Influence of Lavender Essential Oil on the Physical and Antibacterial Properties of Chitosan Sponge for Hemostatic Applications.

Uncontrollable bleeding continues to stand as the primary cause of fatalities globally following surgical procedures, traumatic incidents, disasters, and combat scenarios. The swift and efficient management of bleeding through the application of hemostatic agents has the potential to significantly reduce associated mortality rates. One significant drawback of currently available hemostatic products is their susceptibility to bacterial infections at the bleeding site. As this is a prevalent issue that can potentially delay or compromise the healing process, there is an urgent demand for hemostatic agents with antibacterial properties to enhance survival rates. To mitigate the risk of infection at the site of a lesion, we propose an alternative solution in the form of a chitosan-based sponge and antimicrobial agents such as silver nanoparticles (AgNPs) and lavender essential oil (LEO). The aim of this work is to provide a new type of hemostatic sponge with an antibacterial barrier against a wide range of Gram-positive and Gram-negative microorganisms: Staphylococcus epidermidis 2018 and Enterococcus faecalis VRE 2566 (Gram-positive strains) and Klebsiella pneumoniae ATCC 10031 and Escherichia coli ATCC 35218 (Gram-negative strains).

A Microfluidic Approach for Synthesis of Silver Nanoparticles as a Potential Antimicrobial Agent in Alginate-Hyaluronic Acid-Based Wound Dressings.

The recognized antimicrobial activity of silver nanoparticles is a well-studied property, especially when designing and developing biomaterials with medical applications. As biological activity is closely related to the physicochemical characteristics of a material, aspects such as particle morphology and dimension should be considered. Microfluidic systems in continuous flow represent a promising method to control the size, shape, and size distribution of synthesized nanoparticles. Moreover, using microfluidics widens the synthesis options by creating and controlling parameters that are otherwise difficult to maintain in conventional batch procedures. This study used a microfluidic platform with a cross-shape design as an innovative method for synthesizing silver nanoparticles and varied the precursor concentration and the purging speed as experimental parameters. The compositional and microstructural characterization of the obtained samples was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Four formulations of alginate-based hydrogels with the addition of hyaluronic acid and silver nanoparticles were obtained to highlight the antimicrobial activity of silver nanoparticles and the efficiency of such a composite in wound treatment. The porous structure, swelling capacity, and biological properties were evaluated through physicochemical analysis (FT-IR and SEM) and through contact with prokaryotic and eukaryotic cells. The results of the physicochemical and biological investigations revealed desirable characteristics for performant wound dressings (i.e., biocompatibility, appropriate porous structure, swelling rate, and degradation rate, ability to inhibit biofilm formation, and cell growth stimulation capacity), and the obtained materials are thus recommended for treating chronic and infected wounds.

Snapshot of Phenotypic and Molecular Virulence and Resistance Profiles in Multidrug-Resistant Strains Isolated in a Tertiary Hospital in Romania.

A current major healthcare problem is represented by antibiotic resistance, mainly due to multidrug resistant (MDR) Gram negative bacilli (GNB), because of their extended spread both in hospital facilities and in the community's environment. The aim of this study was to investigate the virulence traits of Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa MDR, XDR, and PDR strains isolated from various hospitalized patients. These GNB strains were investigated for the presence of soluble virulence factors (VF), such as hemolysins, lecithinase, amylase, lipase, caseinase, gelatinase, and esculin hydrolysis, as well as for the presence of virulence genes encoding for VF involved in adherence (TC, fimH, and fimA), biofilm formation (algD, ecpRAB, mrkA, mrkD, ompA, and epsA), tissue destruction (plcH and plcN), and in toxin production (cnfI, hlyA, hlyD, and exo complex). All P. aeruginosa strains produced hemolysins; 90% produced lecithinase; and 80% harbored algD, plcH, and plcN genes. The esculin hydrolysis was detected in 96.1% of the K. pneumoniae strains, whereas 86% of them were positive for the mrkA gene. All of the A. baumannii strains produced lecithinase and 80% presented the ompA gene. A significant association was found between the number of VF and the XDR strains, regardless of the isolation sources. This study opens new research perspectives related to bacterial fitness and pathogenicity, and it provides new insights regarding the connection between biofilm formation, other virulence factors, and antibiotic resistance.

Synergistic Antimicrobial Activity of Magnetite and Vancomycin-Loaded Mesoporous Silica Embedded in Alginate Films.

