Mussel-inspired synthesis of silver nanoparticles as fillers for preparing waterborne polyurethane/Ag nanocomposites with excellent mechanical and antibacterial properties

Silver nanoparticles (AgNPs) were synthesized by a facile, mild and green method using dopamine as a reducing and stabilizing agent and were introduced to waterborne polyurethane (WPU) via an in situ emulsification method to prepare antibacterial nanocomposite films. The formation of AgNPs was characterized by UV–visible spectroscopy and XRD. The dispersion of AgNPs was confirmed by TEM and the thermal stability of WPU/Ag nanocomposites was confirmed by TGA. The results showed that AgNPs were uniformly dispersed in the WPU matrix. The introduction of AgNPs significantly improved the thermal stability of WPU films. With incorporation of 0.1 wt% AgNPs, a five-fold increase in the tensile strength was achieved without sacrificing the ultimate strain. The WPU/Ag nanocomposite films showed antibacterial activity against Escherichia coli and Staphylococcus aureus. © 2021 Society of Industrial Chemistry.     

Antibacterial activity of PVA-based nanofibers loaded with silver sulfadiazine/cyclodextrin nanocapsules

Silver sulfadiazine (SSD) is a highly insoluble drug in water with a significant antibacterial activity. Supramolecular nanocontainers of cyclodextrins (β-CD or HPβ-CD)/SSD were prepared by inclusion complex (IC) forming between CDs and SSD at various conditions. Solubility, bioavailability and in vitro dissolution of obtaining SSD were investigated and the results showed of SSD in CDs that solubility improved and its release is controllable by encapsulation cavity. Electro-spun nanofibers of PVA containing SSD/CDs inclusion complex showed significant antibacterial effect against Escherichia coli and Staphylococcus aureus, which are related to SSD     

Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria

Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases.     

Silver-doped biphasic calcium phosphate/alginate microclusters with antibacterial property and controlled doxorubicin delivery

Biphasic calcium phosphate (BCP) based materials possessed with both excellent biocompatibility and antibacterial activity show potential advantages for biomedical applications. Here, the silver-doped BCP/Alginate (_AgBA) microclusters were first fabricated using the double-emulsions method. First, BCP nanoparticles were incorporated into the alginate network to form BCP/Alginate microclusters via the emulsion process. Then, silver nanoparticles (AgNPs) were in situ involved in BCP/Alginate networks to obtain the final _AgBA microclusters. Transmission electron microscopy and scanning electron microscopy confirmed that BCP nanoparticles and AgNPs were uniformly distributed in _AgBA microclusters. The morphology of _AgBA microclusters could be regulated by adjusting emulsion power, and microclusters using the medium powder (500 W) showed a regular spherical shape. Furthermore, CCK-8 analysis identified that _AgBA microclusters were cytocompatible culturing with human bone marrow-derived mesenchymal stem cells. Qualitative antibacterial tests exhibited the excellent inhibition effects of _AgBA microclusters against Staphylococcus aureus (Gram-positive) and Escherichia coli. (Gram-negative). Lastly, the doxorubicin (DOX)-loaded _AgBA microclusters presented adjustable loading efficiency of DOX and controllable release profiles. The cumulative release could reach 73.3% after 72 h in PBS. The above results raised a new route for antibacterial microclusters development for biomedical applications.     

<Emphasis Type="Italic">Brassica rapa</Emphasis> var. <Emphasis Type="Italic">japonica</Emphasis> Leaf Extract Mediated Green Synthesis of Crystalline Silver Nanoparticles and Evaluation of Their Stability,Cytotoxicity and Antibacterial Activity

Silver nanoparticles (AgNPs) were successfully synthesized from the reduction of Ag⁺ using AgNO₃ solution as a precursor and Brassica rapa var. japonica leaf extract as a reducing and capping agent. This study was aimed at synthesis of AgNPs, exhibiting less toxicity with high antibacterial activity. The characterization of AgNPs was carried out using UV–Vis spectrometry, energy dispersive X-ray spectrometry, fourier transform infrared spectrometry, field emission scanning electron microscopy, X-ray diffraction, atomic absorption spectrometry, and transmission electron microscopy analyses. The analyses data revealed the successful synthesis of nano-crystalline Ag possessing more stability than commercial AgNPs. The cytotoxicity of Brassica AgNPs was compared with commercial AgNPs using in vitro PC12 cell model. Commercial AgNPs reduced cell viability to 23% (control 97%) and increased lactate dehydrogenase activity at a concentration of 3 ppm, whereas, Brassica AgNPs did not show any effects on both of the cytotoxicity parameters up to a concentration level of 10 ppm in PC12 cells. Moreover, Brassica AgNPs exhibited antibacterial activity in terms of zone of inhibition against E. coli (11.1?±?0.5 mm) and Enterobacter sp. (15?±?0.5 mm) which was higher than some previously reported green-synthesised AgNPs. Thus, this finding can be a matter of interest for the production and safe use of green-AgNPs in consumer products.     

