Katarzyna Ranoszek-Soliwoda

The role of tannic acid and sodium citrate in the synthesis of silver nanoparticles

AbstractWe describe herein the significance of a sodium citrate and tannic acid mixture in the synthesis of spherical silver nanoparticles (AgNPs). Monodisperse AgNPs were synthesized via reduction of silver nitrate using a mixture of two chemical agents: sodium citrate and tannic acid. The shape, size and size distribution of silver particles were determined by UV–Vis spectroscopy, dynamic light scattering (DLS) and scanning transmission electron microscopy (STEM). Special attention is given to understanding and experimentally confirming the exact role of the reagents (sodium citrate and tannic acid present in the reaction mixture) in AgNP synthesis. The oxidation and reduction potentials of silver, tannic acid and sodium citrate in their mixtures were determined using cyclic voltammetry. Possible structures of tannic acid and its adducts with citric acid were investigated in aqueous solution by performing computer simulations in conjunction with the semi-empirical PM7 method. The lowest energy structures found from the preliminary conformational search are shown, and the strength of the interaction between the two molecules was calculated. The compounds present on the surface of the AgNPs were identified using FT-IR spectroscopy, and the results are compared with the IR spectrum of tannic acid theoretically calculated using PM6 and PM7 methods. The obtained results clearly indicate that the combined use of sodium citrate and tannic acid produces monodisperse spherical AgNPs, as it allows control of the nucleation, growth and stabilization of the synthesis process. Graphical abstractᅟ

A study on the in vitro percutaneous absorption of silver nanoparticles in combination with aluminum chloride, methyl paraben or di-n-butyl phthalate

Some reports indicate that the silver released from dermally applied products containing silver nanoparticles (AgNP) (e.g. wound dressings or cosmetics) can penetrate the skin, particularly if damaged. AgNP were also shown to have cytotoxic and genotoxic activity. In the present study percutaneous absorption of AgNP of two different nominal sizes (Ag15nm or Ag45nm by STEM) and surface modification, i.e. citrate or PEG stabilized nanoparticles, in combination with cosmetic ingredients, i.e. aluminum chloride (AlCl3), methyl paraben (MPB), or di-n-butyl phthalate (DBPH) was assessed using in vitro model based on dermatomed pig skin. The inductively coupled plasma mass spectrometry (ICP-MS) measurements after 24h in receptor fluid indicated low, but detectable silver absorption and no statistically significant differences in the penetration between the 4 types of AgNP studied at 47, 470 or 750μg/ml. Similarly, no significant differences were observed for silver penetration when the AgNP were used in combinations with AlCl3 (500μM), MPB (1250μM) or DBPH (35μM). The measured highest amount of Ag that penetrated was 0.45ng/cm2 (0.365-0.974ng/cm2) for PEG stabilized Ag15nm+MPB.

Inhibitory effect of silver nanoparticles on proliferation of estrogen-dependent MCF-7/BUS human breast cancer cells induced by butyl paraben or di-n-butyl phthalate

&NA; In this study the effect of silver nanoparticles (AgNPs) on proliferation of estrogen receptor (ER)‐positive human breast cancer MCF‐7/BUS cells was assessed by means of in vitro assay. The cells were exposed in the absence of estrogens to AgNPs alone or in combination with aluminum chloride (AlCl3), butyl paraben (BPB) and di‐n‐butyl phthalate (DBPh). The results revealed that AgNPs at the non‐cytotoxic concentrations (up to 2 &mgr;g/mL) and AlCl3 (up to 500 &mgr;M) did not induce proliferation of MCF‐7/BUS cells whereas BPB and DBPh showed strong estrogenic activity with the highest effect at 16 &mgr;M and 35 &mgr;M, respectively. AgNPs inhibited the proliferation of the cells induced by DBPh, BPB or even with 17&bgr;‐estradiol (E2) during 6‐day incubation in the absence of estrogens. ICI 182,780 (10 nM), a known estrogen receptor (ER) antagonist, induced strong inhibitory effect. AgNPs also decreased transcription of the estrogen‐responsive pS2 and progesterone receptor (PGR) genes but modulated expression neither of ER&agr; nor ER&bgr; in MCF‐7/BUS cells exposed to BPB, DBPh or E2 for 6 h. Our results indicate that AgNPs may inhibit growth of breast cancer cells stimulated by E2 or estrogenic chemicals, i.e. BPB and DBPh. HighlightsAgNPs above 2 &mgr;g/mL are cytotoxic for MCF‐7/BUS cells after 6 day‐exposure.BPB and DBPh (but not AgNPs and AlCl3) induce proliferation of MCF‐7/BUS cells.AgNPs inhibit growth of MCF‐7/BUS cells induced by BPB, DBP or even E2.BPB, DBPh and E2 upregulate pS2 and PGR, but not ESR1 and ESR2 genes.AgNPs reduce transcription of pS2 and PGR genes upregulated by BPB, DBP or E2.

