Production,stabilisation and characterisation of silver nanoparticles coated with bioactive polymers pluronic F68, PVP and PVA

The increasing and alarming panorama of bacterial infections and associated morbidities that occur during medical and hospital procedures makes the development of technologies that aid in controlling such bacterial infections of utmost importance. Recent studies have shown that formulations with metal nanoparticles exhibit good antibacterial properties against a broad spectrum of microorganisms. Moreover, it was demonstrated that some biologically active polymeric materials, when applied in combination with chemical antimicrobial agents, enhance the therapeutic action of the latter. The research effort entertained herein aimed at the physico‐chemical characterisation of silver nanoparticles obtained by chemical reduction, stabilised by bioactive polymers polyvinyl alcohol and polyvinylpyrrolidone, and further co‐stabilised by pluronic F68. Scanning electron microscopy images of the nanoparticles produced, coated with different stabilisers, have shown that the chemical nature of the stabilisation effect promoted incorporation of pluronic in the nanoparticles and was closely related to an increase in the silver concentration in the nanoparticle samples obtained via energy‐dispersive X‐ray spectroscopy. The study described herein also shows that the nature of the stabiliser favours the interaction of pluronic F68 with samples containing silver nanoparticles.Inspec keywords: silver, nanoparticles, polymer films, coatings, nanocomposites, nanofabrication, microorganisms, biomedical materials, nanomedicine, antibacterial activity, reduction (chemical), scanning electron microscopy, X‐ray chemical analysisOther keywords: bioactive polymers pluronic F68 coated silver nanoparticles, PVP coated silver nanoparticles, PVA coated silver nanoparticles, bacterial infections, associated morbidities, medical procedures, hospital procedures, antibacterial properties, microorganisms, biologically active polymeric materials, chemical antimicrobial agents, therapeutic action, physicochemical characterisation, chemical reduction, bioactive polymers polyvinyl alcohol, polyvinylpyrrolidone, scanning electron microscopy, stabilisation effect, energy‐dispersive X‐ray spectroscopy, Ag     

Bio-mechanochemical synthesis of silver nanoparticles with antibacterial activity

By using a bio-mechanochemical approach combining mechanochemistry (ball milling) and green synthesis for the first time, silver nanoparticles (Ag NPs) with antibacterial activity were successfully synthesized. Concretely, eggshell membrane (ESM) or Origanum vulgare L. plant (ORE) and silver nitrate were used as environmentally friendly reducing agent and Ag precursor, respectively. The whole synthesis took 30?min in the former and 45?min in the latter case. The photon cross-correlation measurements have shown finer character of the product in the case of milling with Origanum. UV–Vis measurements have shown the formation of spherical NPs in both samples. TEM study has revealed that both samples are composites of nanosized silver nanoparticles homogenously dispersed within the organic matrices. It has shown that the size and size distribution of the silver nanoparticles is smaller and more uniform in the case of eggshell membrane matrix implying lower silver mobility within this matrix. The antibacterial activity was higher for the silver nanoparticles synthesized with co-milling with Origanum plant than in the case of milling with eggshell membrane.     

Characterisation and antifungal activity of silver nanoparticles biologically synthesised by Amaranthus retroflexus leaf extract

ABSTRACT

Following the emergence of resistant fungal pathogens, silver nanoparticles (AgNPs) biosynthesized by plants have been recognized as promising tools to combat parasitic fungi. This study evaluated the potency of Amaranthus retroflexus in producing AgNPs, followed by testing their antifungal effects. The AgNPs exhibited a maximum absorption at 430 nm through ultraviolet-visible spectroscopy, while the X-ray diffraction indicated that they were crystal in nature. Fourier transform infrared spectroscopy confirmed the conversion of Ag⁺ ions to AgNPs due to the reduction by capping material of plant extract. The transmission electron microscope analysis further revealed that the AgNPs were spherical ranging from 10 nm to 32 nm in size. The AgNPs at the concentrations of 50, 100, 200, and 400 μg/mL were applied to the growth of plant, mushroom, and human pathogenic fungi. The 50% minimum inhibitory concentrations (MIC₅₀) against Macrophomina phaseolina, Alternaria alternata and Fusarium oxysporum were observed to be 159.80 ± 14.49, 337.09 ± 19.72, and 328.05 ± 13.29 μg/mL, respectively. However, no considerable inhibition was observed regarding Trichoderma harzianum or Geotrichum candidum. These findings may suggest A. retroflexus as a green solution for biosynthesizing AgNPs with potent antifungal activities against plant pathogenic fungi.     

