Reduction In Water Contact Angle Research Articles

Exceptional self-cleaning MXene-based membrane for highly efficient oil/water separation

Two-dimensional (2D) MXene-based separation membranes exhibit significant promise for oily wastewater treatment. The intercalation of TiO2 nanoparticles between MXene nanosheets can not only enlarge their interlayer distance for faster transportation of water molecules, but also promote their photocatalytic oxidation for removal of membrane fouling by oil droplets. However, the uniform loading of ultra-small TiO2 nanomaterials between MXene layers without aggregation is challenging. Herein, taking advantages of inherent Ti elements of MXene, we grew ultra-small TiO2 by in-situ one-step oxidation of MXene nanosheets to prepare 2D MXene@TiO2 heterojunctions. They were then loaded on polyethersulfone (PES) support by vacuum filtration for the PES-MXene@TiO2 composite membrane (MXTM) with exceptional water permeance and anti-fouling and self-cleaning properties. It achieves a remarkably high flux of 3045 L·m−2 h−1·bar−1 and oil/water emulsion separation efficiency over 99.8%. Moreover, the MXTM membrane exhibits remarkable hydrophilicity, evidenced by an abrupt reduction in water contact angle from 43.8 to less than 5° within 10 s, which could retard the progress of oil adhesion on the membrane surfaces. The extended Derjaguin-Landau-Verwey-Overbeek theory confirmed high interaction energy between the membrane and pollutants. Furthermore, the MXTM membrane excels in self-cleaning and anti-fouling property, retaining a flux recovery rate of >98% in 10 cycles by visible light driven photodegradation of foulantsirradiation. This innovative 2D self-cleaning membrane offers excellent anti-fouling properties for efficient oil/water separation.

Harnessing plastic waste for sustainable membrane filtration with trimodal structure through acid-catalyzed oxidation

Polyolefin waste is among the most generated yet least recycled. Despite its potential as a feedstock of superhydrophobic membranes for organic solvent filtration, it remains a challenge to achieve high selectivity and permeability for viscous oils. In this study, we valorized polyolefin waste into trimodal water filtration membranes through acid-catalyzed oxidation and a void inducer. This approach enabled the creation of membranes with exceptional wettability and strength, characterized by a combination of micropores, macrovoids (30–70 µm), and cavities (150–200 µm). The acid-catalyzed oxidation introduced oxygen moieties into the membrane structure, resulting in a reduced water contact angle, improved hydrophilicity, and increased permeability. The micropores facilitated capillary action, macrovoids enabled efficient water passage, and cavities acted as oil reservoirs, for optimal oil–water separation. Various membranes were synthesized using low-density and high-density polyethylene (PE), polypropylene (PP), and their blend. The obtained results were compared with commercial membranes, revealing a flow rate of 43 ml/min, a retention capacity of 261 mg, and an oil removal efficiency ranging from 84–94 %. Furthermore, the membranes exhibited recyclability, demonstrating stability over at least 10 cycles. This hybrid process transforms plastic waste into trimodal water filtration membranes, achieving a balance between superoleophilicity and hydrophilicity.

Synthesis and characterization of enhanced polysulfone-based mixed matrix membranes containing ZSM-5 zeolite for protein and dye removal

In this paper, polysulfone (PSf)-based ultrafiltration (UF) mixed matrix membranes (MMMs) embedded with ZSM-5 zeolite nanoparticles were synthesized via the NIPS method. The membranes were characterized by FESEM, ATR-FTIR, AFM, and tensile analyses, along with contact angle, porosity, and mean pore size measurements. The FESEM images indicated that the addition of hydrophilic ZSM-5 nanoparticles has led to formation of more and larger finger-like macrovoids. Moreover, hydrophilicity and pure water flux (PWF) values were consequently augmented, which was also approved by water contact angle reduction. The maximum PWF was equal to 394.7 L m-2h−1 at 3 bar for the optimum MMM, containing 1 wt% ZSM-5 which is 125.4 % greater than the value for the bare membrane. In addition, filtration of the bovine serum albumin (BSA) protein and aqueous solutions of two organic dyes were carried out. The highest BSA flux value was obtained 217.9 L m-2h−1 for the optimum membrane, where the BSA rejection values were all greater than 98 %. Furthermore, the optimum MMM displayed the highest flux recovery ratio (FRR%) of 60.1 % as well as the dyes rejection values equal to 95.5 % and 74.1 % for reactive black 5 (RB 5) and reactive yellow 160 (RY 160), respectively, representing its great potential to be applied in various wastewater treatment applications.