Catalase-modified gold nanoparticles: Determination of the degree of protein adsorption by gel electrophoresis

In this study we present a method to determine the degree to which catalase (CAT) is adsorbed onto gold nanoparticles (AuNPs) using polyacrylamide gel electrophoresis (PAGE) with silver staining. AuNPs (13nm) were synthesized in water by the chemical reduction method and modified with CAT (AuNPs-CAT). The colloidal stability and NP size before and after the modification were investigated by dynamic light scattering and scanning transmission electron microscopy. Electrophoresis was performed under different conditions (native, with and without SDS, and with and without β-mercaptoethanol) to find the optimal conditions for determining the surface coverage of AuNPs with CAT protein. The results clearly indicate that PAGE can be used to determine the amount of protein adsorbed on the NP surface and the use of native PAGE does not alter the colloidal stability of the NPs. These features allowed us to monitor the state of NPs and protein-NP interactions during the electrophoretic process.

Tannic acid-modified silver nanoparticles for wound healing: the importance of size

Introduction Silver nanoparticles (AgNPs) have been shown to promote wound healing and to exhibit antimicrobial properties against a broad range of bacteria. In our previous study, we prepared tannic acid (TA)-modified AgNPs showing a good toxicological profile and immunomodulatory properties useful for potential dermal applications. Methods In this study, in vitro scratch assay, antimicrobial tests, modified lymph node assay as well as a mouse splint wound model were used to access the wound healing potential of TA-modified and unmodified AgNPs. Results TA-modified but not unmodified AgNPs exhibited effective antibacterial activity against Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli and stimulated migration of keratinocytes in vitro. The tests using the mouse splint wound model showed that TA-modified 33 and 46 nm AgNPs promoted better wound closure, epithelialization, angiogenesis and formation of the granulation tissue. Additionally, AgNPs elicited expression of VEGF-α, PDGF-β and TGF-β1 cytokines involved in wound healing more efficiently in comparison to control and TA-treated wounds. However, both the lymph node assay and the wound model showed that TA-modified AgNPs sized 13 nm can elicit strong inflammatory response not only during wound healing but also when applied to the damaged skin. Conclusion TA-modified AgNPs sized >26 nm promote wound healing better than TA-modified or unmodified AgNPs. These findings suggest that TA-modified AgNPs sized >26 nm may have a promising application in wound management.

Chapter 12 – Tannic acid modification of metal nanoparticles: possibility for new antiviral applications

Tannins are phenol derivatives naturally synthesized by plants as metabolic products. For centuries tannins have been used in medicine as agents supporting wound healing, due to their antiinflammatory and antimicrobial properties. Tannic acid is the most common and principal hydrolysable tannin. Here, we describe the method for synthesis of silver or gold copper/silver nanoparticles by chemical reduction method using tannic acid. This method allows for precise shape and size control of metallic nanoparticles having surface modified by tannic acid to increase attachment, antimicrobial and antiinflammatory properties. The interaction between nanoparticles and viruses is attracting great interest due to the need for new antivirals. We demonstrated that tannic acid modified silver nanoparticles are capable of reducing herpes simplex type 2 (HSV-2) infectivity both in vitro and in vivo. The antiviral activity of tannic acid modified silver and silver/copper nanoparticles was size-related, required direct interaction and blocked virus attachment, penetration and further spread. All tested tannic acid modified AgNPs and Ag/CuNPs reduced both infection and inflammatory reaction in the mouse model of HSV infection. Therefore, tannic acid modified silver and silver copper alloy nanoparticles consist good candidates for microbicides used in treatment of infections with enveloped viruses, such as herpes viruses.

Spectroscopic and electrochemical monitoring of band structure changes during the alloying of CdTe QDs by Hg2+ ions

The series of ultrasmall thioglycolic acid-stabilized colloidal Cd1−x Hg x Te QDs (with d ≈ 2.3 nm) with different % Hg2+ content were synthesized by an ion-exchange reaction in water solution. The resulting Cd1−x Hg x Te QDs were characterized using UV–vis absorption and photoluminescent optical spectroscopic studies, cyclic voltammetry and scanning transmission electron microscopy. By comparison of the results from different methods we conclude that Hg-alloying occurs in three stages—with the formation of three different types of QDs structures, namely core/shell CdTe/Cd1−x Hg x Te QDs, core/shell/shell CdTe/Cd1−x Hg x Te/CdHg QDs and core/shell Cd1−x Hg x Te/CdHg QDs.

