Water Contact Angle Analysis Research Articles

Green and Sustainable Hot Melt Adhesive (HMA) Based on Polyhydroxyalkanoate (PHA) and Silanized Cellulose Nanofibers (SCNFs)

Polyhydroxyalkanoate (PHA), with a long chain length and high poly(4-hydroxybutyric acid) (P4HB) ratio, can be used as a base polymer for eco-friendly and biodegradable adhesives owing to its high elasticity, elongation at break, flexibility, and processability; however, its molecular structures must be adjusted for adhesive applications. In this study, surface-modified cellulose nanofibers (CNFs) were used as a hydrophobic additive for the PHA-based adhesive. For the surface modification of CNFs, double silanization using tetraethyl orthosilicate (TEOS) and methyltrimethoxysilane (MTMS) was performed, and the thermal and structural properties were evaluated. The hydrophobicity of the TEOS- and MTMS-treated CNFs (TMCNFs) was confirmed by FT-IR and water contact angle analysis, with hydrophobic CNFs well dispersed in the PHA. The PHA-CNFs composite was prepared with TMCNFs, and its morphological analysis verified the good dispersion of TMCNFs in the PHA. The tensile strength of the composite was enhanced when 10% TMCNFs were added; however, the viscosity decreased as the TMCNFs acted as a thixotropic agent. Adding TMCNFs to PHA enhanced the flowability and infiltration ability of the PHA-TMCNFs-based adhesive, and an increase in the loss tangent (Tan δ) and adjustment of viscosity without reducing the adhesive strength was also observed. These changes in properties can improve the flowability and dispersibility of the PHA-TMCNFs adhesive on a rough adhesive surface at low stress. Thus, it is expected that double-silanized CNFs effectively improve their interfacial adhesion in PHA and the adhesive properties of the PHA-CNFs composites, which can be utilized for more suitable adhesive applications.

Corrosion resistance of commercial glazes of floor tiles

Abstract The main aim of this article was to develop new glaze receipts (NGRs) to build up the acid resistance (AR) of commercial glazes (CGs) used in floor tile production. The glaze is a vitrified material that melts the surface of the ceramic material. Improvements were made during and after the manufacture, based on the glaze samples of the CGs. NGRs were synthesized using different mineral compositions. AR, density, chemical, and physical properties of commercial and new synthesized glazes were determined using X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray spectroscopy, Fourier transform infrared spectrometry, and water contact angle analysis methods. The AR of the obtained samples (standard and developed floor tiles) was examined by treating them with 3% HCl for 3 days. Results showed that synthesized glazes had higher AR than standard glazes (CGs). The NGRs also significantly improved the ceramic surface coating features of the new glazes.

Synthesis and Fabrication of a Betulin-Containing Polyolefin Electrospun Fibrous Mat for Antibacterial Applications.

Biocompounds play a significant role in the area of renewable polymers in terms of sustainability, as they can be employed or converted into monomers for polymerization in a manner similar to many petroleum-derived monomers. In this work, betulin, a plant-derived triterpene with antibacterial and antiviral properties, was converted to two kinds of α,ω-diene derivatives with different methylene spacer lengths between the olefin and the ester group via an esterification reaction. Polyolefins were subsequently made by acyclic diene metathesis (ADMET) polymerization of betulin-based α,ω-diene. The polymer consists of rigid betulin and flexible unsaturated aliphatic segments, which was confirmed by NMR spectroscopy and gel permeation chromatography (GPC). The influence of different parameters including temperature, catalysts, and catalyst loading on ADMET polymerization was investigated. These polyolefins with high molar mass (up to 20.0 kg/mol) were obtained in an elevated yield (≥95%). Thermal analysis of these (co)polymers showed excellent thermal stability (up to 360 °C) and tunable glass transition temperatures depending on the nature of betulin and alkene segments. To evaluate the antimicrobial potential of betulin-containing polymers, the fabrication of polyolefin fibrous mats (ca. 400 nm diameter) via the electrospinning technique was successfully achieved. Their morphology and hydrophobicity were studied by scanning electron microscopy (SEM) and water contact angle analyses. The fibrous mats possessed broad-spectrum antibacterial property, providing a feasible strategy to design betulin-based polymeric fibers for many applications in the biomedical field.

