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Special Issue "Antibacterial Materials and Coatings"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Molecular Diversity".

Deadline for manuscript submissions: closed (30 August 2017)

Special Issue Editors

Guest Editor
Prof. Dr. Krasimir Vasilev

Mawson Institute and School of Engineering, Mawson Lakes Campus, University of South Australia, Mawson Lakes SA 5095, Australia
E-Mail
Phone: +61 8 8302 5697
Fax: +61 8 8302 5689
Interests: Antibacterial coatings; biomaterials; medical devices; plasma polymers; surface modification; biointerfaces; drug delivery; nanomaterials
Guest Editor
Dr. Alex Cavallaro

Future Industries Institute, University of South Australia, GPO Box 2471, Adelaide SA 5001, Australia
Website | E-Mail
Interests: antimicrobial surface coatings; biomaterials; controlled\targeted drug release systems; nanomaterials; nanotoxicology
Guest Editor
Dr. Peter Zilm

Microbiology Laboratory, The School of Dentistry, The University of Adelaide, Adelaide, SA 5005, Australia
Website | E-Mail
Interests: bacterial resistance; oral microbiology; proteomics; endodontic microbiology; continuous culture; Enterococcus faecalis; Fusobacterium nucleatum; Staphylococcus aureus

Special Issue Information

Dear Colleagues,

Undesired bacterial adhesion and colonization is a problem in numerous areas of everyday life. This problem has been well recognized and documented. Bacterial infections cause death and suffering, and enormous added costs to the healthcare worldwide. Undesired bacterial colonization and the subsequent biofilm formation cause major issues in many other industries, such as those of food processing and storage, marine transport and management, and water treatment.
It has been a pivotal goal of humans to control bacteria–surface interactions. Despite the tremendous research efforts by academic researchers, industry and medical workers, a comprehensive solution to the problem of controlling bacterial surface colonization has not been found. Antibiotics, rightly considered as the greatest medical discovery of the 20th century, have provided a substantial relief to patients and society overall. However, the capacity of microorganisms to develop resistance to antibiotics has emerged as a significant challenge.
Over the last couple of decades numerous novel antibacterial materials and coating have been developed. Some of these have even translated from the laboratory to actually saving lives in hospitals. This Special Issue aims to bring together the latest advances in the field of antibacterial materials and coatings and their application in various fields. The Special Issue also aims to highlight the challenges and obstacles that need to be overcome to provide a comprehensive understanding and effective control of bacteria–surface interactions.
We invite investigators to contribute original research articles, as well as review articles, that will inspire research towards the next generation of antibacterial materials and coatings and their applications. Potential topics include, but are not limited to:
•    Antibacterial coatings
•    Antibacterial materials
•    Bacteria–surface interactions
•    Antibacterial  nanomaterials
•    Applications of antibacterial materials and coatings
•    Biofilm dispersing materials
•    Diagnostics of bacterial contamination

Prof. Dr. Krasimir Vasilev
Dr. Alex Cavallaro
Dr. Peter Zilm
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

•    antibacterial materials
•    antibacterial coatings
•    bacteria
•    biofilm
•    infection

Published Papers (25 papers)

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Research

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Open AccessArticle Anti-Bacteria and Microecosystem-Regulating Effects of Dental Implant Coated with Dimethylaminododecyl Methacrylate
Molecules 2017, 22(11), 2013; doi:10.3390/molecules22112013 (registering DOI)
Received: 25 October 2017 / Accepted: 15 November 2017 / Published: 20 November 2017
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Abstract
The effects of dimethylaminododecyl methacrylate (DMADDM) modified titanium implants on bacterial activity and microbial ecosystem of saliva-derived biofilm were investigated for the first time. Titanium discs were coated with DMADDM solutions at mass fractions of 0 mg/mL (control), 1, 5 and 10 mg/mL,
[...] Read more.
The effects of dimethylaminododecyl methacrylate (DMADDM) modified titanium implants on bacterial activity and microbial ecosystem of saliva-derived biofilm were investigated for the first time. Titanium discs were coated with DMADDM solutions at mass fractions of 0 mg/mL (control), 1, 5 and 10 mg/mL, respectively. Biomass accumulation and metabolic activity of biofilms were tested using crystal violet assay and MTT (3-(4,5-Dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. 16S rRNA gene sequencing was performed to measure the microbial community. Live/dead staining and scanning electron microscopy (SEM) were used to value the structure of biofilm. The results showed that the higher mass fraction of DMADDM the coating solution had, the significantly lower the values of metabolic activity and accumulated biofilms got, as well as fewer live cells and less extracellular matrix. Moreover, 5 mg/mL of DMADDM was the most effective concentration, as well as 10 mg/mL. In microecosystem-regulation, the DMADDM modified titanium implant decreased the relative abundance of Neisseria and Actinomyces and increased the relative abundance of Lactobacillus, a probiotic for peri-implant diseases. In conclusion, via inhibiting growth and regulating microecosystem of biofilm, this novel titanium implant coating with DMADDM was promising in preventing peri-implant disease in an ‘ecological manner’. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Chemical Composition of Herbal Macerates and Corresponding Commercial Essential Oils and Their Effect on Bacteria Escherichia coli
Molecules 2017, 22(11), 1887; doi:10.3390/molecules22111887
Received: 28 September 2017 / Accepted: 29 October 2017 / Published: 10 November 2017
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Abstract
This study addresses the chemical composition of some commercial essential oils (clove, juniper, oregano, and marjoram oils), as well as appropriate herbal extracts obtained in the process of cold maceration and their biological activity against selected Escherichia coli strains: E. coli ATTC 25922,
[...] Read more.
