Electrospinning Nonspinnable Sols to Ceramic Fibers and Springs.

Electrospinning has been applied to produce ceramic fibers using sol gel-based spinning solutions consisting of ceramic precursors, a solvent, and a polymer to control the viscosity of the solution. However, the addition of polymers to the spinning solution makes the process more complex, increases the processing time, and results in porous mechanically weak ceramic fibers. Herein, we develop a coelectrospinning technique, where a nonspinnable sol (<10 mPa s) consisting of only the ceramic precursor(s) and solvent(s) is encapsulated inside a polymeric shell, forming core-shell precursor fibers that are further calcined into ceramic fibers with reduced porosity, decreased surface defects, uniform crystal packing, and controlled diameters. We demonstrate the versatility of this method by applying it to a series of nonspinnable sols and creating high-quality ceramic fibers containing TiO2, ZrO2, SiO2, and Al2O3. The polycrystalline TiO2 fibers possess excellent flexibility and a high Young's modulus reaching 54.3 MPa, solving the extreme brittleness problem of the previously reported TiO2 fibers. The single-component ZrO2 fibers exhibit a Young's modulus and toughness of 130.5 MPa and 11.9 KJ/m3, respectively, significantly superior to the counterparts prepared by conventional sol-gel electrospinning. We also report the creation of ceramic fibers in micro- and nanospring morphologies and examine the formation mechanisms using thermomechanical simulations. The fiber assemblies constructed by the helical fibers exhibit a density-normalized toughness of 3.5-5 times that of the straight fibers due to improved fracture strain. This work expands the selection of the electrospinning solution and enables the development of ceramic fibers with more attractive properties.

Effects of Age-Dependent Hormonal Changes and Estrogen Supplementation on Voice in Girls with Anorexia Nervosa-Preliminary Report.

INTRODUCTION: Human development includes lots of physical and emotional changes. The human voice depends on age. Voice production is a complex physiological and acoustic phenomenon that depends on many factors such as structure, hormone level, degree of fatigue or nutrition and hydration of the body, systemic diseases, and emotional state. All these factors can be present in anorexia nervosa (AN), such as excessive weight loss, generated hydro-electrolytic changes, nutritional deficiencies, hormonal disturbances in the function of the hypothalamic-pituitary-adrenal axis, the hypothalamic-pituitary-thyroid axis, the hypothalamic-pituitary-ovarian axis, and emotional distress. The prevalence of AN ranges between 0.3% and 3%, and it is the third most common chronic disease affecting adolescent girls. However, voice changes related to AN have not been fully investigated. OBJECTIVE: The purpose of this study was to evaluate the impact of AN on age-related changes in the voice of adolescent women-before and after puberty, particularly through acoustic analysis. An additional objective was to evaluate estrogen substitution in female patients with AN in order to investigate their effect on voice condition. MATERIALS AND METHODS: 126 girls diagnosed with AN (15.32 ± 2.12 years, range 12-19, BMI = 14.38 ± 1.67), were assessed for the condition of the voice such as perceptual voice evaluation on the GRBAS scale, maximal phonation time (MPT), laryngoscopy, with special attention to voice acoustic analysis-Multi-Dimensional Voice Program (MDVP). The control group (B) included 93 girls without eating disturbances (aged 12-19, mean age 15.52 ± 2.40, BMI = 21.50 ± 1.54). Perceptual voice assessment, aerodynamic test MPT, and acoustic parameters were analyzed in age groups (≤16 years and >16 years). The human vocal tract is sensitive to sex hormones, so the analysis was carried out in the group up to the age of 16 and above 16 to check possible effects. RESULTS: GRBAS scale was higher in girls with AN compared to the control group for breathiness (B) (P = 0.0002) and asthenia (A) (P < 0.05). The median GRBAS scale for the older group of anorexic women was the highest (2.0). The mean MPT for group A was significantly lower (15.40 ± 3.51 seconds). Comparing age subgroups there was a prolongation of MPT in the healthy group (in groups ≤16 years and >16 years respectively 21.13 seconds versus 25.40 seconds) and a shortening in the anorectic group (≤16 years versus >16 years: 17.06 seconds versus 14.17 seconds). There was no difference between groups A and C up to 16 years of age, but above 16 years of age appeared (14.17 seconds versus 25.40 seconds). Acoustic analysis revealed lower F0 values in group A and C in older subgroups (215,85 Hz versus 236,01 Hz-statistically significant), as well as between subgroups both groups (A: 251,38 Hz versus 215,85 Hz; C: 248,20 Hz versus 236,01 Hz). A narrowing of the vocal range in girls over 16 years in group A was observed. There were no statistically significant differences in F0 between subgroups ≤16 years in groups A and C (251.38 Hz versus 248.20 Hz). The ENT study found that more than half of the girls (54.55%) over the age of 16 who took hormone supplementation manifested laryngeal structure that was normal for their age, there was no effect of hormone supplementation on any of the MDVP parameters between the drug-taking and non-drug-taking groups. CONCLUSIONS: The acoustic results of the voice in MDVP measurements in adolescent women with AN are not within the normal range and do not mimic the normal developmental changes of the voice. The most important acoustic characteristics of the voice are changes in the fundamental frequency F0 and the range of the voice tended to be more severe in anorectic women >16 years of age and to increase with age, indicating a possible cumulative effect of malnutrition-related disorders as well as hormonal dysfunctions. MDVP can be considered a simple, non-invasive method of assessing the voice organ in AN. MPT differentiated the study groups well: statistically significant differences were noted both between the groups, as well as between age groups. There was no significant effect of oral hormone supplementation on any parameters of the voice. In conclusion, body mass and fat volume in AN may be related to voice production/physiology, affecting voice quality, voice acoustic parameters, voice aerodynamics, and phonatory range in an age-dependent manner. Future studies are needed to assess the long-term efficacy of estrogen treatment in AN.

