Special Issue "Antibacterial Activity of Nanomaterials"

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (28 February 2018)

Special Issue Editor

Guest Editor
Prof. Dr. Ana María Díez-Pascual

Analytical Chemistry, Physical Chemistry and Chemical Engineering Department, Faculty of Biology, Environmental Sciences and Chemistry, Alcalá University, Alcalá de Henares, Spain
Website | E-Mail
Interests: nanomaterials; polymers; nanocomposites; inorganic nanoparticles; antibacterial agents; surfactants; interphases

Special Issue Information

Dear Colleagues,

Bacterial adhesion and proliferation is a serious and increasing concern in everyday life, and is responsible for significant damage in several industries, including textile, water treatment, marine transport, medicine and food packaging. Notwithstanding the enormous efforts by academic researchers and industry, a general solution for restricting bacterial colonization has not been found yet. Therefore, new strategies for controlling bacteria activity are urgently needed and nanomaterials constitute a very promising approach. This Special Issue plans to give an overview of the most recent advances in the field of antibacterial nanomaterials and their applications in diverse areas. The Special Issue is aimed at providing selected contributions on advances in the synthesis, characterization, and applications of nanomaterials with antibacterial activity.

Potential topics include, but are not limited to:
• Antimicrobial nanoparticles
• Antibacterial nanocoatings and nanocomposites
• Mechanisms of action
• Antimicrobial food packaging
• Adverse effects of nanomaterials
• Future perspectives for antimicrobial nanomaterials
• Role of antimicrobial nanomaterials in medicine

Prof. Dr. Ana María Díez-Pascual
Guest Editor

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Keywords

  • Antibacterial activity
  • Nanocomposites
  • Bacterial infection
  • Nanotoxicology
  • Antibiotic resistance

Published Papers (23 papers)

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Open AccessEditorial Antibacterial Activity of Nanomaterials
Nanomaterials 2018, 8(6), 359; https://doi.org/10.3390/nano8060359
Received: 18 May 2018 / Revised: 23 May 2018 / Accepted: 23 May 2018 / Published: 24 May 2018
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(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)