This study addresses the chemical composition of some commercial essential oils (clove, juniper, oregano, and marjoram oils), as well as appropriate herbal extracts obtained in the process of cold maceration and their biological activity against selected Escherichia coli strains: E. coli ATTC 25922, E. coli ATTC 10536, and E. coli 127 isolated from poultry waste. On the basis of the gas chromatography-mass spectrometry (GCMS) analysis, it was found that the commercial essential oils revealed considerable differences in terms of the composition and diversity of terpenes, terpenoids and sesquiterpenes as compared with the extracts obtained from plant material. The commercial clove, oregano, and marjoram oils showed antibacterial properties against all the tested strains of E. coli. However, these strains were not sensitive to essential oils obtained from the plant material in the process of maceration. The tested strains of E. coli show a high sensitivity, mainly against monoterpenes (α-pinene, β-pinene, α,β,γ-terpinene, limonene) and some terpenoids (thymol, carvacrol). The commercial juniper oil contained mainly monoterpenes and monoterpenoids, while the extracts contained lower amounts of monoterpenes and high amounts of sesquiterpenes—the anti-microbiotic properties of the juniper herbal extract seem to be caused by the synergistic activity of mono- and sesquiterpenes. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Middle Ear Prosthesis with Bactericidal Efficacy—In Vitro Investigation
Molecules 2017, 22(10), 1681; doi:10.3390/molecules22101681
Received: 19 September 2017 / Revised: 5 October 2017 / Accepted: 6 October 2017 / Published: 10 October 2017
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Abstract
Materials used in ossicular replacement prostheses must possess appropriate biological properties, such as biocompatibility, stability, no cytotoxicity. Due to the risk of infection (otitis media and chronic otitis media), it is desirable to use an antibacterial agent for illness prevention during the ossicular
[...] Read more.
Materials used in ossicular replacement prostheses must possess appropriate biological properties, such as biocompatibility, stability, no cytotoxicity. Due to the risk of infection (otitis media and chronic otitis media), it is desirable to use an antibacterial agent for illness prevention during the ossicular reconstruction. The goal of this work was to observe biological properties of a new composite prosthesis made of ABS containing silver nanoparticles (AgNPs 45T). Samples for biological tests and then a prototype of middle ear prosthesis were prepared using injection moulding and extrusion techniques. In vitro experiments were carried out to assess bactericidal efficacy against Staphylococcus aureus and Pseudomona aeruginosa standard strains, cell proliferation, viability and cytotoxicity, using Hs680.Tr. fibroblast cells. Surface parameters of the samples were evaluated, including roughness and wettability. The silver ions were continually released from the polymer in aqueous solution. The silver ions release was measured as increasing with time and concentration of the silver nanoparticles in the polymer matrix. No cytotoxicity effect was observed, while bactericidal efficacy was noticed for silver nanoparticles. The roughness studies showed an increase in roughness for the samples with silver nanoparticles. All polymer and composite materials containing silver nanoparticles showed hydrophilic properties. The composites were found to release silver ions at a concentration level capable of rendering the antimicrobial efficacy even with the lowest concentration of silver nanoparticles in the material. Our results demonstrate that middle ear prosthesis made of polymer and silver nanoparticles may eliminate bacteria during inflammation in the middle ear. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Time-Dependent Antimicrobial Activity of Filtering Nonwovens with Gemini Surfactant-Based Biocides
Molecules 2017, 22(10), 1620; doi:10.3390/molecules22101620
Received: 30 August 2017 / Accepted: 25 September 2017 / Published: 27 September 2017
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Abstract
Previous studies on nonwovens used for respiratory protective devices (RPDs) were related to equipment intended for short-term use. There is only limited research on the development of biocidal nonwoven fabrics for reusable RPDs that could be used safely in an industrial work environment
[...] Read more.
Previous studies on nonwovens used for respiratory protective devices (RPDs) were related to equipment intended for short-term use. There is only limited research on the development of biocidal nonwoven fabrics for reusable RPDs that could be used safely in an industrial work environment where there is a risk of microbial growth. Moreover, a new group of biocides with high antimicrobial activity—gemini surfactants, has never been explored for textile’s application in previous studies. The aim of this study was to develop high-efficiency melt-blown nonwovens containing gemini surfactants with time-dependent biocidal activity, and to validate their antimicrobial properties under conditions simulating their use at a plant biomass-processing unit. A set of porous biocidal structures (SPBS) was prepared and applied to the melt-blown polypropylene (PP) nonwovens. The biocidal properties of the structures were triggered by humidity and had different activation rates. Scanning electron microscopy was used to undertake structural studies of the modified PP/SPBS nonwovens. In addition, simulation of plant biomass dust deposition on the nonwovens was performed. The biocidal activity of PP/SPBS nonwovens was evaluated following incubation with Escherichia coli and Aspergillus niger from the American Type Culture Collection, and with Pseudomonas fluorescens and Penicillium chrysogenum isolated from the biomass. PP/SPBS nonwovens exhibited antimicrobial activity to varying levels. Higher antimicrobial activity was noted for bacteria (R = 87.85–97.46%) and lower for moulds (R = 80.11–94.53%). Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle N-Halamine Biocidal Materials with Superior Antimicrobial Efficacies for Wound Dressings
Molecules 2017, 22(10), 1582; doi:10.3390/molecules22101582
Received: 21 August 2017 / Revised: 18 September 2017 / Accepted: 20 September 2017 / Published: 21 September 2017
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Abstract
This work demonstrated the successful application of N-halamine technology for wound dressings rendered antimicrobial by facile and inexpensive processes. Four N-halamine compounds, which possess different functional groups and chemistry, were synthesized. The N-halamine compounds, which contained oxidative chlorine, the source of antimicrobial activity,
[...] Read more.