Utilization of chitosan as an additive for enhancing the performance of polyethersulfone membranes for water treatment

This research investigates the impact of adding chitosan as an additive to improve membrane performance. Membrane fabrication was conducted using the non-solvent-induced phase separation method with polymer blending. Characterization was conducted by evaluating functional groups using FTIR, morphological structure using SEM, and water contact angle using a WCA meter. The research findings show that chitosan additives have a positive influence on the prepared PES membrane. There was a change in the morphological form on the membrane, as evidenced by SEM photos of the cross-section of the membrane. An increase in chitosan concentration resulted in improved hydrophilic properties of the membrane, indicated by a 63.2° reduction in water contact angle. The results show that the best membrane performance was achieved with 4% chitosan addition, resulting in a water flux of 38.2 L/m2.h as well as humic acid rejection of 67.9%.

Copolymerization of Ethylene with Functionalized 1,1-Disubstituted Olefins Using a Fluorenylamido-Ligated Titanium Catalyst.

Considering the sustainability of material development, coordination polymerization catalysts effective for 1,1-disubstituted olefins are receiving a great deal of attention because they can introduce a variety of plant-derived comonomers, such as β-pinene and limonene, into polyolefins. However, due to their sterically encumbered property, incorporating these monomers is difficult. Herein, we succeeded in the copolymerization of ethylene with various hydroxy- or siloxy-substituted vinylidenes using a fluorenylamido-ligated titanium catalyst-MMAO system. This is the first example of ethylene/polar 1,1-disubstituted olefins' copolymerization using an early transition metal catalyst system. The polymerization proceeded at room temperature without pressurizing ethylene, and high-molecular-weight, functionalized polyethylene was obtained. The obtained copolymer showed a reduced water contact angle compared with that of the ethylene/isobutene copolymer, demonstrating the increment in hydrophilicity by hydroxy groups.

Rosemary particle as a new green additive to improve polysulfone membrane separation performance in removal of organic pollutants

This study used rosemary particles to make PSf nanofiltration membranes with antifouling properties, for medicinal pollutants and Azo dyes removal. The extract of rosemary plant was extracted using the Soxhlet process. Then homogeneous rosemary particles were embedded in the PSf membrane matrix as a green additive using the NIPS method. Characterization of the structure and morphology of rosemary particles and membranes was performed by FTIR, XRD, UV–Vis, FE-SEM, STA, DLS, ATR-FTIR, SEM, AFM, Zeta potential and TGA analyses. The results indicated the formation of homogeneous, hydrophilic, and spherical particles with a negative surface charge as well as physical stability in aqueous solutions and high thermal stability with a particle size of about 229 nm. Adding the optimal amount of rosemary particles increased the hydrophilicity (reduced water contact angle from 60.55° to 52.15°) and porosity (increased from 69.3 to 91.7%). Also, by adding 1 wt% of rosemary particles, the permeability of the membrane increased by 3.5 times. The increase in mean pore radius (from 4.77 to 6.08 nm), smoother surface of modified membranes and negative charge on the membrane surface proved this improvement. Therefore, the amount of 1 wt% caused the best flux performance of pure water (from 126 to 359 LMH) and BSA solution (from 104.5 to 202.3 LMH). Moreover, RE/PSf membranes showed a high rejection for azithromycin: 81.98%, cefixime: 58.07%, O II: 71.75, RY 160: 81.71 and RB 5: 93.69%.

Hydrophilic Nature of Polytetrafluoroethylene through Modification with Perfluorosulfonic Acid-Based Polymers

Polytetrafluoroethylene (PTFE), commercially known as Teflon, is a fluoropolymer with a structure containing (CF2–CF2)n. It has high resistance to acids, alkalis and corrosive chemicals. PTFE is hydrophobic in nature with a water contact angle of 140°. Being hydrophobic in nature is a knotty problem, particularly in electrical applications, as it may lead to short circuits and result in reducing the lifetime of electrical equipment. Herein we describe the surface modification of PTFE from hydrophobic to hydrophilic without altering its bulk property. The surface hydrophilicity is achieved by two different techniques, viz., polymer coating (aquivion and nafion) and plasma treatment. Several characterization techniques including FTIR, Raman, XPS, WCA and SEM were used to analyze the surface of PTFE. It was found that 5% of the polymer solution and N2 plasma treatment for 2 min can produce huge differences in the surface property, as evidenced by the reduction in water contact angle from 140° (neat Teflon) to 80° (surface-modified Teflon). The surface morphology of neat PTFE is completely changed and collapsed as evidenced by the SEM images. The FTIR, Raman and XPS analyses confirm the presence of additional hydrophilic functional groups after the polymer coating and plasma treatment. Hence, this method represents a unique approach to modifying the surface property of Teflon, while maintaining its bulk property.

