Closing the system: production of viral antigen-presenting dendritic cells eliciting specific CD8+ T cell activation in fluorinated ethylene propylene cell culture bags.

BACKGROUND: A major obstacle to anti-viral and -tumor cell vaccination and T cell immunotherapy is the ability to produce dendritic cells (DCs) in a suitable clinical setting. It is imperative to develop closed cell culture systems to accelerate the translation of promising DC-based cell therapy products to the clinic. The objective of this study was to investigate whether viral antigen-loaded monocyte-derived DCs (Mo-DCs) capable of eliciting specific T cell activation can be manufactured in fluorinated ethylene propylene (FEP) bags. METHODS: Mo-DCs were generated through a protocol applying cytokine cocktails combined with lipopolysaccharide or with a CMV viral peptide antigen in conventional tissue culture polystyrene (TCPS) or FEP culture vessels. Research-scale (< 10 mL) FEP bags were implemented to increase R&D throughput. DC surface marker profiles, cytokine production, and ability to activate antigen-specific cytotoxic T cells were characterized. RESULTS: Monocyte differentiation into Mo-DCs led to the loss of CD14 expression with concomitant upregulation of CD80, CD83 and CD86. Significantly increased levels of IL-10 and IL-12 were observed after maturation on day 9. Antigen-pulsed Mo-DCs activated antigen-responsive CD8+ cytotoxic T cells. No significant differences in surface marker expression or tetramer-specific T cell activating potency of Mo-DCs were observed between TCPS and FEP culture vessels. CONCLUSIONS: Our findings demonstrate that viral antigen-loaded Mo-DCs produced in downscaled FEP bags can elicit specific T cell responses. In view of the dire clinical need for closed system DC manufacturing, FEP bags represent an attractive option to accelerate the translation of promising emerging DC-based immunotherapies.

Fast construction of polymer monolithic columns inside fluorinated ethylene propylene (FEP) tubes for separation of proteins by reversed-phase liquid chromatography.

This paper describes the preparation of polymer monolithic columns in the confines of fluorinated ethylene propylene (FEP) tubes. These tubes are cheap, chemically stable, and widely used in flow analysis laboratories. UV-initiated grafting with 5 wt% benzophenone in methanol for 1 h activated the internal surface walls, thus enabling the further covalent binding of ethylene glycol dimethacrylate (EDMA) from a 15 wt% solution in methanol, also via photografting. Both steps used 254 nm radiation under a potency of 120 mJ cm2. ATR-FTIR measurements revealed the presence of carbonyl, alkyl and vinyl groups in the functionalized FEP. The density of vinyl groups was high enough to firmly attach a poly(lauryl methacrylate-co-ethylene glycol dimethacrylate) monolith in 120 × 1.57 mm i.d. tubes, prepared via photopolymerization. The total preparation lasts less than 2-h. The columns were permeable, (1.58 ± 0.06) × 10-13 m2, providing reproducible chromatographic parameters of retention times, retention factor, selectivity, and resolution. The monoliths were stable at flow rates of 500 µL min-1, collapsing only at flow rates >700 µL min-1, a condition that increased the backpressure over 1000 psi (experiments at the room temperature). The separation of proteins by reversed-phase liquid chromatography demonstrated the efficiency of the columns. Determination of egg white proteins (ovalbumin and lysozyme) and myoglobin in spiked urine proved the applicability to the analysis of real samples.

Wearable Device Oriented Flexible and Stretchable Energy Harvester Based on Embedded Liquid-Metal Electrodes and FEP Electret Film.

In this paper, a flexible and stretchable energy harvester based on liquid-metal and fluorinated ethylene propylene (FEP) electret films is proposed and implemented for the application of wearable devices. A gallium liquid-metal alloy with a melting point of 25.0 °C is used to form the stretchable electrode; therefore, the inducted energy harvester will have excellent flexibility and stretchability. The solid-state electrode is wrapped in a dragon-skin silicone rubber shell and then bonded with FEP electret film and conductive film to form a flexible and stretchable energy harvester. Then, the open-circuit voltage of the designed energy harvester is tested and analyzed. Finally, the fabricated energy harvester is mounted on the elbow of a human body to harvest the energy produced by the bending of the elbow. The experimental results show that the flexible and stretchable energy harvester can adapt well to elbow bending and convert elbow motion into electric energy to light the LED in a wearable watch.

