Bioactive Silver Research Articles

Silver release and antimicrobial properties of PMMA films doped with silver ions, nano-particles and complexes.

Materials prepared on the base of bioactive silver compounds have become more and more popular due to low microbial resistance to silver. In the present work, the efficiency of polymethylmethacrylate (PMMA) thin films doped with silver ions, nanoparticles and silver-imidazole polymer complex was studied by a combination of AAS, XPS and AFM techniques. The biological activities of the proposed materials were discussed in view of the rate of silver releasing from the polymer matrix. Concentrations of Ag active form were estimated by its ability to interact with l-cysteine using electronic circular dichroism spectroscopy. Rates of the released silver were compared with the biological activity in dependence on the form of embedded silver. Antimicrobial properties of doped polymer films were studied using two bacterial strains: Staphylococcus epidermidis and Escherichia coli. It was found that PMMA films doped with Ag(+) had greater activity than those doped with nanoparticles and silver-imidazole polymeric complexes. However, the antimicrobial efficiency of Ag(+) doped films was only short-term. Contrary, the antimicrobial activity of silver-imidazole/PMMA films increased in time of sample soaking.

Bioactive bile salt-capped silver nanoparticles activity against destructive plant pathogenic fungi through in vitro system

Sodium deoxycholate (NaDC) capped silver nanoparticles are employed to counteract the fungusColletotrichum gloeosporioideswhich causes anthracnose disease in a wide number of plants throughout the world.

Fabrication of nano-silver particles using Cymodocea serrulata and its cytotoxicity effect against human lung cancer A549 cells line

The present study reports, green synthesis of bioactive silver nanoparticles (AgNPs) under different temperature (60°C, room temperature and 4° refrigerator) using the aqueous extract of sea grass Cymodocea serrulata as a potential bioreductant. Increased temperature fabricates more AgNPs compare to room temperature and refrigerator condition. At first the reduction of Ag+ ions were confirmed through color change which produces an absorbance spectra at 420nm in UV–Visible spectrophotometer. Additionally various exclusive instrumentations such as X-ray diffraction (XRD), Dynamic light scattering (DLS), scanning electron microscope (SEM) analysis and Transmission electron microscope (TEM) were authorizes the biosynthesis and physio-chemical characterization of AgNPs. From Fourier transform infrared spectroscopy (FTIR) analysis, it was identified that the water soluble fractions of the sea grass mainly responsible for reduction of ionic silver (Ag+) into (Ag0) nano-ranged particles and also they act as stabilizing agent to sustain the durability of NPs for long period of time. Further, synthesized AgNPs shows potential cytotoxicity against human lung cancer A549 cells (LD50–100μg/ml). The overall results suggest that C. serrulata is a valuable bioresource to generate rapid and eco-friendly bioactive AgNPs towards cancer therapy.

Synthesis and bioactivities of silver nanoparticles capped with 5-amino-β-resorcylic acid hydrochloride dihydrate.

BackgroundConjugated and drug loaded silver nanoparticles are getting an increased attention for various biomedical applications. Nanoconjugates showed significant enhancement in biological activity in comparison to free drug molecules. In this perspective, we report the synthesis of bioactive silver capped with 5-Amino-?-resorcylic acid hydrochloride dihydrate (AR). The in vitro antimicrobial (antibacterial, antifungal), enzyme inhibition (xanthine oxidase, urease, carbonic anhydrase, ?-chymotrypsin, cholinesterase) and antioxidant activities of the developed nanostructures was investigated before and after conjugation to silver metal.ResultsThe conjugation of AR to silver was confirmed through FTIR, UV¿vis and TEM techniques. The amount of AR conjugated with silver was characterized through UV¿vis spectroscopy and found to be 9% by weight. The stability of synthesized nanoconjugates against temperature, high salt concentration and pH was found to be good. Nanoconjugates, showed significant synergic enzyme inhibition effect against xanthine and urease enzymes in comparison to standard drugs, pure ligand and silver.ConclusionsOur synthesized nanoconjugate was found be to efficient selective xanthine and urease inhibitors in comparison to Ag and AR. On a per weight basis, our nanoconjugates required less amount of AR (about 11 times) for inhibition of these enzymes.

