Tannic Acid-modified Silver Nanoparticles Research Articles

Tannic Acid-Modified Silver Nanoparticles in Conjunction with Contact Lens Solutions Are Useful for Progress against the Adhesion of Acanthamoeba spp. to Contact Lenses.

Acanthamoeba spp. are amphizoic amoebae that are widely distributed in the environment and capable of entering the human body. They can cause pathogenic effects in different tissues and organs, including Acanthamoeba keratitis (AK), which may result in a loss of visual acuity and blindness. The diagnostics, treatment, and prevention of AK are still challenging. More than 90% of AK cases are related to the irresponsible wearing of contact lenses. However, even proper lens care does not sufficiently protect against this eye disease, as amoebae have been also found in contact lens solutions and contact lens storage containers. The adhesion of the amoebae to the contact lens surface is the first step in developing this eye infection. To limit the incidence of AK, it is important to enhance the anti-adhesive activity of the most popular contact lens solutions. Currently, silver nanoparticles (AgNPs) are used as modern antimicrobial agents. Their effectiveness against Acanthamoeba spp., especially with the addition of plant metabolites, such as tannic acid, has been confirmed. Here, we present the results of our further studies on the anti-adhesion potential of tannic acid-modified silver nanoparticles (AgTANPs) in combination with selected contact lens solutions against Acanthamoeba spp. on four groups of contact lenses. The obtained results showed an increased anti-adhesion activity of contact lens solutions in conjunction with AgTANPs with a limited cytotoxicity effect compared to contact lens solutions acting alone. This may provide a benefit in improving the prevention of amoebae eye infections. However, there is still a need for further studies on different pathogenic strains of Acanthamoeba in order to assess the adhesion of the cysts to the contact lens surface and to reveal a more comprehensive picture of the activity of AgTANPs and contact lens solutions.

Tannic acid-modified silver nanoparticles enhance the anti-Acanthamoeba activity of three multipurpose contact lens solutions without increasing their cytotoxicity

BackgroundFree-living amoebae of the genus Acanthamoeba are cosmopolitan, widely distributed protozoans that cause a severe, vision-threatening corneal infection known as Acanthamoeba keratitis (AK). The majority of the increasing number of AK cases are associated with contact lens use. Appropriate eye hygiene and effective contact lens disinfection are crucial in the prevention of AK because of the lack of effective therapies against it. Currently available multipurpose contact lens disinfection systems are not fully effective against Acanthamoeba trophozoites and cysts. There is an urgent need to increase the disinfecting activity of these systems to prevent AK infections. Synthesized nanoparticles (NPs) have been recently studied and proposed as a new generation of anti-microbial agents. It is also known that some plant metabolites, including tannins, have anti-parasitic activity. The aim of this study was to evaluate the anti-amoebic activity and cytotoxicity of tannic acid-modified silver NPs (AgTANPs) conjugated with selected multipurpose contact lens solutions.MethodsThe anti-amoebic activities of pure contact lens care solutions, and NPs conjugated with contact lens care solutions, were examined in vitro by a colorimetric assay based on the oxido-reduction of alamarBlue. The cytotoxicity assays were performed using a fibroblast HS-5 (ATCC CRL-11882) cell line. The results were statistically analysed by ANOVA and Student-Newman-Keuls test using P < 0.05 as the level of statistical significance.ResultsWe show that the NPs enhance the anti-Acanthamoeba activities of the tested contact lens solutions without increasing their cytotoxicity profiles. The activities are enhanced within the minimal disinfection time recommended by the manufacturers.ConclusionsThe conjugation of the selected contact lens solutions with AgTANPs might be a novel and promising approach for the prevention of AK infections among contact lens users.Graphical

Colorimetric detection of Cr3+ in dietary supplements using a smartphone based on EDTA and tannic acid-modified silver nanoparticles