Effects of temperature distribution caused by energy accumulation on the bonding properties of carbon fiber composite components

AbstractInfluence of temperature changes generated by plasma energy accumulation on bonding properties of carbon fiber composites (CFRP) was studied. The temperature field distribution on the bonding surface was built and tensile shear strength of the CFRP bonded components was evaluated. Results showed that the bonding strength was increased by 60.97% after the 5 min‐treatment. Because the energy accumulation could increase the local temperature of the bonding area to 195°C, a large amount of matrix resin was removed from the CFRP specimen. Then the surface wettability of the treated composite was greatly improved and the adhesive layer between the two bonded CFRP specimens became more similar to an interlayer in composites. The cohesive and interlaminar failure types occurred in the bonded component with the increased joint strength. Analysis of water contact angle, infrared spectroscopy, surface roughness and surface morphology indicated that the high‐surface free energy of the treated CFRP specimen and the mechanical interlocking between CFRP and adhesive caused by the decomposition of epoxy resin played a major role. When the treatment time further increased, the bonding area was severely damaged by the temperature of more than 215°C and then brittle fracture of the composites occurred, which was consistent with the subsequent decrease in bonding strength.

Investigation of Hybrid Films Based on Fluorinated Silica Materials Prepared by Sol–Gel Processing

In this research, fluorinated silica materials were prepared through sol–gel processing with tetraethylorthosilicate (TEOS), triethoxymethylsilane (MTES), and trimethoxyhexadecylsilane (HDTMES), using a fluorinated solution (FS) under acidic medium. The fluorinated solution (FS) was obtained by diluting the perfluorooctanoic acid (PFOA) in 2-propanol. These fluorinated sol–gel silica materials were placed on the glass surfaces in order to achieve the antireflective and hydrophobic fluorinated hybrid films. The structure and surface properties of the final samples were investigated by Fourier transform infrared spectroscopy (FTIR), ultraviolet/visible spectroscopy, thermogravimetric analysis (TGA), atomic force microscopy (AFM), and contact angle (CA) determinations. FTIR spectra demonstrated the presence of a silica network modified with alkyl and fluoroalkyl groups. Thermal analysis showed that the fluorinated sol–gel silica materials prepared with HDTMES have a good thermostability in comparison with other samples. Ultraviolet/visible spectra indicated that the fluorinated hybrid films present a reflectance of ~9.5%, measured at 550 nm. The water contact angle analysis found that the wettability of fluorinated hybrid films was changed from hydrophilic (64°) to hydrophobic (~104°). These hybrid films based on fluorinated sol–gel silica materials can be useful in various electronics and optics fields.

Hydrophobic polyacrylonitrile/pitch electrospun nanofibers for oil spill cleanup: Fabrication, optimization, and kinetic investigations

In the present work, the polyacrylonitrile/pitch composite electrospun nanofibers were successfully fabricated to cope with oil spills from the sea surface. The response surface methodology (RSM) was applied to optimize the pitch content, applied voltage, and flow rate to achieve the optimal conditional for absorbing oil. The optimal parameters of pitch content, applied voltage, and flow rate were determined at 18.3 %, 15.3 kV, and 0.95 mL/h, respectively. The hydrophobicity of composite nanofibers was investigated by water contact angle (WCA) analysis. The results showed that the WCA of the composite nanofibers was 139.4°, proving that the fabricated nanofibers were hydrophobic. Compared to pure polyacrylonitrile nanofibers, the polyacrylonitrile/pitch composite nanofibers exhibit better oil-water selectivity and surface roughness under optimized conditions. The composite nanofibers showed good oil absorption for different kinds of oils (up to 42.47 g/g within 5 min), which was 3–5 times that of commercial polypropylene absorbents. The oil absorption of the composite nanofibers was still >70 % after 10 absorption-desorption cycles. Moreover, the absorption kinetics study showed that the pseudo-second-order kinetic model was more suitable for the oil absorption process of the polyacrylonitrile/pitch composite nanofibers. This study explored the potential application value of low-value-added petroleum pitch. The fabricated composite nanofibers have promising applications in the oil/water separation and the absorption of oil spills.

