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The pathogenesis of chronic wounds (CW) involves a multifaceted interplay of biochemical, immunological, hematological, and microbiological interactions. Biofilm development is a significant virulence trait which enhances microbial survival and pathogenicity and has various implications on the development and management of CW. Biofilms induce a prolonged suboptimal inflammation in the wound microenvironment, associated with delayed healing. The composition of wound fluid (WF) adds more complexity to the subject, with proven pro-inflammatory properties and an intricate crosstalk among cytokines, chemokines, microRNAs, proteases, growth factors, and ECM components. One approach to achieve information on the mechanisms of disease progression and therapeutic response is the use of multiple high-throughput 'OMIC' modalities (genomic, proteomic, lipidomic, metabolomic assays), facilitating the discovery of potential biomarkers for wound healing, which may represent a breakthrough in this field and a major help in addressing delayed wound healing. In this review article, we aim to summarize the current progress achieved in host-microbiome crosstalk in the spectrum of CW healing and highlight future innovative strategies to boost the host immune response against infections, focusing on the interaction between pathogens and their hosts (for instance, by harnessing microorganisms like probiotics), which may serve as the prospective advancement of vaccines and treatments against infections.

Staphylococcus aureus (Gram-positive) and Pseudomonas aeruginosa (Gram-negative) bacteria represent major infectious threats in the hospital environment due to their wide distribution, opportunistic behavior, and increasing antibiotic resistance. This study reports on the deposition of polyvinylpyrrolidone/antibiotic/isoflavonoid thin films by the matrix-assisted pulsed laser evaporation (MAPLE) method as anti-adhesion barrier coatings, on biomedical surfaces for improved resistance to microbial colonization. The thin films were characterized by Fourier transform infrared spectroscopy, infrared microscopy, and scanning electron microscopy. In vitro biological assay tests were performed to evaluate the influence of the thin films on the development of biofilms formed by Gram-positive and Gram-negative bacterial strains. In vitro biocompatibility tests were assessed on human endothelial cells examined for up to five days of incubation, via qualitative and quantitative methods. The results of this study revealed that the laser-fabricated coatings are biocompatible and resistant to microbial colonization and biofilm formation, making them successful candidates for biomedical devices and contact surfaces that would otherwise be amenable to contact transmission.

Wound healing involves a complex interaction between immunity and other natural host processes, and to succeed it requires a well-defined cascade of events. Chronic wound infections can be mono- or polymicrobial but their major characteristic is their ability to develop a biofilm. A biofilm reduces the effectiveness of treatment and increases resistance. A biofilm is an ecosystem on its own, enabling the bacteria and the host to establish different social interactions, such as competition or cooperation. With an increasing incidence of chronic wounds and, implicitly, of chronic biofilm infections, there is a need for alternative therapeutic agents. Nanotechnology shows promising openings, either by the intrinsic antimicrobial properties of nanoparticles or their function as drug carriers. Nanoparticles and nanostructured coatings can be active at low concentrations toward a large variety of infectious agents; thus, they are unlikely to elicit emergence of resistance. Nanoparticles might contribute to the modulation of microbial colonization and biofilm formation in wounds. This comprehensive review comprises the pathogenesis of chronic wounds, the role of chronic wound colonization and infection in the healing process, the conventional and alternative topical therapeutic approaches designed to combat infection and stimulate healing, as well as revolutionizing therapies such as nanotechnology-based wound healing approaches., Competing Interests: The authors declare no conflict of interest.