No evidence of improved efficacy of covered stents over uncovered stents in percutaneous palliation of malignant hilar biliary obstruction: results of a prospective randomized trial.

OBJECTIVE: To investigate whether covered stents show a higher efficacy than uncovered stents in percutaneous treatment of malignant hilar biliary obstruction. METHODS: Patients with obstructive jaundice caused by an unresectable hilar malignancy were included after failed endoscopic intervention in a prospective randomized trial comparing expanded polytetrafluoroethylene and fluorinated ethylene propylene (ePTFE-FEP)-covered nitinol stents with uncovered nitinol stents. Exclusion criteria were as follows: primary tumors existing more than 3 months, a biliodigestive anastomosis, previous stenting, and a Karnofsky score of less than 50. Safety, clinical success, and adjuvant chemotherapy were compared as well as occlusion rate, patency, and survival. RESULTS: A total of 120 patients were included. One patient was post hoc excluded. Fourteen patients who died within 7 days and one patient without patency data were excluded from patency analysis. Serious adverse events (p = 0.4), 30-day mortality (p = 0.5), and clinical success (p = 0.8) were equivalent for both stent groups. Twenty-one out of 61 (34%) patients in the covered and 24/58 (41%) in the uncovered stent groups received adjuvant chemotherapy (p = 0.5). Occlusion rate was 54% (27/50) in the covered stent group and 57% (31/54) in the uncovered stent group (p = 0.8). Median patency was 229 days (95% CI 113-345) for covered stents and 130 days (95% CI 75-185) for uncovered stents (p = 0.1). Median survival in patients with covered stents was 79 days (95% CI 52-106) and with uncovered stents 92 days (95% CI 60-124) (p = 0.3). CONCLUSION: In malignant hilar biliary obstruction, there is no evidence that ePTFE-FEP-covered stents are superior to uncovered stents in terms of safety, clinical success, adjuvant chemotherapy, patency, or survival. KEY POINTS: • Percutaneous palliation of hilar biliary obstruction is feasible with both uncovered and covered stents. • Clinical success in terms of bilirubin decrease and adjuvant chemotherapy is achievable with both stents. • Thirty-day mortality is considerable when stenting is also offered to patients with a low performance status.

No Advantage of Expanded Polytetrafluoroethylene and Fluorinated Ethylene Propylene-Covered Stents over Uncovered Nitinol Stents for Percutaneous Palliation of Malignant Infrahilar Biliary Obstruction: Results of a Single-Center Prospective Randomized Trial.

PURPOSE: To prove that covered stents are more efficacious than uncovered stents regarding patency, safety, enabling of chemotherapy, and survival in percutaneous palliation of malignant infrahilar biliary obstruction. MATERIALS AND METHODS: After failed endoscopic treatment, 154 patients with obstructive jaundice caused by unresectable infrahilar malignancy were randomly allocated to receive an expanded polytetrafluoroethylene and fluorinated ethylene propylene-covered or an uncovered nitinol stent. Occlusion rate, patency, and survival were assessed. Safety and clinical success in terms of chemotherapy were compared. RESULTS: Three patients were excluded post hoc. Fifteen patients died within 7 d and were excluded from patency analysis. Occlusion rates were 32% (21 of 66) for covered and 29% (20 of 70) for uncovered stents (P = .7). Estimated median patency durations were 308 d (95% confidence interval [CI], 178-438 d) for covered and 442 d (95% CI, 172-712 d) for uncovered stents (P = .1). Serious adverse events (P = 1.0) and 30-day mortality (P = .5) were equivalent between groups. At hospital discharge, median bilirubin reduction of 8 mg/dL was found in both groups (P < .001). In the covered stent group, 35 patients (48%) received palliative chemotherapy, vs 29 (37%) in the uncovered stent group (P = .2). Estimated median survival times were 96 days (95% CI, 68-124 d) with covered stents and 75 days (95% CI, 42-108 d) with uncovered stents (P = .6). CONCLUSIONS: In malignant infrahilar biliary obstruction not amenable to endoscopy, no improvement in patency or survival with percutaneously placed covered stents could be confirmed. Covered and uncovered stent types exhibit similar safety profiles and clinical success rates.

