devices, ranging from consumer commodities like mobile phones, refrigerators, and clothes to medical devices like catheters, implant surfaces, and plasters. To meet the diversity of application types, many different forms of silver compounds have been developed to serve this market. In particular, there is little information on the types of transformations that silver nanoparticles will undoubtedly undergo in real, complex environments during long-term aging, and the impact of these transformations on their distribution in the environment, bioavailability, and toxicity potential. The biocidal action results from the interaction of silver ions with bacteria. The most potent compounds for a high silver release are soluble silver salts like silver nitrate or silver acetate. These are fully water soluble with a high silver ion release rate. Therefore they are often used as control in cell experiments to elucidate the biological effect of silver nanoparticles. However, in the case of free silver nanoparticles the interactions can be more complex and catalytic reactions on the particle surface which depend on the size and shape of the nanoparticles can render the system very complex. If AgNO3 is used as control, it is tacitly assumed, that the free silver ion concentration is the same as that in the added AgNO3. This obviously cannot be true because of the presence of a whole set of proteins, biomolecules and inorganic ions like Cl- and H2PO4- in the biological medium. These will react with the silver ions in one or the other way. We report on experiments on the behaviour of silver ions in biologically relevant concentrations in different media, from physiological salt solution over phosphate-buffered saline solution to cell culture media. For dissolution and immersion experiments PVP-coated silver nanoparticles were synthesized by reduction with glucose in the presence of PVP. The final silver concentration in all dispersions was determined by atomic absorption spectroscopy. The dissolution of silver nanoparticles was followed in long-term experiments out of a dialysis tube which was permeable only for silver ions. In case of immersion experiments, the nanoparticles and all precipitates were isolated by ultracentrifugation, redispersed in pure water and again subjected to ultracentrifugation. The particles were analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray powder diffraction. The dissolution requires the presence of dissolved oxygen. If no oxygen is present, only a very small fraction of silver is dissolved, possibly by traces of oxygen in the experimental setup. An oxidizing agent like H2O2 clearly enhances the dissolution. The presence of NaCl, either in pure form or as PBS, strongly slows down the dissolution, probably due to silver chloride formation. Cysteine has a clearly inhibiting effect with almost no dissolution of the silver nanoparticles whereas glucose has a decelerating effect but leads to a similar final dissolved fraction. This suggests that cysteine adsorbs onto the silver nanoparticle surface with its thiol group and prevents the oxidation. In contrast, glucose slows down the dissolution, but clearly did not prevent the oxidation on a longer time scale. We have extended the studies by mixing silver nanoparticle dispersions with different media of increasingly biological nature. The solutions/dispersions were stirred for equilibration and then subjected to ultracentrifugation. All precipitates and nanoparticles were isolated by this way and then analyzed. The results show that both initially present silver ions and released silver ions are mainly precipitated as AgCl if chloride is present. Only in the absence of chloride, glucose is able to reduce Ag+ to Ag0. The initially present silver nanoparticles were recovered in all cases. Silver phosphate was not observed in any case, probably due to the moderate pH (around 7) at which phosphate is mostly protonated to hydrogen phosphate and dihydrogen phosphate. We can conclude that released silver ions precipitate mostly as AgCl in biological media, and that most cell culture studies where silver ions are used as control are in fact studying the effect of colloidal silver chloride on the cells. To prove this assumption, human mesenchymal stem cells (hMSC) were cultured in the presence of silver chloride nanoparticles (diameter 120 nm), and the viability of the cells was analyzed by fluorescence microscopy. In general, we clearly observed that pure silver nanoparticles have lower toxicity to hMSC compared to silver chloride nanoparticles with a comparable total silver dose. Silver acetate in the biological medium had a comparable toxicity to hMSC compared to silver chloride nanoparticles with the same total silver dose.

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Antimicrobial Activity of Filtrating Meltblown Nonwoven with the Addition of Silver Ions

Gutarowska B., Michalski A.

Fibres & Textiles in Eastern Europe

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2009

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Vol. 17, no. 3 (74)

23--28

EN

The paper presents the results of studies aimed at the assessment of the antimicrobial activity of filtrating meltblown nonwoven used in the production of protective half-masks. Polypropylene nonwoven materials containing a biologically active compound in their composition Ag/AgCl ions on different carriers: ZnO, TiO, BaSO4, were used in the study. The effect of different carriers and an electric charge on the antimicrobial activity of the nonwoven against four species of bacteria and fungi was tested. Meltblown nonwovens with Ag/AgCl on the carriers added were characterised by high antimicrobial activity against bacteria: E. coli, S. aureus and fungi: C. albicans, A. niger. The antimicrobial activity of Ag/AgCl was demonstrated to depend, to a large extent, on the carrier of the active substance. Simultaneous use of two types of carriers TiO and ZnO, as well as TiO2 and BaSO4, considerably increased the antimicrobial activity of the nonwovens in comparison with those in which one carrier was used. Higher antimicrobial activity was also observed in the presence of a static electric charge on the nonwoven fibres. Microscopic studies demonstrated the correct distribution of the active substance on the surface and just under the surface of the fibres, and oil mist aerosol filtration tests confirmed that the presence of biocide does not affect the filtrating properties of the nonwoven. Biocidal efficiency both against bacteria and fungi after 8 h contact with the nonwoven was demonstrated. A high antimicrobial effect was obtained after 24 h, which indicates the long-term mechanism of the effect of silver on microbial cells

PL

Przedstawiono wyniki badań oceny aktywności przeciwdrobnoustrojowej (APD) bioaktywnych pneumotermicznych włóknin filtracyjnych (WPTF) stosowanych do produkcji półmasek ochronnych. W badaniach stosowano włókniny PP zawierające w swoim składzie związek biologicznie aktywny jony Ag/AgCl na różnych nośnikach: ZnO, TiO, BaSO4. Zbadano wpływ różnych nośników oraz ładunku elektrycznego na APD włóknin wobec czterech gatunków bakterii i grzybów. WPTF z dodatkiem Ag/AgCl na nośnikach charakteryzowały się wysoką APD wobec bakterii E. coli, S. aureus oraz grzybów C. albicans, A. niger. Stwierdzono, iż APD Ag/AgCl zależy w dużym stopniu od nośnika substancji aktywnej. Zastosowanie jednocześnie dwóch rodzajów nośników TiO oraz ZnO jak również TiO2, oraz BaSO4 znacznie podwyższyło APD włóknin, w porównaniu z włókninami, w których stosowany był jeden nośnik. Stwierdzono również wyższą APD przy obecności ładunku elektrostatycznego na włóknach. Badania mikroskopowe wykazały prawidłowe rozmieszczenie substancji aktywnej na powierzchni oraz tuż pod powierzchnią włókien, a badania filtracji aerozolu mgły olejowej potwierdziły, iż obecność biocydu nie zmienia właściwości filtracyjnych włókniny. Wykazano skuteczność bójczą zarówno wobec bakterii jak i grzybów po 8 godzinach kontaktu z włókniną. Wysokie efekty APD uzyskano po 24 godzinach, co wskazuje iż mechanizm działania srebra na komórki drobnoustrojów jest długotrwały.