The increasing rate of antibiotic resistant bacteria associated with nosocomial infections in severely ill patients has urged the need for new antibacterial therapies. Nanostructured materials represent emerging innovative approaches to controlled delivery of different antimicrobial drugs. Delivery systems encapsulating natural compounds with antibacterial effects, such as essential oils have shown a great potential. Herein we report the development of SiO 2 mesoporous nanosystems loaded with eucalyptus (EUC), orange (ORA), and cinnamon (CIN) essential oils. These systems were characterized with respect to morphology (using scanning electron microscopy, SEM, and transmission electron microscopy, TEM), porosity (by BET and TEM analysis), chemical composition (by X-ray diffraction, XRD, and Fourier transform infrared spectrometry, FTIR) and loading capacity (by thermogravimetric analysis, TGA). The anti-bacterial and anti-adherence effects were tested against clinically relevant microbial species (Staphylococcus aureus ATCC 25923; Escherichia coli ATCC 25922; and Candida albicans ATCC 10231), while the biocompatibility was evaluated by in vitro tests with L929 mouse fibroblast cells., (Copyright © 2017 Elsevier B.V. All rights reserved.)

As the severe infections caused by resistant pathogens and biofilm embedded bacteria continue to emerge, alternative antimicrobial strategies could represent a solution. Recent studies support the development of molecular approaches (through signaling molecules) aiming to fight infections by modulating the virulence, behavior and formation of resistance structures such as biofilms. The utilization of such formulations would offer the advantage of reducing the selection of resistant isolates, since most of the proposed molecules do not interfere with the population fitness if utilized in low amounts. Despite the promising results, these therapies are delaying to be applied in the clinical context mainly because of the following: (i) limited knowledge regarding their long and medium term effect, (ii) specific properties that make most of these molecules difficult to be utilized in pharmacological formulations, (iii) low stability, (iv) difficulty to reach a target within the host body, and (v) limited availability. For reducing most of these disadvantages, nanotechnology seem to offer the best option through the development of nanostructured materials and nanoparticles able to improve the efficiency of molecular virulence modulators and novel antimicrobial compounds and to ensure their targeted delivery and controlled release., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The majority of chronic infections are associated with mono- or polymicrobial biofilms, having a significant impact on the patients' quality of life and survival rates. Although the use of medical devices revolutionized health care services and significantly improved patient outcomes, it also led to complications associated with biofilms and to the emergence of multidrug resistant bacteria. Immunocompromised patients, institutionalized or hospitalized individuals, elderly people are at greater risk due to life-threatening septic complications, but immunocompetent individuals with predisposing genetic or acquired diseases can also be affected, almost any body part being able to shelter persistent biofilms. Moreover, chronic biofilm-related infections can lead to the occurrence of systemic diseases, as in the case of chronic periodontitis, linked to atherosclerosis, cardiovascular disease and diabetes. The more researchers discover, new unknown issues add up to the complexity of biofilm infections, in which microbial species establish relationships of cooperation and competition, and elaborate phenotypic differentiation into functional, adapted communities. Their interaction with the host's immune system or with therapeutic agents contributes to the complex puzzle that still misses a lot of pieces. In this comprehensive review we aimed to highlight the microbial composition, developmental stages, architecture and properties of medical biofilms, as well as the diagnostic tools used in the management of biofilm related infections. Also, we present recently acquired knowledge on the etiopathogenesis, diagnosis and treatment of four chronic diseases associated with biofilm development in tissues (chronic periodontitis, chronic lung infection in cystic fibrosis, chronic wounds) and artificial substrata (medical devices-related infections).

This review highlights the current situation of antimicrobial resistance and the use of magnetic nanoparticles (MNPs) in developing novel routes for fighting infectious diseases. The most important two directions developed recently are: (i) improved delivery of antimicrobial compounds based on a drastic decrease of the minimal inhibition concentration (MIC) of the drug used independently; and (ii) inhibition of microbial attachment and biofilm development on coated medical surfaces. These new directions represent promising alternatives in the development of new strategies to eradicate and prevent microbial infections that involve resistant and biofilm-embedded bacteria. Recent promising applications of MNPs, as the development of delivery nanocarriers and improved nanovehicles for the therapy of different diseases are discussed, together with the mechanisms of microbial inhibition.