Research

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Open AccessArticle A Method for Efficient Loading of Ciprofloxacin Hydrochloride in Cationic Solid Lipid Nanoparticles: Formulation and Microbiological Evaluation
Nanomaterials 2018, 8(5), 304; https://doi.org/10.3390/nano8050304
Received: 27 February 2018 / Revised: 9 April 2018 / Accepted: 2 May 2018 / Published: 6 May 2018
Cited by 1 | PDF Full-text (1174 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The aim of the study was the production of solid lipid nanoparticles (SLN) loaded with ciprofloxacin (CIP) through two different production techniques, quasi-emulsion solvent diffusion (QESD) and solvent injection (SI). In order to efficaciously entrap the commercial salt form (hydrochloride) of the antibiotic
[...] Read more.
The aim of the study was the production of solid lipid nanoparticles (SLN) loaded with ciprofloxacin (CIP) through two different production techniques, quasi-emulsion solvent diffusion (QESD) and solvent injection (SI). In order to efficaciously entrap the commercial salt form (hydrochloride) of the antibiotic in these lipid systems, a conversion of CIP hydrochloride to the free base was realized in situ, through the addition of triethylamine. To ensure physical stability to the carriers over time and ameliorate the interaction with bacterial cell membranes, positively charged SLN were produced by addition of the cationic lipid didecyldimethylammonium bromide (DDAB). Homogeneous SLN populations with a mean particle sizes of 250–350 nm were produced by both methods; drug encapsulation was over 85% for most samples. The SLN were physically stable for up to nine months both at 4 °C and 25 °C, although the former condition appears more suitable to guarantee the maintenance of the initial particle size distribution. As expected, CIP encapsulation efficiency underwent a slight reduction after nine months of storage, although the initial high drug content values would ensure a residual concentration of the antibiotic in the SLN still appropriate to exert an acceptable antibacterial activity. Selected SLN formulations were subjected to an in vitro microbiological assay against different bacterial strains, to verify the effect of nanoencapsulation on the cell growth inhibitory activity of CIP. In general, CIP-SLN produced without DDAB showed MIC values for CIP comparable to those of the free drug. Conversely, addition of increasing percentages of the cationic lipid, reflected by a progressive increase of the positive value of the Zeta potential, showed a variety of MIC values against the various bacterial strains, but with values 2–4 order of dilution lower than free CIP. An hypothesis of the effect of the cationic lipid upon the increased antibacterial activity of CIP in the nanocarriers is also formulated. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Characterization of Silver Nanomaterials Derived from Marine Streptomyces sp. Al-Dhabi-87 and Its In Vitro Application against Multidrug Resistant and Extended-Spectrum Beta-Lactamase Clinical Pathogens
Nanomaterials 2018, 8(5), 279; https://doi.org/10.3390/nano8050279
Received: 13 March 2018 / Revised: 19 April 2018 / Accepted: 20 April 2018 / Published: 26 April 2018
Cited by 1 | PDF Full-text (2998 KB) | HTML Full-text | XML Full-text
Abstract
A novel antagonistic marine Streptomyces sp. Al-Dhabi-87 that was recovered from the Gulf region of Saudi Arabia was used to synthesize silver nanoparticles (NP) from the culture free extract. The produced NP were confirmed by UV-visible spectroscopy (UV-Vis), high-resolution scanning electron microscope (HRSEM),
[...] Read more.
A novel antagonistic marine Streptomyces sp. Al-Dhabi-87 that was recovered from the Gulf region of Saudi Arabia was used to synthesize silver nanoparticles (NP) from the culture free extract. The produced NP were confirmed by UV-visible spectroscopy (UV-Vis), high-resolution scanning electron microscope (HRSEM), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), Energy Dispersive Spectroscopy (EDAX), and X-ray Powder Diffraction (XRD), and broth micro dilution techniques were employed for the determination of minimum inhibitory concentrations (MIC) values. The synthesized NP was authenticated by alterations in color and wavelength scanning. HRSEM and TEM analysis confirmed that the size of the NP ranged from 10 to 17 nm and that it was spherical in shape. In addition, the FTIR spectrum revealed a variation in the band values from 500 to 3300 cm−1 respectively. Rietveld refinement analysis of the XRD data confirmed the size of the NP, which coincided with the results of the TEM analysis. In addition, the Riveted refinement analysis supported the TEM data. The NP documented significant activity against the wound infection microbial strains, such as Enterococcus faecalis, Staphylococcus epidermidis, and Staphylococcus aureus. Gram negative bacteria, such as Pseudomonas aeruginosa, Klebsiella pneumonia, and Escherichia coli revealed MIC values of 0.039, 0.078, and 0.152 mg/mL, respectively. The promising activity of NP towards extended-spectrum beta-lactamases E.coli, drug resistant Acinetobacter baumannii, and multidrug resistant S. aureus (at 0.018, 0.039, and 0.039 mg/mL, respectively) was advantageous. Overall, NP that were obtained from the novel Streptomyces sp. Al-Dhabi-87, with its promising antimicrobial activity towards the drug resistant pathogens, would be useful for healing infectious diseases. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Effect of Storage Conditions on the Long-Term Stability of Bactericidal Effects for Laser Generated Silver Nanoparticles
Nanomaterials 2018, 8(4), 218; https://doi.org/10.3390/nano8040218
Received: 4 March 2018 / Revised: 28 March 2018 / Accepted: 1 April 2018 / Published: 4 April 2018
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Abstract
Silver nanoparticles (AgNPs) are widely used as antibacterial agents, but their antibacterial durability and the influence by storage conditions have not been thoroughly investigated. In this study, AgNPs were produced using a picosecond laser and stored under three different conditions: daylight, dark and
[...] Read more.