Synthesis and characterization of dextran-capped silver nanoparticles with enhanced antibacterial activity

Dextran-capped silver nanoparticles were synthesized by reducing silver nitrate with NaBH4 in the presence of dextran as capping agent. The characters of silver nanoparticles were investigated using UV-Vis spectrophotometer, nano-grainsize analyzer, X-ray diffraction, and transmission electron microscopy. Results showed that the silver nanoparticles capped with dextran were in uniform shape and narrow size distribution. Moreover, compared with polyvinylpyrrolidone (PVP)-capped silver nanoparticles, the dextran-capped ones possessed better stability. Antibacterial tests of these silver nanoparticles were carried out for Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Results suggested that the dextran-capped silver nanoparticles had high antibacterial activity against both Gram-positive and Gram-negative bacteria. In addition, the cytotoxicity in vitro of the dextran-capped silver nanoparticles was investigated using mouse fibrosarcoma cells (L929). The toxicity was evaluated by the changes of cell morphology and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. Results indicated that these silver nanoparticles had slight effect on the survival and proliferation of L-929 cells at their minimal inhibitory concentration (MIC). After modified by dextran, the physiochemical properties of the silver nanoparticles had been improved. We anticipated that these dextran-capped silver nanoparticles could be integrated into systems for biological and pharmaceutical applications.     

Synthesis of silver nanoparticles by chemical and biological methods and their antimicrobial properties

Biogenic synthesis of nanoparticles offers an attractive alternate to chemical synthesis methods. Various hazard free, eco-friendly methods of synthesis of silver nanoparticles are in operation. In chemical reduction methods, the reducing agent is a chemical solution, whereas in biological ones, the collection of enzymes, especially nitrate reductase, plays this role. The highest antibacterial activity of silver nanoparticles synthesised by chemical and biological methods was found in Staphylococcus aureus and Escherichia coli. The paper aims to discuss some fundamental issues about non-biological methods and benefits about biological methods for silver nanoparticles synthesis and their antibacterial studies.     

Comparative analysis of the Magnesium Ferrite (MgFe2 O4) nanoparticles synthesised by three different routes

The toxicity of arsenic in drinking water is hazardous for human health. Different strategies are used for arsenic removal from drinking water. Nanoparticles with higher adsorption capacities are useful for arsenic remediation. In the current study, magnesium ferrite nanoparticles were synthesised by three different methods followed by their characterisation XRD, SEM, and EDX. The SEM morphology and the porosity of magnesium ferrite nanoparticles were best in case of auto‐combustion method. These particles had an average particle size of about 20–50 nm with spherical shape. These particles showed efficient remediation of arsenic up to 96% within 0.5 h. However, the co‐precipitation and sol‐gel‐based nanoparticles showed arsenic remediation upto85 and 87% at 0.5‐h time point. Moreover, the minimum inhibitory concentration of nanoparticles against two strains E.coli and Pseudomonas aeruginosa was found to be4.0 mg/L of these nanoparticles. However, the sol‐gel‐based nanoparticles showed efficient anti‐microbial activity against E.coli at 4.0 and 8.0 mg/L against Pseudomonas aeruginosa. The co‐precipitation‐based nanoparticles were least efficient both for arsenic remediation and anti‐microbial purposes. Thus, the synthesised auto‐combustion‐based nanoparticles are multifunctional in nature.Inspec keywords: nanoparticles, sol‐gel processing, nanofabrication, porosity, nanomagnetics, magnesium compounds, antibacterial activity, X‐ray chemical analysis, ferrites, scanning electron microscopy, X‐ray diffraction, particle size, magnetic particles, surface morphology, precipitation (physical chemistry)Other keywords: drinking water, arsenic removal, arsenic remediation, magnesium ferrite nanoparticles, SEM morphology, auto‐combustion method, sol‐gel‐based nanoparticles, co‐precipitation‐based nanoparticles, higher adsorption capacity, particle size, XRD, SEM, EDX, porosity, spherical shape, Escherichia coli, Pseudomonas aeruginosa, anti‐microbial activity, time 0.5 hour, size 20.0 nm to 50.0 nm, MgFe₂ O₄      