A simplistic, portable and low-cost method for the rapid detection of Cr3+ was developed based on a smartphone readout and a co-functionalized silver nanoparticles (AgNPs) system for use as an on-site device in resource-poor areas. The presence of Cr3+ induced aggregation of AgNPs through coordinated complex formation between Cr3+ and stabilizing agents on the NPs surface, resulted in a bright yellow of an AgNPs solution turned to wine red along with a SPR band was red-shifted from 429nm to 625nm. A smartphone with an available free application, called "PhotoMetrix" was used to measure the RGB (red, green, blue) values of the color intensities in the AgNPs system and convert into Cr3+ concentration by using univariate calibration curves in less than 60s. This smartphone-based detection system showed a high selectivity of AgNPs with Cr3+ and gave a positive coefficient correlation (R2=0.9878) between the intensity of channel R and the Cr3+ concentration, with a linear range of 2.0-5.0mgL-1, and a detection limit of 1.52mgL-1. Furthermore, the proposed method has been successfully applied for quantification of Cr3+ in dietary supplement samples. The results obtained were in close agreement with those obtained in FAAS (Flame Atomic Absorption Spectrometry). The developed colorimetric system based on a smartphone readout device exhibits feasibility and reliability for on-site Cr3+ detection in the real samples.

Tannic acid-modified silver nanoparticles for enhancing anti-biofilm activities and modulating biofilm formation.

The formation of bacterial biofilms is a key factor in the emergence of chronic infections due to the strong resistance of biofilms to conventional antibiotics. There is an urgent need to develop an effective strategy to control the formation of biofilms. In this study, a nanocomposite of tannic acid and silver (Tannin-AgNPs) was designed and successfully prepared based on the quorum sensing (QS) inhibitory activity of tannic acid and the anti-bacterial activity of silver. The dynamic light scattering and SEM observations indicated that the obtained Tannin-AgNPs were spherical with a mean particle size of 42.37 nm. Tannic acid was successfully modified on the surface of silver nanoparticles and characterized via Fourier transform infrared (FTIR) spectroscopy. The prepared Tannin-AgNPs demonstrated a more effective anti-bacterial and anti-biofilm activity against E. coli than the unmodified AgNPs or tannic acid. In addition, the Tannin-AgNPs can modulate the formation process of E. coli biofilms, shorten the growth period of biofilms and extend the dispersion period of biofilms. Tannin-AgNPs also showed the function of decreasing the production of the QS signal molecule. The proposed strategy of constructing a nanocomposite using AgNPs and natural components with QS inhibitory activity is effective and promising for inhibiting the formation of biofilms.

Tannic acid-modified silver nanoparticles as a novel therapeutic agent against Acanthamoeba

Free-living amoebae belonging to Acanthamoeba genus are widely distributed protozoans which are able to cause infection in humans and other animals such as keratitis and encephalitis. Acanthamoeba keratitis is a vision-threatening corneal infection with currently no available fully effective treatment. Moreover, the available therapeutic options are insufficient and are very toxic to the eye. Therefore, there is an urgent need for the development of more effective anti-amoebic agents. Nanotechnology approaches have been recently reported to be useful for the elucidation antimicrobial, antiviral, antifungal and antiprotozoal activities and thus, they could be a good approach for the development of anti-Acanthamoeba agents. Therefore, this study was aimed to explore the activity and cytotoxicity of tannic acid-modified silver nanoparticles, pure silver nanoparticles and pure gold nanoparticles against clinical strains of Acanthamoeba spp. The obtained results showed a significant anti-amoebic effect of the tannic acid-modified silver nanoparticles which also presented low cytotoxicity. Moreover, tannic acid-modified silver nanoparticles were well absorbed by the trophozoites and did not induce encystation. On the other hand, pure silver nanoparticles were only slightly active against the trophozoite stage and pure gold nanoparticles did not show any activity. In conclusion and based on the observed results, silver nanoparticle conjugation with tannic acid may be considered as potential agent against Acanthamoeba spp.

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.

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

IntroductionSilver 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.MethodsIn 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.ResultsTA-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.ConclusionTA-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.

Multifunctional Tannic Acid/Silver Nanoparticle-Based Mucoadhesive Hydrogel for Improved Local Treatment of HSV Infection: In Vitro and In Vivo Studies.

Mucoadhesive gelling systems with tannic acid modified silver nanoparticles were developed for effective treatment of herpes virus infections. To increase nanoparticle residence time after local application, semi solid formulations designed from generally regarded as safe (GRAS) excipients were investigated for their rheological and mechanical properties followed with ex vivo mucoadhesive behavior to the porcine vaginal mucosa. Particular effort was made to evaluate the activity of nanoparticle-based hydrogels toward herpes simplex virus (HSV) type 1 and 2 infection in vitro in immortal human keratinocyte cell line and in vivo using murine model of HSV-2 genital infection. The effect of infectivity was determined by real time quantitative polymerase chain reaction, plaque assay, inactivation, attachment, penetration and cell-to-cell assessments. All analyzed nanoparticle-based hydrogels exhibited pseudoplastic and thixotropic properties. Viscosity and mechanical measurements of hydrogels were found to correlate with the mucoadhesive properties. The results confirmed the ability of nanoparticle-based hydrogels to affect viral attachment, impede penetration and cell-to-cell transmission, although profound differences in the activity evoked by tested preparations toward HSV-1 and HSV-2 were noted. In addition, these findings demonstrated the in vivo potential of tannic acid modified silver nanoparticle-based hydrogels for vaginal treatment of HSV-2 genital infection.