The present study reports the fabrication and characterization of a novel nanostructured phyto-bioactive coated rayon/polyester wound dressing (WD) surface refractory to Candida albicans adhesion, colonization and biofilm formation, based on functionalized magnetite nanoparticles and Anethum graveolens (AG) and Salvia officinalis (SO) essential oils (EOs). TEM, XRD, TGA, FT-IR were used for the characterization of the fabricated nanobiocoated WDs. Using magnetic nanoparticles for the stabilization and controlled release of EOs, the activity of natural volatile compounds is significantly enhanced and their effect is stable during time. For this reason the nanobiocoated surfaces exhibited a longer term anti-biofilm effect, maintained for at least 72 h. Besides their excellent anti- adherence properties, the proposed solutions exhibit the advantage of using vegetal natural compounds, which are less toxic and easily biodegradable in comparison with synthetic antifungal drugs, representing thus promising approaches for the development of successful ways to control and prevent fungal biofilms associated infections.

Cutaneous wounds are often superinfected during the healing process and this leads to prolonged convalescence and discomfort. Usage of suitable wound dressings is very important for an appropriate wound care leading to a correct healing. The aim of this study was to demonstrate the influence of a nano-coated wound dressing (WD) on Candida albicans colonization rate and biofilm formation. The modified WD was achieved by submerging the dressing pieces into a nanofluid composed of functionalized magnetite nanoparticles and Satureja hortensis (SO) essential oil (EO). Chemical composition of the EO was established by GC-MS. The fabricated nanostructure was characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Differential Thermal Analysis (DTA) and Fourier Transform-Infrared Spectroscopy (FT-IR). The analysis of the colonized surfaces using (Scanning Electron Microscopy) SEM revealed that C. albicans adherence and subsequent biofilm development are strongly inhibited on the surface of wound dressing fibers coated with the obtained nanofluid, comparing with regular uncoated materials. The results were also confirmed by the assay of the viable fungal cells embedded in the biofilm. Our data demonstrate that the obtained phytonanocoating improve the resistance of wound dressing surface to C. albicans colonization, which is often an etiological cause of local infections, impairing the appropriate wound healing.

Pathogenic bacteria have the ability to sense their versatile environment and adapt by behavioral changes both to the external reservoirs and the infected host, which, in response to microbial colonization, mobilizes equally sophisticated anti-infectious strategies. One of the most important adaptive processes is the ability of pathogenic bacteria to turn from the free, floating, or planktonic state to the adherent one and to develop biofilms on alive and inert substrata; this social lifestyle, based on very complex communication networks, namely, the quorum sensing (QS) and response system, confers them an increased phenotypic or behavioral resistance to different stress factors, including host defense mechanisms and antibiotics. As a consequence, biofilm infections can be difficult to diagnose and treat, requiring complex multidrug therapeutic regimens, which often fail to resolve the infection. One of the most promising avenues for discovering novel and efficient antibiofilm strategies is targeting individual cells and their QS mechanisms. A huge amount of data related to the inhibition of QS and biofilm formation in pathogenic bacteria have been obtained using the well-established gram-positive Staphylococcus aureus and gram-negative Pseudomonas aeruginosa models. The purpose of this paper was to revise the progress on the development of antibiofilm and anti-QS strategies in the less investigated gram-negative ES KA P E pathogens Klebsiella pneumoniae , Acinetobacter baumannii , and Enterobacter sp. and identify promising leads for the therapeutic management of these clinically significant and highly resistant opportunistic pathogens. [ABSTRACT FROM AUTHOR]