Polysulfone hollow fiber membrane containing charcoal‑carbon nanomaterial for wastewater treatment in membrane bioreactor

In this research, charcoal‑carbon nanomaterial (charcoal-CNM) with sheet-like structure and high hydrophilicity was used to modify polysulfone (PSf)-based hollow fiber (HF) ultrafiltration (UF) membrane performance. Polyvinylpyrrolidone (PVP) was used as pore-former. Phase inversion method was employed for membrane preparation. The HF membranes were spun in three different CNM contents via dry/wet method. Field emission scanning electron microscopy (FESEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), tensile strength (TS), and water contact angle (WCA) analyses were used to characterize the fabricated membranes. Performance of the prepared HF membranes in a pre-conditioned bioreactor was also investigated. Compared to the neat membrane, increased porosity and mean pore size, reduced surface roughness and improved surface hydrophilicity were obtained for the nanocomposite membrane fabricated with 0.5 wt% of charcoal-CNM as the optimized membrane. The results demonstrated the positive effect of the charcoal-CNM with sheet-like structure and high hydrophilicity on the membrane surface properties and performance in the bioreactor. For the optimized membrane, chemical oxygen demand (COD) removal and protein rejection were achieved as 95.8 % and 94.3 %, respectively. Also, pure water flux (PWF) of the optimized membrane were achieved as 196.3 LMH.

Modification of Poly(lactic acid) with Orange Peel Powder as Biodegradable Composite.

Traditional fossil-based plastic usage and disposal has been one of the largest environmental concerns due to its non-biodegradable nature and high energy consumption during the manufacturing process. Poly(lactic acid) (PLA) as a renewable polymer derived from natural sources with properties comparable to classical plastics and low environmental cost has gained much attention as a safer alternative. Abundantly generated orange peel waste is rich in valuable components and there is still limited study on the potential uses of orange peel waste in reinforcing the PLA matrix. In this study, orange peel fine powder (OPP) synthesized from dried orange peel waste was added into PLA solution. PLA/OPP solutions at different OPP loadings, i.e., 0, 10, 20, 40, and 60 wt% were then casted out as thin films through solution casting method. Fourier-transform infrared spectroscopy (FTIR) analysis has shown that the OPP is incorporated into the PLA matrix, with OH groups and C=C stretching from OPP can be observed in the spectra. Tensile test results have reviewed that the addition of OPP has decreased the tensile strength and Young’s modulus of PLA, but significantly improve the elongation at break by 49 to 737%. Water contact angle analysis shows that hydrophilic OPP has modified the surface hydrophobicity of PLA with a contact angle ranging from 70.12° to 88.18°, but higher loadings lead to decrease of surface energy. It is proven that addition of OPP improves the biodegradability of PLA, where PLA/60 wt% OPP composite shows the best biodegradation performance after 28 days with 60.43% weight loss. Lastly, all PLA/OPP composites have better absorption in alkaline solution.

Use of Gelatin as a Sacrificial Agent in Combination with Ultrasonication to Improve Cell Infiltration and Osteogenesis of Nanofibrous PCL-nHA Scaffolds for Bone Tissue Engineering.

In this study, gelatin was chosen as a novel sacrificial agent in co-electrospun with polycaprolacton-nanohydroxyapatite (PCL-nHA). After electrospinnig, gelatin was washed with water, and the prepared scaffold was ultrasonicated. Morphological and structural properties of the prepared scaffolds were studied by SEM. Fourier transform infrared (FTIR) spectroscopy and water contact angle analysis were used to evaluate the removal of gelatin. According to the SEM results, the pore size of the modified scaffolds was increased 3-folds compared to the control sample. For PCL-nHA gelatin: (80:20) after the treatment, the average cell infiltration was 42.7 μm, while there was no infiltration for the control group. The modified electrospun scaffold significantly enhanced the osteogenic differentiation of hBMSCs as verified by increased ALP activity and upregulation of runt-related transcription factor 2 (RUNX2), collagen type 1 (COL1) and osteocalcin (OCN) genes. Co-electrospun PCL-nHA with gelatin as a sacrificial agent in combination with ultrasonication may be an effective, economic and controllable method to increase the pore size in electrospun scaffolds for bone tissue engineering applications.

Evaluation of Magnesium-Phosphate Particle Incorporation into Co-Electrospun Chitosan-Elastin Membranes for Skin Wound Healing.