Influence of photo-initiators in the preparation of methacrylate monoliths into poly(ethylene-co-tetrafluoroethylene) tubing for microbore HPLC.

In this study, poly(butyl methacrylate-co-ethyleneglycol dimethacrylate) polymeric monoliths were in situ developed within 0.75 mm i.d. poly(ethylene-co-tetrafluoroethylene) (ETFE) tubing by UV polymerization via three different free-radical initiators (α,α'-azobisisobutyronitrile (AIBN), 2,2-dimethoxy-2-phenylacetophenone (DMPA) and 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (MTMPP). The influence of the nature of each photo-initiator and irradiation time on the morphological features of the polymer was investigated by scanning electron microscopy, and the chromatographic properties of the resulting microbore columns were evaluated using alkyl benzenes as test substances. The beds photo-initiated with MTMPP gave the best performance (minimum plate heights of 38 µm for alkyl benzenes) and exhibited a satisfactory reproducibility in the chromatographic parameters (RSD < 11%). These monolithic columns were also successfully applied to the separation of phenylurea herbicides, proteins and a tryptic digest of ß-casein.

Argon plasma-treated fluorinated ethylene propylene: Growth of primary dermal fibroblasts and mesenchymal stem cells.

Surface modification is an important step in making a synthetic polymer cytocompatible. We have previously reported improved cytocompatibility of immortalized human keratinocytes (HaCaT) with the otherwise bioinert fluorinated ethylene propylene (FEP) upon treatment with argon plasma discharge. In this article, we show that FEP modified with Ar plasma with the power of 3 and 8 W for 40 and 240 s served as a suitable material for cultivation of primary human dermal fibroblasts (HDF), which showed significantly improved proliferation and spreading comparable to standard tissue culture polystyrene. We also evaluated focal adhesions formed by HDF cells on modified FEP, which were far more numerous compared to pristine FEP. Moreover, we attempted spontaneous osteogenic differentiation of adipose-derived mesenchymal stem cells modified with human telomerase reverse transcriptase on Ar plasma-modified FEP. While the spontaneous osteogenic differentiation was unsuccessful, the cells were able to adhere and differentiated on tested matrices upon the administration of osteodifferentiation medium. These combined findings suggest that the treatment of FEP with Ar plasma comprises and efficient method to enable the adhesion and proliferation of various cell types on an otherwise largely bioinert material.

Mechanisms and Characterization of the Pulsed Electron-Induced Grafting of Styrene onto Poly(tetrafluoroethylene-co-hexafluoropropylene) to Prepare a Polymer Electrolyte Membrane.

During the pulsed-electron beam direct grafting of neat styrene onto poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) substrate, the radiolytically-produced styryl and carbon-centered FEP radicals undergo various desired and undesired competing reactions. In this study, a high-dose rate is used to impede the undesired free radical homopolymerization of styrene and ensure uniform covalent grafting through 125-µm FEP films. This outweighs the enhancement of the undesired crosslinking reactions of carbon-centered FEP radicals and the dimerization of the styryl radicals. The degree of uniform grafting through 125-µm FEP films increases from ≈8%, immediately after pulsed electron irradiation to 33% with the subsequent thermal treatment exceeding the glass transition temperature of FEP of 39°C. On the contrary, steady-state radiolysis using 60Co gamma radiolysis, shows that the undesired homopolymerization of the styrene has become the predominant reaction with a negligible degree of grafting. Time-resolved fast kinetic measurements on pulsed neat styrene show that the styryl radicals undergo fast decays via propagation homopolymerization and termination reactions at an observed reaction rate constant of 5 × 108 l · mol-1 · s-1. The proton conductivity of 25-µm film at 80°C is 0.29 ± 0.01 s cm-1 and 0.007 s cm-1 at relative humidity of 92% and 28%, respectively. The aims of this work are: 1. electrolyte membranes are prepared via grafting initiated by a pulsed electron beam; 2. postirradiation heat-treated membranes are uniformly grafted, ideal for industry; 3. High dose rate is the primary parameter to promote the desired reactions; 4. measurement of kinetics of undesired radiation-induced styrene homopolymerization; and 5. The conductivity of prepared membranes is on par or higher than industry standards.