Aim: In order to find new therapeutic alternatives for difficult-to-treat infections produced by Pseudomonas aeruginosa we evaluated the effect of silver nanoparticles (AgNPs) on growth and biofilm production. Method: We selected 30 clinical strains of multidrug resistant Pseudomonas aeruginosa isolated from infected wounds with a prolonged evolution, and control strain Pseudomonas aeruginosa ATCC 27853. We synthetized 4 different types of functionalized silver nanoparticles (Ag@PEG, Ag@EG, AG@PEG/PVP, Ag@EG/PVP). For each type of nanoparticle, we grown the strains in 96 well-plates, concentration 0.5 McFarland, and a dilution of 10% in 150microL liquid Mueller Hinton, with 8 binary dilutions of nanoparticles from 0.5mg/mL to 0.0039mg/mL. After 24 hours of incubation at 37°C, the growth was spectrophotometrically evaluated at 620nm. Subsequently, the wells were fixed with cold methanol, stained with crystal violet 1%, observed at the inversed microscope and resuspended with acetic acid 33% to be spectrophotometrically read at 492nm for biofilm production. Results / Discussion: We determined the median of minimum inhibitory concentration, mode and range for each type of AgNP. All parameters investigated were lowest for nanoparticles functionalised with ethylene glycol and polyvinylpyrrolidone (Ag@EG/PVP), lower than 0.0039 mg/mL. We noticed a reduction of the biofilm production with 0.01-0.05 for concentration of 0.5 mg/mL, most important effect noticed for Ag@EG/PVP. Conclusion: We underline the efficiency of AgNPs in reducing growth and biofilm production. These findings show that nanosystems could be promising antimicrobial agents for highly antibiotic-resistant Pseudomonas aeruginosa. AgNPs may overcome severe microbial infections, since they are useful agents against resistant pathogens and also biofilms. [ABSTRACT FROM AUTHOR]

Polylactic acid was combined with lemongrass essential oil (EO) to produce functional nanocapsules (NCs). The obtained polylactic acid nanoparticles showed antimicrobial activity both with and without the presence of lemongrass oil; however, the presence of EO improved the activity of the NCs. The presence of lemongrass assisted the formation of well-separated NCs and also provided enhanced antimicrobial properties, since lemongrass is known for its antimicrobial character. Fluorescence microscopy was used to optically observe the nanoparticles and NCs and revealed the attachment of lemongrass oil with the polylactic acid NCs. Dynamic light scattering was used to determine their size. UV absorption was used to determine the exact amount of lemongrass oil found in the polylactic acid--lemongrass oil NCs, which was important for understanding the minimum inhibitory concentration for the antimicrobial experiments. A series of clinically important microbial species were used in the study and the obtained NCs proved to have very good antimicrobial properties against all tested strains. Such NCs can be used for the design of ecological strategies, based on natural alternatives, which may be efficient against severe infections, including those that involve resistant pathogens and biofilms or those with difficult to reach localization. [ABSTRACT FROM AUTHOR]

Deposition of bioactive coatings composed of zinc oxide, cyclodextrin and cefepime (ZnO/CD/Cfp) was performed by the Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. The obtained nanostructures were characterized by X-ray diffraction, IR microscopy and scanning electron microscopy. The efficient release of cefepime was correlated with an increased anti-biofilm activity of ZnO/CD/Cfp composites. In vitro and in vivo tests have revealed a good biocompatibility of ZnO/CD/Cfp coatings, which recommend them as competitive candidates for the development of antimicrobial surfaces with biomedical applications. The release of the fourth generation cephalosporin Cfp in a biologically active form from the ZnO matrix could help preventing the bacterial adhesion and the subsequent colonization and biofilm development on various surfaces, and thus decreasing the risk of biofilm-related infections. [ABSTRACT FROM AUTHOR]

Highlights: [•] Thin coatings based on P(3HB-3HV)–PVA–Fe3O4@E microspheres. [•] Anti-adherence and anti-biofilm coatings. [•] New surface to control and prevent microbial biofilms. [ABSTRACT FROM AUTHOR]