Silver nanoparticles (AgNPs) are widely used as antibacterial agents, but their antibacterial durability and the influence by storage conditions have not been thoroughly investigated. In this study, AgNPs were produced using a picosecond laser and stored under three different conditions: daylight, dark and cold (4 °C). The antibacterial effects of the laser AgNPs were examined against Escherichia coli in either a 14-day interval (frequent air exposure) or a 45-day interval (less frequent air exposure) using a well-diffusion method until the antibacterial effects disappeared. Results showed that the antibacterial activity of the laser generated AgNPs lasted 266 to 405 days. Frequent air exposure increased particle oxidation as measured by high-angle annular dark-field detector for scanning transmission electron microscopy (HAADF-STEM) and X-ray energy dispersive (EDX) spectroscopy, and reduced the antibacterial duration by about 13 weeks. Compared to the chemically produced AgNPs, the antibacterial effect of the laser AgNPs lasted over 100 days longer when tested in the 45-day interval, but was susceptible to oxidation when frequently exposed to the air. The laser generated AgNPs had lower antibacterial activity when stored in cold compared to that stored at room temperature. This study demonstrated the long lasting antibacterial durability of the laser generated AgNPs. Such information could help design future medical applications for the AgNPs. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Antimicrobial Activity of Al2O3, CuO, Fe3O4, and ZnO Nanoparticles in Scope of Their Further Application in Cement-Based Building Materials
Nanomaterials 2018, 8(4), 212; https://doi.org/10.3390/nano8040212
Received: 15 February 2018 / Revised: 15 March 2018 / Accepted: 29 March 2018 / Published: 31 March 2018
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Abstract
Nanoparticles were proposed as antibacterial cement admixtures for the production of cement-based composites. Nevertheless, the standards for evaluation of such admixtures still do not indicate which model organisms to use, particularly in regard to the further application of material. Apart from the known
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Nanoparticles were proposed as antibacterial cement admixtures for the production of cement-based composites. Nevertheless, the standards for evaluation of such admixtures still do not indicate which model organisms to use, particularly in regard to the further application of material. Apart from the known toxicity of nanomaterials, in the case of cement-based composites there are limitations associated with the mixing and dispersion of nanomaterials. Therefore, four nanooxides (Al2O3, CuO, Fe3O4, and ZnO) and seven microorganisms were tested to initially evaluate the applicability of nanooxides in relation to their further use in cement-based composites. Studies of nanoparticles included chemical analysis, microbial growth kinetics, 4- and 24 h toxicity, and biofilm formation assay. Nanooxides showed toxicity against microorganisms in the used concentration, although the populations were able to re-grow. Furthermore, the effect of action was variable even between strains from the same genus. The effect of nanoparticles on biofilms depended on the used strain. Gathered results show several problems that can occur while studying nanoparticles for specific further application. Proper protocols for nanomaterial dispersion prior the preparation of cement-based composites, as well as a standardized approach for their testing, are the fundamental issues that have to be resolved to produce efficient composites. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessFeature PaperArticle Antibacterial and Barrier Properties of Gelatin Coated by Electrospun Polycaprolactone Ultrathin Fibers Containing Black Pepper Oleoresin of Interest in Active Food Biopackaging Applications
Nanomaterials 2018, 8(4), 199; https://doi.org/10.3390/nano8040199
Received: 27 February 2018 / Revised: 22 March 2018 / Accepted: 26 March 2018 / Published: 28 March 2018
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Abstract
The present study evaluated the effect of using electrospun polycaprolactone (PCL) as a barrier coating and black pepper oleoresin (OR) as a natural extract on the morphology, thermal, mechanical, antimicrobial, oxygen, and water vapor barrier properties of solvent cast gelatin (GEL). The antimicrobial
[...] Read more.
The present study evaluated the effect of using electrospun polycaprolactone (PCL) as a barrier coating and black pepper oleoresin (OR) as a natural extract on the morphology, thermal, mechanical, antimicrobial, oxygen, and water vapor barrier properties of solvent cast gelatin (GEL). The antimicrobial activity of the developed multilayer system obtained by the so-called electrospinning coating technique was also evaluated against Staphylococcus aureus strains for 10 days. The results showed that the multilayer system containing PCL and OR increased the thermal resistance, elongated the GEL film, and significantly diminished its permeance to water vapor. Active multilayer systems stored in hermetically closed bottles increased their antimicrobial activity after 10 days by inhibiting the growth of Staphylococcus aureus. This study demonstrates that addition of electrospun PCL ultrathin fibers and OR improved the properties of GEL films, which promoted its potential use in active food packaging applications. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Synthesis of Gold Nanoparticles Using Leaf Extract of Ziziphus zizyphus and their Antimicrobial Activity
Nanomaterials 2018, 8(3), 174; https://doi.org/10.3390/nano8030174
Received: 1 March 2018 / Revised: 14 March 2018 / Accepted: 15 March 2018 / Published: 19 March 2018
Cited by 1 | PDF Full-text (4653 KB) | HTML Full-text | XML Full-text
Abstract
(1) Background: There is a growing need for the development of new methods for the synthesis of nanoparticles. The interest in such particles has raised concerns about the environmental safety of their production methods; (2) Objectives: The current methods of nanoparticle production are
[...] Read more.
(1) Background: There is a growing need for the development of new methods for the synthesis of nanoparticles. The interest in such particles has raised concerns about the environmental safety of their production methods; (2) Objectives: The current methods of nanoparticle production are often expensive and employ chemicals that are potentially harmful to the environment, which calls for the development of “greener” protocols. Herein we describe the synthesis of gold nanoparticles (AuNPs) using plant extracts, which offers an alternative, efficient, inexpensive, and environmentally friendly method to produce well-defined geometries of nanoparticles; (3) Methods: The phytochemicals present in the aqueous leaf extract acted as an effective reducing agent. The generated AuNPs were characterized by Transmission electron microscopy (TEM), Scanning electron microscope (SEM), and Atomic Force microscopy (AFM), X-ray diffraction (XRD), UV-visible spectroscopy, energy dispersive X-ray (EDX), and thermogravimetric analyses (TGA); (4) Results and Conclusions: The prepared nanoparticles were found to be biocompatible and exhibited no antimicrobial or antifungal effect, deeming the particles safe for various applications in nanomedicine. TGA analysis revealed that biomolecules, which were present in the plant extract, capped the nanoparticles and acted as stabilizing agents. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle The Preparation of Graphene Oxide-Silver Nanocomposites: The Effect of Silver Loads on Gram-Positive and Gram-Negative Antibacterial Activities