Novel Substrates for Microarrays.

In the microarray platform, the surface substrate is critical to the result quality in terms of signal consistency and detection sensitivity. Traditional substrates such as glass and nitrocellulose often entail complicated preparation processes such as the activation and functionalization of the reaction spots and surface blocking to prevent nonspecific molecule adsorption. In addition, coffee-ring morphology of the spots is a common issue in the traditional substrates. To address these issues, we introduced a novel substrate based on fluorinated ethylene propylene (FEP) membrane for microarrays.

An ultralow background substrate for protein microarray technology.

We herein report an ultralow background substrate for protein microarrays. Conventional protein microarray substrates often suffer from non-specific protein adsorption and inhomogeneous spot morphology. Consequently, surface treatment and a suitable printing solution are required to improve the microarray performance. In the current work, we improved the situation by developing a new microarray substrate based on a fluorinated ethylene propylene (FEP) membrane. A polydopamine microspot array was fabricated on the FEP membrane, with proteins conjugated to the FEP surface through polydopamine. Uniform microspots were obtained on FEP without the application of a special printing solution. The modified FEP membrane demonstrated ultralow background signal and was applied in protein and peptide microarray analysis.

Wafer-scale fabrication of glass-FEP-glass microfluidic devices for lipid bilayer experiments.

We report a wafer-scale fabrication process for the production of glass-FEP-glass microdevices using UV-curable adhesive (NOA81) as gluing material, which is applied using a novel "spin & roll" approach. Devices are characterized for the uniformity of the gluing layer, presence of glue in the microchannels, and alignment precision. Experiments on lipid bilayers with electrophysiological recordings using a model pore-forming polypeptide are demonstrated.

Batch versus flow photochemistry: a revealing comparison of yield and productivity.

The use of flow photochemistry and its apparent superiority over batch has been reported by a number of groups in recent years. To rigorously determine whether flow does indeed have an advantage over batch, a broad range of synthetic photochemical transformations were optimized in both reactor modes and their yields and productivities compared. Surprisingly, yields were essentially identical in all comparative cases. Even more revealing was the observation that the productivity of flow reactors varied very little to that of their batch counterparts when the key reaction parameters were matched. Those with a single layer of fluorinated ethylene propylene (FEP) had an average productivity 20% lower than that of batch, whereas three-layer reactors were 20% more productive. Finally, the utility of flow chemistry was demonstrated in the scale-up of the ring-opening reaction of a potentially explosive [1.1.1] propellane with butane-2,3-dione.

Percutaneous use of ePTFE/FEP-covered metallic stent for palliation of malignant biliary obstruction.

INTRODUCTION: Placement of self-expanding metallic stents has been a standard palliative treatment for patients with inoperable biliary malignancy, aiming at improving quality of life via a minimally invasive procedure. This study aimed to evaluate the efficacy of percutaneous placement of expanded polytetrafluoroethylene/fluorinated ethylene propylene-covered metallic stents for palliation of inoperable biliary malignancy. MATERIAL AND METHODS: Between February 2012 and April 2013, 11 patients with inoperable malignant biliary obstruction were treated with stent implantation. Serum bilirubin and liver enzyme levels were measured before/immediately after stent placement and at one, three, and six months. Patient survival and stent patency were calculated using Kaplan-Meier analysis. RESULTS: No migration occurred. Patients showed clinical improvement immediately and one month after stent placement, with a significant reduction in mean serum bilirubin level (p < 0.05). At six months, bilirubin levels were <1.5 mg/dL in all cases. One patient developed acute liver failure four days after stent implantation, leading to death. Survival rates were 90% at three months and 70% at six months. Primary patency rates were 100%, 100%, and 90% at one, three, and six months, respectively. CONCLUSION: Percutaneous placement of expanded polytetrafluoroethylene/fluorinated ethylene propylene-covered metallic stents offered an effective palliative therapy for patients with inoperable biliary malignancy.