Micro/nano-patterns for enhancing differentiation of human neural stem cells and fabrication of nerve conduits via soft lithography and 3D printing.

Topographical cues on materials can manipulate cellular fate, particularly for neural cells that respond well to such cues. Utilizing biomaterial surfaces with topographical features can effectively influence neuronal differentiation and promote neurite outgrowth. This is crucial for improving the regeneration of damaged neural tissue after injury. Here, we utilized groove patterns to create neural conduits that promote neural differentiation and axonal growth. We investigated the differentiation of human neural stem cells (NSCs) on silicon dioxide groove patterns with varying height-to-width/spacing ratios. We hypothesize that NSCs can sense the microgrooves with nanoscale depth on different aspect ratio substrates and exhibit different morphologies and differentiation fate. A comprehensive approach was employed, analyzing cell morphology, neurite length, and cell-specific markers. These aspects provided insights into the behavior of the investigated NSCs and their response to the topographical cues. Three groove-pattern models were designed with varying height-to-width/spacing ratios of 80, 42, and 30 for groove pattern widths of 1 µm, 5 µm, and 10 µm and nanoheights of 80 nm, 210 nm, and 280 nm. Smaller groove patterns led to longer neurites and more effective differentiation towards neurons, whereas larger patterns promoted multidimensional differentiation towards both neurons and glia. We transferred these cues onto patterned polycaprolactone (PCL) and PCL-graphene oxide (PCL-GO) composite 'stamps' using simple soft lithography and reproducible extrusion 3D printing methods. The patterned scaffolds elicited a response from NSCs comparable to that of silicon dioxide groove patterns. The smallest pattern stimulated the highest neurite outgrowth, while the middle-sized grooves of PCL-GO induced effective synaptogenesis. We demonstrated the potential for such structures to be wrapped into tubes and used as grafts for peripheral nerve regeneration. Grooved PCL and PCL-GO conduits could be a promising alternative to nerve grafting.

Thermal Conductivity of Carbon/Boron Nitride Heteronanotube and Boron Nitride Nanotube Buckypapers: Implications for Thermal Management Composites.

To date, there has been limited reporting on the fabrication and properties of macroscopic sheet assemblies (specifically buckypapers) composed of carbon/boron nitride core-shell heteronanotubes (MWCNT@BNNT) or boron nitride nanotubes (BNNTs). Herein we report the synthesis of MWCNT@BNNTs via a facile method involving Atmospheric Pressure Chemical Vapor Deposition (APCVD) and the safe h-BN precursor ammonia borane. These MWCNT@BNNTs were used as sacrificial templates for BNNT synthesis by thermal oxidation of the core carbon. Buckypaper fabrication was facilitated by facile sonication and filtration steps. To test the thermal conductivity properties of these new buckypapers, in the interest of thermal management applications, we have developed a novel technique of advanced scanning thermal microscopy (SThM) that we call piercing SThM (pSThM). Our measurements show a 14% increase in thermal conductivity of the MWCNT@BNNT buckypaper relative to a control multiwalled carbon nanotube (MWCNT) buckypaper. Meanwhile, our BNNT buckypaper exhibited approximately half the thermal conductivity of the MWCNT control, which we attribute to the turbostratic quality of our BNNTs. To the best of our knowledge, this work achieves the first thermal conductivity measurement of a MWCNT@BNNT buckypaper and of a BNNT buckypaper composed of BNNTs not synthesized by high energy techniques.