Nanomaterials 2018, 8(3), 163; https://doi.org/10.3390/nano8030163
Received: 29 January 2018 / Revised: 6 March 2018 / Accepted: 9 March 2018 / Published: 14 March 2018
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Abstract
In this work, silver nanoparticles (Ag NPs) were decorated on thiol (–SH) grafted graphene oxide (GO) layers to investigate the antibacterial activities in Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa). The quasi-spherical, nano-sized Ag NPs were attached
[...] Read more.
In this work, silver nanoparticles (Ag NPs) were decorated on thiol (–SH) grafted graphene oxide (GO) layers to investigate the antibacterial activities in Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa). The quasi-spherical, nano-sized Ag NPs were attached to the GO surface layers, as confirmed by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), respectively. The average size of GO-Ag nanocomposites was significantly reduced (327 nm) from those of pristine GO (962 nm) while the average size of loaded Ag NPs was significantly smaller than the Ag NPs without GO. Various concentrations of AgNO3 solutions (0.1, 0.2, and 0.25 M) were loaded into GO nanosheets and resulted in the Ag contents of 31, 43, and 65%, respectively, with 1–2 nm sizes of Ag NPs anchored on the GO layers. These GO-Ag samples have negative surface charges but the GO-Ag 0.2 M sample (43% Ag) demonstrated the highest antibacterial efficiency. At 10 ppm load of GO-Ag suspension, only a GO-Ag 0.2 M sample yielded slight bacterial inhibition (5.79–7.82%). As the GO-Ag content was doubled to 20 ppm, the GO-Ag 0.2 M composite exhibited ~49% inhibition. When the GO-Ag 0.2 M composite level was raised to 100 ppm, almost 100% inhibition efficiencies were found on both Staphylococcus aureus (S.A.) and Pseudomonas aeruginosa (P.A.), which were significantly higher than using pristine GO (27% and 33% for S.A. and P.A.). The combined effect of GO and Ag nanoparticles demonstrate efficient antibacterial activities. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle A Comparison of the Effects of Packaging Containing Nano ZnO or Polylysine on the Microbial Purity and Texture of Cod (Gadus morhua) Fillets
Nanomaterials 2018, 8(3), 158; https://doi.org/10.3390/nano8030158
Received: 13 February 2018 / Revised: 7 March 2018 / Accepted: 8 March 2018 / Published: 12 March 2018
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Abstract
Portions of fresh Baltic cod fillets were packed into cellulose boxes (control samples), which were covered with Methyl Hydroxypropyl Celluloses (MHPC) coating with 2% polylysine. The cellulose boxes had square PE films and were enclosed in MHPC coating containing ZnO nanoparticles. The cod
[...] Read more.
Portions of fresh Baltic cod fillets were packed into cellulose boxes (control samples), which were covered with Methyl Hydroxypropyl Celluloses (MHPC) coating with 2% polylysine. The cellulose boxes had square PE films and were enclosed in MHPC coating containing ZnO nanoparticles. The cod fillets were stored at 5 °C and examined after 72 h and 144 h storage times. Results obtained in this study showed that the textural parameters of the cod fillets increased, with both Springiness and Cohesiveness found greater after 144 h of storage for all analysed packaging materials. The Gumminess of fillets increased after storage, but the lowest increase was noted in cod samples that were stored in boxes containing PE films with ZnO nanoparticles. It was found that water loss from the cod fillets in these boxes was also lowest. The Adhesiveness of the fish samples stored in boxes devoid of active coatings also increased. In contrast to the packaging material devoid of active coatings, the storage of fillets in active coating boxes resulted in a decrease of adhesiveness. Microbial analysis showed that packaging material containing nano-ZnO was found to be more active against mesophilic and psychotropic bacterial cells than the coatings with polylysine after 72 h and 144 h of storage. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Inhibition of E. coli Growth by Nanodiamond and Graphene Oxide Enhanced by Luria-Bertani Medium
Nanomaterials 2018, 8(3), 140; https://doi.org/10.3390/nano8030140
Received: 23 January 2018 / Revised: 16 February 2018 / Accepted: 24 February 2018 / Published: 1 March 2018
Cited by 1 | PDF Full-text (2670 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Nanodiamonds (NDs) and graphene oxide (GO) are modern carbon-based nanomaterials with promising features for the inhibition of microorganism growth ability. Here we compare the effects of nanodiamond and graphene oxide in both annealed (oxidized) and reduced (hydrogenated) forms in two types of cultivation
[...] Read more.
Nanodiamonds (NDs) and graphene oxide (GO) are modern carbon-based nanomaterials with promising features for the inhibition of microorganism growth ability. Here we compare the effects of nanodiamond and graphene oxide in both annealed (oxidized) and reduced (hydrogenated) forms in two types of cultivation media—Luria-Bertani (LB) and Mueller-Hinton (MH) broths. The comparison shows that the number of colony forming unit (CFU) of Escherichia coli is significantly lowered (45%) by all the nanomaterials in LB medium for at least 24 h against control. On the contrary, a significant long-term inhibition of E. coli growth (by 45%) in the MH medium is provided only by hydrogenated NDs terminated with C-HX groups. The use of salty agars did not enhance the inhibition effects of nanomaterials used, i.e. disruption of bacterial membrane or differences in ionic concentrations do not play any role in bactericidal effects of nanomaterials used. The specific role of the ND and GO on the enhancement of the oxidative stress of bacteria or possible wrapping bacteria by GO nanosheets, therefore isolating them from both the environment and nutrition was suggested. Analyses by infrared spectroscopy, photoelectron spectroscopy, scanning electron microscopy and dynamic light scattering corroborate these conclusions. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Combined Effect of Ultrasound Stimulations and Autoclaving on the Enhancement of Antibacterial Activity of ZnO and SiO2/ZnO Nanoparticles
