Leveraging the Dielectric Barrier Discharge Plasma Process to Create Regenerative Biocidal ePTFE Membranes.

The utilization of dielectric barrier discharge (DBD) plasma treatment for modifying substrate surfaces constitutes an easy and simple approach with a potential for diverse applications. This technique was used to modify the surface of a commercial porous expanded poly(tetrafluoroethylene) (ePTFE) film with either dimethylaminoethyl methacrylate (DMAEMA) or (trimethylamino)ethyl methacrylate chloride (TMAEMA) monomers, aiming to obtain antibacterial ePTFE. Physicochemical analyses of the membranes revealed that DBD successfully enhanced the surface energy and surface charge of the membranes while maintaining high porosity (>75%) and large pore size (>1.0 µm). Evaluation of the bacteria killing-releasing (K-R) function revealed that both DMAEMA and TMAEMA endowed ePTFE with the ability to kill Escherichia coli bacteria. However, only TMAEMA-grafted ePTFE allowed for the release of dead bacteria from the surface upon washing with sodium hexametaphosphate (SHMP) saline solution, owing to its cationic charge derived from the quaternary amine. Washing with SHMP disturbed the electrostatic force between the polymer brushes and dead bacteria, which caused the release of the dead bacteria. Lastly, dead-end bacteria filtration showed that the TMAEMA-grafted ePTFE was able to kill 99.78% of the bacteria, while approximately 61.55% of bacteria were killed upon contact. The present findings support the feasibility of using DBD plasma treatment for designing surfaces that target bacteria and aid in the containment of disease-causing pathogens.

Recent Advances on the Fabrication of Antifouling Phase-Inversion Membranes by Physical Blending Modification Method.

Membrane technology is an essential tool for water treatment and biomedical applications. Despite their extensive use in these fields, polymeric-based membranes still face several challenges, including instability, low mechanical strength, and propensity to fouling. The latter point has attracted the attention of numerous teams worldwide developing antifouling materials for membranes and interfaces. A convenient method to prepare antifouling membranes is via physical blending (or simply blending), which is a one-step method that consists of mixing the main matrix polymer and the antifouling material prior to casting and film formation by a phase inversion process. This review focuses on the recent development (past 10 years) of antifouling membranes via this method and uses different phase-inversion processes including liquid-induced phase separation, vapor induced phase separation, and thermally induced phase separation. Antifouling materials used in these recent studies including polymers, metals, ceramics, and carbon-based and porous nanomaterials are also surveyed. Furthermore, the assessment of antifouling properties and performances are extensively summarized. Finally, we conclude this review with a list of technical and scientific challenges that still need to be overcome to improve the functional properties and widen the range of applications of antifouling membranes prepared by blending modification.

A Biofouling Resistant Zwitterionic Polysulfone Membrane Prepared by a Dual-Bath Procedure.

This study introduces a zwitterionic material to modify polysulfone (PSf) membranes formed by a dual bath procedure, in view of reducing their fouling propensity. The zwitterionic copolymer, derived from a random polymer of styrene and 4-vinylpyrridine and referred to as zP(S-r-4VP), was incorporated to the PSf solution without any supplementary pore-forming additive to study the effect of the sole copolymer on membrane-structuring, chemical, and arising properties. XPS and mapping FT-IR provided evidence of the modification. Macrovoids appeared and then disappeared as the copolymer content increased in the range 1-4 wt%. The copolymer has hydrophilic units and its addition increases the casting solution viscosity. Both effects play an opposite role on transfers, and so on the growth of macrovoids. Biofouling tests demonstrated the efficiency of the copolymer to mitigate biofouling with a reduction in bacterial and blood cell attachment by more than 85%. Filtration tests revealed that the permeability increased by a twofold factor, the flux recovery ratio was augmented from 40% to 63% after water/BSA cycles, and irreversible fouling was reduced by 1/3. Although improvements are needed, these zwitterionic PSf membranes could be used in biomedical applications where resistance to biofouling by cells is a requirement.

Zwitterionized Nanofibrous Poly(vinylidene fluoride) Membranes for Improving the Healing of Diabetic Wounds.

This work presents nanofibrous membranes made of poly(vinylidene fluoride) (PVDF) and poly(2-methacryloyloxyethyl phosphorylcholine-co-methacryloyloxyethyl butylurethane) (PMBU) for promoting the healing of acute and chronic wounds. Membranes were prepared by an electrospinning process, which led to matrixes with a pore size mimicking the extracellular matrix. PMBU greatly improves the hydration of membranes, resulting in very low biofouling by protein or bacteria and enhanced blood compatibility while the cell viability remains close to 100%. This set of properties exhibited by the suitable combination of physical structure and material composition led to applying the zwitterionic nanofibrous membranes as wound-dressing materials for acute and chronic wounds. The results demonstrated that the zwitterionic membrane could compete with commercial dressings in terms of wound-healing kinetics and could outperform them with regard to the quality of new tissue. Histological analyses suggested that inflammation was reduced while proliferative and maturation phases were accelerated, leading to homogeneous re-epithelialization. This study unveils another potential biomedical application of antifouling zwitterionic membranes.

Electrochemical properties of novel FeV2O4 as an anode for Na-ion batteries.

Spinel based transition metal oxide - FeV2O4 is applied as a novel anode for sodium-ion battery. The electrochemical tests indicate that FeV2O4 is generally controlled by pseudo-capacitive process. Using cost-effective and eco-friendly aqueous based binders, Sodium-Carboxymethylcellulose/Styrene butadiene rubber, a highly stable capacity of ~97 mAh∙g-1 is obtained after 200 cycles. This is attributed to the strong hydrogen bonding of carboxyl and hydroxyl groups indicating superior binding with the active material and current collector which is confirmed by the ex-situ cross-section images of the electrode. Meanwhile, only ~27 mAh∙g-1 is provided by the electrode using poly(vinylidene difluoride) due to severe detachment of the electrode material from the Cu foil after 200 cycles. The obtained results provide an insight into the possible applications of FeV2O4 as an anode material and the use of water-based binders to obtain highly stable electrochemical tests for sodium-ion battery.

Novel Red-Emitting Ba3Y(BO3)3:Bi3+, Eu3+ Phosphors for N-UV White Light-Emitting Diodes.

Ba3Y(BO3)3:Eu3+, Bi3+ were successfully prepared via a solid-state reaction. The crystallinity, photoluminescence properties, energy transfer and thermal quenching properties were studied. Subjecting Ba3Y(BO3)3:Bi3+ samples to different excitation wavelengths (340-370 nm), obtained blue and green emission ascribed to Bi3+(II) and Bi3+(I) sites, respectively. The influence of these two sites were systematically investigated. Bi3+ efficiently transferred its absorbed energy to neighboring Eu3+ sites by enhancing its luminescence intensity. Moreover, Bi3+ greatly enhanced the excitation spectra of Eu3+ in the N-UV region by 2.26 times which indicates that Ba3Y(BO3)3:Eu3+, Bi3+ can be used as a phosphor for w-LEDs using N-UV LED chips.