This work demonstrated the successful application of N-halamine technology for wound dressings rendered antimicrobial by facile and inexpensive processes. Four N-halamine compounds, which possess different functional groups and chemistry, were synthesized. The N-halamine compounds, which contained oxidative chlorine, the source of antimicrobial activity, were impregnated into or coated onto standard non-antimicrobial wound dressings. N-halamine-employed wound dressings inactivated about 6 to 7 logs of Staphylococcus aureus and Pseudomonas aeruginosa bacteria in brief periods of contact time. Moreover, the N-halamine-modified wound dressings showed superior antimicrobial efficacies when compared to commercially available silver wound dressings. Zone of inhibition tests revealed that there was no significant leaching of the oxidative chlorine from the materials, and inactivation of bacteria occurred by direct contact. Shelf life stability tests showed that the dressings were stable to loss of oxidative chlorine when they were stored for 6 months in dark environmental conditions. They also remained stable under florescent lighting for up to 2 months of storage. They could be stored in opaque packaging to improve their shelf life stabilities. In vitro skin irritation testing was performed using a three-dimensional human reconstructed tissue model (EpiDerm™). No potential skin irritation was observed. In vitro cytocompatibility was also evaluated. These results indicate that N-halamine wound dressings potentially can be employed to prevent infections, while at the same time improving the healing process by eliminating undesired bacterial growth. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle The Influence of Accelerated UV-A and Q-SUN Irradiation on the Antimicrobial Properties of Coatings Containing ZnO Nanoparticles
Molecules 2017, 22(9), 1556; doi:10.3390/molecules22091556
Received: 10 August 2017 / Revised: 11 September 2017 / Accepted: 13 September 2017 / Published: 17 September 2017
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Abstract
The influence of accelerated UV-A and Q-SUN irradiation on the antimicrobial properties of coatings containing ZnO nanoparticles was investigated using a polyethylene (PE) film covering. The results of the study showed that Methyl Hydroxypropyl Celluloses (MHPC) coatings did not influence the growth of
[...] Read more.
The influence of accelerated UV-A and Q-SUN irradiation on the antimicrobial properties of coatings containing ZnO nanoparticles was investigated using a polyethylene (PE) film covering. The results of the study showed that Methyl Hydroxypropyl Celluloses (MHPC) coatings did not influence the growth of S. aureus, B. cereus, E. coli, P. aeruginosa or C. albicans cells. MHPC coatings containing ZnO nanoparticles inhibited the growth of bacterial strains and reduced the number of C. albicans strains. Accelerated Q-SUN and UV-A irradiation had no influence on the antimicrobial effect of nano ZnO coatings against S. aureus, B. cereus and E. coli. Q-SUN irradiation decreased the activity of MHPC coatings containing nanoparticles against P. aeruginosa and C. albicans. An FT-IR analysis clearly showed that ZnO nanoparticles shielded the MHPC coating during Q-SUN irradiation. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Silver Oxide Coatings with High Silver-Ion Elution Rates and Characterization of Bactericidal Activity
Molecules 2017, 22(9), 1487; doi:10.3390/molecules22091487
Received: 7 August 2017 / Revised: 29 August 2017 / Accepted: 30 August 2017 / Published: 7 September 2017
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Abstract
This paper reports the synthesis and characterization of silver oxide films for use as bactericidal coatings. Synthesis parameters, dissolution/elution rate, and bactericidal efficacy are reported. Synthesis conditions were developed to create AgO, Ag2O, or mixtures of AgO and Ag2O
[...] Read more.
This paper reports the synthesis and characterization of silver oxide films for use as bactericidal coatings. Synthesis parameters, dissolution/elution rate, and bactericidal efficacy are reported. Synthesis conditions were developed to create AgO, Ag2O, or mixtures of AgO and Ag2O on surfaces by reactive magnetron sputtering. The coatings demonstrate strong adhesion to many substrate materials and impede the growth of all bacterial strains tested. The coatings are effective in killing Escherichia coli and Staphylococcus aureus, demonstrating a clear zone-of-inhibition against bacteria growing on solid media and the ability to rapidly inhibit bacterial growth in planktonic culture. Additionally, the coatings exhibit very high elution of silver ions under conditions that mimic dynamic fluid flow ranging between 0.003 and 0.07 ppm/min depending on the media conditions. The elution of silver ions from the AgO/Ag2O surfaces was directly impacted by the complexity of the elution media, with a reduction in elution rate when examined in complex cell culture media. Both E. coli and S. aureus were shown to bind ~1 ppm Ag+/mL culture. The elution of Ag+ resulted in no increases in mammalian cell apoptosis after 24 h exposure compared to control, but apoptotic cells increased to ~35% by 48 and 72 h of exposure. Taken together, the AgO/Ag2O coatings described are effective in eliciting antibacterial activity and have potential for application on a wide variety of surfaces and devices. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Biosynthesis of Silver Nanoparticles on Orthodontic Elastomeric Modules: Evaluation of Mechanical and Antibacterial Properties
Molecules 2017, 22(9), 1407; doi:10.3390/molecules22091407
Received: 23 June 2017 / Revised: 11 August 2017 / Accepted: 21 August 2017 / Published: 25 August 2017
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Abstract
In the present study, silver nanoparticles (AgNPs) were synthesized in situ on orthodontic elastomeric modules (OEM) using silver nitrate salts as metal-ion precursors and extract of the plant Hetheroteca inuloides (H. inuloides) as bioreductant via a simple and eco-friendly method. The
[...] Read more.
In the present study, silver nanoparticles (AgNPs) were synthesized in situ on orthodontic elastomeric modules (OEM) using silver nitrate salts as metal-ion precursors and extract of the plant Hetheroteca inuloides (H. inuloides) as bioreductant via a simple and eco-friendly method. The synthesized AgNPs were characterized by UV-visible spectroscopy; scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The surface plasmon resonance peak found at 472 nm confirmed the formation of AgNPs. SEM and TEM images reveal that the particles are quasi-spherical. The EDS analysis of the AgNPs confirmed the presence of elemental silver. The antibacterial properties of OEM with AgNPs were evaluated against the clinical isolates Streptococcus mutans, Lactobacillus casei, Staphylococcus aureus and Escherichia coli using agar diffusion tests. The physical properties were evaluated by a universal testing machine. OEM with AgNPs had shown inhibition halos for all microorganisms in comparison with OEM control. Physical properties increased with respect to the control group. The results suggest the potential of the material to combat dental biofilm and in turn decrease the incidence of demineralization in dental enamel, ensuring their performance in patients with orthodontic treatment. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Synthesis and Antimicrobial Studies of New Antibacterial Azo-Compounds Active against Staphylococcus aureus and Listeria monocytogenes
Molecules 2017, 22(8), 1372; doi:10.3390/molecules22081372
Received: 24 July 2017 / Accepted: 18 August 2017 / Published: 19 August 2017
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Abstract
Some novel (phenyl-diazenyl)phenols (4am) were designed and synthesized to be evaluated for their antibacterial activity. Starting from an active previously-synthesized azobenzene chosen as lead compound, we introduced some modifications and optimization of the structure, in order to improve solubility
[...] Read more.