Chitosan–poly(aminopropyl/phenylsilsesquioxane) hybrid nanocomposite membranes for antibacterial and drug delivery applications

We fabricated hybrid (CSSQ) membranes from chitosan and poly(aminopropyl/phenylsilsesquioxane) (PAPSQ) blends via a sol–gel reaction and solution casting followed by crosslinking with glutaraldehyde. The CSSQ membranes were then used for loading of 5‐fluorouracil (5‐FU) as an anticancer drug as well as templates for the production of silver nanoparticles (AgNPs). The physicochemical properties of the CSSQ membranes were examined using UV‐visible spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis and scanning electron microscopy (SEM). SEM results showed the controllable formation of AgNPs around PAPSQ. CSSQ–Ag nanocomposite membranes exhibited good antibacterial activity towards both Escherichia coli and Bacillus subtilis, while the CSSQ membranes worked as good carriers for controlled release of 5‐FU as model drug. The results suggest that both CSSQ and CSSQ–Ag nanocomposite membranes can be potentially applied for biomedical applications such as controlled release carriers as well as antibacterial wound dressing materials. © 2014 Society of Chemical Industry     

Functionalized polymeric silver nanoparticle hybrid network as a dual antimicrobe: Synthesis,characterization, and antibacterial application

The present work describes a novel method for the synthesis of silver polymer nanocomposite for the delivery of amoxicillin (AMO). Silver nanoparticles (AgNPs) were synthesized with chitosan and silver nitrate. The reaction parameters were optimized. Three‐dimensional polymeric networks were synthesized by simple free‐radical graft copolymerization. UV–visible spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, SEM, atomic force microscopy, dynamic light scattering, and zeta potential analysis were used for the complete characterization of the samples. Swelling studies and swelling factors were evaluated. In vitro release of AMO and AgNPs at physiological pHs was analyzed using the Peppas kinetic model to explain the drug delivery mechanism. Cytotoxicity, free‐radical scavenging, and antibacterial activities were analyzed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43479.     

Development of silver nanoparticles‐loaded calcium alginate beads embedded in gelatin scaffolds for use as wound dressings

Silver nanoparticles (AgNPs)‐loaded calcium alginate beads embedded in gelatin scaffolds were developed to sustain and maintain the release of silver (Ag⁺) ions over an extended time period. The UV irradiation technique was used to reduce Ag⁺ ions in alginate solution to AgNPs. The average sizes of AgNPs ranged between ca 20 and ca 22 nm. The AgNPs‐loaded calcium alginate beads were prepared by electrospraying of a sodium alginate solution containing AgNPs into calcium chloride (CaCl₂) solution. The AgNPs‐loaded calcium alginate beads were then embedded into gelatin scaffolds. The release characteristics of Ag⁺ ions from both the AgNPs‐loaded calcium alginate beads and the AgNPs‐loaded calcium alginate beads embedded in gelatin scaffolds were determined in either deionized water or phosphate buffer solution at 37 °C for 7 days. Moreover, the AgNPs‐loaded calcium alginate beads embedded in gelatin scaffolds were tested for their antibacterial activity and cytotoxicity. © 2014 Society of Chemical Industry     

Construction of Silver Nanoparticle-Loaded Micelles Via Coordinate Interaction and Their Antibacterial Activity

Silver nanoparticles (AgNPs) loaded antibacterial micelles were fabricated utilizing the coordinate interaction between silver ion (Ag⁺) and methoxy-poly(ethylene glycol)-block-poly(acrylamide-co-acrylonitrile) followed by in situ reduction. This micelle was characterized by X-ray photoelectron spectroscopy, transmission electron microscopy, and dynamic light scattering. The upper critical solution temperature of Ag⁺-loaded micelles was dependent on Ag⁺ concentration. The AgNPs were approximately 4 nm in diameter and homogenously distributed in the micelles. The AgNPs-loaded micelle displayed high stability during a one week study and excellent antibacterial activity against gram-negative Escherichia coli and was of acceptable toxicity toward human embryonic hepatocytes.     

