Antibacterial and wound healing properties of cellulose acetate electrospun nanofibers loaded with bioactive glass nanoparticles; in-vivo study

Bioactive glasses (BGs) have gained great attention owing to their versatile biological properties. Combining BG nanoparticles (BGNPs) with polymeric nanofibers produced nanocomposites of great performance in various biomedical applications especially in regenerative medicine. In this study, a novel nanocomposite nanofibrous system was developed and optimized from cellulose acetate (CA) electrospun nanofibers containing different concentrations of BGNPs. Morphology, IR and elemental analysis of the prepared electrospun nanofibers were determined using SEM, FT-IR and EDX respectively. Electrical conductivity and viscosity were also studied. Antibacterial properties were then investigated using agar well diffusion method. Moreover, biological wound healing capabilities for the prepared nanofiber dressing were assessed using in-vivo diabetic rat model with induced wounds. The fully characterized CA electrospun uniform nanofiber (100–200 nm) with incorporated BGNPs exhibited broad range of antimicrobial activity against gram negative and positive bacteria. The BGNP loaded CA nanofiber accelerated wound closure efficiently by the 10th day. The remaining wound areas for treated rats were 95.7?±?1.8, 36.4?±?3.2, 6.3?±?1.5 and 0.8?±?0.9 on 1st, 5th, 10th and 15th days respectively. Therefore, the newly prepared BGNP CA nanocomposite nanofiber could be used as a promising antibacterial and wound healing dressing for rapid and efficient recovery.

     

Interaction of cellulose with other polymers: retrospective and prospective

Interaction of cellulose with other polymers is reviewed from retrospective viewpoints, and future opportunities are discussed from prospective scopes. Previous investigations of the interaction of cellulose with other polymers and/or its existence in novel conformations include a brief overview of cellulose crosslinking, grafting, cellulose/other polymer microcomposites and cellulose and its derivatives in the liquid crystalline state. Interaction of cellulose with newer and more novel macromolecular architectures include its ability to form and interact with polyrotoxanes, polymer combs, starburst dendrimers and hyperbranched polymers and its use as an intelligent material. © 1998 John Wiley & Sons, Ltd.     

Antioxidant, antimicrobial and wound healing activities of Boesenbergia rotunda

The ethanolic extract of Boesenbergia rotunda (L.) Mansf was studied for its wound-healing potential. Since wound healing is interrelated with microbial infection and reactive oxygen species (ROS), this study was conducted to evaluate the antimicrobial and antioxidant activity of B. rotunda. The antimicrobial activity of B. rotunda was studied against six bacterial and two yeast strains using disc diffusion, minimum inhibitory concentration (MIC), and minimum microbicidal concentration (MMC). The B. rotunda extract displayed potential antimicrobial and antifungal activities by inhibiting the Gram-positive bacteria Staphylococcus aureus (ATCC 25923), S. epidermidis, and Bacillus subtilis (ATCC 6633), and the yeasts Candida albicans (ATCC 10231), and Saccharomyces cerevisiae. MIC and MMC values varied from 0.04 to 25 mg/mL and from 0.16 to 25 mg/mL, respectively. The antioxidant activity of B. rotunda was evaluated by measuring the Ferric Reducing/Antioxidant Power (FRAP) and DPPH free radical scavenging activity. The FRAP and DPPH values were 22.2 microM/microg and 76.3 mg/mL, respectively. In the wound-healing studies, the topical application of the B. rotunda extract indicated a significantly increased percentage of wound contraction on day 12 compared with the control group. Histological studies showed the complete epidermis and found collagen fibers and hair follicles in the dermis. The results of the present study support the continued and expanded utilization of B. rotunda in Thai folk medicine.     