The aim of the present study was to obtain a hydrogel-based film as a carrier for the sustained and controlled release of vancomycin, an antibiotic commonly used in various types of infections. Considering the high-water solubility of vancomycin (>50 mg/mL) and the aqueous medium underlying the exudates, a prolonged release of vancomycin from an MCM-41 carrier was sought. The present work focused on the synthesis of malic acid coated magnetite (Fe3O4/malic) by co-precipitation, synthesis of MCM-41 by a sol-gel method and loading of MCM-41 with vancomycin, and their use in alginate films for wound dressing. The nanoparticles obtained were physically mixed and embedded in the alginate gel. Prior to incorporation, the nanoparticles were characterized by XRD, FT-IR and FT-Raman spectroscopy, TGA-DSC and DLS. The films were prepared by a simple casting method and were further cross-linked and examined for possible heterogeneities by means of FT-IR microscopy and SEM. The degree of swelling and the water vapor transmission rate were determined, considering their potential use as wound dressings. The obtained films show morpho-structural homogeneity, sustained release over 48 h and a strong synergistic enhancement of the antimicrobial activity as a consequence of the hybrid nature of these films. The antimicrobial efficacy was tested against S. aureus, two strains of E. faecalis (including vancomycin-resistant Enterococcus, VRE) and C. albicans. The incorporation of magnetite was also considered as an external triggering component in case the films were used as a magneto-responsive smart dressing to stimulate vancomycin diffusion.

Increasing Bioavailability of Trans-Ferulic Acid by Encapsulation in Functionalized Mesoporous Silica.

Two types of mesoporous materials, MCM-41 and MCM-48, were functionalized by the soft-template method using (3-aminopropyl)triethoxysilane (APTES) as a modifying agent. The obtained mesoporous silica materials were loaded with trans-ferulic acid (FA). In order to establish the morphology and structure of mesoporous materials, a series of specific techniques were used such as: X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmet-Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). We monitored the in vitro release of the loaded FA at two different pH values, by using simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). Additionally, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Candida albicans ATCC 10231 were used to evaluate the antimicrobial activity of FA loaded mesoporous silica materials. In conclusion such functionalized mesoporous materials can be employed as controlled release systems for polyphenols extracted from natural sources.

Preparation and Characterization of Chitosan/TiO2 Composite Membranes as Adsorbent Materials for Water Purification.

As it is used in all aspects of human life, water has become more and more polluted. For the past few decades, researchers and scientists have focused on developing innovative composite adsorbent membranes for water purification. The purpose of this research was to synthesize a novel composite adsorbent membrane for the removal of toxic pollutants (namely heavy metals, antibiotics and microorganisms). The as-synthesized chitosan/TiO2 composite membranes were successfully prepared through a simple casting method. The TiO2 nanoparticle concentration from the composite membranes was kept low, at 1% and 5%, in order not to block the functional groups of chitosan, which are responsible for the adsorption of metal ions. Nevertheless, the concentration of TiO2 must be high enough to bestow good photocatalytic and antimicrobial activities. The synthesized composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and swelling capacity. The antibacterial activity was determined against four strains, Escherichia coli, Citrobacter spp., Enterococcus faecalis and Staphylococcus aureus. For the Gram-negative strains, a reduction of more than 5 units log CFU/mL was obtained. The adsorption capacity for heavy metal ions was maximum for the chitosan/TiO2 1% composite membrane, the retention values being 297 mg/g for Pb2+ and 315 mg/g for Cd2+ ions. These values were higher for the chitosan/TiO2 1% than for chitosan/TiO2 5%, indicating that a high content of TiO2 can be one of the reasons for modest results reported previously in the literature. The photocatalytic degradation of a five-antibiotic mixture led to removal efficiencies of over 98% for tetracycline and meropenem, while for vancomycin and erythromycin the efficiencies were 86% and 88%, respectively. These values indicate that the chitosan/TiO2 composite membranes exhibit excellent photocatalytic activity under visible light irradiation. The obtained composite membranes can be used for complex water purification processes (removal of heavy metal ions, antibiotics and microorganisms).

Magnetite-Based Nanostructured Coatings Functionalized with Nigella sativa and Dicloxacillin for Improved Wound Dressings.

In this study, we report the performance improvement of wound dressings by covering them with magnetite-based nanostructured coatings. The magnetite nanoparticles (Fe3O4 NPs) were functionalized with Nigella sativa (N. sativa) powder/essential oil and dicloxacillin and were synthesized as coatings by matrix assisted pulsed laser evaporation (MAPLE). The expected effects of this combination of materials are: (i) to reduce microbial contamination, and (ii) to promote rapid wound healing. The crystalline nature of core/shell Fe3O4 NPs and coatings was determined by X-ray diffraction (XRD). Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA) have been coupled to investigate the stability and thermal degradation of core/shell nanoparticle components. The coatings' morphology was examined by scanning electron microscopy (SEM). The distribution of chemical elements and functional groups in the resulting coatings was evidenced by Fourier transform infrared (FTIR) spectrometry. In order to simulate the interaction between wound dressings and epithelial tissues and to evaluate the drug release in time, the samples were immersed in simulated body fluid (SBF) and investigated after different durations of time. The antimicrobial effect was evaluated in planktonic (free-floating) and attached (biofilms) bacteria models. The biocompatibility and regenerative properties of the nanostructured coatings were evaluated in vitro, at cellular, biochemical, and the molecular level. The obtained results show that magnetite-based nanostructured coatings functionalized with N. sativa and dicloxacillin are biocompatible and show an enhanced antimicrobial effect against Gram positive and Gram negative opportunistic bacteria.

Zinc Oxide Nanoparticles for Water Purification.

