Interfacial Engineering of Binder-Free Janus Separator with Ultra-Thin Multifunctional Layer for Simultaneous Enhancement of Both Metallic Li Anode and Sulfur Cathode.

Exploring a scalable strategy to fabricate a multifunctional separator is of great significance to overcome the challenges of lithium polysulfides (LiPSs) and dendritic growth in lithium-sulfur batteries (LSBs). Herein, a binder-free Janus separator is constructed by interfacial engineering. At the cathode interface, an ultra-thin covalent triazine piperazine film containing tailorable micropores and adsorption sites is decorated on polyacrylonitrile (PAN) membrane by in situ interfacial polymerization, building a triple barrier for LiPSs. The combination of steric hindrance and chemical adsorption reduces LiPS's migration by 81.85%. Meanwhile, at the anode interface, a fast-ionic conductor Li6.4 La3 Zr1.4 Ta0.6 O12  (LLZTO) is created on the surface of PAN nanofiber by magnetron sputtering to suppress dendrite growth. Even though there is no binder between the ceramic layer and the fibrous separator, sputtering creates an inter-embedded structure that ensures no depowering after cycling. Furthermore, the PAN-based separator displays a high temperature tolerance of 180 °C. Consequently, the cell delivers a high capacity of 1287.9 mAh g-1 at 0.5 C and stable cycling performance with an ultra-low capacity decay rate of 0.059% per cycle over 500 cycles. This work provides a scalable strategy for functionalizing separators to tackle the challenges in LSBs, which is binder-free, stripping-free, and essentially thickening-free.

Cationic cellulose nanofiber solid electrolytes: A pathway to high lithium-ion migration and polysulfide adsorption for lithium-sulfur batteries.

Polyethylene oxide (PEO) solid electrolytes, acknowledged for their safety advantages over liquid counterparts, confront inherent challenges, including low ionic conductivity, restricted lithium ion migration, and mechanical fragility, notably pronounced in lithium­sulfur batteries due to the polysulfide shuttling phenomenon. To address these limitations, we integrate a quaternary ammonium cation-modified cellulose (QACC) nanofiber, electrospun with cellulose acetate (CA) from recycled cigarette filters, into the PEO electrolyte matrix. The nitrogen atom within the quaternary ammonium group exhibits a pronounced affinity for polysulfide compounds, effectively curtailing polysulfide migration. Concurrently, Lewis acid-base interactions between quaternary ammonium groups and lithium salt anions facilitate the release of additional Li+, achieving a lithium-ion transference number 1.5 times higher than its pure PEO counterpart. Furthermore, the introduction of a larger trifluoromethanesulfonimide (TFSI) group on the QACC macromolecule (TFSI-QACC) disrupts the ordered arrangement of PEO macromolecules, resulting in a noteworthy enhancement in ionic conductivity, reaching 2.07 × 10-4 S cm-1 at 60 °C, thus addressing the challenge of low PEO electrolyte conductivity. Moreover, the nanofiber enhances the mechanical strength of the PEO electrolyte from 0.49 to 7.50 MPa, mitigating safety concerns related to lithium dendrites puncturing the electrolyte. Consequently, the composite PEO demonstrates exemplary performance in lithium symmetrical batteries, enduring 500 h of continuous operation and completing 100 cycles at both room and elevated temperatures. This integrated approach, transitioning from waste to wealth, adeptly addresses a spectrum of challenges in the efficiency of solid-state electrolytes, holding considerable promise for advancing lithium­sulfur battery technology.

Multi-duties for one post: Biodegradable bacterial cellulose-based separator for lithium sulfur batteries.

High-energy density lithium sulfur battery containing highly active materials is more prone to safety hazards. Besides, the infamous shuttle effect of lithium polysulfides (LiPSs) and listless redox kinetic limit its practical applications. Here, a "one-for-all" design concept for separator enabled by interfacial engineering is proposed to relieve the bottlenecks. For one thing, porous bacterial cellulose (PBC) membrane with high thermostability (no shrinking at 200 °C) and puncture resistance was employed to ensure the battery's safety. For another, a difunctional Ti3C2Tx-SnS2 modified layer could capture LiPSs through lewis-acid interaction and promoted the redox kinetics by catalytically active sites. The symmetric cell with anchoring-electrocatalysis Ti3C2Tx-SnS2-PBC separator infiltrated with the electrolyte delivered an ionic conductivity of 2.171 mS/cm at a high temperature of 180 °C. And a capacity retention is improved by 71.2% compared with PP separator. This work furnishes a facial engineering strategy for manufacturing a multifunctional separator for lithium sulfur batteries.