Klebsiella phage KP34gp57 capsular depolymerase structure and function: from a serendipitous finding to the design of active mini-enzymes against K. pneumoniae.

IMPORTANCE: In this work, we determined the structure of Klebsiella phage KP34p57 capsular depolymerase and dissected the role of individual domains in trimerization and functional activity. The crystal structure serendipitously revealed that the enzyme can exist in a monomeric state once deprived of its C-terminal domain. Based on the crystal structure and site-directed mutagenesis, we localized the key catalytic residues in an intra-subunit deep groove. Consistently, we show that C-terminally trimmed KP34p57 variants are monomeric, stable, and fully active. The elaboration of monomeric, fully active phage depolymerases is innovative in the field, as no previous example exists. Indeed, mini phage depolymerases can be combined in chimeric enzymes to extend their activity ranges, allowing their use against multiple serotypes.

Acoustics Features of Voice in Adolescent Females With Anorexia Nervosa.

INTRODUCTION: The process of human voice production is a complex physiological and acoustic phenomenon that depends on many structural, physical, and hormonal factors, systemic diseases as well as emotional states. All these factors can be present in eating disorders. However, studies on eating disorders and voice problems have usually been evaluated in terms of bulimia. Chronic starvation and emotional problems in the course of anorexia nervosa (AN) appear to be under-researched, despite various biochemical, metabolic, and hormonal changes. OBJECTIVE: The purpose of this study was to evaluate voice quality, specifically acoustic analysis, in adolescent female with AN from the point of view of the possible influence on the function and structure of the larynx, low body mass accompanying AN, as well as energy deficiency, hormonal and emotional disturbances. MATERIALS AND METHODS: A total of 84 girls diagnosed with AN (Gr.A) (15.32 years, SD = 2.12; range 12-19, BMI = 14.11 ± 1.72) were assessed for the condition of the voice such as perceptual voice evaluation on the GRBAS scale, maximal phonation time (MPT), laryngoscopy, with special attention to voice acoustic analysis - Multi-Dimensional Voice Program (MDVP). The control group (Gr.C) included 62 girls without eating disturbances (aged 12-19, mean age 15.41 ± 2.40, BMI = 21.60 ± 1.92). Perceptual voice assessment, aerodynamic test MPT, and acoustic parameters were analyzed according to girls' age. RESULTS: Total GRBAS scale was higher in girls with AN compared to the control group mainly for two parameters: breathiness (B) (P = 0.00015) and asthenia (A) (P < 0.05). The MPT for Gr.A was significantly shorter compared to Gr.C (15.40 ± 3.51 seconds vs. 23.19 ± 5.17 seconds) (P < 0.001), and a correlation of MPT values with the age of the adolescent female was observed: Spearman's coefficient for Gr.A = (-)0.5378, for Gr.C = 0.5516 (P = 0.0012). Acoustic analysis revealed the decrease in the basic frequency F0 in Gr.A compared to Gr.C (231.08 Hz vs. 242.30 Hz), and narrowing of the voice scale was observed, resulting mainly from a reduction in the upper limit. Significant differences were found for measures of frequency perturbations (Jita, Jitter, RPA, PPQ, sPPR), with Gr.A scoring significantly higher than Gr.C (P < 0.05 for all). Significant changes in voice acoustic analysis parameters were found with age. Negative correlations were found for measures of F0 for Gr.A to a much greater extent compared to Gr.C. Positive correlations were found with measures of tremor assessment (SPI, FTRI, ATRI) for Gr.A.

Unveiling the Mechanism of the in Situ Formation of 3D Fiber Macroassemblies with Controlled Properties.