Transparent and Superhydrophilic Flexible Protein Films with Antifogging and Self-Cleaning Attributes.

Cyanoglycoside-modified flexible protein films, exhibiting a high level of transparency of ≈46 to 83%, were successfully prepared from lysozyme and glycerol with varying amounts of amygdalin (20, 40, and 60%) using water as a solvent. The increasing percentage of amygdalin leads to a drastic improvement of the hydrophilicity of the surface with a decrease in the water contact angle to 5.6°, resulting in superhydrophilicity. The increasing percentage of amygdalin led to a significant improvement in the surface's hydrophilicity, resulting in a reduced water contact angle of 5.6° and achieving superhydrophilicity. This superhydrophilic characteristic is particularly relevant to the excellent antifogging and self-cleaning properties of the resulting protein films. In addition to enhanced flexibility, the films also exhibited considerably improved thermal stability with a 40% loading of amygdalin in the protein solution. The superior mechanical, optical, and thermal properties of amygdalin-modified films are due to the strong hydrogen bonding with the peptides of lysozyme, as evidenced by the disappearance of amide bands in the cured protein films. Therefore, these transparent protein films, with their antifogging and enhanced thermal stability properties, can be potentially used for different packaging and coating applications.

Polymeric hollow fiber (HF) mixed matrix membranes (MMMs): Mutual effect of graphene oxide (GO) and polyvinylpyrrolidone (PVP) on nano-structuration

Hollow fiber (HF) membranes were fabricated using polysulfone (PSF) and 1.0 wt% graphene oxide (GO) synthesized through Hummer's method. The dry-wet spinning process was employed for their preparation. The structure and properties of both unmodified PSF HF membranes and those modified with GO were characterized. This encompassed analyses using scanning electron microscopy, attenuated total reflection Fourier Transform Infrared spectroscopy, thermo-gravimetric analysis, water contact angle (WCA) measurements, as well as evaluations of water permeability and mechanical attributes. The outcomes highlighted favorable mechanical and thermal characteristics. Moreover, the GO-modified PSF HF membranes exhibited larger surface pore sizes, along with an approximate 10% reduction in WCA and a fourfold increase in water permeability compared to the raw PSF HF membranes. Additionally, the influence of varying wt% of the pore-forming agent Polyvinylpyrrolidone (PVP) on the GO-modified PSF HF membranes was investigated. While no evidence suggests that GO can replace PVP, it is plausible to infer that this two-dimensional material complements the pore-forming agent's role by stabilizing the polymer-lean phase. This contributes to the creation of larger pores via phase separation mechanisms.

Efficient lithium recovery from simulated brine using a hybrid system: Direct contact membrane distillation (DCMD) and electrically switched ion exchange (ESIX)

Seawater reverse osmosis (SWRO) brine is a readily available resource hub in many countries, fulfilling the country's freshwater need by SWRO, yet lower in a concentration of high-demand elements like Li. This study outlines developing a novel hybrid system that combines direct contact membrane distillation (DCMD) and electrically switched ion exchange (ESIX) to facilitate simultaneous SWRO brine enrichment followed by selective Li recovery. The DCMD process concentrates the SWRO brine utilizing electrospun nanofiber membranes (ENMs) composed of polyvinylidene fluoride (PVDF). Incorporating reduced graphene oxide (rGO) nanoparticles augments the morphological, thermal, and mechanical stability of the PVDF ENMs. The water contact angle (WCA) of the 1-rGO/PVDF ENM stands at 142.08°, a testament to an enhanced hydrophobic property which resulted in a 12 % freshwater recovery from simulated SWRO brine and a 2.4-fold increase in Li+ concentration. The durability of the 1-rGO/PVDF ENM is evident in its minimal 11 % reduction in WCA after 15 h of brine concentration. In the context of hybrid operation, a Li-selective LiAlO2 electrode, coupled with an activated carbon counter electrode, demonstrated remarkable Li recovery for Li capture solutions enriched by the rGO-PVDF membrane in the DCMD phase. Compared to the Li concentration in the DCMD feed, sequential Li capture and release cycles recovered 91.8 % of Li, thereby underlining the critical role of the hybrid mode operation in concentrating Li from simulated brine solutions.