Some novel (phenyl-diazenyl)phenols (4am) were designed and synthesized to be evaluated for their antibacterial activity. Starting from an active previously-synthesized azobenzene chosen as lead compound, we introduced some modifications and optimization of the structure, in order to improve solubility and drug conveyance. Structures of all newly-synthesized compounds were confirmed by 1H nuclear magnetic resonance (NMR), mass spectrometry, and UV-Vis spectroscopy. Antibacterial activity of the new compounds was tested with the dilution method against the bacteria strains Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa PAO1. All the compounds were selectively active against Gram-positive bacteria. In particular, compounds 4d, 4h, and 4i showed the highest activity against S. aureus and Listeria monocytogenes, reaching remarkable MIC100 values of 4 μg/mL and 8 μg/mL. The relationship between antimicrobial activity and compound structure has suggested that the presence of hydroxyl groups seems to be essential for antimicrobial activity of phenolic compounds. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Development of HA/Ag-NPs Composite Coating from Green Process for Hip Applications
Molecules 2017, 22(8), 1291; doi:10.3390/molecules22081291
Received: 9 June 2017 / Accepted: 31 July 2017 / Published: 8 August 2017
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Abstract
In the present study, biological hydroxyapatite (HA) was obtained from bovine bones through a thermal process. A total of 0% and 1% of silver nanoparticles (Ag-NPs) synthesized from Opuntia ficus (nopal) were added to the biological hydroxyapatite coatings using an atmospheric plasma spray
[...] Read more.
In the present study, biological hydroxyapatite (HA) was obtained from bovine bones through a thermal process. A total of 0% and 1% of silver nanoparticles (Ag-NPs) synthesized from Opuntia ficus (nopal) were added to the biological hydroxyapatite coatings using an atmospheric plasma spray (APS) on a Ti6Al4V substrate. Following this, its antimicrobial efficiency was evaluated against the following bacterial strains: Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. This was conducted according to the Japanese Industrial Standard (JIS) Z2801:2000 “Antimicrobial Product-Test for Antimicrobial Activity and Efficacy”. Scanning electron microscopy (SEM) showed that the silver nanoparticles (Ag-NPs) were evenly distributed on the coating surface. Energy dispersive X-ray spectroscopy (EDX) shows that apatite deposition occurs on a daily basis, maintaining a Ca/P rate between 2.12 and 1.45. Biocompatibility properties were evaluated with osteoblast-like cells (MC3T3-E1) by single-cell gel electrophoresis assay and Tali image cytometry. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Phenolic Compounds Contained in Little-known Wild Fruits as Antiadhesive Agents Against the Beverage-Spoiling Bacteria Asaia spp.
Molecules 2017, 22(8), 1256; doi:10.3390/molecules22081256
Received: 6 July 2017 / Accepted: 23 July 2017 / Published: 28 July 2017
Cited by 1 | PDF Full-text (4028 KB) | HTML Full-text | XML Full-text
Abstract
The aim of the study was to evaluate antioxidant activity and total phenolic content of juice from three different types of fruits: elderberry (Sambucus nigra), lingonberry (Vaccinium vitis-idaea) and cornelian cherry (Cornus mas), and their action against
[...] Read more.
The aim of the study was to evaluate antioxidant activity and total phenolic content of juice from three different types of fruits: elderberry (Sambucus nigra), lingonberry (Vaccinium vitis-idaea) and cornelian cherry (Cornus mas), and their action against adhesion of bacterial strains of Asaia lannensis and Asaia bogorensis isolated from spoiled soft drinks. The antioxidant profiles were determined by total antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl, DPPH), and ferric-reducing antioxidant power (FRAP). Additionally, total polyphenol content (TPC) was investigated. Chemical compositions of juices were tested using the chromatographic techniques: high-performance liquid chromatography (HPLC) and liquid chromatography–mass spectrometry (LC-MS). Adhesion properties of Asaia spp. cells to various abiotic materials were evaluated by luminometry, plate count and fluorescence microscopy. Antioxidant activity of fruit juices expressed as inhibitory concentration (IC50) ranged from 0.042 ± 0.001 (cornelian cherry) to 0.021 ± 0.001 g/mL (elderberry). TPC ranged from 8.02 ± 0.027 (elderberry) to 2.33 ± 0.013 mg/mL (cornelian cherry). Cyanidin-3-sambubioside-5-glucoside, cyanidin-3-glucoside, and cyanidin-3-sambubioside were detected as the major anthocyanins and caffeic, cinnamic, gallic, protocatechuic, and p-coumaric acids as the major phenolic acids. A significant linear correlation was noted between TPC and antioxidant capacity. In the presence of fruit juices a significant decrease of bacterial adhesion from 74% (elderberry) to 67% (lingonberry) was observed. The high phenolic content indicated that these compounds may contribute to the reduction of Asaia spp. adhesion. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Antibacterial Effect of a 4x Cu-TiO2 Coating Simulating Acute Periprosthetic Infection—An Animal Model
Molecules 2017, 22(7), 1042; doi:10.3390/molecules22071042
Received: 23 May 2017 / Revised: 20 June 2017 / Accepted: 20 June 2017 / Published: 23 June 2017
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Abstract
The purpose of our study was to investigate the antibacterial effect of a spacer (Ti6Al4V) coated with 4x Cu-TiO2 in an animal model simulating an acute periprosthetic infection by Staphylococcus aureus. Ti6Al4 bolts contaminated with Staphylococcus aureus were implanted into the
[...] Read more.