Electrospinning technique is well-known for the generation of different fibers. While it is a "simple" technique, it lies in the fact that the fibers are typically produced in the form of densely packed two-dimensional (2D) mats with limited thickness, shape, and porosity. The highly demanded three-dimensional (3D) fiber assemblies have been explored by time-consuming postprocessing and/or complex setup modifications. Here, we use a classic electrospinning setup to directly produce 3D fiber macrostructures only by modulating the spinning solution. Increasing solution conductivity modifies electrodynamic jet behavior and fiber assembling process; both are observed in situ using a high-speed camera. More viscous solutions render thicker fibers that own enhanced mechanical stiffness as examined by finite element analysis. We reveal the correlation between the universal solution parameters and the dimensionality of fiber assemblies, thereof, enlightening the design of more "3D spinnable" solutions that are compatible with any commercial electrospinning equipment. After a calcination step, ultralightweight ceramic fiber assemblies are generated. These inexpensive materials can clean up exceptionally large fractions of oil spillages and provide high-performance thermal insulation. This work would drive the development and scale-up production of next-generation 3D fiber materials for engineering, biomedical, and environmental applications.

Can Assessment of Rheological Properties of Whole Blood and Plasma Be Useful in the Diagnosis of Tinnitus? A Pilot Study.

Tinnitus is a sensation of ringing in the ears in the absence of any physical source in the environment. Between 9-35% of adults experience some form of tinnitus. Common causes of tinnitus include noise, head injury, ototoxic substances, as well as disorders of blood and blood vessels. Vascular causes include: head-neck tumours, turbulent blood flow, problems with blood supply and inner ear cell damage. The aspect of rheology in terms of tinnitus has not been described yet. In the present study, which comprised 12 patients aged 30 to 74 years presenting with tinnitus, rheological properties of whole blood and plasma were assessed. All the subjects underwent audiological and neurological evaluation. The Quemada model was used to describe the variability of red blood cell shape, as well as their tendency to form aggregates. On the basis of the experimental study, statistically different results of haemorheological measurements were observed in the evaluated group in comparison to a reference group.

Direct Evidence of the Exfoliation Efficiency and Graphene Dispersibility of Green Solvents toward Sustainable Graphene Production.

Achieving a sustainable production of pristine high-quality graphene and other layered materials at a low cost is one of the bottlenecks that needs to be overcome for reaching 2D material applications at a large scale. Liquid phase exfoliation in conjunction with N-methyl-2-pyrrolidone (NMP) is recognized as the most efficient method for both the exfoliation and dispersion of graphene. Unfortunately, NMP is neither sustainable nor suitable for up-scaling production due to its adverse impact on the environment. Here, we show the real potential of green solvents by revealing the independent contributions of their exfoliation efficiency and graphene dispersibility to the graphene yield. By experimentally separating these two factors, we demonstrate that the exfoliation efficiency of a given solvent is independent of its dispersibility. Our studies revealed that isopropanol can be used to exfoliate graphite as efficiently as NMP. Our finding is corroborated by the matching ratio between the polar and dispersive energies of graphite and that of the solvent surface tension. This direct evidence of exfoliation efficiency and dispersibility of solvents paves the way to developing a deeper understanding of the real potential of sustainable graphene manufacturing at a large scale.

The Antibacterial Effect of PEGylated Carbosilane Dendrimers on P. aeruginosa Alone and in Combination with Phage-Derived Endolysin.

The search for new microbicide compounds is of an urgent need, especially against difficult-to-eradicate biofilm-forming bacteria. One attractive option is the application of cationic multivalent dendrimers as antibacterials and also as carriers of active molecules. These compounds require an adequate hydrophilic/hydrophobic structural balance to maximize the effect. Herein, we evaluated the antimicrobial activity of cationic carbosilane (CBS) dendrimers unmodified or modified with polyethylene glycol (PEG) units, against planktonic and biofilm-forming P. aeruginosa culture. Our study revealed that the presence of PEG destabilized the hydrophilic/hydrophobic balance but reduced the antibacterial activity measured by microbiological cultivation methods, laser interferometry and fluorescence microscopy. On the other hand, the activity can be improved by the combination of the CBS dendrimers with endolysin, a bacteriophage-encoded peptidoglycan hydrolase. This enzyme applied in the absence of the cationic CBS dendrimers is ineffective against Gram-negative bacteria because of the protective outer membrane shield. However, the endolysin-CBS dendrimer mixture enables the penetration through the membrane and then deterioration of the peptidoglycan layer, providing a synergic antimicrobial effect.

