Characterization and Antimicrobial Property of Poly(Acrylic Acid) Nanogel Containing Silver Particle Prepared by Electron Beam

In this study, we developed a one step process to synthesize nanogel containing silver nanoparticles involving electron beam irradiation. Water-soluble silver nitrate powder is dissolved in the distilled water and then poly(acrylic acid) (PAAc) and hexane are put into this silver nitrate solution. These samples are irradiated by an electron beam to make the PAAc nanogels containing silver nanoparticles (Ag/PAAc nanogels). The nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). In addition, the particle size and zeta-potential were confirmed by a particle size analyzer (PSA). The antibacterial properties of the nanogels were evaluated by paper diffusion test. The Ag/PAAc nanogels had an antibacterial effect against Escherichia coli and Staphylococcus aureus. The nanogels also demonstrated a good healing effect against diabetic ulcer. The size of the Ag/PAAc nanogels decreased with increasing irradiation doses, and the absolute value of the zeta potential increased with increasing irradiation doses. Also, the Ag/PAAc nanogels exhibited good antibacterial activity against both Gram-negative and Gram-positive bacteria. In in vivo wound healing, the Ag/PAAc nanogels have a good healing effect.     

Activity of Silver Nanoparticles against Staphylococcus spp.

Staphylococcus epidermidis is a bacterium that is part of the human microbiota. It is most abundant on the skin, in the respiratory system and in the human digestive tract. Also, Staphylococcus aureus contributes to human infections and has a high mortality rate. Both of these bacterial species produce biofilm, a pathogenic factor increasing their resistance to antibiotics. For this reason, we are looking for new substances that can neutralize bacterial cells. One of the best-known substances with such effects are silver nanoparticles. They exhibited antibacterial and antibiofilm formation activity that depended on their size, shape and the concentration used. In this review, we presented the data related to the use of silver nanoparticles in counteracting bacterial growth and biofilm formation published in scientific papers between 2017 and 2021. Based on the review of experimental results, the properties of nanoparticles prompt the expansion of research on their activity.     

Nanocomposite of chitosan and silver oxide and its antibacterial property

An aqueous emulsion of chitosan nanoparticles encapsulating silver oxide is prepared from silver nitrate and chitosan. The nanoparticles are positively charged with an average diameter of 300 nm. The dried particle has a spherical shape with a 100 nm diameter. The emulsion is applied onto cotton and delivers a durable antibacterial activity against S. aureus and E. coli, after 20 washings. The coefficient of friction of the treated fabric is similar to that of the untreated cotton fabric. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Antibacterial poly(vinyl alcohol) film containing silver nanoparticles: Preparation and characterization

The importance of antibacterial materials for biomedical applications is growing nowadays. The presented article deals with the characterization of structural, mechanical and thermal properties and of antibacterial polymeric films based on polyvinyl alcohol (PVA) and silver nitrate, which can find their applicability in wound dressing components and protective coating. The methods of transmission electron microscopy, UV–vis and XRD spectroscopy, optical microscopy, differential scanning calorimetry, stress–strain analysis, and agar diffusion test were used to characterize the polymer films prepared. The results showed strong antibacterial activity against Escherichia coli and Staphylococcus aureus already at the lowest addition level of silver nitrate. An improvement of mechanical properties (Young's modulus) was also noticed due to a modification of PVA with silver nitrate up to 1 wt. % of silver content. Furthermore, the results show a strong effect of the thermal history of the sample preparation on the degree of silver‐ion reduction and formation of nanoparticles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A Review on Antimicrobial Chitosan-Silver Nanocomposites: A Roadmap Toward Pathogen Targeted Synthesis

In this review, the authors investigate different methods of synthesizing antimicrobial chitosan-silver nanocomposites and divided these nanocomposites into two major groups on the basis of metallic or ionic nature of silver. Chitosan-metallic silver composites were prepared by following different techniques: chemical, thermal, radiation (gamma ray or UV), and electrochemical. However, the polymeric nature of chitosan allows formation of complexes with silver ions. Their antimicrobial efficacy was evaluated by the disc diffusion method. The authors compare antimicrobial efficacy of all these materials based on the findings of various research groups to come up with a strategy for synthesizing chitosan-silver nanocomposites to target a specific pathogen.     