Major challenges facing clinicians treating burn wounds are the lack of integration of treatment to wound, inadequate mechanical properties of treatments, and high infection rates which ultimately lead to poor wound resolution. Electrospun chitosan membranes (ESCM) are gaining popularity for use in tissue engineering applications due to their drug loading ability, biocompatibility, biomimetic fibrous structure, and antimicrobial characteristics. This work aims to modify ESCMs for improved performance in burn wound applications by incorporating elastin and magnesium-phosphate particles (MgP) to improve mechanical and bioactive properties. The following ESCMs were made to evaluate the individual components’ effects; (C: chitosan, CE: chitosan-elastin, CMg: chitosan-MgP, and CEMg: chitosan-elastin-MgP). Membrane properties analyzed were fiber size and structure, hydrophilic properties, elastin incorporation, MgP incorporation and in vitro release, mechanical properties, degradation profiles, and in vitro cytocompatibility with NIH3T3 fibroblasts. The addition of both elastin and MgP increased the average fiber diameter of CE (~400 nm), CMg (~360 nm), and CEMg (565 nm) compared to C (255 nm). Water contact angle analysis showed elastin incorporated membranes (CE and CEMg) had increased hydrophilicity (~50°) compared to the other groups (C and CMg, ~110°). The results from the degradation study showed mass retention of ~50% for C and CMg groups, compared to ~ 30% seen in CE and CEMg after 4 weeks in a lysozyme/PBS solution. CMg and CEMg exhibited burst-release behavior of ~6 µg/ml or 0.25 mM magnesium within 72 h. In vitro analysis with NIH3T3 fibroblasts showed CE and CEMg groups had superior cytocompatibility compared to C and CMg. This work has demonstrated the successful incorporation of elastin and MgP into ESCMs and allows for future studies on burn wound applications.

Designing of amino silica covalently functionalized carboxylic multi-wall carbon nanotubes-based polyethersulfone membranes for enhancing oily wastewater treatment

The accumulation of oily wastewater is a critical issue that can cause environmental pollution. Membrane technology can play a vital role in the treatment of oily wastewater due to its productivity and economical cost. In this work, the amino silica covalently functionalized carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) nanohybrid was synthesized and blended with polyethersulfone (PES) membranes for oil/water separation to enhance the antifouling property. Membranes were fabricated with various loadings of SiO2-f-MWCNTs nanohybrid (0–2 wt%) using phase inversion technique. The incorporation of nanohybrid resulted in the enhancement of wettability and pore size distribution of nanocomposite membranes. The morphological structure, surface and chemical features of the synthesized membranes were examined using scanning electron microscopy, Fourier transform infrared spectroscopy, water contact angle and X-ray diffraction analyses. Furthermore, the impact of nanohybrid blending with PES membrane on water permeability and oil rejection was investigated. The water permeability enhanced from 188 ± 8 L/m2.h.bar, for the pristine PES membrane, to 293 ± 9 L/m2.h.bar for nanocomposite membrane blended with 2 % SiO2-f-MWCNTs nanohybrid. Similarly, the oil rejection was improved up to 97 ± 0.1 % using the same nanohybrid loading. The results revealed that using 2 % nanohybrid loading has increased the humic acid (HA) flux by 16 %, while the irreversible HA fouling was significantly reduced to 0.9 % compared to 9.9 % for the pristine PES.

Development of Almond gum/alginate composites to enhance the shelf-life of post-harvest Solanum Lycopersicum L

Almond Gum/alginate composite (AG/AL) composites namely A1, A2 and A3 were prepared and their physicochemical properties were evaluated. The measured film thickness, moisture and solubility were indistinguishable among the films whereas water contact angle analysis shows that A2 (83.8±1.65) and A3 (86.2±3.19) film has high hydrophobicity than A1 (58.4±3.21). By increasing plasticizer concentration from 0.4% to 0.66%, elongation was increased from 30 to 53 % whereas tensile strength (3.16 to 1.90 Mpa) and water vapor transmission rate (WVTR) decreased from 212 to 160 g/m2/24hr. FT-IR analysis shows that the edible film has O-H, C-H, C=O and –COO functional groups and SEM analysis reveals that the prepared film has even surface due to the strong interaction between polymer and plasticizer. TGA results show major weight loss at 100°C, 190-220°C and 350°C-400°C due to the dehydration/decomposition of water molecules and carbon containing functional groups. Film solution was used as an edible coating in tomatoes and weight loss (WL), titratable acidity (TA), Total soluble solids (TSS), ascorbic acid content (AAC) and anti-microbial activity were determined. The WL analysis shows a significant delay in decay of coated tomatoes over 40 days of storage time whereas control tomatoes decayed on day 25. TA and TSS test confirms that the coating can significantly (P<0.05) prevent the acidity level of tomaotes. Furthermore, the AG/AL coating has great activity against E. coli, Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus. Therefore, the present study confirms that AG/AL has superior properties and potential as edible films or coating.