Nanomaterials 2018, 8(3), 129; https://doi.org/10.3390/nano8030129
Received: 7 February 2018 / Revised: 17 February 2018 / Accepted: 17 February 2018 / Published: 25 February 2018
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Abstract
This study investigates the antibacterial activity (ABA) of suspensions of pure ZnO nanoparticles (ZnO-NPs) and mesoporous silica doped with ZnO (ZnO-UVM7), as well as electrospun nanofibers containing those nanoparticles. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of these two materials
[...] Read more.
This study investigates the antibacterial activity (ABA) of suspensions of pure ZnO nanoparticles (ZnO-NPs) and mesoporous silica doped with ZnO (ZnO-UVM7), as well as electrospun nanofibers containing those nanoparticles. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of these two materials were also determined under the same conditions. The results showed a concentration-dependent effect of antibacterial nanoparticles on the viability of Escherichia coli (E. coli). Moreover, the combination of the stimulations and sterilization considerably enhanced the antimicrobial activity (AMA) of the ZnO suspensions. Poly (lactic acid) (PLA) solutions in 2,2,2-trifluoroethanol (TFE) were mixed with different contents of nanoparticles and spun into nonwoven mats by the electrospinning process. The morphology of the mats was analyzed by scanning electron microscopy (SEM). The amount of nanoparticles contained in the mats was determined by thermogravimetric analysis (TGA). The obtained PLA-based mats showed a fibrous morphology, with an average diameter ranging from 350 to 450 nm, a porosity above 85%, but with the nanoparticles agglomeration on their surface. TGA analysis showed that the loss of ZnO-NPs increased with the increase of ZnO-NPs content in the PLA solutions and reached 79% for 1 wt % of ZnO-NPs, which was mainly due to the aggregation of nanoparticles in solution. The ABA of the obtained PLA mats was evaluated by the dynamic method according to the ASTM standard E2149. The results showed that, above an optimal concentration, the nanoparticle agglomeration reduced the antimicrobial efficiency of PLA mats. These mats have potential features for use as antimicrobial food packaging material. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Antibacterial Effects of Chitosan/Cationic Peptide Nanoparticles
Nanomaterials 2018, 8(2), 88; https://doi.org/10.3390/nano8020088
Received: 19 December 2017 / Revised: 23 January 2018 / Accepted: 30 January 2018 / Published: 5 February 2018
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Abstract
This study attempted to develop chitosan-based nanoparticles with increased stability and antibacterial activity. The chitosan/protamine hybrid nanoparticles were formed based on an ionic gelation method by mixing chitosan with protamine and subsequently cross-linking the mixtures with sodium tripolyphosphate (TPP). The effects of protamine
[...] Read more.
This study attempted to develop chitosan-based nanoparticles with increased stability and antibacterial activity. The chitosan/protamine hybrid nanoparticles were formed based on an ionic gelation method by mixing chitosan with protamine and subsequently cross-linking the mixtures with sodium tripolyphosphate (TPP). The effects of protamine on the chemical structures, physical properties, and antibacterial activities of the hybrid nanoparticles were investigated. The antibacterial experiments demonstrated that the addition of protamine (125 µg/mL) in the hybrid nanoparticles (500 µg/mL chitosan and 166.67 µg/mL TPP) improved the antimicrobial specificity with the minimum inhibitory concentration (MIC) value of 31.25 µg/mL towards Escherichia coli (E. coli), while the MIC value was higher than 250 µg/mL towards Bacillus cereus. The chitosan/protamine hybrid nanoparticles induced the formation of biofilm-like structure in B. cereus and non-motile-like structure in E. coli. The detection of bacterial cell ruptures showed that the inclusion of protamine in the hybrid nanoparticles caused different membrane permeability compared to chitosan nanoparticles and chitosan alone. The chitosan/protamine nanoparticles also exhibited lower binding affinity towards B. cereus than E. coli. The results suggested that the hybridization of chitosan with protamine improved the antibacterial activity of chitosan nanoparticles towards pathogenic E. coli, but the inhibitory effect against probiotic B. cereus was significantly reduced. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Novel Hybrid Formulations Based on Thiourea Derivatives and Core@Shell Fe3O4@C18 Nanostructures for the Development of Antifungal Strategies
Nanomaterials 2018, 8(1), 47; https://doi.org/10.3390/nano8010047
Received: 16 November 2017 / Revised: 22 December 2017 / Accepted: 5 January 2018 / Published: 17 January 2018
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Abstract
The continuously increasing global impact of fungal infections is requiring the rapid development of novel antifungal agents. Due to their multiple pharmacological activities, thiourea derivatives represent privileged candidates for shaping new drugs. We report here the preparation, physico-chemical characterization and bioevaluation of hybrid
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The continuously increasing global impact of fungal infections is requiring the rapid development of novel antifungal agents. Due to their multiple pharmacological activities, thiourea derivatives represent privileged candidates for shaping new drugs. We report here the preparation, physico-chemical characterization and bioevaluation of hybrid nanosystems based on new 2-((4-chlorophenoxy)methyl)-N-(substituted phenylcarbamo-thioyl)benzamides and Fe3O4@C18 core@shell nanoparticles. The new benzamides were prepared by an efficient method, then their structure was confirmed by spectral studies and elemental analysis and they were further loaded on Fe3O4@C18 nanostructures. Both the obtained benzamides and the resulting hybrid nanosystems were tested for their efficiency against planktonic and adherent fungal cells, as well as for their in vitro biocompatibility, using mesenchymal cells. The antibiofilm activity of the obtained benzamides was dependent on the position and nature of substituents, demonstrating that structure modulation could be a very useful approach to enhance their antimicrobial properties. The hybrid nanosystems have shown an increased efficiency in preventing the development of Candida albicans (C. albicans) biofilms and moreover, they exhibited a good biocompatibility, suggesting that Fe3O4@C18core@shell nanoparticles could represent promising nanocarriers for antifungal substances, paving the way to the development of novel effective strategies with prophylactic and therapeutic value for fighting biofilm associated C. albicans infections. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Gentamicin Sulfate PEG-PLGA/PLGA-H Nanoparticles: Screening Design and Antimicrobial Effect Evaluation toward Clinic Bacterial Isolates