Development and Characterization of Highly Stable Silver NanoParticles as Novel Potential Antimicrobial Agents for Wound Healing Hydrogels

Recurrent microbial infections are a major cause of surgical failure and morbidity. Wound healing strategies based on hydrogels have been proposed to provide at once a barrier against pathogen microbial colonization, as well as a favorable environment for tissue repair. Nevertheless, most biocompatible hydrogel materials are more bacteriostatic than antimicrobial materials, and lack specific action against pathogens. Silver-loaded polymeric nanocomposites have efficient and selective activity against pathogenic organisms exploitable for wound healing. However, the loading of metallic nanostructures into hydrogels represents a major challenge due to the low stability of metal colloids in aqueous environments. In this context, the aim of the present study was the development of highly stable silver nanoparticles (AgNPs) as novel potential antimicrobial agents for hyaluronic acids hydrogels. Two candidate stabilizing agents obtained from natural and renewable sources, namely cellulose nanocrystals and ulvan polysaccharide, were exploited to ensure high stability of the silver colloid. Both stabilizing agents possess inherent bioactivity and biocompatibility, as well as the ability to stabilize metal nanostructures thanks to their supramolecular structures. Silver nitrate reduction through sodium borohydride in presence of the selected stabilizing agents was adopted as a model strategy to achieve AgNPs with narrow size distribution. Optimized AgNPs stabilized with the two investigated polysaccharides demonstrated high stability in phosphate buffer saline solution and strong antimicrobial activity. Loading of the developed AgNPs into photocrosslinked methacrylated hyaluronic acid hydrogels was also investigated for the first time as an effective strategy to develop novel antimicrobial wound dressing materials.     

甲壳胺纤维和含银甲壳胺纤维的抗菌性能比较

从定性、定量的角度探讨了甲壳胺纤维和含银甲壳胺纤维对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌三种常见的、具有代表性的细菌的抑制作用,并把这两种纤维和粘胶纤维的抗菌性能作了比较。实验结果表明:含银甲壳胺纤维比普通的甲壳胺纤维具有更好的抗菌性能。     

The Physical and Antimicrobial Properties of Silver Doped Hydroxyapatite Sintered by Microwave and Conventional Sintering

In this paper, the silver-doped hydroxyapatite (AgHAp) nanoparticles were successfully synthesized by conventional and microwave sintering. The structural and antibacterial properties of AgHAp without heat treatment (AgHAp-90) and after heat treated at 800 and 1000?°C by conventional (AgHAp-800CS, AgHAp-1000CS) and microwave sintering (AgHAp-800MS, AgHAp-1000MS) were discussed respectively. The results of X-ray diffraction and fourier transform infrared spectroscopy suggested that the pure phase of AgHAp nanoparticles were obtained at 800?°C, but the β-TCP phase was observed when the temperature up to 1000?°C. Scanning electron microscopy images showed that the morphology and size of the nanoparticles changed with the improvement of temperature. The energy dispersive X-ray analysis identified the existence of Ag, Ca, P. The antibacterial test of AgHAp showed the excellent antimicrobial activity against gram-negative strains Escherichia coli and gram-positive strains Staphylococcus aureus. Also, the results showed the AgHAp had a smaller effect on gram-positive strains compare with gram-negative strains, and the antimicrobial activity of particles sintered by microwave was better than samples sintered by conventional. It showed the great advantages of microwave sintering. The silver ion releasing in solution was measured by the inductively coupled plasma and elucidated the results of antibacterial tests.     

γ-Ray assisted synthesis of silver nanoparticles in chitosan solution and the antibacterial properties

In the present study, chitosan had been utilized as a “green” stabilizing agent for the synthesis of spherical silver nanoparticles in the range of 5–30 nm depending on the percentage of chitosan used (0.1, 0.5, 1.0 and 2.0 wt%) under γ-irradiation. X-ray diffractometer identified the nanoparticles as pure silver having face-centered cubic phase. Ultraviolet–visible spectra exhibited the influence of γ-irradiation total absorbed dose and chitosan concentration on the yield of silver nanoparticles. The antibacterial properties of the silver nanoparticles were tested against Methicillin-resistant Staphylococcus aureus (MRSA) (gram-positive) and Aeromonas hydrophila (gram-negative) bacteria. This work provides a simple and “green” method for the synthesis of highly stable silver nanoparticles in aqueous solution with good antibacterial property.     