Towards Ge-based electronic devices: Increased longevity of alkanethiol-passivated Ge(100) in low humidity environments

Germanium is a critically important material for future complementary metal-oxide-semiconductor devices, however, to maximise its potential it is necessary to develop a robust passivation process that prevents Ge re-oxidation for a queue time of 24 h. Self-assembled monolayers (SAMs) of alkanethiols on Ge have previously been shown to inhibit oxidation; however, re-oxidation eventually occurs when exposed to ambient conditions. Herein, it is shown that humidity plays a key role in the degradation of the SAM, ultimately resulting in re-oxidation. To demonstrate this, thiol-passivated Ge(100) surfaces are exposed to controlled humidity environments with different levels of relative humidity (RH). The rate of re-oxidation of the Ge surfaces are tracked using X-ray photoelectron spectroscopy and water contact angle analysis to discern what role RH plays in the re-oxidation of the Ge and the degradation of the SAM passivation. Atomic force microscopy data is presented to show that humidity-mediated re-oxidation of the Ge has little or no impact on the route mean square roughness of those surfaces. Finally, atomistic modelling of thiol-SAM passivated Ge in the presence of water molecules has been studied using first principles density functional theory in order to simulate experimental conditions and to understand the atomic level processes that determine stability in hydrophilic and hydrophobic configurations.

Removal of linear siloxanes and dimethyl sulfone from water using hierarchical zeolite porous carbon adsorbents

Low molecular weight linear siloxanes are problematic compounds known to occur in water bodies, especially in water reclaimed from closed volumes. Remediation was attempted using a hierarchical porous composite adsorbent containing a Faujasite zeolite imprinted in activated carbon, namely CFAU. Although CFAU was prepared using procedures reported elsewhere, it was modified also to include extra-framework Ag+ cations. The composites long-range, textural, and compositional characteristics were verified via XRD, nitrogen porosimetry, water contact angle, zeta potential, TGA, and ICP elemental analyses. Furthermore, the composites were tested for the adsorption of siloxanes (i.e., monomethylsilanetriol, dimethylsilanediol, and trimethylsilanol (TMS)) as well as dimethyl sulfone (DMSO2) from water (mg L−1 level) in single and multicomponent fashion at ambient temperature and neutral pH. DMSO2 is highly ubiquitous in reclaimed waters where these siloxanes occur. Ag+-CFAU was the superior adsorbent, with siloxane and DMSO2 loadings of up to 20 and 87 mg cm−3 (or 17 and 72 mg g−1), respectively. These are at least an order of magnitude larger than commercial alternatives like carbon and resins. FTIR data suggest that the adsorption interaction with siloxanes is of Van der Waals type, whereas interactions between Ag+-CFAU and DMSO2 plausibly involve complexation. Moreover, multicomponent adsorption tests showed that Ag+-CFAU excels probably because of the complexation with DMSO2 and a TMS-driven siloxane co-adsorption.

High molecular weight multifunctional fluorescent polyurea: Isocyanate-free fast synthesis, coating applications and photoluminescence studies

Isocyanate-free synthesis of high molecular weight polyurea (PUrea) is a challenging and important area of research, considering the health and safety concerns related to isocyanates and a wide range of day-to-day uses of polyurea. In this article, an isocyanate and phosgene-free synthesis of high molecular weight fluorescent polyurea (Mn > 150,000) is reported via triazolinedione (TAD)-indole click reactions. Both the bisTAD and bis-indole monomers are synthesized from diphenyl carbonate using solvent-free reactions. The synthesis of polyurea is finished within 15 min under ambient conditions, without the use of any additives and catalysts, which is a remarkable advantage in comparison to all other reported methods in the literature. The molecular weight (Mn) of the polyurea can be defined as either very high molecular weight >150,000 g/mol or low molecular weight ∼ 3500–4000 g/mol via choosing a suitable solvent for the polymerization reaction. This approach is also useful for polyurea-based hydrophobic coatings as evidenced by the water contact angle analysis. The indole-derived aromatic moieties introduced within the polymer backbone; impart photoluminescence properties and polymers show excitation-dependent emission behavior.