Bioactive compound loaded stable silver nanoparticle synthesis from microwave irradiated aqueous extracellular leaf extracts of Naringi crenulata and its wound healing activity in experimental rat model

An efficient and eco-friendly protocol for the synthesis of bioactive silver nanoparticles was developed using Naringi crenulata leaf extracts via microwave irradiation method. Silver nanoparticles were synthesized by treating N. crenulata leaf extracts with 1mM of aqueous silver nitrate solution. An effective bioactive compound such as alkaloids, phenols, saponins and quinines present in the N. crenulata reduces the Ag+ into Ag0. The synthesized silver nanoparticles were monitored by UV–vis spectrophotometer and further characterized by X-ray diffraction (XRD), Fourier Transform Infra Red (FTIR), Energy-dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscopy (FESEM). UV–vis spectroscopy showed maximum absorbance at 390nm due to surface plasmon resonance of AgNPs. From FESEM results, an average crystal size of the synthesized nanoparticle was 72–98nm. FT-IR results showed sharp absorption peaks and they were assigned to phosphine, alkyl halides and sulfonate groups. Silver nanoparticles synthesized were generally found to be spherical and cubic shape. Topical application of ointment prepared from silver nanoparticles of N. crenulata were formulated and evaluated in vivo using the excision wound healing model on Wistar albino rats. The measurement of the wound areas was performed on 3rd, 6th, 9th, 12th and 15th days and the percentage of wound closures was calculated accordingly. By the 15th day, the ointment base containing 5% (w/w) of silver nanoparticles showed 100% wound healing activity compared with that of the reference as well as control bases. The results strongly suggested that the batch C ointment containing silver nanaoparticles synthesized from the leaf extracts of N. crenulata was found to be very effective in wound repair and encourages harnessing the potentials of the plant biomolecules loaded silver nanoparticle in the treatment of tropical diseases including wound healing.

Synthesis and bioactivities of silver nanoparticles capped with 5-Amino-ß-resorcylic acid hydrochloride dihydrate

BackgroundConjugated and drug loaded silver nanoparticles are getting an increased attention for various biomedical applications. Nanoconjugates showed significant enhancement in biological activity in comparison to free drug molecules. In this perspective, we report the synthesis of bioactive silver capped with 5-Amino-?-resorcylic acid hydrochloride dihydrate (AR). The in vitro antimicrobial (antibacterial, antifungal), enzyme inhibition (xanthine oxidase, urease, carbonic anhydrase, ?-chymotrypsin, cholinesterase) and antioxidant activities of the developed nanostructures was investigated before and after conjugation to silver metal.ResultsThe conjugation of AR to silver was confirmed through FTIR, UV-vis and TEM techniques. The amount of AR conjugated with silver was characterized through UV-vis spectroscopy and found to be 9% by weight. The stability of synthesized nanoconjugates against temperature, high salt concentration and pH was found to be good. Nanoconjugates, showed significant synergic enzyme inhibition effect against xanthine and urease enzymes in comparison to standard drugs, pure ligand and silver.ConclusionsOur synthesized nanoconjugate was found be to efficient selective xanthine and urease inhibitors in comparison to Ag and AR. On a per weight basis, our nanoconjugates required less amount of AR (about 11 times) for inhibition of these enzymes.

Antibacterial and Bioactive <I>α</I>- and <I>β</I>-Chitin Hydrogel/Nanobioactive Glass Ceramic/Nano Silver Composite Scaffolds for Periodontal Regeneration

Alveolar bone loss and bone defects are the commonly encountered periodontal problems. Large defects do not heal spontaneously and thus require surgical interventions with bone substitutes. Bone grafts have the disadvantages of eliciting an immunologic response with subsequent graft rejection. The success rate of Guided Tissue Regeneration (GTR) is variable because of high susceptibility to infection. Thus emerged the important role of synthetic biomaterials and hence for this purpose we developed a nanocomposite scaffold, using alpha- and beta-chitin hydrogel with bioactive glass ceramic nanoparticles (nBGC) and silver nanoparticles (nAg) by lyophilization technique (aalpha and beta-chitin hydrogel/nBGC/nAg nanocomposite scaffold). The prepared nanoparticles and nanocomposite scaffolds were characterized. In addition, the porosity, swelling, mechanical properties, antibacterial activity, in vitro degradation and biomineralization, cell viability, cell attachment and cell proliferation ability of the prepared composite scaffolds were also evaluated. The results showed that alpha- and beta-chitin/nBGC/nAg composite scaffolds were porous and have the capacity to absorb fluids and swell. The composite scaffolds also showed enhanced antibacterial activity, bioactivity and controlled degradation in comparison to the control scaffolds. Cell viability studies proved the non-toxic nature of the nanocomposite scaffolds. Cell attachment and cell proliferation studies revealed the attachment and spreading nature of cells. All these studies revealed that, these antibacterial nanocomposite scaffolds could be a promising approach for the management of periodontal defects.

