Effect of chitosan crosslinking time on the structure and antifouling performance of polyvinylidene fluoride membrane by surface gelation-immersion precipitation phase inversion

Polyvinylidene fluoride (PVDF) porous membrane was prepared by a two-step method of surface gelation-immersion precipitation phase inversion. Chitosan/acetic acid solution and glutaraldehyde aqueous solution were sequentially sprayed onto the surface of the PVDF solution film, with chitosan crosslinking and gelation occurring simultaneously on the film surface. The solution film was then immersed in a coagulation bath to obtain a modified PVDF porous membrane. The effect of the crosslinking time of chitosan and glutaraldehyde on the structure and properties of the PVDF porous membrane was discussed. The results showed that with the prolongation of crosslinking time, the surface structure of the membrane changed from a dense skin layer to a porous structure; the porosity and the mean pore size of the modified PVDF membranes increased first and then decreased, and the contact angle gradually decreased. When the crosslinking time extended to 15 min, the water flux of modified membrane (M153) reached a maximum value. BSA dynamic cyclic filtration experiment showed that the retention rate (R) of the modified membrane was significantly improved, compared to 68.3% retention rate of the blank membrane (M000), but the crosslinking time had little effect on the retention rates of the four modified membranes. The antifouling data showed that the flux recovery rate of the blank membrane was 73.0%, while the flux recovery rate of the modified membrane can reach as high as 84.40%, and the irreversible pollution rate of the blank membrane was 27.7%, while the irreversible pollution rate of the modified membrane reduced to 15.6%. These results indicated that, after surface chitosan crosslinking, the hydrophilicity and antifouling properties of PVDF membranes were improved. PRACTITIONER POINTS: Modified PVDF membranes with crosslinking CS coating were prepared by a two-step method of surface gelation-immersion precipitation phase inversion. -OH groups and -NH2 groups of CS coating improve the hydrophilicity and the antifouling property of modified PVDF membranes. Modified PVDF membranes had larger mean pore size and higher porosity than unmodified membrane. Flux recovery rates of the modified membranes were higher than that of unmodified membrane. Pollution degree, reversible pollution rate, and irreversible pollution rate of modified membranes were lower than those of unmodified membrane.

An Ultrasound Array of Emitter-Receiver Stacks for Microbubble-Based Therapy

Most therapeutic ultrasound devices place emitters and receivers in separate locations, so that the long therapeutic pulses (>1 ms) can be emitted while receivers monitor the procedure. However, with such placement, emitters and receivers are competing for the same space, producing a trade-off between emission efficiency and reception sensitivity. Taking advantage of recent studies demonstrating that short-pulse ultrasound can be used therapeutically, we aimed to develop a device that overcomes such trade-offs. The array was composed of emitter-receiver stacks, which enabled both emission and reception from the same location. Each element was made of a lead zirconate titanate (PZT)-polyvinylidene fluoride (PVDF) stack. The PZT (frequency: 500 kHz, diameter: 16 mm) was used for emission and the PVDF (thickness: 28 μm, diameter: 16 mm) for broadband reception. 32 elements were assembled in a 3D-printed dome-shaped frame (focal length: 150 mm; [Formula: see text]-number: 1) and was tested in free-field and through an ex-vivo human skull. In free-field, the array had a 4.5 × 4.5 × 32 mm focus and produced a peak-negative pressure (PNP) of 2.12 MPa at its geometric center. The electronic steering range was ±15 mm laterally and larger than ±15 mm axially. Through the skull, the array produced a PNP of 0.63 MPa. The PVDF elements were able to localize broadband microbubble emissions across the skull. We built the first multi-element array for short-pulse and microbubble-based therapeutic applications. Stacked arrays overcome traditional trade-offs between the transmission and reception quality and have the potential to create a step change in treatment safety and efficacy.

Enhanced management and antifouling performance of a novel NiFe-LDH@MnO2/PVDF hybrid membrane for efficient oily wastewater treatment