Improving the mechanical and methanol crossover properties of fluorinated sulfonic acid functional polyphosphazenes by blending with polyvinylidene difluoride for fuel cell applications

Sulfonic acid functional polyaryloxyphosphazenes are attractive alternatives to perfluorinated sulfonic acid membranes for fuel cells due to their high oxidative and thermal stability features. However, they usually suffer from low mechanical properties which is a barrier to their highly sought application as a membrane in polymer electrolyte membrane fuel cells. In this study, we synthesized a series of novel sulfonic acid functional polyaryloxyphosphazenes which have various amounts of hydrophobic 4-trifluoromethylphenol and hydrophilic 4-hydroxybenzenesulfonic acid co-substituents on the polymer backbone. Although the resulting materials exhibited better mechanical properties compared to other sulfonic acid functional polyaryloxyphosphazenes available in the literature, they were required to improve mechanical properties to act as a standalone membrane material in a fuel cell. Therefore, polyvinylidene difluoride has been used to enhance the mechanical properties whilst it also provided a low methanol crossover to the resulting blend membranes compared to the commercial perfluoro sulfonic acid Nafion 117. The blend membranes exhibited good oxidative stability, low water uptake, and swelling behaviors. The water contact angle and morphological analysis showed that the blend membranes have high hydrophobicity and porous structures which might contribute to the proton conductivity. The proton conductivity of blend membrane samples which have over the 60% sulfonic acid functional polyaryloxyphosphazene constituent, was over 140 mS/cm which was higher than that of Nafion 117 under hydrated conditions at 50 °C. These membranes also showed over ten times lower methanol crossover and good selectivity compared to Nafion 117.

Hydrophobic-oleophilic gamma-irradiated modified cellulose nanocrystal/gelatin aerogel for oil absorption

This study highlights the potential use of cellulose nanocrystals (CNCs) from kenaf fiber as a dominant phase for aerogel application. CNCs were modified with methyltrimethoxysilane (MTMS) using the sol-gel method and bound with gamma-irradiated cross-linked gelatin. The properties of the aerogel were studied using Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and water contact angle (WCA). Compression and oil absorption tests were performed to study the aerogels' mechanical and oil absorption properties. A decrease in the OH peak and improved hydrophobicity of CNCs in CNC-MTMS suggested the successful grafting of MTMS onto CNCs, as shown in the FTIR and WCA analyses. Several absorption peaks in the FTIR spectrum shifted, disappeared, or reduced, implying a formation of crosslink between gelatin molecules and hydrogen bonding between CNC and gelatin. FESEM micrographs showed well-organized pores in the gamma-irradiated aerogel, which contribute to increased compressive strength. The oil absorption test indicated that gamma-irradiated CNC-MTMS/gelatin could be a good oil absorbent. Furthermore, this aerogel showed good reusability, where only 4 % of crude oil absorption reduction occurred by the eighth cycle. The combined properties of these aerogel materials can provide good mechanical and oil absorption performance.

Conducting Polymer-Coated Carbon Cloth Captures and Releases Extracellular Vesicles by a Rapid and Controlled Redox Process.