Photovoltaic and thermal properties of electrolytes based on electrospun poly(vinylidene fluoride-hexafluoro propylene)/poly(methyl methacrylate) nanofibers for dye-sensitized solar cells.

We prepared electrospun polymer nanofibers by electrospnning method and investigated about their applications to dye-sensitized solar cells (DSSCs). Electrospun polymer nanofibers applied to the polymer matrix in electrolyte for DSSCs. To improve the stiffness of polymer nanofiber, poly(vinylidene fluoride-hexafluoro propylene)/Poly(methyl methacrylate) (PVDF-HFP/PMMA) blend nanofibers were prepared and examined. In the electrospun PVDF-HFP/PMMA (1:1) blend nanofibers, the best results of VOC, JSC, FF, and efficiency of the DSSC devices showed 0.71 V, 12.8 mA/cm2, 0.61, and 5.56% under AM 1.5 illumination.

Multilayer mounting enables long-term imaging of zebrafish development in a light sheet microscope.

Light sheet microscopy techniques, such as selective plane illumination microscopy (SPIM), are ideally suited for time-lapse imaging of developmental processes lasting several hours to a few days. The success of this promising technology has mainly been limited by the lack of suitable techniques for mounting fragile samples. Embedding zebrafish embryos in agarose, which is common in conventional confocal microscopy, has resulted in severe growth defects and unreliable results. In this study, we systematically quantified the viability and mobility of zebrafish embryos mounted under more suitable conditions. We found that tubes made of fluorinated ethylene propylene (FEP) filled with low concentrations of agarose or methylcellulose provided an optimal balance between sufficient confinement of the living embryo in a physiological environment over 3 days and optical clarity suitable for fluorescence imaging. We also compared the effect of different concentrations of Tricaine on the development of zebrafish and provide guidelines for its optimal use depending on the application. Our results will make light sheet microscopy techniques applicable to more fields of developmental biology, in particular the multiview long-term imaging of zebrafish embryos and other small organisms. Furthermore, the refinement of sample preparation for in toto and in vivo imaging will promote other emerging optical imaging techniques, such as optical projection tomography (OPT).

Extracorporeal bypass model of blood circulation for the study of microvascular hemodynamics.

Many studies have been performed to better understand the hemodynamics in microvessels, such as arterioles and venules. However, due to the heterogeneous features of size, shape, blood-flow velocity, and pulsatility of microvessels, conducting a systematic study on these factors has been almost impossible. Although in vitro studies have been performed for this purpose, the usefulness of in vitro data is limited by the fact that the rheological properties of blood are changed as blood is exposed to in vitro environments. The purpose of the present study is to investigate the feasibility of a rat extracorporeal bypass model that combines in vivo and in vitro models. An arteriovenous shunt loop with a sub-bypass loop of fluorinated ethylene propylene (FEP) microtube was constructed between the jugular vein and femoral artery of a rat. Three pinch valves were installed in the main loop. Microscopic images of the blood flow in the FEP tube were sequentially captured with a high-speed camera, and the whole velocity field information was obtained using a micro-particle image velocimetry technique. Experimental results reveal that the velocity fields of the blood flow inside the microtube are well measured because the FEP tube is transparent and has nearly the same refractive index as water. The flow velocity and the pulsatility index of the blood flow in the microtube can be controlled by adjusting the three pinch valves installed upstream, midstream, and downstream of the bypass loop. This hybrid model that combines in vivo and in vitro models can be useful in studying microvascular hemodynamics.

Percutaneous palliation of pancreatic head cancer: randomized comparison of ePTFE/FEP-covered versus uncovered nitinol biliary stents.