Electrospun nano-barium titanate/polycaprolactone composite coatings on titanium and Ti13Nb13Zr alloy

Using coated implant materials has been demonstrated to enhance bone regeneration and expedite healing around implant sites significantly. Generally, employing a polymeric matrix reinforced with ceramic materials has been considered a promising composite material for the coating of implants. The present study aimed to evaluate the effect of mixing varying concentrations of nano-barium titanate (nanoBaTiO3) (9, 18, and 36 wt%) to polycaprolactone (PCL) (18 wt%) on the properties of coatings applied to commercially pure titanium (CpTi) and Ti13Nb13Zr alloys implant materials. The electrospinning technique was utilised to fabricate the coatings, and the samples were characterised using atomic force microscopy (AFM) to investigate the composite coating’s surface roughness and topography; the incorporation of a high amount of BaTiO3 resulted in increased roughness of the coating layer on CpTi and Ti13Nb13Zr alloys (69.78 nm and 96.88 nm, respectively). Field emission scanning electron microscopy (FE-SEM) was used to investigate the surface morphology; the fibre diameters of BT/PCL composite were 80 to 534 nm for different mixture concentrations. Fourier transform infrared spectroscopy (FTIR) verified the chemical bonds in the composite coating. Results indicated that increasing the proportion of nano-barium titanate in the coating composition reduced water contact angles and enhanced the adhesion strength of the composite coating to the substrate. These findings provide valuable information for developing new coating materials to promote the growth of new bone and accelerate healing around implants.

Enhancing photoelectrochemical performance through surface engineering of CdSe and Al-doped CdSe nanoparticles on ZnO/FTO photoanodes

This study presents a comprehensive investigation into the enhanced performance of photoelectrochemical (PEC) cells through the decoration of CdSe and Al-doped CdSe nanoparticles on ZnO rods. The capacitance-voltage study reveals that Al doping increases the donor concentration and improves minority carrier diffusion time while reducing dispersion at grain boundaries. Spectral response analysis demonstrates that CdSe/ZnO/FTO and Al: CdSe/ZnO/FTO photoanodes exhibit maximum short-circuit currents at a wavelength of 675 nm, corresponding to a bandgap of 1.84 eV. Al doping shifts the spectral response to longer wavelengths, indicating an estimated bandgap of 1.72 eV. Furthermore, the effect of surface free energy and polarity on the developed photoanode materials is investigated. CdSe and Al-doped CdSe nano particles on ZnO/FTO surfaces exhibit reduced water contact angles, indicating improved wettability. The surface free energy decreases with Al doping, potentially influencing electrolyte absorption and the interaction between photoanodes and electrolytes. The presence of polar hydroxyl (-OH) groups and Al+++ ions on the Al: CdSe nano particles contributes to their impact on surface free energy. These findings provide valuable insights for optimizing PEC cell performance by manipulating doping concentrations and surface characteristics.

Preparation and characterization of drug-loaded, electrospun nanofiber mats formulated with zein or zein-based mixtures for wound healing applications.

Electrospun zein mats are known to have poor mechanical and water uptake properties limiting their usefulness as wound dressings.
 In this study, the effects of the solvent system used, the incorporation of the polymeric additives; polyethylene glycol 20000 (PEG20K) and polyvinylpyrrolidone K30 (PVPK30); and the crosslinking agent Tannic Acid (TA) on the mechanical and water uptake characteristics of zein – based nanofiber mats were investigated.
 The incorporation of either PEG20K or PVPK30 resulted in an improvement in water vapor sorption and a reduction in water contact-angle of the nanofiber mats. In addition, the incorporation of PEG20K and PVPK30 reduced the ultimate tensile strength, and Young’s modulus while increasing the percent elongation of the nanofiber mats. The use of tannic acid as a crosslinking agent led to an increase in the water vapor sorption, ultimate tensile strength, and Young’s modulus of the nanofiber mats.
 Mats with smaller average fiber diameter, greater ultimate tensile strength, higher Young's modulus, and greater water vapor sorption were obtained when using 80% (v/v) aqueous ethanol as a solvent system during the preparation of the nanofiber mats when compared to those produced using 60% (v/v) aqueous ethanol. In addition, using solutions with lower zein concentration resulted in mats with lower average fiber diameter, lower ultimate tensile strength and Young’s modulus, and higher percent elongation.
 Selected formulations were loaded with tetracycline hydrochloride and drug release was evaluated in bulk liquid and using Franz diffusion cells. The use of Franz diffusion cells allowed the discrimination between formulation performance as a function of composition and water uptake properties. Drug release from nanofiber mats was also confirmed by observing the formation of an inhibition zone in cultures of E. coli and S. aureus using the agar diffusion assay.
 Improved performance of zein nanofiber mats was achieved using polymeric modifiers and crosslinking with tannic acid improving their suitability for wound dressing applications.

