Wettability of smooth and rough surfaces of perfluoroacrylate copolymers

In this study, it was primarily shown that random copolymers of perfluoroacrylates can have sufficient hydrophobicity to be effectively employed for the production of ultrahydrophobic surfaces via electrospinning. Presence of small molar amounts of perfluoroacrylate in the copolymer chain resulted in the formation of rather hydrophobic copolymers surfaces that had lower surface free energy than poly(tetrafluoroethylene) due to the orientation of fluorinated groups to the solid-vapor interface on the outermost surface layer. The surface energy measurements of the copolymers indicated that amphiphilic copolymers may have lower surface free energy than the copolymers of perfluoroacrylates with non-polar monomers due to the higher excess of the fluorinated groups on the surface. However, it was also shown for the ultrahydrophobic surfaces of amphiphilic copolymers that reorientation of polar groups to the solid-liquid interface due to water contact on the protrusion tops, where the long interval solid-liquid contact took place, can increase the threshold water sliding angle on the surface remarkably while the high advancing contact angles were maintained for long days. The former was detected to be a direct result of the enhanced adhesive bonds between the three phase contact line and the tops of the solid protrusions, which prevented the receding of the drops; while the latter was attributed to the preserved composite surface structure by the inability of water in penetrating through the hydrophobic walls of the cavities. Consequently, ultrahydrophobicity was lost while superhydrophobic character was preserved. This result one more time showed that high advancing contact angle values do not indicate water repellence all the time. Due to the stability of the styrene-perfluoroacrylate copolymer surface against water exposure, this polymer was chosen to study for further improvements such as enhancing the ultrahydrophobic character. Experiments showed that the effect of applied voltage in electrospinning on the water repellence of surfaces electrospun at low solution concentrations is remarkable. By increasing the applied voltage to high values, a surface on which the microtopology was composed of nanometric beads covering the micron level roughness everywhere was produced. The resultant surface showed no contact angle hysteresis and was perfectly non-wetting, and exhibited no adhesion with water while a pendant drop was made to touch and retreat from the surface

Dual scale roughness driven perfectly hydrophobic surfaces prepared by electrospraying a polymer in good solvent-poor solvent systems

A facile method to produce perfectly hydrophobic surfaces (advancing and receding water contact angles both 180°) via electrospraying is demonstrated. When a copolymer of styrene and a perfluoroalkyl acrylate monomer was electrosprayed in good solvents, surfaces composed of micron size beads were formed and fairly low threshold sliding angles could be achieved. Addition of high boiling point poor solvents to the solutions resulted nanoscale roughness on the beads. However, even the nanoscale roughness dominated topographies achieved by this method exhibited contact angle hysteresis although deducted to be relatively small. On the other hand, when the electrospraying process parameters were set such that micron size hills of nanoscopically rough beads were formed, 0° sliding angles, implying zero contact angle hysteresis, were measured. Videos of droplets recorded and the adhesive forces measured during a contact and release experiment revealed that these dual scale rough surfaces were indeed perfectly hydrophobic. Application of the method with other binary good solvent-poor solvent systems also resulted in perfect hydrophobicity. Overall results showed how the differences in surface topology affected the wettability of surfaces within a very narrow range between perfect and extreme hydrophobicity (advancing and receding water contact angles both close to 180°). In order to interpret the formation of different surface topographies achieved by electrospraying the corresponding copolymer in good, poor and binary solvent systems, dissipative particle dynamics simulations and dynamic light scattering analysis were performed. Simulations of the polymer in good solvent revealed relatively homogenous solutions at all concentrations, whereas phase separation was observed in the poor solvent even at low concentrations. Light scattering experiments yielded useful information about the hydrodynamics of the real chains in the corresponding solvent systems in the dilute regime. It was found that the polymer forms stable aggregates in the poor solvent due to weak interaction with the solvent. Overall results indicated that formation of smooth bead morphologies is due to homogenous drying of the polymer from the good solvent. On the other hand, polymer aggregates lead to nanoscopic features in the regions where the solidi cation occurs mainly in the poor solvent environment

Molecular basis for solvent dependent morphologies observed on electrosprayed surfaces