The purpose of our study was to investigate the antibacterial effect of a spacer (Ti6Al4V) coated with 4x Cu-TiO2 in an animal model simulating an acute periprosthetic infection by Staphylococcus aureus. Ti6Al4 bolts contaminated with Staphylococcus aureus were implanted into the femoral condyle of rabbits (n = 36) divided into 3 groups. After one week in group 1 (control) the bolts were removed without any replacement. In group2 Ti6Al4V bolts with a 4x Cu-TiO2 coating and in group 3 beads of a gentamicin-PMMA chain were imbedded into the borehole. Microbiological investigation was performed at the primary surgery, at the revision surgery and after scarification of the rabbits 3 weeks after the first surgery. Blood tests were conducted weekly. The initial overall infection rate was 88.9%. In group 2 and 3 a significant decrease of the infection rate was shown in contrast to the control group. The C-reactive protein (CRP) levels declined one week after the first surgery except in the control group where the CRP level even increased. This is the first in vivo study that demonstrated the antibacterial effects of a fourfold Cu-TiO2 coating. For the future, the coating investigated could be a promising option in the treatment of implant-associated infections. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle UV-Curable Aliphatic Silicone Acrylate Organic–Inorganic Hybrid Coatings with Antibacterial Activity
Molecules 2017, 22(6), 964; doi:10.3390/molecules22060964
Received: 31 March 2017 / Revised: 26 May 2017 / Accepted: 7 June 2017 / Published: 9 June 2017
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Abstract
The most effective means to protect against bacterial invasion and to reduce the risk of healthcare-associated infections are antibacterial components synthesis. In this study, a novel process for the synthesis of organic–inorganic hybrid coatings containing silver nanoparticles is presented. Silver nanoparticles and polymer
[...] Read more.
The most effective means to protect against bacterial invasion and to reduce the risk of healthcare-associated infections are antibacterial components synthesis. In this study, a novel process for the synthesis of organic–inorganic hybrid coatings containing silver nanoparticles is presented. Silver nanoparticles and polymer formation proceeds simultaneously through the in situ photoreduction of silver salt to silver nanoparticles and UV-crosslinking of bifunctional aliphatic silicone acrylate. The nanocomposite films with 0.5–1.43 wt % of silver nanoparticles concentration were obtained and investigated. The formation of silver nanoparticles in polymer matrix was confirmed via UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron spectroscopy, and energy dispersive spectroscopy. Our investigations clearly show the formation of silver nanoparticles in silicone acrylate network. Direct photoreduction of silver salt by UV-radiation in the organic media produced silver nanoparticles exhibiting cubic crystal structure. The size of nanoparticles was determined to be near 20 ± 5 nm. The antibacterial activities of coatings were determined using the disc diffusion and direct contact methods. UV-curable silicone acrylate hybrid coatings exhibited antibacterial activity against harmful bacteria strains. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Structure Modification of an Active Azo-Compound as a Route to New Antimicrobial Compounds
Molecules 2017, 22(6), 875; doi:10.3390/molecules22060875
Received: 4 May 2017 / Revised: 19 May 2017 / Accepted: 22 May 2017 / Published: 25 May 2017
Cited by 1 | PDF Full-text (1209 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Some novel (phenyl-diazenyl)phenols 3ag were designed and synthesized to be evaluated for their antimicrobial activity. A previously synthesized molecule, active against bacteria and fungi, was used as lead for modifications and optimization of the structure, by introduction/removal or displacement of hydroxyl
[...] Read more.
Some novel (phenyl-diazenyl)phenols 3ag were designed and synthesized to be evaluated for their antimicrobial activity. A previously synthesized molecule, active against bacteria and fungi, was used as lead for modifications and optimization of the structure, by introduction/removal or displacement of hydroxyl groups on the azobenzene rings. The aim of this work was to evaluate the consequent changes of the antimicrobial activity and to validate the hypothesis that, for these compounds, a plausible mechanism could involve an interaction with protein receptors, rather than an interaction with membrane. All newly synthesized compounds were analyzed by 1H-NMR, DSC thermal analysis and UV-Vis spectroscopy. The in vitro minimal inhibitory concentrations (MIC) of each compound was determined against Gram-positive and Gram-negative bacteria and Candida albicans. Compounds 3b and 3g showed the highest activity against S. aureus and C. albicans, with remarkable MIC values of 10 µg/mL and 3 µg/mL, respectively. Structure-activity relationship studies were capable to rationalize the effect of different substitutions on the phenyl ring of the azobenzene on antimicrobial activity. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle In Vitro Assessment of Early Bacterial Activity on Micro/Nanostructured Ti6Al4V Surfaces
Molecules 2017, 22(5), 832; doi:10.3390/molecules22050832
Received: 29 March 2017 / Revised: 13 May 2017 / Accepted: 16 May 2017 / Published: 18 May 2017
PDF Full-text (15357 KB) | HTML Full-text | XML Full-text
Abstract
It is imperative to understand and systematically compare the initial interactions between bacteria genre and surface properties. Thus, we fabricated a flat, anodized with 80 nm TiO2 nanotubes (NTs), and a rough Ti6Al4V surface. The materials were characterized using field-emission scanning electron
[...] Read more.