Electrospun antibacterial nylon nanofibers through in situ synthesis of nanosilver: preparation and characteristics

A new method for production of nylon nanofibers with antibacterial properties containing silver nanoparticles (nylon nanofibers/Ag NPs) is introduced via in situ synthesis of nano-silver by reduction of silver nitrate in the polymer solution prior to electrospinning. The properties of the electrospinning solutions and the structures of the electrospun fibers were studied using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), UV?Cvis spectrophotometer and reflection spectrophotometer. Further, the antibacterial properties of the nanofibers were investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. Interestingly, an antibacterial properties has been found on nylon 6 nanofibers while the nylon nanofibers/Ag NPs showed excellent antibacterial activities against both tested bacteria. The produced nylon nanofibers/Ag NPs can be a good candidate for biomedical applications, water and air filtration.     

Characterization and antibacterial properties of aminophenol grafted and Ag NPs decorated graphene nanocomposites

A new route for the synthesis of aminophenol grafted and Ag NPs decorated reduced graphene sheet (Ag-RGS) was developed as an effective antibacterial nanostructure. The nucleophilic substitution reaction of amine group of aminophenol with epoxy group of GO in the presence of silver nitrate and subsequent reduction with hydrazine generated Ag-RGS nanocomposite. The morphology and structure of the as-synthesized nanocomposite was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. TEM images of Ag-RGS revealed that the silver nanoparticles were decorated on the surface of the graphene sheet. The presence of phenolic groups and silver nanoparticles on the surface of Ag-RGS showed synergistic effect on antibacterial activity against Escherichia coli and Staphylococcus aureus. This feature of the Ag-RGS nanocomposite showed that it can be a promising candidate in broad range of antibiotics.     

Synthesis of antimicrobial silver nanoparticles on silk fibers via γ‐radiation

Antimicrobial silver nanoparticles (NPs) were successfully synthesized on the surface of silk fibers via γ‐ray irradiation. The products were characterized with scanning electron microscope (SEM), energy dispersion spectrum, and X‐ray diffraction. The results revealed that the silver particles with a diameter of less than 20 nm were immobilized and well dispersed on the surface of silk fibers. The antimicrobial capability against the gram positive bacterium Staphylococcus aureus and the washing stability of the silk fibers produced with different conditions were tested and found to be excellent. The silk fibers treated with 1 mM solution and 10 kGy γ‐radiation showed 96% antimicrobial activity and still kept above 85% antibacterial activity after 10 washing cycles. Moreover, a mechanism for the formation of silver NPs on silk fibers under γ‐radiation was generally discussed. The resulting silk fibers coated with silver NPs can be useful as functional fabrics in a range of applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Green Synthesis and Characterization of Silver/Chitosan/Polyethylene Glycol Nanocomposites without any Reducing Agent

This paper presents the green synthesis of silver nanoparticles (Ag NPs) in aqueous medium. This method was performed by reducing AgNO(3) in different stirring times of reaction at a moderate temperature using green agents, chitosan (Cts) and polyethylene glycol (PEG). In this work, silver nitrate (AgNO(3)) was used as the silver precursor while Cts and PEG were used as the solid support and polymeric stabilizer. The properties of Ag/Cts/PEG nanocomposites (NCs) were studied under different stirring times of reaction. The developed Ag/Cts/PEG NCs were then characterized by the ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy.     

Hyaluronic Acid Derivative Molecular Weight-Dependent Synthesis and Antimicrobial Effect of Hybrid Silver Nanoparticles

Silver nanoparticles (Ag NPs) appeared as promising antimicrobial candidates to face the development of antibiotic resistance. Although reported as toxic towards mammalian cells, their combination with biomolecules have shown reduced toxicity, while maintaining the antimicrobial function. Herein, hyaluronic acid (HA) with low (40 kDa), medium (200 and 600 kDa) and high (2 MDa) molecular weight (Mw) was modified with adipic acid dihydrazide (ADH) and used as reducing and capping agents to synthesise antimicrobial hybrid Ag NPs. The Mw of the polymer played a crucial role in the morphology, size and antibacterial activity of the Ag NPs. The 600 and 200 kDa HA-ADH-Ag NPs were able to reduce the Escherichia coli and Staphylococcus aureus concentration by more than 3 logs, while the 40 kDa NPs reached ~2 logs reduction. The 2 MDa HA-ADH failed to form homogenous NPs with strong bactericidal activity. A mechanistic study of the interaction with a model bacterial membrane using Langmuir isotherms confirmed the greater interaction between bacteria and higher Mw polymers and the effect of the NP’s morphology. The nanocomposites low toxicity to human skin cells was demonstrated in vitro, showing more than 90% cell viability after incubation with the NPs.     