Antibacterial effect of silver nanoparticles prepared in bipolymers at moderate temperature

The purpose of this study was to investigate the antibacterial effect of silver nanoparticles in chitosan–poly(ethylene glycol) suspension. The silver nanoparticles (AgNPs) were prepared by use of an environmentally benign method from chitosan (Cts) and poly(ethylene glycol) (PEG) at moderate temperature and with stirring for different times. Silver nitrate (AgNO₃) was used as the metal precursor and Cts and PEG were used as solid support and polymeric stabilizer, respectively. The antibacterial activity of silver–chitosan–poly(ethylene glycol) nanocomposites (Ag–Cts–PEG NCs) against Staphylococcus aureus, Micrococcus luteum, Pseudomonas aeruginosa, and Escherichia coli was tested by use of the Mueller–Hinton agar disk-diffusion method. Formation of AgNPs was determined by UV–visible spectroscopy; surface plasmon absorption maxima were observed at 415–430 nm in the UV–visible spectrum. The peaks in the XRD pattern confirmed that the AgNPs had a face-centered cubic structure; peaks of contaminated crystalline phases were not observed. Transmission electron microscopy (TEM) revealed that the AgNPs synthesized were spherical. The optimum stirring time for synthesis of the smallest particle size (mean diameter 5.50 nm) was 12 h. The AgNPs in Cts–PEG were effective against all the bacteria tested. Higher antibacterial activity was observed for AgNPs with smaller size. These results suggest that AgNPs can be used as an effective inhibitor of bacteria and can be used in medical applications. These results also suggest that AgNPs were successfully synthesized in Cts–PEG suspension at moderate temperature with different stirring times.     

A plasmonic photocatalyst consisting of silver nanoparticles embedded in titanium dioxide

Titanium dioxide (TiO2) displays photocatalytic behavior under near-ultraviolet (UV) illumination. In another scientific field, it is well understood that the excitation of localized plasmon polaritons on the surface of silver (Ag) nanoparticles (NPs) causes a tremendous increase of the near-field amplitude at well-defined wavelengths in the near UV. The exact resonance wavelength depends on the shape and the dielectric environment of the NPs. We expected that the photocatalytic behavior of TiO2 would be greatly boosted if it gets assisted by the enhanced near-field amplitudes of localized surface plasmon (LSP). Here we show that this is true indeed. We named this new phenomenon "plasmonic photocatalysis". The key to enable plasmonic photocatalysis is to deposit TiO2 on a NP comprising an Ag core covered with a silica (SiO2) shell to prevent oxidation of Ag by direct contact with TiO2. The most appropriate diameter for Ag NPs and thickness for the SiO2 shell giving rise to LSP in the near UV were estimated from Mie scattering theory. Upon implementing a device that took these design considerations into account, the measured photocatalytic activity under near UV illumination of such a plasmonic photocatalyst, monitored by decomposition of methylene blue, was enhanced by a factor of 7. The enhancement of the photocatalytic activity increases with a decreased thickness of the SiO2 shell. The plasmonic photocatalysis will be of use as a high performance photocatalyst in nearly all current applications but will be of particular importance for applications in locations of minimal light exposure.     

Structure and properties of biodegradable carboxymethyl cellulose films containing silver nanoparticles

Silver nanoparticles stabilized in a solution of sodium carboxymethyl cellulose with a degree of substitution of 0.85 and a degree of polymerization of 600 have been synthesized. The structuring; physical, chemical, and mechanical properties; and antimicrobial activities of films prepared from sodium carboxymethyl cellulose solutions containing silver nanoparticles have been studied. The shapes, quantities, and sizes of the silver nanoparticles occurring in the sodium carboxymethyl cellulose films were determined with the use of transmission electron microscopy, atomic force microscopy, and UV spectroscopy. It was found that an increase in the concentration of silver nitrate in sodium carboxymethyl cellulose solutions, as well as photoirradiation of the films, leads to the changes in the sizes and shapes of silver nanoparticles. The shapes, sizes, and quantities of silver nanoparticles determine their biological activity. An increase in the quantity of 5- to 25-nm silver nanoparticles was found to enhance the microbicidal activities of the carboxymethyl cellulose films.     