Tannic Acid-Modified Silver and Gold Nanoparticles as Novel Stimulators of Dendritic Cells Activation

Silver nanoparticles (AgNPs) are promising new antimicrobial agents against a wide range of skin and mucosal pathogens. However, their interaction with the immune system is currently not fully understood. Dendritic cells (DCs) are crucial during development of T cell-specific responses against bacterial and viral pathogens. We have previously shown that tannic acid-modified silver nanoparticles (TA-AgNPs) consist of a promising microbicide against HSV-2. The aim of this study was to compare the ability of TA-AgNPs or TA-AuNPs of similar sizes (TA-Ag/AuNPs) to induce DCs maturation and activation in the presence of HSV-2 antigens when used at non-toxic doses. First, we used JAWS II DC line to test toxicity, ultrastructure as well as activation markers (MHC I and II, CD40, CD80, CD86, PD-L1) and cytokine production in the presence of TA-Ag/AuNPs. Preparations of HSV-2 treated with nanoparticles (TA-Ag/AuNPs-HSV-2) were further used to investigate HSV-2 antigen uptake, activation markers, TLR9 expression, and cytokine production. Additionally, we accessed proliferation and activation of HSV-2-specific T cells by DCs treated with TA-AgNP/AuNPs-HSV-2. We found that both TA-AgNPs and TA-AuNPs were efficiently internalized by DCs and induced activated ultrastructure. Although TA-AgNPs were more toxic than TA-AuNPs in corresponding sizes, they were also more potent stimulators of DCs maturation and TLR9 expression. TA-Ag/AuNPs-HSV-2 helped to overcome inhibition of DCs maturation by live or inactivated virus through up-regulation of MHC II and CD86 and down-regulation of CD80 expression. Down-regulation of CD40 expression in HSV-2-infected DCs was reversed when HSV-2 was treated with TA-NPs sized >30 nm. On the other hand, small-sized TA-AgNPs helped to better internalize HSV-2 antigens. HSV-2 treated with both types of NPs stimulated activation of JAWS II and memory CD8+ T cells, while TA-AgNPs treatment induced IFN-γ producing CD4+ and CD8+ T cells. Our study shows that TA-AgNPs or TA-AuNPs are good activators of DCs, albeit their final effect upon maturation and activation may be metal and size dependent. We conclude that TA-Ag/AuNPs consist of a novel class of nano-adjuvants, which can help to overcome virus-induced suppression of DCs activation.

Comparison of the antioxidant activity of catalase immobilized on gold nanoparticles via specific and non-specific adsorption

In this study, we present a comparison of the antioxidant activity of catalase immobilized on gold nanoparticles (AuNPs) by two methods: i) directly on the surface of AuNPs (non-specific immobilization), and ii) via chemical bonding using a linker (specific immobilization). Quantification of the enzyme amount adsorbed on the nanoparticle surface was determined by native-polyacrylamide gel electrophoresis (native-PAGE). Colloidal stability of AuNPs before and after the enzyme immobilization was monitored with dynamic light scattering (DLS) and UV-vis spectroscopy. The size of the metallic core was determined by scanning-transmission electron microscopy (STEM). The enzymatic activity of catalase immobilized on AuNPs was investigated by antioxidant tests and compared with free (non-immobilized) catalase. It was found that the activity of catalase immobilized on AuNPs is affected by the immobilization method. Moreover, it was found that the non-specific immobilization decreased the antioxidant activity while the specific immobilization of catalase allowed the catalase activity to remain at the same level as that of free catalase.

A Study of the Activity of Recombinant Mn-Superoxide Dismutase in the Presence of Gold and Silver Nanoparticles

Superoxide dismutase (SOD) is one of the best characterized enzyme maintaining the redox state in the cell. A bacterial expression system was used to produce human recombinant manganese SOD with a His-tag on the C-end of the protein for better purification. In addition, gold and silver nanoparticles were chemically synthesized in a variety of sizes, and then mixed with the enzyme for immobilization. Analysis by dynamic light scattering and scanning transmission electron microscopy revealed no aggregates or agglomerates of the obtained colloids. After immobilization of the protein on AuNPs and AgNPs, the conjugates were analyzed by SDS-PAGE. It was determined that SOD was adsorbed only on the gold nanoparticles. Enzyme activity was analyzed in colloids of the gold and silver nanoparticles bearing SOD. The presence of a nanoparticle did not affect enzyme activity; however, the amount of protein and size of the gold nanoparticle did influence the enzymatic activity of the conjugate. Our findings confirm that active recombinant human superoxide dismutase can be produced using a bacterial expression system, and that the enzyme can be immobilized on metal nanoparticles. The interaction between enzymes and metal nanoparticles requires further investigation.