Layered double hydroxides (LDHs) have gained significant recognition for their facile synthesis and super-hydrophilic two-dimensional (2D) structure to fabricate antifouling membranes for oily wastewater separation. However, conventional PVDF membranes, due to their hydrophobic nature and inert matrix, often exhibit insufficient permeance and compatibility. In this study, a novel NiFe-LDH@MnO2/PVDF membrane was synthesized using ultrasonic, redox, and microwave-hydrothermal processes. This innovative approach cultivated grass-like NiFe-LDH@MnO2 nanoparticles within an inert PVDF matrix, promoting the growth of highly hydrophilic composites. The presence of NiFe-LDH@MnO2 resulted in pronounced enhancements in surface morphology, interfacial wettability, and oil rejection for the fabricated membrane. The optimal NiFe-LDH@MnO2/PVDF-2 membrane exhibited an extremely high pure water flux (1364 L m-2•h-1), and increased oil rejection (from 81.2% to 93.5%) without sacrificing water permeation compared to the original PVDF membrane. Additionally, the NiFe-LDH@MnO2/PVDF membrane demonstrated remarkable antifouling properties, evident by an exceptional fouling resistance ratio of 96.8% following slight water rinsing. Mechanistic insights into the enhanced antifouling performance were elucidated through a comparative "semi-immersion" investigation. The facile synthesis method, coupled with the improved membrane performance, highlights the potential application prospects of this hybrid membrane in emulsified oily wastewater treatment and environmental remediation.

Nanomaterial grafted polymorphous activated carbon cloth surface for antibacterial, capacitive deionization and oil spill cleaning applications

This work reports the development of multifunctional or polymorphous surfaces using zinc oxide (ZnO) nanorods, silica (SiO2), and fluoropolymer functionalization in a sequential process. Firstly, zinc oxide nanorods were grown on activated carbon cloth (ACC) using a simple low-temperature synthesis process. ZnO nanorods-coated ACC substrate was applied to investigate the antimicrobial properties, and the results showed inhibition of 50% for Escherichia coli (E.coli) and 55% for Bacillus subtilis (B.subtilis) over 48 h of incubation time. Subsequent in-situ modification of silica nanoparticles like layer on ZnO nanorods-coated ACC surface was developed and used as an electrode for brackish water desalination in a capacitive deionization system. ZnO-SiO2 modified ACC surface enhanced the desalination efficiency by 1.6 times, the salt removal rate (SRR) by threefold, and the durability (fouling prevention) for long-term usage compared to pristine ACC. Further modification of the ZnO-SiO2-ACC surface using fluoropolymer rendered the surface superhydrophobic and oleophilic. Vegetable (1.4 g/g) and crude oil (1.6 g/g) adsorption capacities were achieved for modified surface which was 70% enhancement compared with pristine ACC. The dynamic oil spill adsorption test exhibited the complete removal of oil spills on water surfaces within a few seconds, suggesting a potential application in oil spill cleaning.

Tough, Antifreezing, and Piezoelectric Organohydrogel as a Flexible Wearable Sensor for Human-Machine Interaction

Piezoelectric hydrogel sensors are becoming increasingly popular for wearable sensing applications due to their high sensitivity, self-powered performance, and simple preparation process. However, conventional piezoelectric hydrogels lack antifreezing properties and are thus confronted with the liability of rupture in low temperatures owing to the use of water as the dispersion medium. Herein, a kind of piezoelectric organohydrogel that integrates piezoelectricity, low-temperature tolerance, mechanical robustness, and stable electrical performance is reported by using poly(vinylidene fluoride) (PVDF), acrylonitrile (AN), acrylamide (AAm), p-styrenesulfonate (NaSS), glycerol, and zinc chloride. In detail, the dipolar interaction of the PVDF chain with the PAN chain facilitates the crystal phase transition of PVDF from the α to β phase, which endows the organohydrogels with a high piezoelectric constant d33 of 35 pC/N. In addition, the organohydrogels are highly ductile and can withstand significant tensile and compressive forces through the synergy of the dipolar interaction and amide hydrogen bonding. Besides, by incorporating glycerol and zinc chloride, the growth of ice crystals is inhibited, allowing the organohydrogels to maintain stable flexibility and sensitivity even at -20 °C. The real-time monitoring of the pulse signal for up to 2 min indicates that the gel sensor has stable sensitivity. It is believed that our organohydrogels will have good prospects in future wearable electronics.

Tailored Fluorosurfactants through Controlled/Living Radical Polymerization for Highly Stable Microfluidic Droplet Generation

Droplet-based microfluidics represents a disruptive technology in the field of chemistry and biology through the generation and manipulation of sub-microlitre droplets. To avoid droplet coalescence, fluoropolymer-based surfactants are commonly used to reduce the interfacial tension between two immiscible phases to stabilize droplet interfaces. However, the conventional preparation of fluorosurfactants involves multiple steps of conjugation reactions between fluorinated and hydrophilic segments to form multiple-block copolymers. In addition, synthesis of customized surfactants with tailored properties is challenging due to the complex synthesis process. Here, we report a highly efficient synthetic method that utilizes living radical polymerization (LRP) to produce fluorosurfactants with tailored functionalities. Compared to the commercialized surfactant, our surfactants outperform in thermal cycling for polymerase chain reaction (PCR) testing, and exhibit exceptional biocompatibility for cell and yeast culturing in a double-emulsion system. This breakthrough synthetic approach has the potential to revolutionize the field of droplet-based microfluidics by enabling the development of novel designs that generate droplets with superior stability and functionality for a wide range of applications.