Electrochemical techniques offer great opportunities for the capture of chemical and biological entities from complex mixtures and their subsequent release into clean buffers for analysis. Such methods are clean, robust, rapid, and compatible with a wide range of biological fluids. Here, we designed an electrochemically addressable system, based on a conducting terpolymer [P(EDOT-co-EDOTSAc-co-EDOTEG)] coated onto a carbon cloth substrate, to selectively capture and release biological entities using a simple electrochemical redox process. The conducting terpolymer composition was optimized and the terpolymer-coated carbon cloth was extensively characterized using electrochemical analysis, Raman and Fourier transform-infrared spectroscopy, water contact angle analysis, and scanning electron microscopy. The conductive terpolymer possesses a derivative of EDOT with an acetylthiomethyl moiety (EDOTSAc), which is converted into a "free" thiol that then undergoes reversible oxidation/reduction cycles at +1.0 V and -0.8 V (vs Ag/AgCl), respectively. That redox process enables electrochemical capture and on-demand release. We first demonstrated the successful electrochemical capture/release of a fluorescently labeled IgG antibody. The same capture/release procedure was then applied to release extracellular vesicles (EVs), originating from both MCF7 and SKBR3 breast cancer cell line bioreactors. EVs were captured using the substrate-conjugated HER2 antibody which was purified from commercially available trastuzumab. Capture and release of breast cancer EVs using a trastuzumab-derived HER2 antibody has not been reported before (to the best of our knowledge). A rapid (2 min) release at a low potential (-0.8 V) achieved a high release efficiency (>70%) of the captured, HER2+ve, SKBR3 EVs. The developed system and the electrochemical method are efficient and straightforward and have vast potential for the isolation and concentration of various biological targets from large volumes of biological and other (e.g., environmental) samples.

Characterization of Contemporary Conventional, Bulk-fill, and Self-adhesive Resin Composite Materials

To evaluate the physical and biological properties of different types of flowable resin composites and their bonding ability to dentin, comparing the performance of self-adhesive and bulk-fill materials with a conventional control. Four flowable resin composites were tested: two self-adhesive (Y-flow [SA_YF]; and Dyad Flow [SA_DF]); one bulk-fill (Filtek Bulk Fill Flow [BF]); and one conventional composite (Opallis Flow [OF]). The microshear bond strength (μSBS) to dentin (bovine samples) was investigated at 24 hours and 6 months of storage. The materials were also characterized by degree of conversion, cross-link density, water contact angle, color stability, and cell viability (ISO 10993-5/2009) analyses. Data were analyzed using Analysis of Variance and Tukey tests (α=0.05). The μSBS values were higher for control specimens at 24 hours, whereas the resin-dentin bonds were similarly distributed among the groups after aging. Adhesive failure was the most frequent pattern observed at both time intervals. SA_YF was the only material that increased the bond strength over time. Degree of conversion increased in the following order: SA_YF (28.6±1.4%) < BF (49.7±0.8%) < OF (60.0±2.0%) = SA_DF (63.6±2.3%). Cross-link density was similar among all materials. The self-adhesive composites were more hydrophilic than the other types, with BF showing the lowest water contact angle and the greatest color alteration. All resin composites had a biocompatible behavior. Chemical composition appeared to be an influential factor affecting the physico-mechanical and biological behavior of the materials tested.

Enhancing the flux and salt rejection of thin-film composite nanofiltration membranes prepared on plasma-treated polyethylene using PVA/TS-1 composite

The high hydrophobicity of polyethylene (PE) film restricts its application as a thin-film composite (TFC) support layer. Therefore, in this study, oxygen plasma treatment was used to generate hydrophilic groups on PE and facilitate the formation of the TFC membrane. The difference in the performance of the plasma treated-PE (P-PE) membrane compared to untreated-PE indicated the significant effect of plasma pretreatment. In the following, to enhance the hydrophilicity of the P-PE membrane, titanium silicate-1 (TS-1) was synthesized as a zeotype through the hydrothermal method and added to the aqueous solution of the interfacial polymerization process. Due to the decrease in the agglomeration of TS-1 in the membrane matrix, PVA/TS-1 composites with distinct concentrations of polymer were prepared and applied for modifying membrane properties. Membranes were characterized by FESEM, ATR-FTIR, AFM, zeta potential, and water contact angle analyses. Permeability, rejection of monovalent and divalent salts, and antifouling ability of the fabricated nanofiltration membranes were studied and the optimal polymer concentration was determined. Comparison of P-PE-TFC 0.1 membrane with P-PE showed an increase of ~42% in pure water flux. Also, the rejection of Na2SO4, MgSO4, MgCl2, and NaCl salts were 90.28%, 81.77%, 74.79%, and 70.94% for P-PE-TFC 0.1 membrane, respectively, which showed a notable improvement compared to the P-PE membrane. Evaluation of antifouling ability showed that P-PE-TFC 0.1 membrane had a higher resistance to fouling compared to other membranes. Flux recovery ratio of this membrane after three cycles of bovine serum albumin (BSA) filtration was higher than other membranes resulting from the reduced roughness due to the combined effect of PVA and TS-1.