Nanomaterials 2018, 8(1), 37; https://doi.org/10.3390/nano8010037
Received: 15 December 2017 / Revised: 2 January 2018 / Accepted: 4 January 2018 / Published: 12 January 2018
Cited by 3 | PDF Full-text (3490 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Nanotechnology is a promising approach both for restoring or enhancing activity of old and conventional antimicrobial agents and for treating intracellular infections by providing intracellular targeting and sustained release of drug inside infected cells. The present paper introduces a formulation study of gentamicin
[...] Read more.
Nanotechnology is a promising approach both for restoring or enhancing activity of old and conventional antimicrobial agents and for treating intracellular infections by providing intracellular targeting and sustained release of drug inside infected cells. The present paper introduces a formulation study of gentamicin loaded biodegradable nanoparticles (Nps). Solid-oil-in water technique was studied for gentamicin sulfate nanoencapsulation using uncapped Polylactide-co-glycolide (PLGA-H) and Polylactide-co-glycolide-co-Polyethylenglycol (PLGA-PEG) blends. Screening design was applied to optimize: drug payload, Nps size and size distribution, stability and resuspendability after freeze-drying. PLGA-PEG concentration resulted most significant factor influencing particles size and drug content (DC): 8 w/w% DC and 200 nm Nps were obtained. Stirring rate resulted most influencing factor for size distribution (PDI): 700 rpm permitted to obtain homogeneous Nps dispersion (PDI = 1). Further experimental parameters investigated, by 23 screening design, were: polymer blend composition (PLGA-PEG and PLGA-H), Polyvinylalcohol (PVA) and methanol concentrations into aqueous phase. Drug content was increased to 10.5 w/w%. Nanoparticle lyophilization was studied adding cryoprotectants, polyvinypirrolidone K17 and K32, and sodiumcarboxymetylcellulose. Freeze-drying protocol was optimized by a mixture design. A freeze-dried Nps powder free resuspendable with stable Nps size and payload, was developed. The powder was tested on clinic bacterial isolates demonstrating that after encapsulation, gentamicin sulfate kept its activity. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Cationic Biomimetic Particles of Polystyrene/Cationic Bilayer/Gramicidin for Optimal Bactericidal Activity
Nanomaterials 2017, 7(12), 422; https://doi.org/10.3390/nano7120422
Received: 30 October 2017 / Revised: 23 November 2017 / Accepted: 29 November 2017 / Published: 2 December 2017
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Abstract
Nanostructured particles of polystyrene sulfate (PSS) covered by a cationic lipid bilayer of dioctadecyldimethylammonium bromide (DODAB) incorporated gramicidin D (Gr) yielding optimal and broadened bactericidal activity against both Escherichia coli and Staphylococcus aureus. The adsorption of DODAB/Gr bilayer onto PSS nanoparticles (NPs)
[...] Read more.
Nanostructured particles of polystyrene sulfate (PSS) covered by a cationic lipid bilayer of dioctadecyldimethylammonium bromide (DODAB) incorporated gramicidin D (Gr) yielding optimal and broadened bactericidal activity against both Escherichia coli and Staphylococcus aureus. The adsorption of DODAB/Gr bilayer onto PSS nanoparticles (NPs) increased the zeta-average diameter by 8–10 nm, changed the zeta-potential of the NPs from negative to positive, and yielded a narrow size distributions for the PSS/DODAB/Gr NPs, which displayed broad and maximal microbicidal activity at very small concentrations of the antimicrobials, namely, 0.057 and 0.0057 mM DODAB and Gr, respectively. The results emphasized the advantages of highly-organized, nanostructured, and cationic particles to achieve hybrid combinations of antimicrobials with broad spectrum activity at considerably reduced DODAB and Gr concentrations. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Inhibition of Bacteria Associated with Wound Infection by Biocompatible Green Synthesized Gold Nanoparticles from South African Plant Extracts
Nanomaterials 2017, 7(12), 417; https://doi.org/10.3390/nano7120417
Received: 11 October 2017 / Revised: 9 November 2017 / Accepted: 10 November 2017 / Published: 26 November 2017
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Abstract
Unlike conventional physical and chemical methods, the biogenic synthesis of gold nanoparticles (GNPs) is considered a green and non-toxic approach to produce biocompatible GNPs that can be utilized in various biomedical applications. This can be achieved by using plant-derived phytochemicals to reduce gold
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Unlike conventional physical and chemical methods, the biogenic synthesis of gold nanoparticles (GNPs) is considered a green and non-toxic approach to produce biocompatible GNPs that can be utilized in various biomedical applications. This can be achieved by using plant-derived phytochemicals to reduce gold salt into GNPs. Several green synthesized GNPs have been shown to have antibacterial effects, which can be applied in wound dressings to prevent wound infections. Therefore, the aim of this study is to synthesize biogenic GNPs from the South African Galenia africana and Hypoxis hemerocallidea plants extracts and evaluate their antibacterial activity, using the Alamar blue assay, against bacterial strains that are known to cause wound infections. Additionally, we investigated the toxicity of the biogenic GNPs to non-cancerous human fibroblast cells (KMST-6) using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay. In this paper, spherical GNPs, with particle sizes ranging from 9 to 27 nm, were synthesized and fully characterized. The GNPs from H. hemerocallidea exhibited antibacterial activity against all the tested bacterial strains, whereas GNPs produced from G. africana only exhibited antibacterial activity against Pseudomonas aeruginosa. The GNPs did not show any significant toxicity towards KMST-6 cells, which may suggest that these nanoparticles can be safely applied in wound dressings. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Synergistic Effect of Fluorinated and N Doped TiO2 Nanoparticles Leading to Different Microstructure and Enhanced Photocatalytic Bacterial Inactivation