Polymorphic variants in genes related to stress coping are associated with the awake bruxism.

BACKGROUND: Chronic stress is one of the leading predisposing factors in bruxism aetiology, but the influence of genetic factors is also suggested. We aimed to study whether sequence variants in genes involved in stress regulation pathways: NTRK2 and BDNF, may be associated with awake bruxism susceptibility, clinical presentation, and patients' perceived stress level. METHODS: The study group included 104 patients with probable awake bruxism and 191 population controls. Patients underwent dental examination concerning the symptoms of bruxism and psychological testing. Genotyping was performed using HRMA and sequencing. Statistical analyses were conducted, and P values below 0.05 were considered statistically significant. RESULTS: We observed a positive correlation of measured stress level and pathological teeth attrition in the anterior segment (r = 0.45, P < 0.001), enamel attritions (r = 0.44, P < 0.001), tongue impressions (r = 0.50, P < 0.001) and posterior teeth attrition (r = 0.27, P = 0.005). Moreover, the c.196A variant (p.66Met) of the BDNF gene and c.1397-31392G allele of the NTRK2 gene were present with elevated frequency, comparing to controls. CONCLUSIONS: This study hence the thesis that perceived stress level is a substantial contributing factor to awake bruxism occurrence and its clinical manifestations. Moreover, sequence variants in genes related to stress coping may be correlated with awake bruxism's susceptibility via elevated perceived stress level.

Engineering the Modular Receptor-Binding Proteins of Klebsiella Phages Switches Their Capsule Serotype Specificity.

The high specificity of bacteriophages is driven by their receptor-binding proteins (RBPs). Many Klebsiella bacteriophages target the capsular exopolysaccharide as the receptor and encode RBPs with depolymerase activity. The modular structure of these RBPs with an N-terminal structural module to attach the RBP to the phage tail, and a C-terminal specificity module for exopolysaccharide degradation, supports horizontal transfer as a major evolutionary driver for Klebsiella phage RBPs. We mimicked this natural evolutionary process by the construction of modular RBP chimeras, exchanging N-terminal structural modules and C-terminal specificity modules. All chimeras strictly follow the capsular serotype specificity of the C-terminal module. Transplanting chimeras with a K11 N-terminal structural RBP module in a Klebsiella phage K11 scaffold results in a capsular serotype switch and corresponding host range modification of the synthetic phages, demonstrating that horizontal transfer of C-terminal specificity modules offers Klebsiella phages an evolutionary highway for rapid adaptation to new capsular serotypes.IMPORTANCE The antimicrobial resistance crisis has rekindled interest in bacteriophage therapy. Phages have been studied over a century as therapeutics to treat bacterial infections, but one of the biggest challenges for the use of phages in therapeutic interventions remains their high specificity. In particular, many Klebsiella phages have a narrow spectrum constrained by the high diversity of exopolysaccharide capsules that shield access to the cells. In this work, we have elaborated how Klebsiella phages deal with this high diversity by exchanging building blocks of their receptor-binding proteins.

Special Issue: "Bacteriophages and Biofilms".

Biofilms are a community of surface-associated microorganisms characterized by the presence of different cell types in terms of physiology and phenotype [...].

Musical hallucinations in cerebrovascular disease.

Purpose: Musical hallucinations (MH) are a subset of complex auditory hallucinations in which individuals perceive music in the absence of an external auditory stimulus. It is a rare phenomenon, first described by Ballinger in 1846, with diverse presentations from familiar childhood melodies to a simple pitch which evolved into the harmonies Robert Schumann incorporated in his sole Violin Concerto. Views: This uncommon phenomenon has diverse etiologies, including psychiatric and neurological backgrounds, which guide its classification and methods of treatment. The pathophysiological basis of MH remains understood incompletely, potentially resulting from lesions anywhere along the auditory pathway, from the external auditory canal to the auditory cortex. The strong association between MH and hearing impairment has led researchers to hypothesize that MH represent a "release phenomenon," in which sensory deprivation, eliminating the afferent input to the auditory sensory network, instigates spontaneous activity within a system - comparable to the Charles Bonnet syndrome, in which visual impairment precipitates the development of visual hallucinations (so called auditory Charles Bonnet syndrome), and phantom limb syndrome, in which amputees experience sensations in a limb that is not no longer there. In this paper, we report on six cases of MH in patients with cerebrovascular disease, who presented to the neurology department at the Poznan University of Medical Sciences from 2015 to 2018. Conclusions: We discuss the findings of computed tomography and magnetic resonance imaging of six cases of MH in patients with cerebrovascular disease, and the treatment leading to its resolution. We briefly review the literature on MH in patients with cerebrovascular diseases, discussing their suggested pathophysiology, clinical presentations and response to medical treatment.