Molecular characterization of a virulent genotype VIId strain of Newcastle disease virus from farmed chickens in Shanghai.

A virulent Newcastle disease virus strain was isolated from diseased chickens in Shanghai, China. The isolated strain was initially characterized as highly virulent because of a short mean death time in embryonated chicken eggs and specific-pathogen-free chickens and was typed as neurotropic by intracloacal inoculation of chickens. The isolated strain had a dibasic amino acid motif in the fusion protein cleavage site sequence required for systemic replication in the host cell. The strain fell into subgenotype VIId by phylogenetic analysis of the fusion protein gene. Although these results demonstrated some sequence similarity between the isolated strain and strains responsible for outbreaks of Newcastle disease in China and Taiwan, the unusually high mortality (86.4%) set this strain aside from other VII strains. Finally, a cross-protection assay demonstrated that La Sota and clone 30 live vaccines could not protect chickens from infection with the isolated strain, with a zero survival rate being observed when chickens were challenged with a high dose of virulent VIId virus.

PCN-224 Nanoparticle/Polyacrylonitrile Nanofiber Membrane for Light-Driven Bacterial Inactivation.

Increasing issues of pathogen drug resistance and spreading pose a serious threat to the ability to treat common infectious diseases, which encourages people to explore effective technology to meet the challenge. Photodynamic antibacterial inactivation (aPDI) is being explored for inactivating pathogens, which could be used as a novel approach to prevent this threat. Here, porphyrin-embedded MOF material (PCN-224) with photodynamic effect was synthesized, then the PCN-224 nanoparticles (NPs) were embedded into PAN nanofibers with an electrospinning process (PAN-PCN nanofiber membrane). On the one hand, polyacrylonitrile (PAN) nanofibers help to improve the stability of PCN-224 NPs, which could avoid their leakage. On the other, the PAN nanofibers are used as a support material to load bactericidal PCN-224 NPs, realizing recycling after bacterial elimination. An antibacterial photodynamic inactivation (aPDI) study demonstrated that the PAN-PCN 0.6% nanofiber membrane processed 3.00 log unit elimination towards a E. coli bacterial strain and 4.70 log unit towards a S. aureus strain under illumination. A mechanism study revealed that this efficient bacterial elimination was due to singlet oxygen (1O2). Although the materials are highly phototoxic, an MTT assay showed that the as fabricated nanofiber membranes had good biocompatibility in the dark, and the cell survival rates were all above 85%. Taken together, this work provided an application prospect of nanofibers with an aPDI effect to deal with the issues of pathogen drug resistance and spreading.

Smart Textiles with Self-Disinfection and Photothermochromic Effects.

Self-disinfecting textile materials employing combined photodynamic/photothermal effects enable the prevention of microbial infections, a property that has great potential in healthcare applications. However, smart textiles with stimulus responses to ambient temperature are marvelous materials for enhancing their photothermal applications with additional functions. It is still challenging to realize vivid and contrasting color changes as temperature indicators. Herein, through the in situ growth of PCN-224 metal-organic frameworks (MOFs), the electrospraying of a Ti3C2 MXene colloid, and the screen printing of a thermochromic dye, a smart photothermochromic self-disinfecting textile has been fabricated. An antibacterial inactivation study revealed 99.9999% inactivation toward gram-negative (Escherichia coli ATCC 8099) and gram-positive (Staphylococcus aureus ATCC 6538) bacteria in 30 min. A mechanism study revealed that light-driven singlet oxygen and heat are the main reasons for bacterial inactivation. Interestingly, the fabrics presented photothermal effects not only under a handheld 780 nm NIR laser but also under visible Xe lamp (λ ≥ 420 nm) illumination. The color of the fabrics (S-CF@PCN0.08) changed completely from dark green to dark red when the temperature exceeded 45 °C under Xe lamp illumination. Furthermore, the photothermochromic effect occurred in just 1 s under a 780 nm laser. Taken together, this smart photothermochromic self-disinfecting textile permits a new way to feedback the timely signal of temperature by color change and provides novel insights into the development of self-disinfecting textiles.

Light-driven self-disinfecting textiles functionalized by PCN-224 and Ag nanoparticles.