Nanomaterials 2017, 7(11), 391; https://doi.org/10.3390/nano7110391
Received: 9 October 2017 / Revised: 9 November 2017 / Accepted: 10 November 2017 / Published: 15 November 2017
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Abstract
This work focuses on the development of a facile and scalable wet milling method followed by heat treatment to prepare fluorinated and/or N-doped TiO2 nanopowders with improved photocatalytic properties under visible light. The structural and electronic properties of doped particles were investigated
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This work focuses on the development of a facile and scalable wet milling method followed by heat treatment to prepare fluorinated and/or N-doped TiO2 nanopowders with improved photocatalytic properties under visible light. The structural and electronic properties of doped particles were investigated by various techniques. The successful doping of TiO2 was confirmed by X-ray photoelectron spectroscopy (XPS), and the atoms appeared to be mainly located in interstitial positions for N whereas the fluorination is located at the TiO2 surface. The formation of intragap states was found to be responsible for the band gap narrowing leading to the faster bacterial inactivation dynamics observed for the fluorinated and N doped TiO2 particles compared to N-doped TiO2. This was attributed to a synergistic effect. The results presented in this study confirmed the suitability of the preparation approach for the large-scale production of cost-efficient doped TiO2 for effective bacterial inactivation. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle One-Pot Facile Methodology to Synthesize Chitosan-ZnO-Graphene Oxide Hybrid Composites for Better Dye Adsorption and Antibacterial Activity
Nanomaterials 2017, 7(11), 363; https://doi.org/10.3390/nano7110363
Received: 16 September 2017 / Revised: 27 October 2017 / Accepted: 30 October 2017 / Published: 2 November 2017
Cited by 2 | PDF Full-text (6658 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Novel chitosan–ZnO–graphene oxide hybrid composites were prepared using a one-pot chemical strategy, and their dye adsorption characteristics and antibacterial activity were demonstrated. The prepared chitosan and the hybrids such as chitosan–ZnO and chitosan–ZnO–graphene oxide were characterized by UV-Vis absorption spectroscopy, X-ray diffraction, Fourier
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Novel chitosan–ZnO–graphene oxide hybrid composites were prepared using a one-pot chemical strategy, and their dye adsorption characteristics and antibacterial activity were demonstrated. The prepared chitosan and the hybrids such as chitosan–ZnO and chitosan–ZnO–graphene oxide were characterized by UV-Vis absorption spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The thermal and mechanical properties indicate a significant improvement over chitosan in the hybrid composites. Dye adsorption experiments were carried out using methylene blue and chromium complex as model pollutants with the function of dye concentration. The antibacterial properties of chitosan and the hybrids were tested against Gram-positive and Gram-negative bacterial species, which revealed minimum inhibitory concentrations (MICs) of 0.1 µg/mL. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Poly-L-arginine Coated Silver Nanoprisms and Their Anti-Bacterial Properties
Nanomaterials 2017, 7(10), 296; https://doi.org/10.3390/nano7100296
Received: 26 July 2017 / Revised: 13 September 2017 / Accepted: 22 September 2017 / Published: 27 September 2017
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Abstract
The aim of this study was to test the effect of two different morphologies of silver nanoparticles, spheres, and prisms, on their antibacterial properties when coated with poly-L-arginine (poly-Arg) to enhance the interactions with cells. Silver nanoparticle solutions were characterized by
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The aim of this study was to test the effect of two different morphologies of silver nanoparticles, spheres, and prisms, on their antibacterial properties when coated with poly-L-arginine (poly-Arg) to enhance the interactions with cells. Silver nanoparticle solutions were characterized by UV–visible spectroscopy, transmission electron microscopy, dynamic light scattering, zeta potential, as well as antimicrobial tests. These ultimately showed that a prismatic morphology exhibited stronger antimicrobial effects against Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica. The minimum bactericidal concentration was found to be 0.65 μg/mL in the case of a prismatic AgNP-poly-Arg-PVP (silver nanoparticle-poly-L-arginine-polyvinylpyrrolidone) nanocomposite. The anticancer cell activity of the silver nanoparticles was also studied, where the maximum effect against a HeLa cell line was 80% mortality with a prismatic AgNP-poly-Arg-PVP nanocomposite at a concentration of 11 μg/mL. The antimicrobial activity of these silver nanocomposites demonstrates the potential of such coated silver nanoparticles in the area of nano-medicine. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Nanosilver–Silica Composite: Prolonged Antibacterial Effects and Bacterial Interaction Mechanisms for Wound Dressings
Nanomaterials 2017, 7(9), 261; https://doi.org/10.3390/nano7090261
Received: 24 July 2017 / Revised: 22 August 2017 / Accepted: 3 September 2017 / Published: 6 September 2017
Cited by 4 | PDF Full-text (6915 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Infected superficial wounds were traditionally controlled by topical antibiotics until the emergence of antibiotic-resistant bacteria. Silver (Ag) is a kernel for alternative antibacterial agents to fight this resistance quandary. The present study demonstrates a method for immobilizing small-sized (~5 nm) silver nanoparticles on