In vitro and in vivo investigational studies of a nanocomposite‐hydrogel‐based dressing with a silver‐coated chitosan wafer for full‐thickness skin wounds

A nanocomposite reservoir‐type hydrogel dressing of poly vinyl alcohol (PVA) was fabricated by a freeze–thaw method and loaded with silver‐nanoparticle‐coated chitosan wafers (Ag–CHWs). The Ag–CHWs were synthesized by a sonication technique with silver nitrate (AgNO₃) and chitosan powder. Scanning electron microscopy images showed silver nanoparticles (AgNPs) with a size range of 10 ± 4 nm on the surface of the chitosan wafers, and the antibacterial efficacy (minimum inhibitory concentration) of the Ag–CHWs was measured against Pseudomonas aeruginosa (32 µg/mL), Staphylococcus aureus, (30 µg/mL) and Escherichia coli (32 µg/mL). The antimicrobial PVA hydrogel showed an improved tensile strength (～0.28 MPa) and gel content (～92%) in comparison with the blank hydrogels. Full‐thickness‐excision wound studies of the nanocomposite dressing on Wistar rats revealed enhanced wound contraction, improved inflammation response, re‐epithelization rate, neoangiogenesis, and granulation tissue formation in comparison to the control group. A flexible, biocompatible, nanocomposite reservoir dressing not only established the chitosan as a stabilizer but also proved the efficacious and safe utility of AgNPs toward chronic wound management. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43472.     

Synthesis and study of antimicrobial activity of bioconjugates of silver nanoparticles and endogenous antibiotics

Bioconjugates of silver nanoparticles and antimicrobial peptides of the bactenecin family, which are endogenous antibiotics, have been synthesized. The biological activity of the prepared bioconjugates has been evaluated. It has been established that the conjugates of silver nanoparticles with the peptide G-Bac3.4 exhibit an antimicrobial activity, including the activity with respect to the strain Pseudomonas aeruginosa resistant to traditional antibiotics and the strain Staphylococcus aureus (MRSA ATCC 33591) resistant to methicillin. It has been demonstrated that the complexes of silver nanoparticles with antimicrobial peptides do not possess a pronounced membranolytic effect inherent in peptides. The results obtained have made it possible to draw the conclusion that the properties of the synthesized conjugates differ from those characteristic of constituting peptides and silver nanoparticles.     

A study of antimicrobial property of textile fabric treated with modified dendrimers

Dendrimers have been used as a vehicle to develop the antimicrobial properties of textile fabrics. We have taken advantage of the large number of functional groups present in the regular and highly branched three‐dimensional architecture of dendrimers. In this study, the poly(amidoamine) (PAMAM) G‐3 dendrimer was modified to provide antimicrobial properties. Following a procedure similar to what is suggested in the literature, PAMAM (G3) with primary amine end groups was converted into ammonium functionalities. The modification was then confirmed by FTIR and ¹³C‐NMR analysis. Dendrimers have unique properties owing to their globular shape and tunable cavities, this allows them to form complexes with a variety of ions and compounds; and also act as a template to fabricate metal nanoparticles. AgNO₃–PAMAM (G3) complex as well as a MesoSilver–PAMAM (G3) complex were formed and these modified dendrimers were characterized by a UV–Visible spectrophotometer to study the complex formation. Modified dendrimers were applied to the Cotton/Nylon blend fabric. SEM and EDX analysis were performed to study the dispersion of silver nanoparticles onto the fabric. An antimicrobial test of the treated‐fabric against Staphylococcus aureus exhibited significant biocidal activities for each type of modified‐dendrimer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study of antibacterial properties of polypropylene filled with surfactant‐coated silver nanoparticles