Evaluation of anti‐bacterial activity of silver nanoparticles synthesised by coprophilous fungus PM0651419

The study explored biological synthesis of metallic silver nanoparticles (AgNPs) from the less explored non‐pathogenic coprophilous fungus, sterile mycelium, PM0651419 and evaluates the antimicrobial efficacy of biosynthesised AgNPs when impregnated in wound fabrics and in combination with six antimicrobial agents. AgNPs alone proved to be potent antibacterial agents and in combination they enhanced the antibacterial activity and spectrum of antibacterials used in the study against a microbiologically diverse battery of Gram positive, Gram negative and multidrug‐resistant bacteria. AgNPs impregnated on the wound dressings established their antibacterial activity by significantly reducing the bacterial load of pathogenic bacteria like Staphylococcus aureus and Bacillus subtilis e stablishing potential as effective antimicrobial wound dressings for treatment of polymicrobial wound infections. This study presents the first report on the potential of biosynthesis of AgNPs from the under explored class of coprophilous fungi. Their promise to be used in wound dressings and as potent antibacterials alone and in combination is evaluatedInspec keywords: silver, nanoparticles, nanofabrication, nanomedicine, biomedical materials, microorganisms, antibacterial activity, wounds, fabricsOther keywords: antibacterial activity, coprophilous fungus PM0651419, biological synthesis, metallic silver nanoparticles, nonpathogenic coprophilous fungus, sterile mycelium, antimicrobial efficacy, biosynthesised AgNPs, wound fabrics, microbiologically diverse battery, Gram positive bacteria, Gram negative bacteria, multidrug‐resistant bacteria, wound dressings, bacterial load, pathogenic bacteria, Staphylococcus aureus, Bacillus subtilis, polymicrobial wound infections, Ag     

Study of mechanism of enhanced antibacterial activity by green synthesis of silver nanoparticles

The extensive use of silver nanoparticles needs a synthesis process that is greener without compromising their properties. The present study describes a novel green synthesis of silver nanoparticles using Guava (Psidium guajava) leaf extract. In order to compare with the conventionally synthesized ones, we also prepared Ag-NPs by chemical reduction. Their optical and morphological characteristics were thoroughly investigated and tested for their antibacterial properties on Escherichia coli. The green synthesized silver nanoparticles showed better antibacterial properties than their chemical counterparts even though there was not much difference between their morphologies. Fourier transform infrared (FTIR) spectroscopic analysis of the used extract and as-synthesized silver nanoparticles suggests the possible reduction of Ag(+) by the water-soluble ingredients of the guava leaf like tannins, eugenol and flavonoids. The possible reaction mechanism for the reduction of Ag(+) has been proposed and discussed. The time-dependent electron micrographs and the simulation studies indicated that a physical interaction between the silver nanoparticles and the bacterial cell membrane may be responsible for this effect. Based on the findings, it seems very reasonable to believe that this greener way of synthesizing silver nanoparticles is not just an environmentally viable technique but it also opens up scope to improve their antibacterial properties.     