Effect of plasma duty cycle on silver nanoparticles loading of cotton fabrics for durable antibacterial properties

A facile method for strongly anchoring silver nanoparticles (AgNPs) onto cotton fabrics was reported. It consists in loading AgNPs onto the cotton fiber preliminary coated with maleic anhydride plasma polymer layer. This results in hydrolyzis and ring opening of anhydride groups followed by electrovalent bonding of silver ions and reduction in NaBH₄. X‐ray photoelectron spectroscopy (XPS), infrared spectroscopy, and scanning electron microscope (SEM) were used to analyze changes in the surface chemical composition and morphology of the plasma modified fibers. The presence of AgNPs was confirmed by UV–Visible spectroscopy and atomic force microscopy (AFM) images. Remarkably, varying plasma duty cycle for plasma polymer deposition allowed tailoring the amount of loaded AgNPs. The highest amount of AgNPs was obtained with the lowest duty cycle values. Qualitative tests showed that silver containing plasma modified cotton displays significant antibacterial activity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41279.     

Preparation and characterization of miglitol-loaded Poly (d,l-lactide-co-glycolide) microparticles using high pressure homogenization-solvent evaporation method

Sustained release Miglitol-loaded poly (d, l-lactide-co-glycolide) (PLGA) microparticles were prepared using high pressure homogenization-solvent evaporation method. 2³ full factorial design was employed to study effect of independent variables (X₁-Polymer amount; X₂-Surfactant concentration and X₃-Homogenization Pressure) on percent encapsulation efficiency (%EE) as response. The microparticles produced were characterized for particle size, morphology, % EE, drug polymer compatibility and in vitro drug release. An average particle size of Miglitol-loaded PLGA microparticles was 230.1?nm and found almost spherical with smooth surface. % EE ranged from 58.7%?±?2.11 to 86.5%?±?0.24 depending on the polymer amount, surfactant concentration and homogenization pressure. An absence of chemical interaction between drug-polymer and reduction in % crystallinity of drug was confirmed by FTIR and X-ray diffraction analysis respectively. In vitro release studies showed a sustained release of Miglitol from microparticles up to 12?hrs.     

Development of Novel Green Synthesized Silver Nanoparticles with Superior Antibacterial and Wound Healing Properties in Nursing Care After Rectal Surgery

The present investigation showed the green synthesis of silver nanoparticles (AgNPs) using Ficus benghalensis (F. benghalensis) leaf extract. UV–Vis spectra of the biofabricated AgNPs displayed its maximum peak of absorption at 461 nm. High resolution-transmission electron microscopy images displayed the shape of AgNPs as spherical with an average diameter of 35 nm size. The analysis of X-ray diffraction confirmed the presence of crystalline AgNPs. The analysis of Fourier-transform infrared spectroscopy confirmed the existence of bioconstituents such as terpenoids, phenolics and flavonoids, which functions as bio-reducing agents. When compared with F. benghalensis extract, AgNPs displayed the considerably greater bioactivities. The exceptional antimicrobial functionalities of AgNPs against both the gram positive and gram negative bacteria makes them appropriate candidates for the production of antibiotics against the species that are resistant to traditional antibiotics. The assay of HDFa cell scratch confirmed that the AgNPs have greater ability of wound healing than the leaf extract of F. benghalensis. Altogether, the obtained results showed the application of synthesized AgNPs in the production of novel drugs that are used for wound healing in nursing care after rectal surgery.