Structural Characterization and Physicochemical Properties of Functionally Porous Proton-Exchange Membrane Based on PVDF-SPA Graft Copolymers

Fluorinated proton-exchange membranes (PEMs) based on graft copolymers of dehydrofluorinated polyvinylidene fluoride (D-PVDF), 3-sulfopropyl acrylate (SPA), and 1H, 1H, 2H-perfluoro-1-hexene (PFH) were prepared via free radical copolymerization and characterized for fuel cell application. The membrane morphology and physical properties were studied via small-(SAXS) and wide-angle X-ray scattering (WAXS), SEM, and DSC. It was found that the crystallinity degree is 17% for PEM-RCF (co-polymer with SPA) and 16% for PEM-RCF-2 (copolymer with SPA and PFH). The designed membranes possess crystallite grains of 5-6 nm in diameter. SEM images reveal a structure with open pores on the surface of diameters from 20 to 140 nm. Their transport and electrochemical characterization shows that the lowest membrane area resistance (0.9 Ωcm2) is comparable to perfluorosulfonic acid PEMs (such as Nafion®) and polyvinylidene fluoride (PVDF) based CJMC cation-exchange membranes (ChemJoy Polymer Materials, China). Key transport and physicochemical properties of new and commercial membranes were compared. The PEM-RCF permeability to NaCl diffusion is rather high, which is due to a relatively low concentration of fixed sulfonate groups. Voltammetry confers that the electrochemical behavior of new PEM correlates to that of commercial cation-exchange membranes, while the ionic conductivity reveals an impact of the extended pores, as in track-etched membranes.

[The results of clinical application of the mesh with anti-adhesive fluoropolymer coating in laparoscopic intraperitoneal repair of primary ventral hernia]

OBJECTIVE

The purpose of the study was to evaluate the results of using fluoropolymer-coated mesh during intraperitoneal onlay mesh hernia repair in patients with primary ventral hernias.

MATERIAL AND METHODS

The multicenter, non-randomized, controlled clinical study included 88 patients of both sexes who were operated on using a laparoscopic approach using the IPOM technique for a primary ventral hernia. The duration of observation ranged from 3 to 12 months. In the main group, 48 patients received fluoropolymer-coated meshes (Ftorex). A comparison was made with a retrospective group of 40 patients who were treated with anti-adhesive collagen-coated meshes (Parietene composite, Parietex Composite, Symbotex).

RESULTS

The number of early and late postoperative complications in the groups did not have significant differences, at the same time, their number was lower in the group of patients in whom fluoropolymer-coated meshes were used. Most of the complications corresponded to Clavien-Dindo class I and II and did not pose a significant threat to health. There were no recurrences of hernias observed in patients included in the study. There were slightly more adhesions in the fluoropolymer-coated mesh group (35.4% vs. 25.0% in the collagen-coated mesh group). The quality of life of patients in the study groups did not differ.

CONCLUSION

In laparoscopic IPOM hernia repair fluoropolymer-coated meshes are not inferior in effectiveness and safety to traditionally used collagen-coated meshes and can be recommended for use in patients with primary ventral hernias.

Investigation of different molecular weight Polyvinylidene Fluoride (PVDF) polymer for the fabrication and performance of braid hollow fiber membranes

In the current study, braid reinforced membranes were fabricated from polyvinylidene fluoride (PVDF) polymers with two different molecular weights, and the blending of the polymers in a 1:1 ratio to upgrade the performance of the membrane. Characterization, filtration studies, and membrane bioreactor (MBR) application were done to evaluate membrane performance by applying the same operation conditions on each membrane. Characterization studies indicated that the fabricated membrane from blending polymers was a hydrophilic structure with a contact angle of 50.78° and smoother surface properties compared to the other fabricated membranes. According to the MBR results, at the end of the operation process, TMP levels of the membrane from the blending method are found 150 mbar, membrane from high molecular weight PVDF polymer had 250 mbar, and membrane from low molecular weight PVDF polymer had 800 mbar. As a consequence of the investigation, it is seen that the hydrophilic structure of the membrane allows the pollutant to adsorb less to the blend membrane surface, and the lower roughness is also a factor in reducing fouling.