Tungsten film as a hard and compatible carrier for antibacterial agent of silver

Silver-containing tungsten (W–Ag) films for antibacterial applications were deposited on glass, silicon, and 316L stainless-steel substrates by magnetron sputtering with the silver target current of 0–2.0 A. The addition of silver improves adhesion of the films on glass substrate due to the reduced residual stress in the films. SEM and EDX analyses reveal Ag-rich tiny dots (~?20 nm) at the surface of W–Ag films with high silver contents. In XRD patterns, silver peaks are present for the samples deposited at 1.5 and 2.0 A, and tungsten grain size is decreased from?~?23 to 10 nm by silver addition. XPS analysis shows that tungsten is slightly oxidized (WO₃) at the top surface of the film, and silver presents mainly in metallic state. The low Ag/W ratios and the small surface roughness (<?8 nm) indicate that silver segregation at the film surface is not obvious. Microhardness of the samples with ≤?6.7 at.% silver is nearly seven times that of the stainless steel (~?250 HV). The coated samples are hydrophobic tested by contact angle measurement. The potentiodynamic polarization and the soaking test simulating the inflammatory state show that even corrosion occurs and silver addition decreases corrosion resistance of the films. The antibacterial ratio of the coated samples increases with silver content, being 91% at 4.2 at.% silver content tested by agar plate counting method. In agar disk diffusion assay, no inhibition zone is observed for all samples. The antibacterial property of the W–Ag films is localized, long-lasting, and reusable, which would be beneficial for their potential biomedical and environmental applications.     

Polyvinyl alcohol/silver nanoparticles (PVA/AgNps) as a model for testing the biological activity of hybrid materials with included silver nanoparticles

Comparing the influence of two different stabilizers as polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP), as well as organosilanes as tetraethoxysilane (TEOS), allows determining the main role of the silver nanoparticles included in hybrid materials for the realization of their antimicrobial activity. The proposed two-step testing scheme first onto control strains and then onto clinical bacterial and fungal strains resistant to antibiotics allows full investigation of these properties.     

Antimicrobial activity of silver nanoparticles synthesised by using microbial biosurfactant produced by a newly isolated Bacillus vallismortis MDU6 strain

Microbial biosurfactants has evolved as green molecules and their chemical diversity has gained momentum in recent time not only in the field of environmental and industrial sectors but also in the pharmaceutical sector. In this study, an effort was made for the biosynthesis of silver nanoparticle (AgNPs) having antimicrobial and non‐cytotoxic activities with the help of microbial biosurfactant extracted from a novel Bacillus vallismortis strain MDU6 (Genbank accession no. {"type":"entrez-nucleotide","attrs":{"text":"MH382951","term_id":"1546647362"}}MH382951) from petroleum oil logged soil sample in Dibrugarh, Assam. The isolate shows excellent potential for the production of biosurfactant by reducing the surface tension of diesel supplemented medium up to 56.57% only within 5 days. FTIR spectra of the crude biosurfactant show the presence of ʋ _CH2 (asymmetric stretching), ʋ _CH2 (symmetric stretching), ʋ _C=C (stretch), ʋ _C−C (stretch), ʋ _C−H (bending), ʋ _C−O (stretch) and ʋ _C−H (bending) functional groups and LC‐MS/MS analysis confirms it as a cyclic lipopeptide which is a mixture of surfactin and iturin. The synthesized AgNPs showed excellent antimicrobial activities against Escherichia coli (ATCC no. 25922), Listeria monocytogenes (ATCC No. BAA‐751), Staphylococcus aureus (ATCC No. 9542) and Bacillus subtilis (ATCC no. 6051) and showed no cytotoxicity against primary mouse liver cell lines.Inspec keywords: nanoparticles, molecular biophysics, silver, liver, nanofabrication, microorganisms, petroleum, biotechnology, antibacterial activity, surfactants, cellular biophysics, toxicology, surface tension, nanomedicine, Fourier transform infrared spectraOther keywords: C−H functional groups, bending, synthesised AgNPs, excellent antimicrobial activities, ATCC no, bacillus subtilis, antimicrobial activity, silver nanoparticles, bacillus vallismortis MDU6 strain, microbial biosurfactants, green molecules, chemical diversity, environmental sectors, industrial sectors, pharmaceutical sector, noncytotoxic activities, petroleum oil, soil sample, isolate, surface tension, crude biosurfactant show, asymmetric stretching, symmetric stretching, Genbank accession no. {"type":"entrez-nucleotide","attrs":{"text":"MH382951","term_id":"1546647362"}}MH382951, time 5.0 d, Ag     