It is imperative to understand and systematically compare the initial interactions between bacteria genre and surface properties. Thus, we fabricated a flat, anodized with 80 nm TiO2 nanotubes (NTs), and a rough Ti6Al4V surface. The materials were characterized using field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). We cultured in vitro Staphylococcus epidermidis (S. epidermidis) and Pseudomonas aeruginosa (P. aeruginosa) to evaluate the bacterial-surface behavior by FE-SEM and viability calculation. In addition, the initial effects of human osteoblasts were tested on the materials. Gram-negative bacteria showed promoted adherence and viability over the flat and rough surface, while NTs displayed opposite activity with altered morphology. Gram-positive bacteria illustrated similar cellular architecture over the surfaces but with promoted surface adhesion bonds on the flat alloy. Rough surfaces supported S. epidermidis viability, whilst NTs exhibited lower vitality. NTs advocated promoted better osteoblast organization with enhanced vitality. Gram-positive bacteria suggested preferred adhesion capability over flat and carbon-rich surfaces. Gram-negative bacteria were strongly disturbed by NTs but largely stimulated by flat and rough materials. Our work proposed that the chemical profile of the material surface and the bacterial cell wall characteristics might play an important role in the bacteria-surface interactions. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle One-Step Synthesis of Silver Nanoparticles on Polydopamine-Coated Sericin/Polyvinyl Alcohol Composite Films for Potential Antimicrobial Applications
Molecules 2017, 22(5), 721; doi:10.3390/molecules22050721
Received: 25 March 2017 / Revised: 19 April 2017 / Accepted: 27 April 2017 / Published: 30 April 2017
Cited by 3 | PDF Full-text (18225 KB) | HTML Full-text | XML Full-text
Abstract
Silk sericin has great potential as a biomaterial for biomedical applications due to its good hydrophilicity, reactivity, and biodegradability. To develop multifunctional sericin materials for potential antibacterial application, a one-step synthesis method for preparing silver nanoparticles (AgNPs) modified on polydopamine-coated sericin/polyvinyl alcohol (PVA)
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Silk sericin has great potential as a biomaterial for biomedical applications due to its good hydrophilicity, reactivity, and biodegradability. To develop multifunctional sericin materials for potential antibacterial application, a one-step synthesis method for preparing silver nanoparticles (AgNPs) modified on polydopamine-coated sericin/polyvinyl alcohol (PVA) composite films was developed. Polydopamine (PDA) acted as both metal ion chelating and reducing agent to synthesize AgNPs in situ on the sericin/PVA composite film. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed that polydopamine could effectively facilitate the high-density growth of AgNPs as a 3-D matrix. X-ray diffractometry studies suggested the synthesized AgNPs formed good face-centered cubic crystalline structures. Contact angle measurement and mechanical test indicated AgNPs modified PDA-sericin/PVA composite film had good hydrophilicity and mechanical property. The bacterial growth curve and inhibition zone assays showed the AgNPs modified PDA-sericin/PVA composite film had long-term antibacterial activities. This work develops a new method for the preparation of AgNPs modified PDA-sericin/PVA film with good hydrophilicity, mechanical performance and antibacterial activities for the potential antimicrobial application in biomedicine. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Formulation, Characterization and Properties of Hemp Seed Oil and Its Emulsions
Molecules 2017, 22(5), 700; doi:10.3390/molecules22050700
Received: 9 March 2017 / Revised: 13 April 2017 / Accepted: 25 April 2017 / Published: 27 April 2017
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Abstract
The formulation, characterization, and anticipated antibacterial properties of hemp seed oil and its emulsions were investigated. The oil obtained from the seeds of Cannabis sativa L. in refined and unrefined form was characterized using iodine, saponification, acid values, and gas chromatography, and was
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The formulation, characterization, and anticipated antibacterial properties of hemp seed oil and its emulsions were investigated. The oil obtained from the seeds of Cannabis sativa L. in refined and unrefined form was characterized using iodine, saponification, acid values, and gas chromatography, and was employed for the preparation of stable oil-in-water emulsions. The emulsions were prepared using pairs of non-ionic surfactants (Tween, Span). The effects of the emulsification method (spontaneous emulsification vs. high-intensity stirring), hydrophilic lipophilic balance (HLB), type and concentration of surfactant, and oil type on the size and distribution of the emulsion particles were investigated. It was found that the ability to form stable emulsions with small, initial particle sizes is primarily dependent on the given method of preparation and the HLB value. The most efficient method of emulsification that afforded the best emulsions with the smallest particles (151 ± 1 nm) comprised the high-energy method, and emulsions stable over the long-term were observed at HBL 9 with 10 wt % concentration of surfactants. Under high-intensity emulsification, refined and unrefined oils performed similarly. The oils as well as their emulsions were tested against the growth of selected bacteria using the disk diffusion and broth microdilution methods. The antibacterial effect of hemp seed oil was documented against Micrococcus luteus and Staphylococcus aureus subsp. aureus. The formulated emulsions did not exhibit the antibacterial activity that had been anticipated. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Structural Characterization and Antifungal Studies of Zinc-Doped Hydroxyapatite Coatings
Molecules 2017, 22(4), 604; doi:10.3390/molecules22040604
Received: 6 March 2017 / Revised: 31 March 2017 / Accepted: 7 April 2017 / Published: 9 April 2017
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Abstract
The present study is focused on the synthesis, characterization and antifungal evaluation of zinc-doped hydroxyapatite (Zn:HAp) coatings. The Zn:HAp coatings were deposited on a pure Si (Zn:HAp_Si) and Ti (Zn:HAp_Ti) substrate by a sol-gel dip coating method using a zinc-doped hydroxyapatite nanogel. The
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The present study is focused on the synthesis, characterization and antifungal evaluation of zinc-doped hydroxyapatite (Zn:HAp) coatings. The Zn:HAp coatings were deposited on a pure Si (Zn:HAp_Si) and Ti (Zn:HAp_Ti) substrate by a sol-gel dip coating method using a zinc-doped hydroxyapatite nanogel. The nature of the crystal phase was determined by X-ray diffraction (XRD). The crystalline phase of the prepared Zn:HAp composite was assigned to hexagonal hydroxyapatite in the P63/m space group. The colloidal properties of the resulting Zn:HAp (xZn = 0.1) nanogel were analyzed by Dynamic Light Scattering (DLS) and zeta potential. Scanning Electron Microscopy (SEM) was used to investigate the morphology of the zinc-doped hydroxyapatite (Zn:HAp) nanogel composite and Zn:HAp coatings. The elements Ca, P, O and Zn were found in the Zn:HAp composite. According to the EDX results, the degree of Zn substitution in the structure of Zn:HAp composite was 1.67 wt%. Moreover, the antifungal activity of Zn:HAp_Si and Zn:HAp_Ti against Candida albicans (C. albicans) was evaluated. A decrease in the number of surviving cells was not observed under dark conditions, whereas under daylight and UV light illumination a major decrease in the number of surviving cells was observed. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Mechanism of Action of Electrospun Chitosan-Based Nanofibers against Meat Spoilage and Pathogenic Bacteria