NanoIEA: A Nanopatterned Interdigitated Electrode Array-Based Impedance Assay for Real-Time Measurement of Aligned Endothelial Cell Barrier Functions

A nanopatterned interdigitated electrode array (nanoIEA)-based impedance assay is developed for quantitative real-time measurement of aligned endothelial cell (EC) barrier functions in vitro. A bioinspired poly(3,4-dihydroxy-L-phenylalanine) (poly (l-DOPA)) coating is applied to improve the human brain EC adhesion onto the Nafion nanopatterned surfaces. It is found that a poly (l-DOPA)-coated Nafion grooved nanopattern makes the human brain ECs orient along the nanopattern direction. Aligned human brain ECs on Nafion nanopatterns exhibit increased expression of genes encoding tight and adherens junction proteins. Aligned human brain ECs also have enhanced impedance and resistance versus unaligned ones. Treatment with a glycogen synthase kinase-3 inhibitor (GSK3i) further increases impedance and resistance, suggesting synergistic effects occur on the cell-cell tightness of in vitro human brain ECs via a combination of anisotropic matrix nanotopography and GSK3i treatment. It is found that this enhanced cell-cell tightness of the combined approach is accompanied by increased expression of claudin protein. These data demonstrate that the proposed nanoIEA assay integrated with poly (l-DOPA)-coated Nafion nanopatterns and interdigitated electrode arrays can make not only biomimetic aligned ECs, but also enable real-time measurement of the enhanced barrier functions of aligned ECs via tighter cell-cell junctions.

Performance investigation of poly(vinylidene fluoride-cohexafluoropropylene) membranes containing SiO2 nanoparticles in a newly designed single vacuum membrane distillation system

The current study focuses on the development of a superhydrophobic poly(vinylidene fluoride-cohexafluoropropylene) nanocomposite membrane suitable for vacuum membrane distillation by incorporating SiO2 nanoparticles. At loading hydrophobic nano-SiO2 particle concentration (0.50-1.50 wt.%), the developed nanocomposite membranes are optimized in terms of vacuum membrane distillation performance. The influence of temperature, vacuum pressure, and feed water flow is studied for desalinating high-salinity brine. The results show that the developed vacuum distillation membrane is capable of 95% salt rejection during the treatment of a highly saline feed (65,000 ppm) at fixed flow rates of 120 L/h saline feed and different operating conditions consisting of feed inlet temperatures ranging from 40°C to 70°C and distillate inlet temperatures of 7-15°C. The vacuum membrane distillation process achieves 0.38-1.66% water recovery with increasing concentration factor, meaning that recovery is increased, and shows a specific electrical energy consumption of 5.16-23.90 kWh/m3 for product water. Overall, the newly designed membrane demonstrates suitability for a vacuum membrane distillation system. PRACTITIONER POINTS: Desalinate high-salinity brine (TDS > 35,000 ppm) using a vacuum membrane distillation system. A hydrophobic PVDF-HFP/SiO2 nanocomposite membrane development for vacuum membrane distillation. A newly designed single vacuum membrane distillation system for RO brine treatment.

Succinylation-Alcian Blue Staining of Mucins on Polyvinylidene Difluoride Membrane

Mucins are often stained with the basic dye Alcian blue, but mucins with a low acidic glycan content cannot be stained with it. Succinylation-Alcian blue staining is a method that temporarily modifies glycans with succinic acid to visualize mucins with low acidic glycan content. This method can be used to stain mucins on polyvinylidene difluoride (PVDF) membranes separated via supported molecular matrix electrophoresis (SMME) and mucins blotted onto PVDF membranes from gel electrophoreses. The succinyl groups of the modified glycans can be easily and completely removed by releasing O-glycan from the stained mucin bands. Therefore, the glycans can be analyzed using the same methods as those used for mucins with a high acidic glycan content.