Layer-by-layer deposition of green synthesised silver nanoparticles on polyester air filters and its antimicrobial activity

Silver nanoparticles stabilised with anionic polymeric polyelectrolytes were successfully synthesised by high-energy UV reduction. Three types of polyelectrolytes were used including poly(methacrylic acid) (PMA), poly(acrylic acid) (PAA) and poly(4-styrenesulphonic acid-co-maleic acid) (CoPSS). The formation of the prepared solutions exhibited surface plasmon resonance at the wavelength of 475, 730 and 408 nm by using PMA, PAA and CoPSS as the stabilising agents. UV–visible spectrophotometer, transmission electron microscope (TEM) and zeta potential analyser were employed to characterise the formation of the prepared solutions. The silver nanoparticles stabilised with anionic polyelectrolytes were immobilised on polyester air filters using a layer-by-layer technique. This is the sequential dipping of polyester air filters in a dilute solution of cationic poly(diallyldimethylammonium chloride) and anionic polymeric polyelectrolytes capped silver. The surface topography of the polyester air filters were measured by field emission scanning electron microscope. Results showed that silver nanoparticles had the highest surface coverage on the polyester air filters probably because it is a good bonding candidate and insures strong film growth. The multilayers polyester air filters coated silver nanoparticles were tested against the gram positive pathogen Staphylococcus aureus. The deposition of silver nanoparticles onto the polyester air filters resulted in 92.18%, 84.32% and 71.19% of bacteria removal using PMA, PAA and CoPSS as the stabilising agent.     

Synthesis of oleic acid-stabilized silver nanoparticles and analysis of their antibacterial activity

The development of new and simple green chemical methods for synthesizing colloidal solutions of functional nanoparticles is desirable for environment-friendly applications. In the present work, we report a feasible method for synthesizing colloidal solutions of silver nanoparticles (Ag NPs) based on the modified Tollens technique. The Ag NPs were stabilized by using oleic acid as a surfactant and were produced for the first time by the reduction of silver ammonium complex [Ag(NH₃)₂]⁺_(aq) by glucose with UV irradiation treatment. A stable and nearly monodisperse aqueous Ag NPs solution with average-sized particles (~ 9–10 nm) was obtained. The Ag NPs exhibited high antibacterial activity against both Gram-negative Escherichia Coli (E. coli) and Gram-positive Staphylococcus aureus bacteria. Electron microscopic images and analyses provided further insights into the interaction and bactericidal mechanism of the Ag NPs. The proposed method of synthesis is an effective way to produce highly bactericidal colloidal solutions for medical, microbiological, and industrial applications.     

Preparation and antibacterial properties of hybrid-zirconia films with silver nanoparticles

The antimicrobial effect of incorporating silver nanoparticles (AgNps) into zirconia matrix–polyether glycol was studied. AgNps of 4–6 nm in size were synthesized using the inverse micelles method, and different doses of metallic nanoparticles were incorporated into zirconia–polyether glycol mixtures during the ageing procedure. Atomic force microscopy (AFM) of the modified hybrid film showed a homogenous distribution of 20–80 nm diameter AgNps, indicating agglomeration of these structures during film modification; such agglomerations were greater when increasing the dosage of the colloidal system. The AgNps-hybrid films showed higher antimicrobial activity against Gram-positive bacteria than for Gram-negative bacteria. Hybrid films prepared with dioctyl sodium sulfosuccinate (AOT) stabilized AgNps presented enhanced antibacterial activity compared to that obtained through the addition of a high AgNO₃ concentration (0.3 wt%).     