Molecules 2017, 22(4), 585; doi:10.3390/molecules22040585
Received: 28 January 2017 / Revised: 27 March 2017 / Accepted: 28 March 2017 / Published: 6 April 2017
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Abstract
This study investigates the antibacterial mechanism of action of electrospun chitosan-based nanofibers (CNFs), against Escherichia coli, Salmonella enterica serovar Typhimurium, Staphylococcus aureus and Listeria innocua, bacteria frequently involved in food contamination and spoilage. CNFs were prepared by electrospinning of chitosan and
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This study investigates the antibacterial mechanism of action of electrospun chitosan-based nanofibers (CNFs), against Escherichia coli, Salmonella enterica serovar Typhimurium, Staphylococcus aureus and Listeria innocua, bacteria frequently involved in food contamination and spoilage. CNFs were prepared by electrospinning of chitosan and poly(ethylene oxide) (PEO) blends. The in vitro antibacterial activity of CNFs was evaluated and the susceptibility/resistance of the selected bacteria toward CNFs was examined. Strain susceptibility was evaluated in terms of bacterial type, cell surface hydrophobicity, and charge density, as well as pathogenicity. The efficiency of CNFs on the preservation and shelf life extension of fresh red meat was also assessed. Our results demonstrate that the antibacterial action of CNFs depends on the protonation of their amino groups, regardless of bacterial type and their mechanism of action was bactericidal rather than bacteriostatic. Results also indicate that bacterial susceptibility was not Gram-dependent but strain-dependent, with non-virulent bacteria showing higher susceptibility at a reduction rate of 99.9%. The susceptibility order was: E. coli > L. innocua > S. aureus > S. Typhimurium. Finally, an extension of one week of the shelf life of fresh meat was successfully achieved. These results are promising and of great utility for the potential use of CNFs as bioactive food packaging materials in the food industry, and more specifically in meat quality preservation. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Polysaccharide-Based Edible Coatings Containing Cellulase for Improved Preservation of Meat Quality during Storage
Molecules 2017, 22(3), 390; doi:10.3390/molecules22030390
Received: 19 January 2017 / Revised: 21 February 2017 / Accepted: 28 February 2017 / Published: 2 March 2017
Cited by 1 | PDF Full-text (910 KB) | HTML Full-text | XML Full-text
Abstract
The objectives of this study were to optimize the composition of edible food coatings and to extend the shelf-life of pork meat. Initially, nine meat samples were coated with solutions containing chitosan and hydroxypropyl methylcellulose at various cellulase concentrations: 0%, 0.05%, and 0.1%,
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The objectives of this study were to optimize the composition of edible food coatings and to extend the shelf-life of pork meat. Initially, nine meat samples were coated with solutions containing chitosan and hydroxypropyl methylcellulose at various cellulase concentrations: 0%, 0.05%, and 0.1%, stored for 0, 7, and 14 days. Uncoated meat served as the controls. The samples were tested for pH, water activity (aw), total number of microorganisms (TNM), psychrotrophs (P), number of yeast and molds (NYM), colour, and thiobarbituric acid-reactive substances (TBARS). The pH and aw values varied from 5.42 to 5.54 and 0.919 to 0.926, respectively. The reductions in the TNM, P, and NYM after 14 days of storage were approximately 2.71 log cycles, 1.46 log cycles, and 0.78 log cycles, respectively. The enzyme addition improved the stability of the red colour. Significant reduction in TBARS was noted with the inclusion of cellulase in the coating material. Overall, this study provides a promising alternative method for the preservation of pork meat in industry. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Antibacterial Activity of Neat Chitosan Powder and Flakes
Molecules 2017, 22(1), 100; doi:10.3390/molecules22010100
Received: 9 November 2016 / Revised: 21 December 2016 / Accepted: 3 January 2017 / Published: 6 January 2017
Cited by 3 | PDF Full-text (4989 KB) | HTML Full-text | XML Full-text
Abstract
This study investigates the antibacterial activity of neat chitosan powder and flakes against three different bacterial species, Escherichia coli, Listeria innocua and Staphylococcus aureus, which are frequent causes of food spoilage. The effect of chitosan concentration and purity, as well as
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This study investigates the antibacterial activity of neat chitosan powder and flakes against three different bacterial species, Escherichia coli, Listeria innocua and Staphylococcus aureus, which are frequent causes of food spoilage. The effect of chitosan concentration and purity, as well as the influence of temperature, ionic strength (salt) and impact of a solid physical support in the medium are examined. Results show that the antibacterial activity of neat chitosan: (i) requires partial solubilisation; (ii) can be promoted by environmental factors such as adequate temperature range, ionic strength and the presence of a solid physical support that may facilitate the attachment of bacteria; (iii) depends on bacterial species, with a sensitivity order of E. coli > L. innocua > S. aureus; and (iv) increases with chitosan concentration, up to a critical point above which this effect decreases. The latter may be due to remaining proteins in chitosan acting as nutrients for bacteria therefore limiting its antibacterial activity. These results on the direct use of chitosan powder and flakes as potential antimicrobial agents for food protection at pH values lower than the chitosan pKa (6.2–6.7) are promising. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Effect of Film-Forming Alginate/Chitosan Polyelectrolyte Complex on the Storage Quality of Pork
Molecules 2017, 22(1), 98; doi:10.3390/molecules22010098
Received: 3 November 2016 / Revised: 25 December 2016 / Accepted: 4 January 2017 / Published: 6 January 2017
Cited by 3 | PDF Full-text (1298 KB) | HTML Full-text | XML Full-text
Abstract
Meat is one of the most challenging food products in the context of maintaining quality and safety. The aim of this work was to improve the quality of raw/cooked meat by coating it with sodium alginate (A), chitosan (C), and sodium alginate-chitosan polyelectrolyte