Antiferroelectric AgNbO3 @KH550 Doped PVDF/PMMA Composites with High Energy Storage Performance

The residual polarization of antiferroelectric ceramics is very small, yet they possess high energy storage density and efficiency. Incorporating antiferroelectric ceramic particles into a polymer matrix is beneficial for improving the energy storage performance of composites. However, excessive amounts of ceramic particles can lead to aggregation within the polymer, resulting in defects and a significant reduction in composite film performance. In this study, the antiferroelectric AgNbO3 is selected as the filler and modified with silane coupling agent KH550. poly(vinylidene fluoride) (PVDF) and polymethyl methacrylate (PMMA) are blended as the matrix, and the energy storage performance of the composite is improved by adjusting the additional amount of PVDF. The structure, dielectric properties, and energy storage properties of the composites are systematically studied. The results show that hydrogen bonds are formed between PVDF and PMMA, and PVDF and PMMA are tightly bonded under the action of hydrogen bonds. The compatibility of PVDF with PMMA is optimal when the mass fraction of PVDF is 30 wt%. Moreover, with the synergistic effect of the antiferroelectric filler AgNbO3 , the breakdown strength of AgNbO3 /PVDF/PMMA composites reaches 430 kV mm-1 , and the energy storage density reaches 14.35 J cm-3 .

Direct-coating of cellulose hydrogel on PVDF membranes with superhydrophilic and antifouling properties for high-efficiency oil/water emulsion separation

As a well-known natural and innocuous plant constituent, cellulose consists of abundant hydroxyl groups and can tightly adsorb onto material surfaces hydrogen bonding, resulting in a superhydrophilic surface. In this work, the hydrophobic polyvinylidene fluoride (PVDF) membranes were modified by immersing them in cellulose hydrogel using a simple one-step process. The modified PVDF membrane exhibited excellent resistance to fouling and oil adhesion, making it highly effective in separating various oil-in-water emulsions. The cellulose-modified PVDF membranes achieved a high oil rejection rate (>99 %) and a maximum separation flux of 2675.2 L·m-2·h-1. Furthermore, even an oil-in-water emulsion containing bovine serum albumin maintained a steady permeation flux after four filtration cycles. Additionally, these cellulose-modified PVDF membranes demonstrated excellent underwater superoleophobicity across a wide range of pH levels and high saline conditions. Overall, these cellulose-modified superhydrophilic PVDF membranes are sustainable, environmentally friendly, easily scalable, and hold great promise for practical applications in oily wastewater treatment.

Per- and polyfluoroalkyl ether acids in well water and blood serum from private well users residing by a fluorochemical facility near Fayetteville, North Carolina

BACKGROUND

A fluorochemical facility near Fayetteville, North Carolina, emitted per- and polyfluoroalkyl ether acids (PFEAs), a subgroup of per- and polyfluoroalkyl substances (PFAS), to air.

OBJECTIVE

Analyze PFAS in private wells near the facility and in blood from well users to assess relationships between PFEA levels in water and serum.

METHODS

In 2019, we recruited private well users into the GenX Exposure Study and collected well water and blood samples. We targeted 26 PFAS (11 PFEAs) in water and 27 PFAS (9 PFEAs) in serum using liquid chromatography-mass spectrometry. We used regression modeling to explore relationships between water and serum PFAS. For the only PFEA detected frequently in water and serum, Nafion byproduct 2, we used generalized estimating equation (GEE) models to assess well water exposure metrics and then adjusted for covariates that may influence Nafion byproduct 2 serum concentrations.

RESULTS

We enrolled 153 participants ages 6 and older (median = 56 years) using 84 private wells. Most wells (74%) had ≥6 detectable PFEAs; median ∑PFEAs was 842 ng/L (interquartile range = 197-1760 ng/L). Low molecular weight PFEAs (PMPA, HFPO-DA [GenX], PEPA, PFO2HxA) were frequently detected in well water, had the highest median concentrations, but were not detectable in serum. Nafion byproduct 2 was detected in 73% of wells (median = 14 ng/L) and 56% of serum samples (median = 0.2 ng/mL). Cumulative dose (well concentration × duration at address) was positively associated with Nafion byproduct 2 serum levels and explained the most variability (10%). In the adjusted model, cumulative dose was associated with higher Nafion byproduct 2 serum levels while time outside the home was associated with lower levels.

IMPACT

PFAS are a large class of synthetic, fluorinated chemicals. Fluorochemical facilities are important sources of environmental PFAS contamination globally. The fluorochemical industry is producing derivatives of perfluoroalkyl acids, including per- and polyfluoroalkyl ether acids (PFEAs). PFEAs have been detected in various environmental samples but information on PFEA-exposed populations is limited. While serum biomonitoring is often used for PFAS exposure assessment, serum biomarkers were not good measures of long-term exposure to low molecular weight PFEAs in a private well community. Environmental measurements and other approaches besides serum monitoring will be needed to better characterize PFEA exposure.