Optical and morphological studies of L-histidine functionalised silver nanoparticles synthesised by two different methods

Silver nanoparticles (NPs) functionalised with L-histidine is synthesised by a chemical reduction approach using two different methods of stirring – using a magnetic stirrer and an ultrasonicator. The former method exhibits a strong narrow absorption peak at 396 nm and the latter a blue-shifted weak broad plasmon band for the bare silver NPs. When the capping agent is incorporated, a single broad peak at low intensity evolves for the first method of stirring whereas two distinct peaks are noticed for the second. The Transmission Electron Microscope (TEM) results confirm the spherical shape of the silver NPs in the first case. In the second case, both spherical and elliptical particles are obtained. Zeta potential measurements further confirm the stability of the histidine-capped silver NPs in comparison with the pure silver NPs. A study of the variation of the plasmon peak with pH indicates that a basic medium favours the growth of the histidine-capped silver NPs. A surface-enhanced Raman scattering investigation confirms the adsorption of the capping molecule through the nitrogen of the imidazole ring with the carboxylate group pointing outwards. L-histidine-capped silver NPs can find application in biosensors and biomedicine, particularly when prepared by the magnetic stirrer method due to its greater stability.     

Comparative study of antifungal effect of green and chemically synthesised silver nanoparticles in combination with carbendazim,mancozeb, and thiram

This study reports synthesis and characterisation of silver nanoparticles and their effect on antifungal efficacy of common agricultural fungicides. Silver nanoparticles were synthesised using biological and chemical reduction methods employing Elettaria cardamomum leaf extract and sodium citrate, respectively. Nanoparticles were then characterised using UV–Visible spectroscopy, X‐ray diffraction (XRD), transmission electron microscopy, and dynamic light scattering (DLS). While XRD assigned particles size of 31.86 nm for green and 41.91 nm for chemical silver nanoparticles with the help of the Debye–Scherrer formula, DLS specified monodisperse nature of both suspensions. Nanoparticles were tested individually and in combination with fungicides (carbendazim, mancozeb, and thiram) against fungal phytopathogens. Silver nanoparticles exhibited good antifungal activity and minimum inhibitory concentration (MIC) was observed in the range of 8–64 µg/ml. Also, they positively influenced the efficacy of fungicides. The mean MIC value (mean ± SD) for combination of all three fungicides with green AgNPs was 1.37 ± 0.6 µg/ml and for chemical AgNPs was 1.73 ± 1.0 µg/ml. Hence, it could be concluded that green AgNPs performed better than chemical AgNPs. Synergy was observed between green AgNPs and fungicides against Fusarium oxysporum. In conclusion, this study reports synthesis of monodisperse silver nanoparticles which serve as efficient antifungal agents and also enhance the fungicidal action of reported agricultural fungicides in combination studies.Inspec keywords: X‐ray diffraction, reduction (chemical), visible spectra, ultraviolet spectra, microorganisms, particle size, nanomedicine, nanofabrication, nanoparticles, agrochemicals, antibacterial activity, transmission electron microscopy, silver, light scattering, scanning electron microscopyOther keywords: antifungal effect, green silver nanoparticles, chemically synthesised silver nanoparticles, carbendazim, mancozeb, thiram, antifungal efficacy, common agricultural fungicides, biological reduction methods, chemical reduction methods, transmission electron microscopy, XRD assigned particles size, chemical silver nanoparticles, green AgNPs, chemical AgNPs, monodisperse silver nanoparticles, antifungal activity, agricultural fungicides, Elettaria cardamomum leaf extract, sodium citrate, UV‐visible spectroscopy, X‐ray diffraction, dynamic light scattering, size 31.86 nm, size 41.91 nm     

化学还原法制备纳米银粒子及其表征

采用化学还原法, 通过一系列条件实验,借助紫外-可见分光光度计(UV-vis)得到最佳实验条件,在最佳实验条件下制得紫黑色溶胶,在40℃下真空干燥3h,获纳米银粉.制备的纳米银粉用X射线衍射仪(XRD)和透射电镜(TEM)分析表明,其粒径大小分布范围窄,形状为单一球形,平均粒径为18nm.     