Bioactive Silver(I) Complexes with Phenolic Derivatives of Thioglycolic and Thiopropionic Acids

Ag(I) complexes formed by polydentate phenolic derivatives of thioglycolic and thiopropionic acids with Ag(I) ions could be a promising field of search for potential chemotherapeutic agents. Convenient synthetic methods to prepare these ligands have been developed on the basis of addition reactions occurring between S-nucleophiles and o- benzoquinones. The results are presented of physicochemical investigation of Ag(I) ions complexation with phenolic ligands, which made it possible to determine ionic and redox ligand forms with high nucleophilicity of metal-ion binding sites, the peculiarities of the structural organization of the coordination cores of the newly synthesized complexes. The in- vestigation of the molecular and electronic structure of Ag(I) complexes has been performed within the density functional theory framework. On the basis of the pharmacological screening results the selection is justified of a lead compound pos- sessing antibacterial, antifungal and antiherpetic activity comparable to those of some standard drugs to develop effective pharmaceuticals for combination therapy of mixed infections. Data have been obtained on the ability of some phenolic de- rivatives of thioglycolic and thiopropionic acids as well as their Ag(I) complexes to reduce bovine cytochrome c.

New silver BioMOFs driven by 1,3,5-triaza-7-phosphaadamantane-7-sulfide (PTAS): synthesis, topological analysis and antimicrobial activity

Two new bioactive silver–organic frameworks [Ag(μ3-PTAS)]n(NO3)n·nH2O (1) and [Ag4(μ4-PTAS)(μ5-PTAS)(μ2-SO4)2(H2O)2]n·2nH2O (2) were easily assembled, thus opening up the application of PTAS as a versatile N,S-building block in the crystal engineering of MOFs. The obtained products reveal infinite 3D networks driven by multiply bridging PTAS spacers that adopt unprecedented N2S-coordination modes. The topological analysis of 1 discloses an uninodal 3-connected net with the srs (SrSi2) topology, whereas 2 features a pentanodal 3,4,5-connected net with a hitherto undocumented topology. Apart from representing the first MOFs derived from PTAS, the compounds 1 and 2 display notable antibacterial and antifungal activities.

Antibacterial Activity of Biologically Synthesized Nanosilver against Drug-Resistant Bacterial Pathogens

ABSTRACT Biosynthesis of nanoparticles by plant extracts is currently under exploration. Biological methods are a good competent to chemical procedures, which are environmentally friendly and convenient. We report the use of new plant extract of Cuscuta reflexa in the extracellular biosynthesis of silver nanoparticles. Bioactive silver nanoparticle synthesis was achieved by reacting the biomass of C. reflexa with aqueous solutions of silver nitrate (AgNO3) at ambient temperature. The formation of silver nanoparticles was confirmed by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction patterns, and transmission electron microscopy (TEM). In the present study we report the excellent antibacterial activity of silver nanoparticle (with C. reflexa extract) against gram-positive and gram-negative multi-drug-resistant (MDR) bacterial strains using a zone of inhibition method. Scanning electron microscopy (SEM) imaging studies revealed that silver nanoparticles physically damaged the bacterial cell and ...

Fabrication of corrosion resistant, bioactive and antibacterial silver substituted hydroxyapatite/titania composite coating on Cp Ti

The present work is aimed at developing a bioactive, corrosion resistant and anti bacterial nanostructured silver substituted hydroxyapatite/titania (AgHA/TiO 2) composite coating in a single step on commercially pure titanium (Cp Ti) by plasma electrolytic processing (PEP) technique. For this purpose 2.5 wt% silver substituted hydroxyapatite (AgHA) nanoparticles were prepared by microwave processing technique and were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM) methods. The as-synthesized AgHA particles with particle length ranging from 60 to 70 nm and width ranging from 15 to 20 nm were used for the subsequent development of coating on Cp Ti. The PEP treated Cp Ti showed both titania and AgHA in its coating and exhibited an improved corrosion resistance in 7.4 pH simulated body fluid (SBF) and 4.5 pH osteoclast bioresorbable conditions compared to untreated Cp Ti. The in vitro bioactivity test conducted under Kokubo SBF conditions indicated an enhanced apatite forming ability of PEP treated Cp Ti surface compared to that of the untreated Cp Ti. The Kirby–Bauer disc diffusion method or antibiotic sensitivity test conducted with the test organisms of Escherichia coli ( E. coli) for 24 h showed a significant zone of inhibition for PEP treated Cp Ti compared to untreated Cp Ti.

Bioactive Electrospun Silver Nanoparticles-Containing Polyurethane Nanofibers as Wound Dressings

Nanofibrous membrane (NFM) intended as wound dressing was prepared by electrospinning polyurethane (PU) solution containing silver ion, followed by reduction of silver ion to silver nanoparticles. The electrospun PU membrane has high surface area-to-volume ratio, controlled evaporative water transmission rate, good fluid drainage ability, and excellent antimicrobial activity. With an aim to promote wound healing, collagen was grafted to fiber surface by low temperature oxygen plasma treatment, which could improve surface hydrophilicity and facilitate covalent binding of collagen molecules to the plasma-treated PU surface. A NFM with no bead formation was obtained with fiber diameters around 159 nm. The presence of embedded silver nanoparticles and surface-grafted collagen was confirmed qualitatively and quantitatively. After modification, the NFM's antimicrobial activity improved to approximately 100% inhibition of bacterial growth with concomitant increase of membrane water absorption ability, which facilitates its use as a functional wound dressing. From animal studies, the NFM was better than gauze and commercial collagen sponge wound dressing in wound healing rate.