Metabolic and Microbial Profiling of Soil Microbial Community under Per- and Polyfluoroalkyl Substance (PFAS) Stress

Per- and polyfluoroalkyl substances (PFAS) represent significant stress to organisms and are known to disrupt microbial community structure and function. Nevertheless, a detailed knowledge of the soil microbial community responding to PFAS stress at the metabolism level is required. Here we integrated UPLC-HRMS-based metabolomics data with 16S rRNA and ITS amplicon data across soil samples collected adjacent to a fluoropolymer production facility to directly identify the biochemical intermediates in microbial metabolic pathways and the interactions with microbial community structure under PFAS stress. A strong correlation between metabolite and microbial diversity was observed, which demonstrated significant variations in soil metabolite profiles and microbial community structures along with the sampling locations relative to the facility. Certain key metabolites were identified in the metabolite-PFAS co-occurrence network, functioning on microbial metabolisms including lipid metabolism, amino acid metabolism, and secondary metabolite biosynthesis. These results provide novel insights into the impacts of PFAS contamination on soil metabolomes and microbiomes. We suggest that soil metabolomics is an informative and useful tool that could be applied to reinforce the chemical evidence on the disruption of microbial ecological traits.

Reaching High Piezoelectric Performance with Rotating Directional-Field-Aligned PVDF-MoS2 Piezo-Polymer Applicable for Large-Area Flexible Electronics

Wearable electronics and smart harvesting textile studies require a material system that resists physical stimulation. Such applications require receptive piezo-polymers, and their activation-free preparation that can translate into a continuous large-area film. In this work, it is discussed whether the β-content of piezo-polymer is extended with no use of any activation (i.e. poling), and if the β-content increases, it can be processed over a wide range of surfaces like large-area piezo-film. Such prerequisites within polyvinylidene fluoride-molybdenum disulfide ((PVDF)-MoS2 ) piezo-polymer are thoroughly experimented here to develop a high-performance piezo-film. A MoS2 -mediated PVDF piezo-polymer (termed as P+ -MoS2 ) is introduced, in which no extra β-enhancement activation step is required after spin coating. Experimental results record β ≧ 80% which allows to harvest the voltage and current in the level of ≈17 V and 1 µA, respectively which satisfies 5 V supply voltage requirement of the current microelectronics, and internet of things (IoT). In addition, the capacitors having different capacities are charged using the developed nanogenerator to check its practical applicability. Therefore, the transition process of P-MoS2 to aligned P+ -MoS2 due to passive interlocking (PiL) through rotating directional field is novel and found to be a principal reason for β-enhancement in fabricated devices.

Dermal bioaccessibility of perfluoroalkyl substances from household dust; influence of topically applied cosmetics

PFAS are known contaminants of indoor dust. Despite the adherence of such dust to skin, the dermal penetration potential of PFAS is not well understood. By applying in vitro physiologically based extraction tests, the bioaccessibility of 17 PFAS from indoor dust to synthetic human sweat sebum mixtures (SSSM) was assessed. The composition of the SSSM substantially impacted the bioaccessibility of all target compounds. PFAS bioaccessibility in a 1:1 sweat:sebum mixture ranged from 54 to 92% for perfluorocarboxylic acids (PFCAs) and 61-77% for perfluorosulfonic acids (PFSAs). Commonly applied cosmetics (foundation, sunscreen, moisturiser, and deodorant) significantly impacted the dermal bioaccessibility of target PFAS, e.g., the presence of moisturiser significantly decreased the total bioaccessibility of both PFCAs and PFSAs. Preliminary human exposure estimates revealed dermal contact with indoor dust could contribute as much as pathways such as drinking water and dust ingestion to an adult's daily intake of PFAS. While further research is needed to assess the percutaneous penetration of PFAS in humans, the current study highlights the potential substantial contribution of dermal exposure to human body burdens of PFAS and the need for further consideration of this pathway in PFAS risk assessment studies.