Evaluation of ‘green’ synthesis and biological activity of gold nanoparticles using Tragopogon dubius leaf extract as an antibacterial agent

Currently, the use of ‘green’ synthesised nanoparticles with environmentally friendly properties is considered a novel therapeutic approach in medicine. Here, the authors evaluated gold nanoparticles (AuNPs) conjugated with Tragopogon dubius leaf extract and their antibacterial activity in vitro and in vivo. Colour changes from yellow to dark brown and a peak at 560 nm on ultraviolet–visible spectroscopy confirmed the formation of nanoparticles. Additionally, transmission electron microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy analyses were performed to determine particle sizes and functional groups involved in gold reduction. Moreover, using standard micro‐dilution and disc‐diffusion assays against Klebsiella pneumoniae, Bacillus cereus, Escherichia coli, and Staphylococcus aureus, the antimicrobial properties of synthesised AuNPs were investigated. To confirm antibacterial activity, synthesised AuNPs were applied in a rat model on burn wounds infected with S. aureus, and the nanoparticles were as effective as tetracycline in bacterial reduction and wound healing. In conclusion, the synthesis of AuNPs with aqueous T. dubius extract was rapid, simple, and inexpensive, and the synthesised nanoparticles had significant antibacterial activity in vitro and in vivo.Inspec keywords: transmission electron microscopy, wounds, nanoparticles, ultraviolet spectra, reduction (chemical), particle size, nanofabrication, gold, X‐ray diffraction, antibacterial activity, microorganisms, visible spectra, nanomedicine, biomedical materials, Fourier transform infrared spectraOther keywords: biological activity, gold nanoparticles, antibacterial agent, therapeutic approach, colour changes, ultraviolet–visible spectroscopy, transmission electron microscopy, gold reduction, antimicrobial properties, Fourier transform infrared spectroscopy analyses, disc‐diffusion assay, green synthesis, Tragopogon dubius leaf, in vitro antibacterial activity, in vivo antibacterial activity, X‐ray diffraction, particle sizes, functional groups, standard microdilution assay, burn wounds, S. aureus, tetracycline, bacterial reduction, wound healing, wavelength 560.0 nm     

Synthesis,characterization and antibacterial activity studies of poly-{styrene-acrylic acid} with silver nanoparticles

This work reports the preparation and characterization of copolymer poly-{styrene-acrylic acid} with monomeric ratio of styrene/acrylic acid of 9:1 using benzoyl peroxide as initiator and furthermore filled with nanosilver (25 ppm and 50 ppm) in water/acetone (1:40 v/v). The nanosilver emulsion was obtained from chemical reduction using NaBH₄ as reducing agent and sodium citrate as the stabilizer. The preparation of nanosilver emulsion was monitored by the appearance of a Plasmon Resonant Absorption band in a UV–visible spectrophotometer and the particles sizes were observed through TEM. Microbiological studies were performed to investigate the antimicrobial activity of this new material against the microorganisms Escherichia coli (ATCC-25922) and Staphylococcus aureus (ATCC-6538), used as reference strains. The antimicrobial activity of the poly-{styrene-acrylic acid} filled with nanosilver was confirmed by the presence of an inhibition halo of the bacterial growth in seeded culture media, but was not found with the poly(styrene-acrylic acid) alone. The present work suggests that silver ions are released from the polymeric matrix to the culture media and have the ability to tune the Ag⁺ ions released by controlling the amount of Ag nanoparticles embedded in the composite.