Application of titanium nanoparticles containing natural compounds in cutaneous wound healing

The aim of the study was the rapid green synthesis of titanium nanoparticles using the aqueous extract of Falcaria vulgaris leaves (TiNPs@FV) and exploring their antioxidant, cytotoxicity, antifungal, antibacterial, and cutaneous wound healing activities under in vitro and in vivo condition. These nanoparticles were characterized by UV-Vis, Fourier transform-infrared(FT-IR), X-ray diffraction XRD), field emission-scanning electron microscopy FE-SEM), and transmission electron microscopy TEM) analyses. The synthesized TiNPs@FV had great cell viability on human umbilical vein endothelial cells and indicted this method was nontoxic. DPPH (2,2-diphenyl-1-picrylhydrazyl) test revealed similar antioxidant potentials for F. vulgaris, TiNPs@FV, and butylated hydroxytoluene. All data of antibacterial, antifungal, and cutaneous wound healing tests were analyzed by SPSS 22 software. In the antimicrobial part of this study, TiNPs@FV indicated higher antifungal and antibacterial effects than all standard antibiotics (p ≤ 0.01). Minimal inhibitory concentration (MIC) and minimal fungicidal concentration of TiNPs@FV against all fungi were at 2–4 mg/mL and 2-8 mg/mL ranges, respectively. But, MIC and minimal bactericidal concentration of TiNPs@FV against all bacteria were at 2-8 mg/mL and 2-16 mg/mL ranges, respectively. In the part of cutaneous wound healing, use of TiNPs@FV ointment significantly (p ≤ 0.01) raised the wound contracture, vessel, hydroxyl proline, hexuronic acid, hexosamine, fibrocyte, and fibrocytes/fibroblast rate and significantly (p ≤ 0.01) decreased the wound area, total cells, neutrophil, and lymphocyte compared to other groups in rats. The results of FT-IR, UV-Vis, XRD, TEM, and FE-SEM confirm that the aqueous extract of F. vulgaris leaves can be used to yield titanium nanoparticles with a notable amount of remedial effects.     

Formulation and characterization of a novel cutaneous wound healing ointment by silver nanoparticles containing Citrus lemon leaf: A chemobiological study

IntroductionFormulating new wound-healing ointments by natural compounds is the first research priority in the developing and developed countries. This study was intended to provide green formulation of Ag-NP ointment containing Citrus lemon leaf aqueous extract and examine its capability of healing cutaneous wounds and its antioxidant and cytotoxicity activities under in vitro and in vivo conditions.Materials and methodsDifferent techniques, including UV–Vis and FT-IR spectroscopy, were used to characterize Ag-NPs. MTT assay was used to investigate cytotoxicity property of Ag-NPs. Antioxidant activity of Ag-NPs were examined by DPPH in the presence of butylated hydroxytoluene as positive control. Parameters of cutaneous wound healing were measured both histopathologically and biochemically.ResultsClear peak at 429 nm shown by UV–Vis spectroscopy indicated formation of Ag-NPs. In FT-IR spectroscopy, presence of many antioxidant compounds provided an excellent condition to reduce silver in Ag-NPs. FE-SEM and TEM images showed spherical Ag-NPs with an average size of 25.1 nm. The synthesized silver nanoparticles had excellent cell viability on the HUVECs line and indicated this method was nontoxic. Application of Ag-NP ointment improved wound healing parameters significantly (P ≤ 0.01). Ag-NPs reduced wound areas, total cells, neutrophils and lymphocytes significantly (P ≤ 0.01) and increased wound contracture, vessels, hexosamines, hydroxyl proline, hexuronic acid, fibrocytes, fibroblasts and fibrocyte/ fibroblast ratios significantly (P ≤ 0.01).ConclusionsOnce our results are verified by clinically experimental studies, Ag-NP ointment can be used as a modern one to treat several types of wounds, especially cutaneous ones, in humans.     