Subjective and Objective Assessments of Post-traumatic Olfactory Dysfunction.

Introduction: Traumatic brain injuries are the most common cause of olfactory dysfunction. Deficits in olfaction may be conductive or neurosensory in nature, with varying degrees of impairment resulting in a diminished quality of life and an increased risk for personal injury among patients. The aim of this research is to evaluate the results of the subjective and objective quantitative examinations of olfactory function in a group of patients with post-traumatic anosmia in order to predict its value in identifying olfactory deficits in clinical practice. Materials and Methods: The present study included 38 patients who reported anosmia or hyposmia caused by a traumatic head injury, and a group of 31 age- and sex-matched controls without olfactory dysfunction or prior history of head injury. The comparison of odor perception and identification of two oils (mint and anise) was assessed with the use of blast olfactometry with cortical olfactory event-related potentials. Results: Subjective olfactory tests revealed anosmia or hyposmia in 94% of patients with head injury-related olfactory dysfunction. Objective tests revealed olfactory event-related potentials from cranial nerve I produced by the stimulation with both mint and anise in 20 patients (52.6%). Olfactory event-related potentials from cranial nerve V produced by the stimulation with mint were registered in 26 patients (68.4%). The lack of any responses, from both cranial nerve I and V, was found in 12 patients (32% of cases). Conclusions: Findings from our study indicate the application of both subjective and objective examinations in the evaluation of patients with olfactory impairment. In the diagnosis of post-traumatic anosmia or hyposmia, objective examinations are particularly useful when the patients' level of cognition may be impaired or when subjects may be exaggerating their olfactory defects for a secondary gain. The diagnosis of damage to the olfactory system, specifically in the receptive part of the olfactory pathway, can be established in patients who showed reduced amplitudes or absent cortical responses in addition to absent odor identification and perception threshold in the subjective examination.

Structural and Functional Studies of a Klebsiella Phage Capsule Depolymerase Tailspike: Mechanistic Insights into Capsular Degradation.

Capsule polysaccharide is a major virulence factor of Klebsiella pneumoniae, a nosocomial pathogen associated with a wide range of infections. It protects bacteria from harsh environmental conditions, immune system response, and phage infection. To access cell wall-located receptors, some phages possess tailspike depolymerases that degrade the capsular polysaccharide. Here, we present the crystal structure of a tailspike against Klebsiella, KP32gp38, whose primary sequence shares no similarity to other proteins of known structure. In the trimeric structure of KP32gp38, each chain contains a flexible N-terminal domain, a right-handed parallel ß helix domain and two ß sandwiches with carbohydrate binding features. The crystal structure and activity assays allowed us to locate the catalytic site. Also, our data provide experimental evidence of a branching architecture of depolymerases in KP32 Klebsiella viruses, as KP32gp38 displays nanomolar affinity to another depolymerase from the same phage, KP32gp37. Results provide a structural framework for enzyme engineering to produce serotype-broad-active enzyme complexes against K. pneumoniae.

Dendronized Silver Nanoparticles as Bacterial Membrane Permeabilizers and Their Interactions With P. aeruginosa Lipopolysaccharides, Lysozymes, and Phage-Derived Endolysins.

Antimicrobial proteins, like lysozymes produced by animals or bacteriophage lysins, enable the degradation of bacterial peptidoglycan (PG) and, consequently, lead to bacterial cell lysis. However, the activity of those enzymes is not satisfactory against gram-negative bacteria because of the presence of an outer membrane (OM) barrier. Lytic enzymes can therefore be combined with membrane-disrupting agents, such as dendritic silver nanoparticles. Nevertheless, a lipopolysaccharide (LPS), especially the smooth type, could be the main hindrance for highly charged nanoparticles to get direct access to the bacterial OM and to help lytic enzymes to reach their target PG. Herein, we have investigated the interactions of PEGylated carbosilane dendritic nanoparticles with P. aeruginosa 010 LPS in the presence of lysozymes and KP27 endolysin to find out the main aspects of the OM destabilization process. Our results showed that PEGylated dendronized AgNPs overcame the LPS barrier and enhanced the antibacterial effect of endolysin more efficiently than unPEGylated nanoparticles.