Toward the goal of preventing microbial infections in hospitals or other healthcare institutions, here we developed a self-disinfecting textile with synergistic photodynamic/photothermal antibacterial property. Porphyrinic Metal-organic frameworks (PCN-224) and Ag nanoparticles (NPs) were in situ grown on knitted cotton textile (KCT) successively to achieve rapid photodynamic antibacterial and durable bacteriostatic effect. Light-driven singlet oxygen (1O2) generated from PCN-224 and heat generated from Ag could function synergistically to realize rapid bacterial inactivation. Interestingly, 1O2 could promote Ag NPs to be degraded to release more Ag+ ions, achieving durable bacteriostatic effect. Antibacterial assay demonstrated 6 and 4.49 log unit inactivation toward two typical bacterial strains (E. coli and S. aureus) under Xe arc lamp in 30 min, respectively. Even after ten washes, the textile still maintained 6 log unit bacterial inactivation. Mechanism study proved light-driven 1O2 and heat are main factors causing bacterial inactivation, they could work synergistically to enhance bacterial inactivation efficiency. Photothermal study revealed that the textile could reach to 69 â„ƒ under visible light and 79.1 â„ƒ under 780-nm light-laser, which showed much potential in photothermal material applications. Taken together, our findings demonstrated a synergistic self-disinfecting cotton textile that exhibited constructive significance for preventing microbial infections and transmissions.

Carbon quantum dots embedded electrospun nanofibers for efficient antibacterial photodynamic inactivation.

Faced with the emergence and proliferation of antibiotic resistant pathogens, novel nonspecific materials and approaches are required. Herein, we employed electrospinning technology to fabricate nanofibers with antibacterial photodynamic inactivation. This material combines polyacrylonitrile, as a photostable polymer, and biocompatible carbon quantum dots. The resulted nanofibers were successfully characterized by physical and spectroscopic methods. The microbicidal reactive oxygen species (i.e., singlet oxygen) upon illumination was confirmed, and cytotoxicity assay demonstrated that the nanofibers had low cytotoxicity and good biocompatibility. Antibacterial photodynamic inactivation studies demonstrated broad antibacterial efficacy of Gram-negative Escherichia coli ATCC-8099 (99.9999+%, 6 log units inactivation), Gram-negative Pseudomonas aeruginosa CMCC (B) 10104 (99.9999+%, 6 log units inactivation), and Gram-positive Bacillus subtilis CMCC (B) 63501 (99.9999+%, 6 log units inactivation) upon illumination with visible light (Xe lamp, 500 W, 12 cm sample distance, λ ≥ 420 nm, 1.5 h). However modest inactivation results were observed against Gram-positive Staphylococcus aureus ATCC-6538 (98.3%, 1.8 log units inactivation). Owing to the prepared nanofibers exhibiting efficient antibacterial activity against Gram-negative and Gram-positive bacteria, such materials could be potentially used in anti-infective therapy.

Insight into light-driven antibacterial cotton fabrics decorated by in situ growth strategy.

Development of ease-fabricated and effectively self-disinfecting textile materials for antimicrobial and infection prevention has been urgently desired by both consumers and industry. However, some nonresponsive antibacterial agents finished fabrics may be harmful to human. To address this issue, we developed a facile finishing method to endow woven cotton fabrics (WCF) with light-driven antibacterial property. Here in, porphyrinic metal-organic frameworks (PCN-224) were in situ synthesized on WCF (termed PCN-224/WCF) and PCN-224/WCF was proven to be used for antibacterial photodynamic inactivation (aPDI). aPDI studies indicated no difference in bacterial inactivation, the inactivation was 99.9999% of Gram-negative Escherichia coli 8099 and Pseudomonas aeruginosa CMCC (B) 10104 as well as Gram-positive Staphylococcus aureus ATCC-6538 and Bacillus subtilis CMCC (B) 63501 under visible light illumination (500 W, 15 cm vertical distance, λ ≥ 420 nm, 45 min). Cytotoxicity tests revealed PCN-224/WCF had low biological toxicity and good biocompatibility. Mechanism study revealed that singlet oxygen (1O2) was produced by PCN-224/WCF and caused severe damage to bacteria which was observed from the SEM images. This study provided a facile guideline to functionalize cotton fabrics with responsive bactericidal property which showed great potential for new generation of textiles with practical applications.

Carbon quantum dots: A bright future as photosensitizers for in vitro antibacterial photodynamic inactivation.