Toxicity of tannic acid-modified silver nanoparticles in keratinocytes: potential for immunomodulatory applications

Hydrolyzable tannins are known to exhibit anti-inflammatory activity, which can be used in combination with silver nanoparticles (AgNPs) for dermal uses. In this study, we investigated the effects of tannic acid-modified 13, 33, 46nm and unmodified 10–65nm AgNPs using the human-derived keratinocyte HaCaT and VK2-E6/E7 cell lines in the form of stationary and spheroids cultures. After exposition to tannic acid-modified AgNPs, VK2-E6/E7 cells showed higher toxicity, increased production of reactive oxygen species (ROS) and activity of JNK stress kinase, while HaCaT cell line demonstrated less ROS production and activation of ERK kinase. AgNPs internalization was detected both in the superficial and internal layers of spheroids prepared from both cell lines. Tannic acid modified AgNPs sized above 30nm did not induce DNA breaks in comet assay performed in both cell lines. Tannic acid-modified but not unmodified AgNPs down-regulated TNF-α and LPS-triggered production of IL-8 in VK2-E6/E7 but not in HaCaT cells. In summary, tannic acid-modified AgNPs sized above 30nm show good toxicological profile both in vitro and possess immunomodulatory properties useful for potential dermal applications in humans.

Tannic acid modified silver nanoparticles show antiviral activity in herpes simplex virus type 2 infection.

The interaction between silver nanoparticles and herpesviruses is attracting great interest due to their antiviral activity and possibility to use as microbicides for oral and anogenital herpes. In this work, we demonstrate that tannic acid modified silver nanoparticles sized 13 nm, 33 nm and 46 nm are capable of reducing HSV-2 infectivity both in vitro and in vivo. The antiviral activity of tannic acid modified silver nanoparticles was size-related, required direct interaction and blocked virus attachment, penetration and further spread. All tested tannic acid modified silver nanoparticles reduced both infection and inflammatory reaction in the mouse model of HSV-2 infection when used at infection or for a post-infection treatment. Smaller-sized nanoparticles induced production of cytokines and chemokines important for anti-viral response. The corresponding control buffers with tannic acid showed inferior antiviral effects in vitro and were ineffective in blocking in vivo infection. Our results show that tannic acid modified silver nanoparticles are good candidates for microbicides used in treatment of herpesvirus infections.

Assessment of in vitro cellular responses of monocytes and keratinocytes to tannic acid modified silver nanoparticles

Hydrolyzable tannins are known to exhibit diverse biological effects, which can be used in combination with silver nanoparticles (AgNPs). In this study, we tested toxic and inflammatory properties of tannic-acid modified 13, 33, 46nm and unmodified 10–65nm AgNPs using murine 291.03C keratinocyte and RAW 264.7 monocyte cell lines. Both cell lines exposed for 24h to 1–10μg/ml of 13nm, 33nm, 46nm and unmodified AgNPs showed dose-dependent toxicity and decreased cell proliferation. Only small-sized AgNPs induced production of ROS by monocytes, but not keratinocytes. Monocytes internalized large aggregates of 33, 46nm and 10–65nm AgNPs in cytoplasmic vacuoles, whereas keratinocytes accumulated less particles. AgNPs of 13nm were localized ubiquitously within both cell types. The tested AgNPs strongly down-regulated production of tumor necrosis factor-α (TNF-α) by monocytes, whereas keratinocytes exposed to AgNPs showed an opposite effect. Unmodified but not tannic acid-modified AgNPs increased production of the pro-inflammatory MCP-1 by monocytes and keratinocytes. In summary, low inflammatory potential and lack of ROS production by tannic-acid modified AgNPs sized above 30nm suggests that tannic acid modification of large silver nanoparticles may help to increase AgNPs biosafety.