In this study, zinc oxide nanoparticles were synthesized through a simple co-precipitation method starting from zinc acetate dihydrate and sodium hydroxide as reactants. The as-obtained ZnO nanoparticles were morphologically and structurally characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photocatalytic activity, and by determining the antimicrobial activity against Gram-negative and Gram-positive bacteria. The XRD pattern of the zinc oxide nanoparticles showed the wurtzite hexagonal structure, and its purity highlighted that the crystallinity correlated with the presence of a single product, zinc oxide. The ZnO nanoparticles have an average crystallite size of 19 ± 11 nm, which is in accordance with the microscopic data. ZnO nanoparticles were tested against methyl orange, used as a model pollutant, and it was found that they exhibit strong photocatalytic activity against this dye. The antibacterial activity of ZnO nanoparticles was tested against Gram-negative and Gram-positive strains (Escherichia coli, Staphylococcus aureus, and Candida albicans). The strongest activity was found against Gram-positive bacteria (S. aureus).

ZnO Nanoparticles-Modified Dressings to Inhibit Wound Pathogens.

Zinc oxide (ZnO) nanoparticles (NPs) have been investigated for various skin therapies in recent years. These NPs can improve the healing and modulate inflammation in the wounds, but the mechanisms involved in such changes are yet to be known. In this study, we have designed a facile ZnO nano-coated dressing with improved antimicrobial efficiency against typical wound pathogens involved in biofilm and chronic infections. ZnO NPs were obtained by hydrothermal method and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy. Antibacterial and antibiofilm effects were evaluated against laboratory and clinical isolates of significant Gram-negative (Pseudomonas aeruginosa and Escherichia coli) and Gram-positive (Staphylococcus aureus and Enterococcus faecalis) opportunistic pathogens, by quantitative methods. Our results have shown that the developed dressings have a high antibacterial efficiency after 6-24 h of contact when containing 0.6 and 0.9% ZnO NPs and this effect is similar against reference and clinical isolates. Moreover, biofilm development is significantly impaired for up to three days of contact, depending on the NPs load and microbial species. These results show that ZnO-coated dressings prevent biofilm development of main wound pathogens and represent efficient candidates for developing bioactive dressings to fight chronic wounds.

Phenotypic and genotypic virulence features of staphylococcal strains isolated from difficult-to-treat skin and soft tissue infections.

Chronic infections represent an important burden on the healthcare system and have a significant impact on the patients' quality of life. While Staphylococcus spp. are commensal bacteria, they can become pathogenic, leading to various types of infections. In this study we aimed to characterize the virulence profiles of staphylococcal strains involved in difficult-to-treat skin and soft tissue infections, from both phenotypic and genotypic points of view. Phenotypic ability of the strains to secrete soluble virulence factors was assessed by a culturing dependent assay and their capacity to develop biofilms on inert substrate was screened by an adapted crystal violet microtiter method. We also tested the presence of several virulence genes by PCR. Most of the studied strains were isolated from purulent secretions of acne lesions and frequently secreted two or three soluble virulence factors. Most frequently secreted soluble virulence factors were caseinase (89%), lipase (71%) and lecithinase (67%). Almost half of the strains produced a well-represented biofilm. The molecular characterization showed the presence of the genes cna, hlg, clfA, and clfB. Staphylococcal strains that produce difficult-to-treat skin and soft tissue infections seem to be characterized by an enhanced ability to produce different soluble virulence factors and to develop biofilms in vitro. Further studies need to be developed in other Staphylococcus spp. infections in order to confirm this hypothesis.

Polyphenols of Honeybee Origin with Applications in Dental Medicine.

Honeybee products are a great source of polyphenols with recognized applications in dental medicine. Although their biological mechanisms in oral diseases are not fully understood, numerous in vitro, in vivo and clinical studies have reported promising results in the prevention and treatment of oral diseases. Bioactivities, such as antibacterial, antiviral, antiparasite, anticancer, anti-inflammatory and anti-oxidant properties, recommend their future study in order to develop efficient alternatives in the management of widespread oral conditions, such as dental caries and periodontitis. The most investigated mechanisms of polyphenols in oral health rely on their ability to strengthen the dental enamel, decrease the development of dental plaque formation, inhibit the progression of dental caries and development of dental pathogens and show anti-inflammatory properties. These features recommend them as useful honeybee candidates in the management of emerging oral diseases.

Antibacterial Activity of Bacterial Cellulose Loaded with Bacitracin and Amoxicillin: In Vitro Studies.

The use of bacterial cellulose (BC) in skin wound treatment is very attractive due to its unique characteristics. These dressings' wet environment is an important feature that ensures efficient healing. In order to enhance the antimicrobial performances, bacterial-cellulose dressings were loaded with amoxicillin and bacitracin as antibacterial agents. Infrared characterization and thermal analysis confirmed bacterial-cellulose binding to the drug. Hydration capacity showed good hydrophilicity, an efficient dressing's property. The results confirmed the drugs' presence in the bacterial-cellulose dressing's structure as well as the antimicrobial efficiency against Staphylococcus aureus and Escherichia coli. The antimicrobial assessments were evaluated by contacting these dressings with the above-mentioned bacterial strains and evaluating the growth inhibition of these microorganisms.