The purpose of this study was to compare the clinical effectiveness of expanded polytetrafluoroethylene/fluorinated-ethylene-propylene (ePTFE/FEP)-covered stents with that of uncovered nitinol stents for the palliation of malignant jaundice caused by inoperable pancreatic head cancer. Eighty patients were enrolled in a prospective randomized study. Bare nitinol stents were used in half of the patients, and ePTFE/FEP-covered stents were used in the remaining patients. Patency, survival, complications, and mean cost were calculated in both groups. Mean patency was 166.0 ± 13.11 days for the bare-stent group and 234.0 ± 20.87 days for the covered-stent group (p = 0.007). Primary patency rates at 3, 6, and 12 months were 77.5, 69.8, and 69.8% for the bare-stent group and 97.5, 92.2, and 87.6% for the covered-stent group, respectively. Mean secondary patency was 123.7 ± 22.5 days for the bare-stent group and 130.3 ± 21.4 days for the covered-stent group. Tumour ingrowth occurred exclusively in the bare-stent group in 27.5% of cases (p = 0.002). Median survival was 203.2 ± 11.8 days for the bare-stent group and 247.0 ± 20 days for the covered-stent group (p = 0.06). Complications and mean cost were similar in both groups. Regarding primary patency and ingrowth rate, ePTFE/FEP-covered stents have shown to be significantly superior to bare nitinol stents for the palliation of malignant jaundice caused by inoperable pancreatic head cancer and pose comparable cost and complications. Use of a covered stent does not significantly influence overall survival rate; nevertheless, the covered endoprosthesis seems to offer result in fewer reinterventions and better quality of patient life.

SCORE imaging: specimen in a corrected optical rotational enclosure.

Visual data collection is paramount for the majority of scientific research. The added transparency of the zebrafish (Danio rerio) allows for a greater detail of complex biological research that accompanies seemingly simple observational tools. We developed a visual data analysis and collection approach that takes advantage of the cylindrical nature of the zebrafish allowing for an efficient and effective method for image capture that we call Specimen in a Corrected Optical Rotational Enclosure imaging. To achieve a nondistorted image, zebrafish were placed in a fluorinated ethylene propylene tube with a surrounding optically corrected imaging solution (water). By similarly matching the refractive index of the housing (fluorinated ethylene propylene tubing) to that of the inner liquid and outer liquid (water), distortion was markedly reduced, producing a crisp imagable specimen that is able to be fully rotated 360 degrees. A similar procedure was established for fixed zebrafish embryos using convenient, readily available borosilicate capillaries surrounded by 75% glycerol. The method described here could be applied to chemical genetic screening and other related high-throughput methods within the fish community and among other scientific fields.

The first prospective endoscopic experience with the ePTFE-covered Viabil stent in patients with a distal malignant biliary stenosis.

BACKGROUND AND STUDY AIMS: Endoscopic insertion of a biliary stent is standard practice in the palliative treatment of malignant biliary obstructions. Experience with the new ePTFE-covered Viabil stent is mainly limited to the percutaneous approach. We report our experience with its endoscopic application in patients with distal malignant biliary obstructions. PATIENTS AND METHODS: Eleven patients with an inoperable tumour, without apparent metastatic disease, and with an ECOG score of 0 to 1, were included. All patients received an ePTFE-covered Viabil stent of 10 mm diameter, with transmural side-holes. Primary endpoints were stent patency and patient survival. RESULTS: Overall median patient survival was 220 days; 10 patients died free of jaundice from non-stent related causes. Due to malfunction of the prototype stents at insertion, the introduction of 2 Viabils was required in 3 patients to acquire complete bile duct drainage. Thus, a total of 14 stents was needed in 11 patients. Stent dysfunction occurred in 3/11 patients. It always resulted from massive stone impaction needing stone removal with additional stenting in two out of 3 patients. Stent patency was 80% at 3 and 6 months, and 63% at 9 and 12 months. Lifetime palliation was 73%. CONCLUSIONS: Although the biliary Viabil device has been developed to minimize bacterial adherence and sludge formation, stent dysfunctions in this series always resulted from stone impaction. Moreover, malfunction of the prototype stents needed the insertion of a second stent in 3 patients. Overall life time palliation was 73%. Further experience with newer versions of the device as well as comparative studies versus other metallic stents are needed.