The internal structure of gadolinium and perfluorocarbon-loaded polymer nanoparticles affects 19F MRI relaxation times

19F magnetic resonance imaging (19F MRI) is an emerging technique for quantitative imaging in novel therapies, such as cellular therapies and theranostic nanocarriers. Nanocarriers loaded with liquid perfluorocarbon (PFC) typically have a (single) core-shell structure with PFC in the core due to the poor miscibility of PFC with organic and inorganic solvents. Paramagnetic relaxation enhancement acts only at a distance of a few angstroms. Thus, efficient modulation of the 19F signal is possible only with fluorophilic PFC-soluble chelates. However, these chelates cannot interact with the surrounding environment and they might result in image artifacts. Conversely, chelates bound to the nanoparticle shell typically have a minimal effect on the 19F signal and a strong impact on the aqueous environment. We show that the confinement of PFC in biodegradable polymeric nanoparticles (NPs) with a multicore structure enables the modulation of longitudinal (T1) and transverse (T2) 19F relaxation, as well as proton (1H) signals, using non-fluorophilic paramagnetic chelates. We compared multicore NPs versus a conventional single core structure, where the PFC is encapsulated in the core(s) and the chelate in the surrounding polymeric matrix. This modulated relaxation also makes multicore NPs sensitive to various acidic pH environments, while preserving their stability. This effect was not observed with single core nanocapsules (NCs). Importantly, paramagnetic chelates affected both T1 and T219F relaxation in multicore NPs, but not in single core NCs. Both relaxation times of the 19F nucleus were enhanced with an increasing concentration of the paramagnetic chelate. Moreover, as the polymeric matrix remained water permeable, proton enhancement additionally was observed in MRI.

Fabrication of a photo-crosslinkable fluoropolymer-passivated flexible neural probe and acute recording and stimulation performances in vivo

Herein, we fabricated fluorine-containing, polymer-based, flexible neural probes with fluorinated ethylene propylene (FEP) films as the substrates and photo-crosslinkable fluoropolymers as the passivation material. For fabrication, metal-free Au layer formation on the FEP film, the simultaneous photo-adhesion and photo-patterning technique, and the pulsed-laser scanning probe shaping technique were combined, followed by Au electrode surface modification. The resultant probes achieved a charge injection limit equal to 5.18 mC cm-2 by implementing iridium oxide-modified nanoporous Au (IrOx/NPG) structures. We performed simultaneous in vivo micro-stimulations of the Schaffer collateral fibres and recorded the evoked field excitatory postsynaptic potentials (fEPSPs) in the stratum radiatum layer of the hippocampal Cornu Ammonis 1 region using a single probe. Inducing the fEPSP at very low charge per pulse settings (3.2-3.6 nC/pulse) indicates the efficient charge injection capability of the IrOx/NPG electrode, thereby enabling safe, prolonged, and thrifty micro-stimulations. Furthermore, the single probe-induced and recorded long-term potentiation persisted for periods longer than 60 min following theta-burst stimulation. The materials used in this study are all biocompatible and chemically robust. The fabricated neural probes can be applied in chronic clinical trials in vivo.

Poor Below Knee Runoff Impacts Femoropopliteal Stent Failure and Fluoropolymer Antithrombotic Effect in Healthy Swine Model

OBJECTIVE

Poor below knee (BTK) runoff is a predictor of stent failure after endovascular femoropopliteal artery treatment; however, lack of pathological evaluation has prevented characterisation of stent failure. The study aimed to investigate the impact of poor BTK runoff and the antithrombotic effect of the polymer of fluoropolymer coated paclitaxel eluting stents (FP-PESs) in a healthy swine femoropopliteal artery model.

METHODS

FP-PESs and bare metal stents (BMSs) and FP-PES and polymer free paclitaxel coated stents (PF-PCSs) were implanted in the bilateral femoral arteries of healthy swine (n = 6, respectively) following coil embolisation in both tibial arteries to induce poor BTK runoff. Histological assessment and intravascular imaging device evaluation were performed at one month. The Japanese Association for Laboratory Animal Science approved the study protocol (reference number: IVT22-90).

RESULTS

Optical coherence tomography showed significantly lower percent area stenosis in FP-PES compared with BMS (37.3%, [interquartile range (IQR), 25.6 - 54.3] % vs. 92.5% [IQR, 75.5 - 96.1] %, respectively, p = .031), and PF-PCS (8.3% [IQR, 4.5 - 27.0] % vs. 31.2% [IQR, 23.3 - 52.2] %, respectively, p = .031). Histopathological evaluation demonstrated that thin fibrin attachment without re-stenosis was the most dominant neointimal tissue characteristic in FP-PES. On the other hand, neointimal tissue characteristics with significant restenosis of BMS and PF-PCS were mainly organising or organised thrombus.

CONCLUSION

Organising and or organised thrombus attachment due to poor BTK runoff was the main cause of in stent restenosis of the swine femoral artery. FP-PES demonstrated the least percent area stenosis, suggesting the importance of the antithrombotic effect of polymer.