We study the causes of the observed tunable hydrophobicity of poly(styrene-co-perfluoroalkyl ethylacrylate) electrosprayed in THF, DMF, and THF : DMF (1 : 1) solvents. Under the assumption that equilibrium morphologies in the solvent significantly affect the patterns observed on electrosprayed surfaces, we use atomistic and coarse-grained simulations supported by dynamic light scattering (DLS) experiments to focus on the parameters that affect the resulting morphology of superhydrophobic electrosprayed beads. The differing equilibrium chain size distributions in these solvents examined by DLS are corroborated by chain dimensions obtained via molecular dynamics simulations. Mesoscopic morphologies monitored by dissipative particle dynamics simulations explain experimental observations; in particular, the preference of the polymer for THF over DMF in the binary mixture rationalizes the dual scale roughness driven by stable microphase separation. Drying phenomena that affect resultant dual-scale roughness are described in three stages, each interpreted by concentration dependent diffusion and surface mass transfer coefficients of the solvents. Irrespective of the presence of polar groups in the structure, a conflict between the lower-boiling point solvent adhering to the polymer and the less volatile solvent abundant in the bulk leads to perfectly hydrophobic surfaces

Disrupted epithelial permeability as a predictor of severe COVID-19 development

BackgroundAn impaired epithelial barrier integrity in the gastrointestinal tract is important to the pathogenesis of many inflammatory diseases. Accordingly, we assessed the potential of biomarkers of epithelial barrier dysfunction as predictive of severe COVID‐19.MethodsLevels of bacterial DNA and zonulin family peptides (ZFP) as markers of bacterial translocation and intestinal permeability and a total of 180 immune and inflammatory proteins were analyzed from the sera of 328 COVID‐19 patients and 49 healthy controls.ResultsSignificantly high levels of circulating bacterial DNA were detected in severe COVID‐19 cases. In mild COVID‐19 cases, serum bacterial DNA levels were significantly lower than in healthy controls suggesting epithelial barrier tightness as a predictor of a mild disease course. COVID‐19 patients were characterized by significantly elevated levels of circulating ZFP. We identified 36 proteins as potential early biomarkers of COVID‐19, and six of them (AREG, AXIN1, CLEC4C, CXCL10, CXCL11, and TRANCE) correlated strongly with bacterial translocation and can be used to predict and discriminate severe cases from healthy controls and mild cases (area under the curve (AUC): 1 and 0.88, respectively). Proteomic analysis of the serum of 21 patients with moderate disease at admission which progressed to severe disease revealed 10 proteins associated with disease progression and mortality (AUC: 0.88), including CLEC7A, EIF4EBP1, TRANCE, CXCL10, HGF, KRT19, LAMP3, CKAP4, CXADR, and ITGB6.ConclusionOur results demonstrate that biomarkers of intact or defective epithelial barriers are associated with disease severity and can provide early information on the prediction at the time of hospital admission

The Turkish Version of the Juvenile Arthritis Multidimensional Assessment Report (JAMAR)

The Juvenile Arthritis Multidimensional Assessment Report (JAMAR) is a new parent/patient reported outcome measure that enables a thorough assessment of the disease status in children with juvenile idiopathic arthritis (JIA). We report the results of the cross-cultural adaptation and validation of the parent and patient versions of the JAMAR in the Turkish language. The reading comprehension of the questionnaire was tested in 10 JIA parents and patients. Each participating centre was asked to collect demographic, clinical data and the JAMAR in 100 consecutive JIA patients or all consecutive patients seen in a 6-month period and to administer the JAMAR to 100 healthy children and their parents. The statistical validation phase explored descriptive statistics and the psychometric issues of the JAMAR: the 3 Likert assumptions, floor/ceiling effects, internal consistency, Cronbach\u27s alpha, interscale correlations, test-retest reliability, and construct validity (convergent and discriminant validity). A total of 466 JIA patients (13.7% systemic, 40.6% oligoarticular, 22.5% RF negative poly-arthritis, and 23.2% other categories) and 93 healthy children were enrolled in four centres. The JAMAR components discriminated well-healthy subjects from JIA patients. All JAMAR components revealed good psychometric performances. In conclusion, the Turkish version of the JAMAR is a valid tool for the assessment of children with JIA and is suitable for use both in routine clinical practice and clinical research