     

Physicochemical properties and antimicrobial activity of biocompatible carboxymethylcellulose‐silver nanoparticle hybrids for wound dressing and epidermal repair

Skin loss can be caused by accident, burn, trauma, chronic wounds, and diseases, which is severely aggravated by multidrug‐resistant bacterial infections. Soft hybrids based on biopolymers combined with silver nanoparticles (AgNPs) have potential applications as wound dressing supports and skin tissue repair. Thus, our study focused on the design, green synthesis, and comprehensive characterization of carboxymethyl cellulose (CMC–AgNP) nanocomposites for producing hydrogel membranes, with tunable physicochemical properties, cytocompatibility, and biocidal activity for potential application as wound dressing and skin repair. These nanocomposites were prepared using CMC with two degrees of carboxymethylation, distinct concentrations of citric acid (CA) crosslinker, and AgNPs by in situ chemical reduction, forming hybrid membranes by the solvent casting method. The results demonstrated that superabsorbent hydrogels were produced with swelling and degradation behaviors dependent on the concentration of CA crosslinker, degree of carboxymethylation of CMC, and content of AgNP in the matrices. Moreover, the Fourier transform infrared spectroscopy analysis evidenced that the CMC functional groups (e.g., ? COOH and ? OH) were directly involved in the chemical reactions for the formation of AgNPs and hydrogel crosslinking pathway. These nanocomposites were cytocompatible using in vitro 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyltetrazolium bromide cell viability assay with of human embryonic kidney cells. Conclusively, the CMC–AgNP nanohybrids demonstrated to be simultaneously non‐toxic combined with highly effective antibacterial activity against gram‐positive multi‐resistant wound/skin pathogens (Staphylococcus aureus) and moderate effect towards gram‐negative strains (Escherichia coli and Pseudomonas aeruginosa). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45812.     

Study on antibacterial activity of silver nanoparticles synthesized by gamma irradiation method using different stabilizers

Colloidal solutions of silver nanoparticles (AgNPs) were synthesized by gamma Co-60 irradiation using different stabilizers, namely polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), alginate, and sericin. The particle size measured from TEM images was 4.3, 6.1, 7.6, and 10.2 nm for AgNPs/PVP, AgNPs/PVA, AgNPs/alginate, and AgNPs/sericin, respectively. The influence of different stabilizers on the antibacterial activity of AgNPs was investigated. Results showed that AgNPs/alginate exhibited the highest antibacterial activity against Escherichia coli (E. coli) among the as-synthesized AgNPs. Handwash solution has been prepared using Na lauryl sulfate as surfactant, hydroxyethyl cellulose as binder, and 15 mg/L of AgNPs/alginate as antimicrobial agent. The obtained results on the antibacterial test of handwash for the dilution to 3 mg AgNPs/L showed that the antibacterial efficiency against E. coli was of 74.6%, 89.8%, and 99.0% for the contacted time of 1, 3, and 5 min, respectively. Thus, due to the biocompatibility of alginate extracted from seaweed and highly antimicrobial activity of AgNPs synthesized by gamma Co-60 irradiation, AgNPs/alginate is promising to use as an antimicrobial agent in biomedicine, cosmetic, and in other fields.     

Biodegradable chitosan-based composites with dual functions acting as the bone scaffold and the inflammation inhibitor in the treatment of bone defects

A composite based on nano-hydroxyapatite (n-HA)/chitosan (CS) and loaded with ciprofloxacin (CIP) was prepared and its physicochemical properties, antibacterial properties, drug release ability, and bone regeneration ability were characterized. The physicochemical results indicated that the n-HA/CS composite exhibited about a 70/30 ratio of n-HA to CS, and the size of n-HA in the n-HA/CS composite was about 100?nm. According to the results of the antibacterial test, the materials loaded with CIP presented excellent antibacterial activity. In addition, the in vivo concentration of CIP far surpassed the minimum inhibitory concentration (0.25–2?µg?mL^?1). In vitro standard deviation-rats marrow mesenchymal stem cells (MSCs) tests, including cell counting kit-8 assay and scanning electron microscopy images of MSCs, revealed that both of the scaffolds could support MSCs proliferation and attachment. The in vivo results indicated that n-HA/CS-CIP could promote the formation of bone tissues and blood vessels, and displayed a better repair ability for bone defect than the control group of n-HA-CIP. The CS-based composite with dual functions has a good perspective which would justify further research.     

Development of antimicrobial‐loaded polyurethane films for drug‐eluting catheters

To prepare antibacterial, polymeric catheters for preventing catheter‐induced infections, sulfathiazole was loaded into polyurethane by solubilizing with solvents and the resultant films were cast. Fourier transform infrared spectroscopy confirmed the presence of sulfathiazole in the drug‐loaded polyurethane films. The thermal and mechanical properties of the films were assessed using differential scanning calorimetry and dynamic mechanical analysis. The drug‐loaded films were immersed in constantly stirred, deionized water at 37 °C for in vitro drug release study. The experimental data obtained from the in vitro drug release study were fit into mathematical models. Antibacterial efficiency of released sulfathiazole was evaluated by Escherichia coli growth inhibition test. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46467.     