Fluoropolymer Coated DNA Nanoclews for Volumetric Visualization of Oligonucleotides Delivery and Near Infrared Light Activated Anti-Angiogenic Oncotherapy

The potential of microRNA regulation in oncotherapy is limited by the lack of delivery vehicles. Herein, it is shown that fluoropolymer coated DNA nanoclews (FNCs) provide outstanding ability to deliver oligonucleotide through circulation and realize near infrared (NIR) light activated angiogenesis suppression to abrogate tumors. Oligonucleotides are loaded in DNA nanoclews through sequence specific bindings and then a fluorinated zwitterionic polymer is coated onto the surface of nanoclews. Further incorporating quantum dots in the polymer coating endows the vectors with NIR-IIb (1500-1700 nm) fluorescence and NIR light triggered release ability. The FNC vector can deliver oligonucleotides to cancer cells systemically and realize on-demand cytosolic release of the cargo with high transfection efficiency. Taking advantage of the NIR-IIb emission, the whole delivery process of FNCs is visualized volumetrically in vivo with a NIR light sheet microscope. Loaded by FNCs, an oligonucleotide can effectively silence the target miRNA when activated with NIR light, and inhibit angiogenesis inside tumor, leading to complete ablation of cancer. These findings suggest FNCs can be used as an efficient oligonucleotide delivery platform to modulate the expression of endogenous microRNA in gene therapy of cancer.

A novel fluoropolymer as a protein delivery vector with robust adjuvant effect for cancer immunotherapy

The inefficient treatment using protein-based nanovaccines is largely attributed to their inadequate immunogenicity. Herein, we developed a novel fluoropolymer (PF) via ring-opening polymerization and constructed a fluoropolymer-based nanovaccine for tumor immunotherapy. Due to the existence of fluoroalkyl chains, PF not only played a crucial role in tumor antigen delivery but also exhibited a remarkable adjuvant effect in enhancing the immunogenicity of nanovaccines. The nanovaccines formed by mixing PF with a model antigen ovalbumin (OVA) enhanced the uptake of antigen proteins by dendritic cells (DCs) and promoted the maturation and antigen presentation of DCs. Compared with free OVA, PF/OVA showed better efficacy in both pre-cancer prevention and tumor treatment. Furthermore, the proportion of CD4+ T and CD8+ T cells was significantly increased in lymph nodes and tumors of mice immunized with PF/OVA. Additionally, there was a great enhancement in the levels of key anti-tumor cytokines (TNF-α and IFN-γ) in the serum of the PF/OVA immunized mice. Our research has shown that fluoropolymer PF applied as a protein vector and adjuvant has great potential for the development of nanovaccines with robust immunogenicity.

Detection of membrane-anchoring lipid modifications of proteins in cells by radioactive metabolic labeling

Prenylation and palmitoylation are two major lipid modifications of cellular proteins that anchor proteins to cell membranes. Here, we present a protocol for detecting these modifications in cellular proteins by radioactive metabolic labeling. We describe steps for metabolic labeling of cells, cell harvesting for carrying out immunoprecipitations, subjecting immunocomplexes to SDS-PAGE, and transferring them to polyvinylidine flouride (PVDF) membranes. We then detail detection of labeled target proteins by exposing PVDF membranes to phosphor screens and using a phosphor imager machine. For complete details of this protocol, please refer to Liang et al.1.

Evaluation of a novel silicone oil free primary packaging system with PTFE-based barrier stopper for biologics

In order to overcome silicone oil related problems for biopharmaceuticals, novel container systems are of interest with a focus on the reduction, fixation or complete avoidance of silicone oil in the primary container. Ultimately, silicone oil free (SOF) container systems made from cyclic olefin (co-)polymer or glass combined with the respective silicone-oil free plungers were developed. In the following study we evaluated the potential of a SOF container system based on a glass barrel in combination with a fluoropolymer coated syringe plunger. In a long-term stability study, the system was compared to other alternative container systems in terms of functionality and particle formation when filled with placebo buffers. The system proved to be a valuable alternative to marketed siliconized container systems with acceptable and consistent break-loose gliding forces and it was clearly superior in terms of particle formation over storage time. Additionally, we evaluated the importance of the glass barrel surface for functionality. The interaction of the fill medium with the glass surface significantly impacted friction forces. Consequently, storage conditions and production processes like washing and sterilization, which can easily alter the surface properties, should be carefully evaluated, and controlled. The novel combination of non-lubricated glass barrel and fluoropolymer coated plunger provides a highly valuable SOF packaging alternative for biopharmaceuticals.