Antimicrobial surface functionalization of plastic catheters by silver nanoparticles

To test the antimicrobial activity and evaluate the risk of systemic toxicity of novel catheters coated with silver nanoparticles. Catheters were coated with silver using AgNO3, a surfactant and N,N,N ',N '-tetramethylethylenediamine as a reducing agent. Particle size was determined by electron microscopy. Silver release from the catheters was determined in vitro and in vivo using radioactive silver ((110m)Ag+). Activity on microbial growth and biofilm formation was evaluated against pathogens most commonly involved in catheter-related infections, and the risk for systemic toxicity was estimated by measuring silver biodistribution in mice implanted subcutaneously with (110 m)Ag+-coated catheters. The coating method yielded a thin ( approximately 100 nm) layer of nanoparticles of silver on the surface of the catheters. Variations in AgNO3 concentration translated into proportional changes in silver coating (from 0.1 to 30 microg/cm(2)). Sustained release of silver was demonstrated over a period of 10 days. Coated catheters showed significant in vitro antimicrobial activity and prevented biofilm formation using Escherichia coli, Enterococcus, Staphylococcus aureus, coagulase-negative staphylococci, Pseudomonas aeruginosa and Candida albicans. Approximately 15% of the coated silver eluted from the catheters in 10 days in vivo, with predominant excretion in faeces (8%), accumulation at the implantation site (3%) and no organ accumulation (< or = 0.1%). A method to coat plastic catheters with bioactive silver nanoparticles was developed. These catheters are non-toxic and are capable of targeted and sustained release of silver at the implantation site. Because of their demonstrated antimicrobial properties, they may be useful in reducing the risk of infectious complications in patients with indwelling catheters.

Prevention of Staphylococcus epidermidis biofilm formation using a low-temperature processed silver-doped phenyltriethoxysilane sol–gel coating

Sol–gel coatings which elute bioactive silver ions are presented as a potential solution to the problem of biofilm formation on indwelling surfaces. There is evidence that high-temperature processing of such materials can lead to diffusion of silver away from the coating surface, reducing the amount of available silver. In this study, we report the biofilm inhibition of a Staphylococcus epidermidis biofilm using a low-temperature processed silver-doped phenyltriethoxysilane sol–gel coating. The incorporation of a silver salt into a sol–gel matrix resulted in an initial high release of silver in de-ionised water and physiological buffered saline (PBS), followed by a lower sustained release for at least 6 days—as determined by graphite furnace-atomic absorption spectroscopy (GF-AAS). The release of silver ions from the sol–gel coating reduced the adhesion and prevented formation of a S. epidermidis biofilm over a 10-day period. The presence of surface silver before and after 24 h immersion in PBS was confirmed by X-ray photoelectron spectroscopy (XPS). These silver-doped coatings also exhibited significant antibacterial activity against planktonic S. epidermidis. A simple test to visualise the antibacterial effect of silver release coatings on neighbouring bacterial cultures is also reported.

Highly bioactive silver and silver/titania composite films grown by chemical vapour deposition

This paper describes how photocatalytically active films of TiO 2, grown by thermal CVD, may be functionally and structurally modified by deposition of nano-structured silver via a novel flame assisted CVD process. The resulting composite films are shown to be highly durable, highly photocatalytically active and are also shown to possess strong antibacterial behaviour. The deposition control, arising from the described approach, offers the potential to control the film nanostructure, which is proposed to be crucial in determining the photo and bio-activity of the combined film structure, and the transparency of the composite films. Furthermore, we show that the resultant films also exhibit “self-regeneration” capability, in that they both kill bacteria present on the film surface and then photo-degrade the residues. Such a dual action significantly reducing the problems of surface deactivation due to build up of contamination. These properties are especially significant when combined with the well-known durability of CVD deposited thin films, offering new opportunities for enhanced application in areas where bioactive surface functionality is sought.

Sustained release of silver from periodontal wafers for treatment of periodontitis

Periodontal wafers intended to treat the underlying infections in patients with periodontitis have been developed. The wafers consist of poly(lactic-co-glycolic acid) as a primary bioerodible polymeric component, poly(ethylene glycol) as a plasticizer and encapsulation aid, and silver nitrate as the antimicrobial agent. The wafers are capable of sustained in vitro release of bioactive silver for at least 4 weeks. The wafers exhibit silver release that follows erosion kinetics, confirming a bulk erosion/release mechanism. In clinical evaluation, sustained release of silver at bactericidal levels for at least 21 days is observed. Staining of hard and soft tissues due to the released silver is minimal and reversible.