All Ag Nanoparticles Are Not the Same: Covalent Interactions between Ag Nanoparticles and Nitrile Groups Help Combat Drug- and Ag-Resistant Bacteria

Antimicrobial resistance has long been viewed as a lethal threat to global health. Despite the availability of a wide range of antibacterial medicines all around the world, organisms have evolved a resistance mechanism to these therapies. As a result, a scenario has emerged requiring the development of effective antibacterial drugs/agents. In this article, we exclusively highlight a significant finding reported by Zbořil and associates (Adv. Sci. 2021, 2003090). The authors construct a covalently bounded silver-cyanographene (GCN/Ag) with the antibacterial activity of 30 fold higher than that of free Ag ions or typical Ag nanoparticles (AgNPs). Ascribed to the strong covalent bond between nitrile and Ag, an immense cytocompatibility is shown by the GCN/Ag towards healthy human cells with a minute leaching of Ag ions. Firm interactions between the microbial membrane and the GCN/Ag are confirmed by molecular dynamics simulations, which rule out the dependence of antibacterial activity upon the Ag ions alone. Thus, this study furnishes ample scope to unfold next-generation hybrid antimicrobial drugs to confront infections arising from drug and Ag-resistant bacterial strains.     

Biosynthesis of silver nanoparticles from the culture supernatant of Bacillus marisflavi and their potential antibacterial activity

Silver nanoparticles (AgNPs) were prepared using culture supernatant of Bacillus marisflavi, a novel strain isolated from agricultural wastes. The formation of the AgNPs was confirmed using various analytical techniques such as UV–vis absorption spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The antibacterial effect of synthesized nanoparticles was investigated against Pseudomonas aeruginosa. Furthermore, the mechanism of action of cell death of P. aeruginosa was confirmed by reactive oxygen species (ROS) generation in AgNPs treated cells and also our results clearly indicate that AgNPs could induce generation of ROS by dose dependent manner.     

Spectral,thermal stability and antibacterial studies of copper,nickel and cobalt complexes of N-methyl-N-phenyl dithiocarbamate

Copper(II), cobalt(II) and nickel(II) bis(N-methyl-N-phenyl dithiocarbamate) complexes having the general formula [M{S₂CN(MePh)}₂] (where M?=?Cu, Co and Ni) have been prepared and characterized by spectral and thermal analysis. The IR spectra suggest that coordination of dithiocarbamate (DTC) occurred through the two sulfur atoms in a symmetrical bidentate fashion. The electronic spectra, conductance measurement and magnetic moment analysis support the proposed geometry for the electronically dilute complexes. The results of the thermal analysis showed that after dehydration, a one-step decomposition pattern leading to the formation of respective metal sulfide as the end-product occurred. The results are consistent with the proposed composition of the complexes. The in vitro antibacterial activity of the complexes was investigated against strains of gram-negative Escherichia coli, Klebsiella oxytoea and Pseudomonas aureginosa, and gram-positive Bacillus cereus, Staphylococcus aureus and Protues mirabilis. The antibacterial activity of the complexes compared favorably with that of streptomycin and augmentine against S. aureus and B. cereus. The cobalt complex had the best antibacterial activity against the test compounds with inhibitory zone range of 11–14.5?mm.     

Antibacterial activity and cytotoxicity of hydrogel–nanosilver composites based on copolymers from 2‐acrylamido‐2‐methylpropanesulfonate sodium

In this research, we contributed to the search for potential hydrogel–silver dressings by generating hydrogel–silver nanoparticles (AgNPs) composites prepared by the dipping of the crosslinked hydrogel poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium) (1:1) and poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium) (1:1) into an aqueous suspension of citrate‐stabilized AgNPs. The composites obtained were evaluated by an antibacterial activity assay on Staphylococcus aureus and Escherichia coli and subjected to an in vitro cytotoxicity assay for human fibroblasts. The composite formed from the hydrogel poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium) with 3 mol % N,N‐methylene bisacrylamide showed the highest antibacterial activity and the least cytotoxicity among the composites tested; this makes it an excellent alternative as a potential dressing for the treatment of deep and exudative wounds. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39644.