Despite the technological progress of the last decade, dental caries is still the most frequent oral health threat in children and adults alike. Such a condition has multiple triggers and is caused mainly by enamel degradation under the acidic attack of microbial cells, which compose the biofilm of the dental plaque. The biofilm of the dental plaque is a multispecific microbial consortium that periodically develops on mammalian teeth. It can be partially removed through mechanical forces by individual brushing or in specialized oral care facilities. Inhibition of microbial attachment and biofilm formation, as well as methods to strengthen dental enamel to microbial attack, represent the key factors in caries prevention. The purpose of this study was to elaborate a cold plasma-based method in order to modulate microbial attachment and biofilm formation and to improve the retention of fluoride (F−) in an enamel-like hydroxyapatite (HAP) model sample. Our results showed improved F retention in the HAP model, which correlated with an increased antimicrobial and antibiofilm effect. The obtained cold plasma with a dual effect exhibited through biofilm modulation and enamel strengthening through fluoridation is intended for dental application, such as preventing and treating dental caries and enamel deterioration. [ABSTRACT FROM AUTHOR]

This paper reports a newly fabricated nanophyto-modified wound dressing with microbicidal and anti-adherence properties. Nanofluid-based magnetite doped with eugenol or limonene was used to fabricate modified wound dressings. Nanostructure coated materials were characterized by TEM, XRD, and FT-IR. For the quantitative measurement of biofilm-embedded microbial cells, a culture-based method for viable cell count was used. The optimized textile dressing samples proved to be more resistant to staphylococcal and pseudomonal colonization and biofilm formation compared to the uncoated controls. The functionalized surfaces for wound dressing seems to be a very useful tool for the prevention of wound microbial contamination on viable tissues. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The method creating cellulose acetate - essential oils nanocapsules was optimized. • No surfactant was needed for the formation of nanocapsules. • The nanocapsules have antimicrobial activity against 3 bacteria and a yeast strain. • The nanocapsules prevent microbial colonization and biofilm development. Abstract This study aimed to obtain bioactive nanosystems by combining cellulose acetate with three selected essential oils (EOs) to create spherical nanocapsules (NCs) using the solvent/anti-solvent technique. The biological activity of the obtained NCs was promoted by the use of some antimicrobial EOs: Peppermint, Cinnamon and lemongrass which were grafted on the cellulose acetate molecules. Due to their chemistry, such as long hydrocarbon tails and heads with functional groups these EOs were playing also the role of surfactant-like substance facilitating the formation of NCs. A dispersion of NCs was obtained in water and various spectroscopy techniques used to examine their size, morphology and chemistry. Dynamic light scattering calculate the size of the NCs whereas scanning electron microscopy showed their morphology. Fluorescent microscopy and Raman spectroscopy proved the attachment of the EOs in the cellulose acetate molecules. The antimicrobial activity of the obtained nanomaterials was tested against four microbial strains (bacteria: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli , and a yeast strain of Candida albicans). The obtained results demonstrated that such NCs can be used in a variety of applications including medical, pharmaceutical recipients and in household products for treating or preventing microbial colonization and biofilm development. [ABSTRACT FROM AUTHOR]

Implant- related infections are a consequence of microbial’ adhesion to an implant surface followed by biofilm development on the implanted device. Chemical and biological functionalization of medical surfaces represents topical tactic of enhancing biocompatibility, together with the prevention of bacterial contamination and biofilm inhibition. For this purpose, we focused our work on laser surface modification of medical devices. We prepared nanoparticles of Fe 3 O 4 loaded with Nigella sativa oil by a modified co-precipitation method in aqueous solution of NH 4 OH by oil-in-water emulsion. For further studies, we mixed them with poly(lactic-co-glycolic acid) spheres. The functionalized nanoparticles were deposited on glass and silicone surfaces by Matrix Assisted Pulsed Laser Evaporation technique. The influence of experimental factors, such as laser fluences was studied. The obtained thin coatings were analyzed by high resolution transmission electron microscopy, scanning electron microscopy and infrared microscopy. The most suitable coatings were selected and tested against a broad spectrum of pathogens found in the most implant rejection issues, such as S. aureus , E. coli and C. albicans , at different time intervals and proved to limit microbial colonization and biofilm formation. In addition, biocompatibility studies using MG-63 cells adopting MTS assay confirmed the possible use of the obtained thin coatings to safely modify medical surfaces. [ABSTRACT FROM AUTHOR]