Chitosan films plasticized with choline-based deep eutectic solvents: UV shielding, antioxidant, and antibacterial properties

Deep eutectic solvents (DES) as plasticizers of chitosan film show great potential for food packaging. This paper introduced some novel antioxidant and antibacterial films based on chitosan and DES consisting of choline chloride (ChCl) and organic acids. The effects of the composition and contents of choline-based DES on structures, mechanical properties, thermal stability, contact angle, optical, antioxidant and antibacterial properties of chitosan films were studied. FTIR analysis showed that choline-based DES did exist in the chitosan film with good polymer matrix compatibility. Most of the films exhibited uniform, flat surfaces and cross sections. The Young's modulus of the films decreased inversely to the level of choline-based DES, and maximal mechanical characteristics were achieved for films plasticized with ChCl and acetylsalicylic acid. The addition of choline-based DES apparently reduced water contact angles, decreased the decomposition temperature and the thermal stability of chitosan films. In terms of antioxidant capacities and ultraviolet (UV) shielding, chitosan films plasticized with choline-based DES containing acetylsalicylic acid and vitamin C had strong UV shielding and antioxidant properties. Chitosan films plasticized with choline-based DES containing acetylsalicylic acid, malonic acid and lactic acid showed excellent antibacterial properties against Escherichia coli and Staphylococcus aureus . In conclusion, the chitosan film with the choline-based DES, especially for ChCl and acetylsalicylic acid showed a good application prospect in food active packaging. Chitosan films plasticized with choline-based deep eutectic solvents: UV shielding, antioxidant, and antibacterial properties. • Novel chitosan films plasticized with 6 kind of deep eutectic solvents (DES) and 2 different levels addition were studied. • Chitosan films plasticized with choline-based DES containing acetylsalicylic acid or vitamin C had strong ultraviolet shielding and antioxidant activities. • Chitosan films plasticized with choline-based DES containing acetylsalicylic acid, malonic acid or lactic acid showed excellent antibacterial properties.

Hybrid Inorganic Organic PSF/Hap Dual-Layer Hollow Fibre Membrane for the Treatment of Lead Contaminated Water

Lead (Pb) exposure can be harmful to public health, especially through drinking water. One of the promising treatment methods for lead contaminated water is the adsorption-filtration method. To ensure the cost-effectiveness of the process, naturally derived adsorbent shall be utilised. In this study, hydroxyapatite particles, Ca10(PO4)6(OH)2 (HAP) derived from waste cockle shell, were incorporated into the outer layer of polysulfone/HAP (PSf/HAP) dual-layer hollow fibre (DLHF) membrane to enhance the removal of lead from the water source due to its hydrophilic nature and excellent adsorption capacity. The PSf/HAP DLHF membranes at different HAP loadings in the outer layer (0, 10, 20, 30 and 40 wt%) were fabricated via the co-extrusion phase inversion technique. The performance of the DLHF membranes was evaluated in terms of pure water flux, permeability and adsorption capacity towards lead. The results indicated that the HAP was successfully incorporated into the outer layer of the membrane, as visibly confirmed by microscopic analysis. The trend was towards an increase in pure water flux, permeability and lead adsorption capacity as the HAP loading increased to the optimum loading of 30 wt%. The optimized DLHF membrane displayed a reduced water contact angle by 95%, indicating its improved surface hydrophilicity, which positively affects the pure water flux and permeability of the membrane. Furthermore, the DLHF membrane possessed the highest lead adsorption capacity, 141.2 mg/g. The development of a hybrid inorganic-organic DLHF membrane via the incorporation of the naturally derived HAP in the outer layer is a cost-effective approach to treat lead contaminated water.