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Meat is one of the most challenging food products in the context of maintaining quality and safety. The aim of this work was to improve the quality of raw/cooked meat by coating it with sodium alginate (A), chitosan (C), and sodium alginate-chitosan polyelectrolyte complex (PEC) hydrosols. Antioxidant properties of A, C, and PEC hydrosols were determined. Subsequently, total antioxidant capacity (TAC), sensory quality of raw/cooked pork coated with experimental hydrosols, and antimicrobial efficiency of those hydrosols on the surface microbiota were analysed. Application analyses of hydrosol were performed during 0, 7, and 14 days of refrigerated storage in MAP (modified atmosphere packaging). Ferric reducing antioxidant power (FRAP) and (2,2-diphenyll-picrylhydrazyl (DPPH) analysis confirmed the antioxidant properties of A, C, and PEC. Sample C (1.0%) was characterized by the highest DPPH value (174.67 μM Trolox/mL) of all variants. PEC samples consisted of A 0.3%/C 1.0% and A 0.6%/C 1.0% were characterized by the greatest FRAP value (~7.21 μM Fe2+/mL) of all variants. TAC losses caused by thermal treatment of meat were reduced by 45% by coating meat with experimental hydrosols. Application of PEC on the meat surface resulted in reducing the total number of micro-organisms, psychrotrophs, and lactic acid bacteria by about 61%, and yeast and molds by about 45% compared to control after a two-week storage. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Synthesis, Characterization, and Bactericidal Evaluation of Chitosan/Guanidine Functionalized Graphene Oxide Composites
Molecules 2017, 22(1), 12; doi:10.3390/molecules22010012
Received: 21 November 2016 / Revised: 16 December 2016 / Accepted: 21 December 2016 / Published: 23 December 2016
Cited by 3 | PDF Full-text (10544 KB) | HTML Full-text | XML Full-text
Abstract
In response to the wide spread of microbial contamination induced by bacterial pathogens, the development of novel materials with excellent antibacterial activity is of great interest. In this study, novel antibacterial chitosan (CS) and polyhexamethylene guanidine hydrochloride (PHGC) dual-polymer-functionalized graphene oxide (GO) (GO-CS-PHGC)
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In response to the wide spread of microbial contamination induced by bacterial pathogens, the development of novel materials with excellent antibacterial activity is of great interest. In this study, novel antibacterial chitosan (CS) and polyhexamethylene guanidine hydrochloride (PHGC) dual-polymer-functionalized graphene oxide (GO) (GO-CS-PHGC) composites were designed and easily fabricated. The as-prepared materials were characterized by Fourier transform infrared (FTIR), X-ray photoelectron spectrometer (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA) and Raman spectroscopy. Their antibacterial capability towards bacterial strains was also studied by incubating both Gram-negative bacteria and Gram-positive bacteria in their presence. More significantly, the synergistic antibacterial action of the three components was assayed, and the findings implied that the as-prepared GO-CS-PHGC shows enhanced antibacterial activity when compared to its single components (GO, CS, PHGC or CS-PHGC) and the mixture of individual components. Not only Gram-negative bacteria but also Gram-positive bacteria are greatly inhibited by GO-CS-PHGC composites. The minimum inhibitory concentration (MIC) value of GO-CS-PHGC against E. coli was 32 μg/mL. With the powerful antibacterial activity as well as its low cost and facile preparation, GO-CS-PHGC has potential applications as a novel antibacterial agent in a wide range of biomedical uses. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessArticle Comparative Study on the Characteristics of Weissella cibaria CMU and Probiotic Strains for Oral Care
Molecules 2016, 21(12), 1752; doi:10.3390/molecules21121752
Received: 4 October 2016 / Revised: 9 December 2016 / Accepted: 13 December 2016 / Published: 20 December 2016
Cited by 2 | PDF Full-text (562 KB) | HTML Full-text | XML Full-text
Abstract
Probiotics have been demonstrated as a new paradigm to substitute antibiotic treatment for dental caries, gingivitis, and chronic periodontitis. The present work was conducted to compare the characteristics of oral care probiotics: Weissella cibaria CMU (Chonnam Medical University) and four commercial probiotic strains.
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Probiotics have been demonstrated as a new paradigm to substitute antibiotic treatment for dental caries, gingivitis, and chronic periodontitis. The present work was conducted to compare the characteristics of oral care probiotics: Weissella cibaria CMU (Chonnam Medical University) and four commercial probiotic strains. Survival rates under poor oral conditions, acid production, hydrogen peroxide production, as well as inhibition of biofilm formation, coaggregation, antibacterial activity, and inhibition of volatile sulfur compounds were evaluated. The viability of W. cibaria CMU was not affected by treatment of 100 mg/L lysozyme for 90 min and 1 mM hydrogen peroxide for 6 h. Interestingly, W. cibaria produced less acid and more hydrogen peroxide than the other four probiotics. W. cibaria inhibited biofilm formation by Streptococcus mutans at lower concentrations (S. mutans/CMU = 8) and efficiently coaggregated with Fusobacterium nucleatum. W. cibaria CMU and two commercial probiotics, including Lactobacillus salivarius and Lactobacillus reuteri, showed high antibacterial activities (>97%) against cariogens (S. mutans and Streptococcus sobrinus), and against periodontopathogens (F. nucleatum and Porphyromonas gingivalis). All of the lactic acid bacterial strains in this study significantly reduced levels of hydrogen sulfide and methyl mercaptan produced by F. nucleatum and P. gingivalis (p < 0.05). These results suggest that W. cibaria CMU is applicable as an oral care probiotic. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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Open AccessReview Flexible Antibacterial Coatings
Molecules 2017, 22(5), 813; doi:10.3390/molecules22050813
Received: 14 March 2017 / Revised: 10 May 2017 / Accepted: 10 May 2017 / Published: 16 May 2017
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Abstract
This article reviews the present state of the art in the field of flexible antibacterial coatings which efficiently kill bacteria on their surfaces. Coatings are formed using a reactive magnetron sputtering. The effect of the elemental composition and structure of the coating on
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This article reviews the present state of the art in the field of flexible antibacterial coatings which efficiently kill bacteria on their surfaces. Coatings are formed using a reactive magnetron sputtering. The effect of the elemental composition and structure of the coating on its antibacterial and mechanical properties is explained. The properties of Cr–Cu–O, Al–Cu–N, and Zr–Cu–N antibacterial coatings are used as examples and described in detail. The efficiency of killing of bacteria was tested for the Escherichia coli bacterium. The principle of the formation of thick, flexible antibacterial coatings which are resistant to cracking under bending is explained. It is shown that magnetron sputtering enables production of robust, several-micrometer thick, flexible antibacterial coatings for long-term use. The antibacterial coatings produced by magnetron sputtering present huge potential for many applications. Full article
(This article belongs to the Special Issue Antibacterial Materials and Coatings)
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