The aim of this study was to obtain improved coatings for advanced surfaces with increased biocompatibility and resistance to microbial colonization and biofilm formation. The prepared magnetite nanoparticles functionalized with gentamicin (Fe 3 O 4 @G) have been embedded into poly(lactic-co-glycolic acid) (PLGA) spheres by oil-in-water emulsion. The PLGA-Fe 3 O 4 @G spheres were deposited on glass and silicone surfaces by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. The obtained thin coatings were analyzed by Scanning Electron Microscopy (SEM) and Infrared Microscopy (IRM). The antimicrobial and antibiofilm efficiency of coatings was tested with respect to Gram-positive ( Staphylococcus aureus ) and Gram-negative ( Pseudomonas aeruginosa ) clinical strains by viable cells counts assay, performed at different time intervals. The obtained results proved that coatings based on PLGA-Fe 3 O 4 @G spheres exhibited an efficient antimicrobial activity against both adherent and sessile bacterial cells. Besides their excellent anti-adherence and antibiofilm effect, the obtained MAPLE-deposited coatings were highly biocompatible, allowing the normal development and growth of cultured human amniotic fluid stem cells. This approach could be successfully applied for the optimization of medical surfaces in order to control and prevent microbial colonization and further development of biofilm associated infections. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a nanostructured bioactive surface based on zinc oxide, sodium stearate (C18) and usnic acid (UA) exhibiting harmless effects with respect to the human cells, but with a significant antimicrobial effect, limiting the attachment and biofilm formation of food pathogens. ZnO nanoparticles were synthesized by sol–gel method and functionalized with C18 and UA. The coatings were fabricated by matrix assisted pulsed laser evaporation technique (MAPLE) and further characterized by TEM, SEM, SAED, XRD and IRM. The biological characterization of the prepared coatings consisted in cytotoxicity and antimicrobial assays. The cytotoxicity of ZnO@C 18 and ZnO@C 18 -UA films was evaluated with respect to the human skin fibroblasts (CCD 1070SK cell line) by phase contrast microscopy, MTT assay and nitric oxide (NO) release. The covered surfaces exhibited a decreased cell attachment, effect which was more pronounced in the presence of UA as shown by purple formazan staining of adhered cells. The unattached fibroblasts remained viable after 24 h in the culture media as it was revealed by their morphology analysis and NO level which were similar to uncovered slides. The quantitative microbiological assays results have demonstrated that the bioactive coatings have significantly inhibited the adherence and biofilm formation of Salmonella enterica . The obtained results recommend these materials as efficient approaches in developing anti-adherent coatings for various industrial, medical and food processing applications. [ABSTRACT FROM AUTHOR]

This study reports on the successful deposition of γ-cyclodextrin/usnic acid (γCD/UA) thin film by Matrix Assisted Pulsed Laser Evaporation (MAPLE) as anti-adherent coating on medical surfaces against microbial colonization. The obtained results demonstrate that these bioactive thin films inhibit Staphylococcus aureus biofilm formation at all stages, starting with their initiation. The antibiofilm effect was constant along the bacterial incubation time. Furthermore, the γCD/UA coatings show a great biocompatibility which means that this material is suitable for the development of modern medical devices with antimicrobial properties. [ABSTRACT FROM AUTHOR]

Highlights: [•] MAPLE deposition of microspheres to prepare antibiofilm surfaces. [•] Novel thin coatings with anti-adherent properties. [•] Novel thin coatings based PLA–PVA microspheres. [•] Novel microspheres based PLA–PVA and natural compounds (usnic acid). [Copyright &y& Elsevier]