Fabrication and Characterization of Piezoelectric Polymer Composites and Cytocompatibility with Mesenchymal Stem Cells.

Piezoelectric materials are promising for biomedical applications because they can provide mechanical or electrical stimulations via converse or direct piezoelectric effects. The stimulations have been proven to be beneficial for cell proliferation and tissue regeneration. Recent reports showed that doping different contents of reduced graphene oxide (rGO) or polyaniline (PANi) into biodegradable polyhydroxybutyrate (PHB) enhanced their piezoelectric response, showing potential for biomedical applications. In this study, we aim to determine the correlation between physiochemical properties and the in vitro cell response to the PHB-based composite scaffolds with rGO or PANi. Specifically, we characterized the surface morphology, wetting behavior, electrochemical impedance, and piezoelectric properties of the composites and controls. The addition of rGO and PANi resulted in decreased fiber diameters and hydrophobicity of PHB. The increased surface energy of PHB after doping nanofillers led to a reduced water contact angle (WCA) from 101.84 ± 2.18° (for PHB) to 88.43 ± 0.83° after the addition of 3 wt % PANi, whereas doping 1 wt % rGO decreased the WCA value to 92.56 ± 2.43°. Meanwhile, doping 0.2 wt % rGO into PHB improved the piezoelectric properties compared to the PHB control and other composites. Adding up to 1 wt % rGO or 3 wt % PANi nanofillers in PHB did not affect the adhesion densities of bone marrow-derived mesenchymal stem cells (BMSCs) on the scaffolds. The aspect ratios of attached BMSCs on the composite scaffolds increased compared to the PHB control. The study indicated that the PHB-based composites are promising for potential applications such as regenerative medicine, tissue stimulation, and bio-sensing, which should be further studied.

Oxidized carbide-derived carbon as a novel filler for improved antifouling characteristics and permeate flux of hybrid polyethersulfone ultrafiltration membranes

Polyethersulfone (PES) is a widely used polymer for ultrafiltration (UF) membrane fabrication. In the current study, carbide-derived carbon (CDC) oxidized by acid treatment was utilized as a filler to fabricate a novel PES composites UF membranes. The successful oxidation of CDC was validated from presence of oxygen containing functional groups and improved oxygen content, from 5.08 at.% for CDC to 26.22 at.% for oxidized CDC (OCDC). The OCDC PES UF membranes were prepared at different loadings of OCDC between 0.5 and 3.0 wt%. The membrane porosity, pore size and surface free energy found to be improved while a noticeable reduction in water contact angle was observed with OCDC loading implying the improved hydrophilicity of PES membranes. Consequently, the pure water flux found to improve from 151.6 to 569.6 (L/(m2. h)) for the 3.0 wt% modified OCDC membrane (M−3) which is 3.8 folds of the bare PES membrane. The antifouling characteristics were evaluated by humic acid (HA) filtration. The results revealed a significant enhancement in HA rejection with OCDC loading, the highest rejection was 96.8% for M−3 membrane. Additionally, the adsorption capacity of OCDC modified membranes found to decrease with OCDC loading indicating improved rejection of HA from the membrane surface. Moreover, M−3 demonstrated the maximum flux recovery ratio (FRR) of 92.3%. Reusability of the fabricated membranes was evaluated by deionized water/humic acid cycling filtration. The FRR was higher than 86.7% over three cycles of pure water/HA filtration for 140 min, indicated the excellent stability and reusability of the membranes. Overall, the OCDC was an effective filler for enhancing the PES UF membranes antifouling and permeability properties.

Abiotic aging assisted bio-oxidation and degradation of LLDPE/LDPE packaging polyethylene film by stimulated enrichment culture