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Infected superficial wounds were traditionally controlled by topical antibiotics until the emergence of antibiotic-resistant bacteria. Silver (Ag) is a kernel for alternative antibacterial agents to fight this resistance quandary. The present study demonstrates a method for immobilizing small-sized (~5 nm) silver nanoparticles on silica matrix to form a nanosilver–silica (Ag–SiO2) composite and shows the prolonged antibacterial effects of the composite in vitro. The composite exhibited a rapid initial Ag release after 24 h and a slower leaching after 48 and 72 h and was effective against both methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). Ultraviolet (UV)-irradiation was superior to filter-sterilization in retaining the antibacterial effects of the composite, through the higher remaining Ag concentration. A gauze, impregnated with the Ag–SiO2 composite, showed higher antibacterial effects against MRSA and E. coli than a commercial Ag-containing dressing, indicating a potential for the management and infection control of superficial wounds. Transmission and scanning transmission electron microscope analyses of the composite-treated MRSA revealed an interaction of the released silver ions with the bacterial cytoplasmic constituents, causing ultimately the loss of bacterial membranes. The present results indicate that the Ag–SiO2 composite, with prolonged antibacterial effects, is a promising candidate for wound dressing applications. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Antimicrobial Properties of Silver Cations Substituted to Faujasite Mineral
Nanomaterials 2017, 7(9), 240; https://doi.org/10.3390/nano7090240
Received: 10 July 2017 / Revised: 7 August 2017 / Accepted: 25 August 2017 / Published: 27 August 2017
Cited by 1 | PDF Full-text (2269 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A goal of our study was to find an alternative to nano-silver-based antimicrobial materials which would contain active silver immobilized in a solid matrix that prevents its migration into the surrounding environment. In this study, we investigated whether silver cations dispersed in an
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A goal of our study was to find an alternative to nano-silver-based antimicrobial materials which would contain active silver immobilized in a solid matrix that prevents its migration into the surrounding environment. In this study, we investigated whether silver cations dispersed in an atomic form and trapped in an ion-exchanged zeolite show comparable antimicrobial activity to silver nanoparticles (NPs). The biocidal active material was prepared from the sodium form of faujasite type zeolite in two steps: (1) exchange with silver cations, (2) removal of the external silver oxide NPs by elution with Na2EDTA solution. The modified biocidal zeolite was then added to paper pulp to obtain sheets. The zeolite paper samples and reference samples containing silver NPs were tested in terms of biocidal activity against an array of fungi and bacteria strains, including Escherichia coli, Serratia marcescens, Bacillus subtilis, Bacillus megaterium, Trichoderma viride, Chaetomium globosum, Aspergillus niger, Cladosporium cladosporioides, and Mortierella alpina. The paper with the modified faujasite additive showed higher or similar antibacterial and antifungal activities towards the majority of tested microbes in comparison with the silver NP-filled paper. A reverse effect was observed for the Mortierella alpina strain. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Eco-Friendly Acaricidal Effects of Nylon 66 Nanofibers via Grafted Clove Bud Oil-Loaded Capsules on House Dust Mites
Nanomaterials 2017, 7(7), 179; https://doi.org/10.3390/nano7070179
Received: 23 June 2017 / Revised: 4 July 2017 / Accepted: 6 July 2017 / Published: 10 July 2017
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Abstract
Acaricidal nylon 66 fabrics (AN66Fs) grafted with clove oil-loaded microcapsules (COMCs) were developed against Dermatophagoides farina (D. gallinae). The average diameter was about 2.9 µm with a range of 100 nm–8.5 µm. COMCs carried clove oil loading of about 65 vol
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Acaricidal nylon 66 fabrics (AN66Fs) grafted with clove oil-loaded microcapsules (COMCs) were developed against Dermatophagoides farina (D. gallinae). The average diameter was about 2.9 µm with a range of 100 nm–8.5 µm. COMCs carried clove oil loading of about 65 vol %. COMCs were chemically grafted to electrospun nylon nanofibers by the chemical reactions between –OH groups of COMCs and –COOH end groups of nylon fabrics to form ester linkages. AN66Fs had an effect on D. farinae depending on COMCs loadings. The increase in COMCs loading of AN66Fs from 5 to 15 wt % increased from 22% to 93% mortality against D. farinae within 72 h. However, AN66Fs containing over 20 wt % COMCs were more effective, showing up to 100% mortality within 24 h because the large amount of monoterpene alcohol, eugenol. This research suggests the use of clove oil and its major constituent eugenol as eco-friendly bioactive agents that can serve as a replacement for synthetic acaricides in controlling the population of D. farinae. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessCommentary Antimicrobial Nanomaterials: Why Evolution Matters
Nanomaterials 2017, 7(10), 283; https://doi.org/10.3390/nano7100283
Received: 29 August 2017 / Revised: 14 September 2017 / Accepted: 18 September 2017 / Published: 21 September 2017
Cited by 3 | PDF Full-text (247 KB) | HTML Full-text | XML Full-text
Abstract
Due to the widespread occurrence of multidrug resistant microbes there is increasing interest in the use of novel nanostructured materials as antimicrobials. Specifically, metallic nanoparticles such as silver, copper, and gold have been deployed due to the multiple impacts they have on bacterial
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Due to the widespread occurrence of multidrug resistant microbes there is increasing interest in the use of novel nanostructured materials as antimicrobials. Specifically, metallic nanoparticles such as silver, copper, and gold have been deployed due to the multiple impacts they have on bacterial physiology. From this, many have concluded that such nanomaterials represent steep obstacles against the evolution of resistance. However, we have already shown that this view is fallacious. For this reason, the significance of our initial experiments are beginning to be recognized in the antimicrobial effects of nanomaterials literature. This recognition is not yet fully understood and here we further explain why nanomaterials research requires a more nuanced understanding of core microbial evolution principles. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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