Carbon nanomaterials have increasingly gained the attention of the nano-, photo- and biomedical communities owing to their unique photophysical properties. Here, we facilely synthesized carbon quantum dots (CQDs) in a one-pot solvothermal reaction, and demonstrated their utility as photosensitizers for in vitro antibacterial photodynamic inactivation (aPDI). The bottom-up synthesis employed inexpensive and sustainable starting materials (citric acid), used ethanol as an environmentally-friendly solvent, was relatively energy efficient, produced minimal waste, and purification was accomplished simply by filtration. The CQDs were characterized by both physical (TEM, X-ray diffraction) and spectroscopic (UV-visible, fluorescence, and ATR-FTIR) methods, which together confirmed their nanoscale dimensions and photophysical properties. aPDI studies demonstrated detection limit inactivation (99.9999 + %) of Gram-negative Escherichia coli 8099 and Gram-positive Staphylococcus aureus ATCC-6538 upon visible light illumination (λ ≥ 420 nm, 65 ± 5 mW/cm2; 60 min). Post-illumination SEM images of the bacteria incubated with the CQDs showed perforated and fragmented cell membranes consistent with damage from reactive oxygen species (ROS), and mechanistic studies revealed that the bacteria were inactivated by singlet oxygen, with no discernable roles for other ROS (e.g., superoxide or hydroxyl radicals). These findings demonstrated that CQDs can be facilely prepared, operate via a Type II mechanism, and are effective photosensitizers for in vitro aPDI.

Ceramic Nanoparticle-Decorated Melt-Electrospun PVDF Nanofiber Membrane with Enhanced Performance as a Lithium-Ion Battery Separator.

Designing a composite separator that can withstand high temperature, deliver high capacity, and offer fast charge-discharge capability is imperative for developing a high-performance lithium-ion battery. Here, a series of ceramic nanoparticle-coated nanofiber membranes, including Al2O3/poly(vinylidene fluoride) (PVDF), SiO2/PVDF, and Al2O3/SiO2/PVDF, were prepared by melt-electrospinning and magnetron sputtering deposition. Among all of these composite separators, Al2O3/SiO2/PVDF showed several advantages including excellent thermal stability (no dimensional shrinkage at temperature up to 130 °C and an onset degradation temperature of 445 °C) and superb electrolyte compatibility (340% electrolyte uptake). In addition, the ß phase of the fibrous PVDF membrane as well as the presence of polar ceramic nanoparticles on the fiber surface can synergistically improve the ion conductivity to 2.055 mS/cm at room temperature, which is more than 8 times higher than that of the commercial polyethylene (PE) separator. Performance of these ceramic nanoparticle-coated separators in a lithium-ion battery demonstrated an improved discharge capacity of 161.5 mAh/g and more than 84.3% capacity retention rate after 100 cycles. The ceramic nanoparticle-coated PVDF separators also maintained 58.4% capacity at a high current density of 8C, which is better than the 49.8% capacity for the commercial PE separator. Therefore, the ceramic nanoparticle-coated PVDF membrane proves to be a promising separator for a high-power and more secure lithium-ion battery.

[Expression in Escherichia coli, purification and enzymatic properties of porcine urate oxidase].

The aims of this research were to construct prokaryotic expression vector containing the gene of porcine urate oxidase (pUOX), optimize the conditions of the expression of pUOX in recombinant Escherichia coli BL21(DE3), and analyze the in vitro activity and the enzymological properties of pUOX. The pUOX gene was amplified by RT-PCR from the extracted total RNA of porcine liver, and was inserted into the prokaryotic expression vector pET30a(+) to construct a recombinant expression vector pET30a(+)/pUOX. We identified the recombinant vector by endonuclease digestion and sequence analysis. The pUOX gene was amplified and cloned into the vector pET30a(+) successfully. And then the recombinant vector was transformed into E. coli BL21(DE3). The expression of pUOX with a molecular of approximately 41 kD was induced by IPTG. We also optimized the expression conditions of the recombinant protein. The recombinant protein was mostly located in the cytoplasm and it was insoluble. After the inclusion body was solved in 8 mol/L urea and refolding in 2 mol/L urea, the recombinant protein was collected and purified by Ni2+-NTA column. This recombinant protein had a specific activity of 50.61 IU/mg and showed similar properties of optimum temperature and thermal stability, base on the enzymatic assay and analysis of enzymological properties. These results would help to analyze the in vivo activity by testing animal.