Antibacterial and antioxidant properties of phyto-synthesized silver nanoparticles using Lavandula stoechas extract

Due to environmentally friendly and cost- effective issues, biological methods for silver nanoparticles (AgNPs) synthesis are advantageous over chemical and physical ones. In this study, AgNPs synthesized using Lavandula stoechas extract as a reductant and its antioxidant capacity, antibacterial property and cytotoxicity effect were investigated. The phyto-synthesized AgNPs were characterized using various analyses such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD) as well as Fourier transform infrared (FT-IR). The prepared nanoparticles were spherical on shape with the size about 20–50 nm. Antibacterial studies through agar disk diffusion method confirmed the antibacterial potential of phyto-synthesized AgNPs toward two clinical Staphylococus aureus and Pseudomonas aeruginosa bacteria, although MTT assay demonstrated that S. aureus (MIC = 125 μg/ml) was more susceptible to AgNPs than P. aeruginosa (MIC = 250 μg/ml). Moreover, the cytotoxicity assay of phyto-synthezied AgNPs showed a low cytotoxic effect on RAW264 cell line at 62.5 μg/ml as an effective concentration. Also the considerable antioxidant capacity of the AgNPs confirmed through DPPH assay. Great antibacterial and antioxidant properties along with biocompatibility make the suggested phyto-synthesized AgNPs a great candidate for different biomedical applications including wound healing.     

Synthesis of silver nanoparticles in NMMO and their in situ doping into cellulose fibers

We present a method for synthesis of silver nanoparticles in N-methylmorpholine N-oxide (NMMO) and the associated mechanism, as well as their use for in situ volume modification of cellulose fibers. The synthesized particles had diameter of about 4 nm, and their colloid solution was stable for 1 year. The nanoparticles were stabilized using polyethylenimine, which apart from preventing nanoparticle agglomeration, also accelerated Ag⁺ ion reduction and prevented NMMO degradation. A mechanism for the nanoparticle synthesis is suggested based on the electrochemical potentials of all ions in solution, with perhydroxyl ions resulting from NMMO reducing the silver ions. We also created nanocomposites from fibers and silver nanoparticles, in which the latter showed very good dispersion in the fiber volume. Such spun fibers showed improved mechanical parameters in comparison with unmodified fibers.     

Antibacterial activity of glutathione-coated silver nanoparticles against Gram positive and Gram negative bacteria

In the present paper, we study the mechanism of antibacterial activity of glutathione (GSH) coated silver nanoparticles (Ag NPs) on model Gram negative and Gram positive bacterial strains. Interference in bacterial cell replication is observed for both cellular strains when exposed to GSH stabilized colloidal silver in solution, and microbicidal activity was studied when GSH coated Ag NPs are (i) dispersed in colloidal suspensions or (ii) grafted on thiol-functionalized glass surfaces. The obtained results confirm that the effect of dispersed GSH capped Ag NPs (GSH Ag NPs) on Escherichia coli is more intense because it can be associated with the penetration of the colloid into the cytoplasm, with the subsequent local interaction of silver with cell components causing damages to the cells. Conversely, for Staphylococcus aureus, since the thick peptidoglycan layer of the cell wall prevents the penetration of the NPs inside the cytoplasm, the antimicrobial effect is limited and seems related to the interaction with the bacterial surfaces. Experiments on GSH Ag NPs grafted on glass allowed us to elucidate more precisely the antibacterial mechanism, showing that the action is reduced because of GSH coating and the limitation of the translational freedom of NPs.     

Electrospun cellulose acetate wound dressings loaded with Pramipexole for diabetic wound healing: an in vitro and in vivo study

In the current study, a Pramipexole-loaded wound dressing was produced via electrospinning of cellulose acetate solution. Pramipexole was added to cellulose acetate solution at 3, 5, and 10% w/w concentrations and then electrospun. The produced wound dressings were studied regarding their physicochemical and biological properties. Results of cell viability assay and cytoprotection studies showed that cellulose acetate wound dressings containing 3% w/w Pramipexole had significantly higher cell viability compared with other concentrations. The wound healing potential of dressings incorporated with 3% drug was studied in a rat model of diabetic wound. Study showed that the cellulose acetate/3% Pramipexole scaffolds had significantly higher percentage of wound closure, epithelial thickness, and collagen deposition compared with drug-free dressings and control group. Gene expression study showed that the drug-loaded wound dressings could reduce oxidative stress and alleviate inflammation at significantly higher extent compared with other groups.