Polyethylene (PE), designed to be a packaging film with a short usage life cycle, is dominantly contributing to plastic waste. Here, the preliminary degradation of packaging PE film composed of a blend of LLDPE and LDPE has been investigated. A two-stage process of oxidation, linking abiotic and biotic treatment using enrichment cultures derived from the landfill site of the Deonar dumping ground, was employed to escalate the degradation process. The primary effects of abiotic aging on LLDPE/LDPE film were prominent in natural weathering conditions than thermal aging, resulting in the formation of oxidized functional macromolecules. Further, the enrichment cultures were potentially able to increase the oxidation level of naturally weathered film, detected by increased carbonyl peaks in the ATR-FTIR spectra. Also, the biotic aging concomitantly results in the reduction in water contact angle (WCA), demonstrating the deterioration in the surface property of LLDPE/LDPE film. Additionally, the stimulated enrichment cultures showed a significant variation in oxidation peaks of weathered film. The ATR-FTIR spectrum of the treated film reveals that the glucose-stimulated enrichment cultures (LPG) exhibited increased carbonyl peak intensity whereas yeast extract enrichment cultures (LPYE) showed increased intensity for the –C=C– unsaturated group. A dense biofilm layer with extracellular polymeric substances (EPS) attached to the LLDPE/LDPE surface, as indicated through SEM analysis, confirms microbial growth and utilization of PE material. Further, the bio-oxidation and degradation of LLDPE/LDPE film were verified using Gas chromatography-mass spectrometry (GC-MS). The GC-MS analysis confirms the presence of compounds having short linear hydrocarbon chains with alcohol and ester groups. These results demonstrate the degradation of LLDPE/LDPE packaging PE film in suitable abiotic conditions with emphasis on the enrichment culture's dependability for efficient biotic oxidation. Thus, the approach can be used to develop methods to alleviate the environmental pollution caused by plastic waste.

The effect of polyethylene glycol on printability, physical and mechanical properties and osteogenic potential of 3D-printed poly (l-lactic acid)/polyethylene glycol scaffold for bone tissue engineering

One of the challenges in critical size bone defect repairing is the use of a porous degradable scaffold with appropriate properties to the host tissue. Nowadays, the three-dimensional (3D) printing method can produce custom and personalized scaffolds and overcome the problems of traditional methods by controlling the porosity and dimensions of biomaterial scaffolds. In this study, polylactic acid/polyethylene glycol (PLA/PEG) scaffolds were prepared with different PEG percentages (0, 5, 10, 15 and 20 wt%) by fused deposition modeling (FDM) to optimize printability and achieve suitable physico-mechanical properties and also enhance cellular behavior for bone tissue engineering and actually, this study complements previous studies. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were employed for chemical, morphological and thermal evaluations, respectively. It was shown that the adding of 20 wt% PEG to PLA 3D printed scaffolds reduced water contact angle (from 78.16 ± 3.27 to 60.00 ± 2.16), and increased surface wettability. The results also showed that the mechanical properties of the printed scaffolds were not significantly reduced by adding 5 and 10 wt% of PEG. The addition of PEG increased the degradability of scaffolds during immersion in phosphate buffer saline (PBS) solution for 8 weeks and PLA/PEG20 scaffold with 50.96 % had the highest rate of degradation. MTT assay showed that none of the studied scaffolds had cytotoxicity against MG-63 cells and increasing the PEG levels to 20 wt%, increased cell viability and adhesion and osteogenic differentiation. According to the obtained physical, mechanical and biological results, PLA/PEG scaffold printed by the FDM method can be an appropriate candidate for use in bone repair applications.

Microcontact Printing of Biomolecules on Various Polymeric Substrates: Limitations and Applicability for Fluorescence Microscopy and Subcellular Micropatterning Assays.

Polymeric materials play an emerging role in biosensing interfaces. Within this regard, polymers can serve as a superior surface for binding and printing of biomolecules. In this study, we characterized 11 different polymer foils [cyclic olefin polymer (COP), cyclic olefin copolymer (COC), polymethylmethacrylate (PMMA), DI-Acetate, Lumirror 4001, Melinex 506, Melinex ST 504, polyamide 6, polyethersulfone, polyether ether ketone, and polyimide] to test for the applicability for surface functionalization, biomolecule micropatterning, and fluorescence microscopy approaches. Pristine polymer foils were characterized via UV–vis spectroscopy. Functional groups were introduced by plasma activation and epoxysilane-coating. Polymer modification was evaluated by water contact angle measurement and X-ray photoelectron spectroscopy. Protein micropatterns were fabricated using microcontact printing. Functionalized substrates were characterized via fluorescence contrast measurements using epifluorescence and total internal reflection fluorescence microscopy. Results showed that all polymer substrates could be chemically modified with epoxide functional groups, as indicated by reduced water contact angles compared to untreated surfaces. However, transmission and refractive index measurements revealed differences in important optical parameters, which was further proved by fluorescence contrast measurements of printed biomolecules. COC, COP, and PMMA were identified as the most promising alternatives to commonly used glass coverslips, which also showed superior applicability in subcellular micropatterning experiments.