Medical applications require, in most cases, antibacterial protection. The use of silver (Ag) gives important antibacterial properties since silver is highly toxic for bacteria. In this research work, we have used silver nanoparticles (Ag NPs) with different surfactants, polyvinyl pyrrolidone (PVP) and oleic acid (OA) to facilitate dispersion. PP‐Ag NPs compounds were prepared by melt mixing, and the effects of the processing conditions on nanoparticles' dispersion were investigated by transmission electron microscopy (TEM). The antibacterial efficiency of PP‐Ag NPs compounds against Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 8379 was evaluated. Results show that good dispersion is obtained with rotating speeds in the 350–500 rpm range. TEM analysis reveals balanced dispersion and presence of some Ag NPs aggregates. Regarding antimicrobial properties, the use of PVP as surfactant leads to “significant” antimicrobial activity of 1.5 against Staphylococcus aureus and Escherichia coli; on other hand, the use of oleic acid (OA) as surfactant leads to strong protection against Staphylococcus aureus (antimicrobial activity between 2.5 and 3.3) but the overall protection against Escherichia coli is very low (lower than 1). Results show that the use of surfactants for Ag NPs has important effects on antibacterial properties of polypropylene filled with coated Ag NPs. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Silver Nanoparticles/Ibuprofen-Loaded Poly(l-lactide) Fibrous Membrane: Anti-Infection and Anti-Adhesion Effects

Infection caused by bacteria is one of the crucial risk factors for tendon adhesion formation. Silver nanoparticles (AgNP)-loaded physical barriers were reported to be effective in anti-infection and anti-adhesion. However, high silver load may lead to kidney and liver damages. This study was designed for Ibuprofen (IBU)-loaded poly(l-lactide) (PLLA) electrospun fibrous membranes containing a low dosage of Ag to evaluate its potential in maintaining suitable anti-infection and good anti-adhesion effects. The in vitro drug release study showed a sustained release of Ag ions and IBU from the membrane. Inferior adherence and proliferation of fibroblasts were found on the Ag4%–IBU4%-loaded PLLA electrospun fibrous membranes in comparison with pure PLLA and 4% Ag-loaded PLLA membranes. In the antibacterial test, all Ag-loaded PLLA electrospun fibrous membranes prevented the adhesion of Staphylococcus aureus and Staphylococcus epidermidis. Taken together, these results demonstrate that Ibuprofen is effective in enhancing the anti-adhesion and anti-proliferation effects of 4% Ag-loaded PLLA fibrous membrane. The medical potential of infection reduction and adhesion prevention of Ag4%–IBU4%-loaded PLLA electrospun fibrous membrane deserves to be further studied.     

Novel Silver-Functionalized Poly(ε-Caprolactone)/Biphasic Calcium Phosphate Scaffolds Designed to Counteract Post-Surgical Infections in Orthopedic Applications

In this study, we designed and developed novel poly(ε-caprolactone) (PCL)-based biomaterials, for use as bone scaffolds, through modification with both biphasic calcium phosphate (BCP), to impart bioactive/bioresorbable properties, and with silver nitrate, to provide antibacterial protection against Staphylococcus aureus, a microorganism involved in prosthetic joint infections (PJIs). Field emission scanning electron microscopy (FESEM) showed that the samples were characterized by square-shaped macropores, and energy dispersive X-ray spectroscopy analysis confirmed the presence of PCL and BCP phases, while inductively coupled plasma–mass spectrometry (ICP–MS) established the release of Ag⁺ in the medium (~0.15–0.8 wt% of initial Ag content). Adhesion assays revealed a significant (p < 0.0001) reduction in both adherent and planktonic staphylococci on the Ag-functionalized biomaterials, and the presence of an inhibition halo confirmed Ag release from enriched samples. To assess the potential outcome in promoting bone integration, preliminary tests on sarcoma osteogenic-2 (Saos-2) cells indicated PCL and BCP/PCL biocompatibility, but a reduction in viability was observed for Ag-added biomaterials. Due to their combined biodegrading and antimicrobial properties, the silver-enriched BCP/PCL-based scaffolds showed good potential for engineering of bone tissue and for reducing PJIs as a microbial anti-adhesive tool used in the delivery of targeted antimicrobial molecules, even if the amount of silver needs to be tuned to improve osteointegration.