     

Antibacterial and antibiofilm activity of nanochelating based silver nanoparticles against several nosocomial pathogens

The emergence of multi‐drug resistant (MDR) bacteria and dynamic pattern of infectious diseases demand to develop alternative and more effective therapeutic strategies. Silver nanoparticles (AgNPs) are among the most widely commercialized engineered nanomaterials, because of their unique properties and increasing use for various applications in nanomedicine. This study for the first time aimed to evaluate the antibacterial and antibiofilm activities of newly synthesized nanochelating based AgNPs against several Gram‐positive and ‐negative nosocomial pathogens. Nanochelating technology was used to design and synthesize the AgNPs. The cytotoxicity was tested in human cell line using the MTT assay. AgNPs minimal inhibitory concentration (MIC) was determined by standard broth microdilution. Antibiofilm activity was assayed by a microtiter‐plate screening method. The two synthesized AgNPs including AgNPs (A) with the size of about 20‐25 nm, and AgNPs (B) with 30‐35 nm were tested against Staphylococcus aureus, Staphylococcus epidermidis, Acinetobacter baumannii, and Pseudomonas aeruginosa. AgNPs exhibited higher antibacterial activity against Gram‐positive strains. AgNPs were found to significantly inhibit the biofilm formation of tested strains in concentration 0.01 to 10 mg/mL. AgNPs (A) showed significant effective antibiofilm activity compared to AgNPs (B). In summary, our results showed the promising antibacterial and antibiofilm activity of our new nanochelating based synthesized AgNPs against several nosocomial pathogens.     

Biogenic fabrication of silver nanoparticles,oxidative dissolution and antimicrobial activities

Metallic silver nanoparticles (AgNPs) were prepared by using Foeniculum vulgare Mill seeds extract. The silver nitrate was used as silver precursor in an aqueous solution. The photooxidative dissolution of AgNPs with persulfate (K₂S₂O₈) under UV light was investigated. Effects of initial concentration of K₂S₂O₈, AgNPs, initial solution pH, and temperature were studied on dissolution of AgNPs. The 100% AgNPs dissolution was achieved in 60 min under typical conditions (pH = 4.0, 1.2 mM K₂S₂O₈, and 30 ⁰C). The experimental results showed higher temperature brought faster dissolution rate, and the activation energy was 65.2 kJ/mol. The effects of ethanol, tertiary butanol, and nitrobenzene were studied to establish the role of SO₄^? and HO radical species. AgNPs dissolution was inhibited by Cl^?, Br^?, I^?, and NO₃^? ions. Staphylococcus auerus (s. aureus), Escherichia coli (E. coli) and Candida albicans (C. albicans) were the effective human pathogens against the AgNPs. The lag phase, growth kinetics, minimum bactericidal concentration, death rate, and antimicrobial efficacy depend on the concentration of AgNPs.     

Antimicrobial activity of silver nanoparticles in situ growth on TEMPO-mediated oxidized bacterial cellulose

In order to improve the antimicrobial activity of bacterial cellulose (BC), the silver nanoparticles (Ag NPs) were in situ fabricated on the BC membranes, affording BC and Ag hybrid antimicrobial materials, BC + Ag, which possesses excellent antimicrobial performance. Typically, carboxyl groups were firstly introduced into BC by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation. Then, the carboxyl-functionalized BC was performed with ion-exchange reaction to change the sodium ions into Ag⁺ by immersing in AgNO₃ aqueous solution, generating Ag⁺ anchored BC. Finally, two types of distinct reductive reagents including NaBH₄ and sodium citrate were employed to transform Ag⁺ into Ag NPs to fabricate BC + Ag. The diameters of Ag NPs were determined to be 3.8 nm for NaBH₄-reduced BC + Ag, and 22.0 nm for sodium citrate-reduced one, respectively. The silver content of BC + Ag were determined to be 1.944 and 2.895 wt% for NaBH₄-reduced sample and sodium citrate-reduced one, respectively. Two types of BC + Ag both showed a slow and persistent Ag⁺ release profile, but the NaBH₄-reduced one released much more Ag⁺ than that of sodium citrate under the same measurement condition. In-depth antibacterial analysis via the disc diffusion and colony forming count method disclosed that BC + Ag exhibited strong bactericidal effects against both Escherichia coli and Staphylococcus aureus. And the antibacterial activity of NaBH₄-reduced BC + Ag was higher than the sodium citrate-reduced one. Overall, this study would further improve the antibacterial efficiency of BC + Ag.     