Pseudomonas aeruginosa PA5oct Jumbo Phage Impacts Planktonic and Biofilm Population and Reduces Its Host Virulence.

The emergence of phage-resistant mutants is a key aspect of lytic phages-bacteria interaction and the main driver for the co-evolution between both organisms. Here, we analyze the impact of PA5oct jumbo phage treatment on planktonic/cell line associated and sessile P. aeruginosa population. Besides its broad-spectrum activity and efficient bacteria reduction in both airway surface liquid (ASL) model, and biofilm matrix degradation, PA5oct appears to persist in most of phage-resistant clones. Indeed, a high percentage of resistance (20/30 clones) to PA5oct is accompanied by the presence of phage DNA within bacterial culture. Moreover, the maintenance of this phage in the bacterial population correlates with reduced P. aeruginosa virulence, coupled with a sensitization to innate immune mechanisms, and a significantly reduced growth rate. We observed rather unusual consequences of PA5oct infection causing an increased inflammatory response of monocytes to P. aeruginosa. This phenomenon, combined with the loss or modification of the phage receptor, makes most of the phage-resistant clones significantly less pathogenic in in vivo model. These findings provide new insights into the general knowledge of giant phages biology and the impact of their application in phage therapy.

UV cross-linked polyvinylpyrrolidone electrospun fibres as antibacterial surfaces.

Many bacteria become progressively more resistant to antibiotics and it remains a challenging task to control their overall levels. Polymers combined with active biomolecules come to the forefront for the design of antibacterial materials that can address this encounter. In this work, we investigated the photo-crosslinking approach of UV-sensitive benzophenone molecule (BP) with polyvinylpyrrolidone (PVP) polymer within electrospun fibres. The BP and PVP solutions allowed fabricating polymer mats that were subsequently functionalised with antibacterial lysozyme. The physical properties of the crosslinked electrospun fibres were investigated by scanning electron microscopy and atomic force microscopy. The average diameter of the obtained fibres decreased from 290 ± 50 nm to 270 ± 70 nm upon the addition of the crosslinking molecules and then to 240 ± 80 nm and 180 ± 90 nm after subsequent crosslinking reaction at an increasing time: 3 and 5 h, respectively. The peak force quantitative nanomechanical mapping (PF-QNM) indicated the increase of DMT modulus of obtained cross-linked fibres from 4.1 ± 0.8 GPa to 7.2 ± 0.5 GPa. Furthermore, the successful crosslinking reaction of PVP and BP solution into hydrogels was investigated in terms of examining photo-crosslinking mechanism and was confirmed by rheology, Raman, Fourier transform infrared and nuclear magnetic resonance. Finally, lysozyme was successfully encapsulated within cross-linked PVP-BP hydrogels and these were successfully electrospun into mats which were found to be as effective antibacterial agents as pure lysozyme molecules. The dissolution rate of photo cross-linked PVP mats was observed to increase in comparison to pure PVP electrospun mats which opened a potential route for their use as antibacterial, on-demand, dissolvable coatings for various biomedical applications.

The influence of cationic dendrimers on antibacterial activity of phage endolysin against P. aeruginosa cells.

Nowadays, the researchers make a big effort to find new alternatives to overcome bacterial drug resistance. One option is the application of bacteriophage endolysins enable to degrade peptidoglycan (PG) what in consequence leads to bacterial cell lysis. In this study we examine phage KP27 endolysin mixed with poly(propyleneimine) dendrimers to evaluate an antimicrobial effect against Pseudomonas aeruginosa. Polycationic compounds destabilize bacterial outer membrane (OM) helping endolysins to gain access to PG. We found out that not only bacterial lipopolysaccharide (LPS) is the main hindrance for highly charged cationic dendrimers to disrupt OM and make endolysin reaching the target but also the dendrimer surface modification. The reduction of a positive charge and concentration in maltose poly(propyleneimine) dendrimers significantly increased an antibacterial effect of endolysin. The application of recombinant lysins against Gram-negative bacteria is one of the future therapy options, thus OM permeabilizers such as cationic dendrimers may be of high interest to be combined with PG-degrading enzymes.