Preparation and properties of cellulose/silver nanoparticle composites with in situ-generated silver nanoparticles using Ocimum sanctum leaf extract

In the present work, silver nanoparticles were in situ-generated in cellulose matrix using Ocimum sanctum leaf extract as a reducing agent. Regenerated wet cellulose films were first immersed in O. sanctum leaf extract and then it was allowed to diffuse into the films. The leaf extract–diffused wet films were dipped in different concentrated aq.AgNO₃ solutions. The leaf extract inside the wet films reduced AgNO₃ into nanosilver. The dry composite films were black in color. Some of the nanoparticles were also formed outside the film in the solution. The nanoparticles were viewed by transmission electron microscopy and scanning electronic microscopy techniques. The composite films showed good antibacterial activity. The cellulose, matrix, and the composite films were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis techniques. The tensile properties of the composite films were higher than those of the matrix. These biodegradable films can be used for packaging and medical purposes.     

Interactions of ionic liquids with polysaccharides. VI. Pure cellulose nanoparticles from trimethylsilyl cellulose synthesized in ionic liquids

Trimethylsilyl cellulose (TMSC) can be efficiently synthesized with 1,1,1,3,3,3‐hexamethyldisilazane (HMDS) by applying the ionic liquids (ILs) 1‐ethyl‐3‐methylimidazolium acetate, 1‐ethyl‐3‐methylimidazolium chloride, and 1‐butyl‐3‐methylimidazolium chloride as reaction medium, yielding pure biopolymer derivatives with degrees of substitution (DS) up to 2.89. Cosolvents, for example, chloroform, could be used to adjust the viscosity of the system and to achieve the miscibility of the components. During the synthesis of highly functionalized derivatives precipitation of the TMSC occurred, which simplifies the recycling of the IL. The high tendency of TMSC toward the formation of supermolecular structures was exploited for the formation of nanoparticles studying a simple dialysis process. Amazingly, pure cellulose nanoparticles can be obtained by dissolving TMSC in tetrahydrofurane or N,N‐dimethyl acetamide and dialysis against water. FTIR spectroscopy confirmed the complete removal of the TMS functions during this process. Scanning electron microscopy, dynamic light scattering, atomic force microscopy, and particle size distribution analysis showed that cellulose particles down to a size of 170 nm are accessible in this simple manner. The nanoparticle suspensions exhibit viscosities in the range of water. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4070–4080, 2008     

Pongamia pinnata seed extract‐mediated green synthesis of silver nanoparticles: Preparation,formulation and evaluation of bactericidal and wound healing potential

Pongamia pinnata – a plant used since olden times in Ayurvedic treatment – is reported to have diverse functions including antibacterial, antidiabetic, antineurodegenerative, antiepileptic, antiulcer, etc. In this study, our objective was to prepare silver nanoparticles (AgNPs) by green synthesis mediated by methanolic seed extract of P. pinnata and to determine their antimicrobial and antioxidant potential and wound healing activity. AgNPs were characterized for particle size and shape and for antioxidant potential. Further, the AgNPs were incorporated in a gel. The wound healing activity was investigated using an excision wound healing model in Wistar rats. The AgNP‐loaded gel was applied topically to the wounded rats daily for 30 days. The wound contraction was calculated and histopathological studies of the healed tissues were conducted. Karanjin content of the extract was found to be 349 ± 2.16 mg g^?1. Formation of AgNPs was confirmed using transmission and scanning electron microscopies and X‐ray diffraction. AgNPs showed good antioxidant potential and were active against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa. Significant wound healing activity (p < 0.05) was shown by the AgNP gel as compared to 5% Betadine ointment. Thus, the prepared AgNPs have antimicrobial and wound healing effects that may be useful in treatment of topical infections especially in wounds.