Polyethylene Terephthalate Membranes Research Articles

Convenient rapid prototyping microphysiological niche for mimicking liver native basement membrane: Liver sinusoid on a chip

Liver is responsible for the metabolization processes of up to 90 % of compounds and toxins in the body. Therefore liver-on-a-chip systems, as an in vitro promising cell culture platform, have great importance for fundamental science and drug development. In most of the liver-on-a-chip studies, seeding cells on both sides of a porous membrane, which represents the basement membrane, fail to resemble the native characteristics of biochemical, biophysical, and mechanical properties. In this study, polycarbonate (PC) and polyethylene terephthalate (PET) membranes were coated with gelatin to address this issue by accurately mimicking the native basement membrane present in the space of Disse. Various coating methods were used, including doctor blade, gel micro-injection, electrospinning, and spin coating. Spin coating was demonstrated to be the most effective technique owing to the ability to produce thin gel thickness with desirable surface roughness for cell interactions on both sides of the membrane. HepG2 and EA.HY926 cells were seeded on the upper and bottom sides of the gelatin-coated PET membrane and cultured on-chip for 7 days. Cell viability increased from 90 % to 95 %, while apoptotic index decreased. Albumin secretion notably rose between days 1–7 and 4–7, while GST-α secretion decreased from day 1 to day 7. In conclusion, the optimized spin coating process reported here can effectively modify the membranes to better mimic the native basement membrane niche characteristics.

Experimental and theoretical insights into bioethanol recovery: Valorizing waste PET bottles for sustainable pervaporation membranes

The use of bioethanol as an alternative source of fuel could solve energy and pollution concerns. However, its conventional recovery procedures make the overall process costly and energy intensive. Membrane-based pervaporation (PV) has gained significant attention in recent years. Most membranes that purify bioethanol are fabricated from conventional fossil-based polymers. This study presents the first work for biofuel separation by valorizing waste polyethylene terephthalate (PET) bottles into PV membranes. The performance of the membrane was characterized in terms of FTIR, XRD, TGA, WCA, SEM, and AFM and tested for a 10 wt% ethanol–water feed mixture at different temperatures. The mild hydrophobic character of PET allowed the PV membrane to achieve a separation factor of 10.45, a total flux of 1.7 kg m−2h−1, and a pervaporation separation index (PSI) of 18.72 at 45 °C. The recycled PET membrane (rPET) has higher mass transfer resistance for water compared to ethanol. The density functional theory (DFT) analysis confirms a stronger affinity of PET membrane towards ethanol than water. The results showed that rPET membranes have competitive performance compared to conventional fossil-based derived membranes. This study explores an energy-environment nexus approach, which could significantly contribute to achieving the key United Nations’ sustainable development goals.

Optimizing equine sperm quality: an alternative to single layer centrifugation for sperm isolation.

In vitro semen purification techniques have been developed that seek to mimic the in vivo selection process in order to generate the highest possible chance of oocyte fertilization following artificial insemination. Numerous methods have been developed to isolate functional spermatozoa for artificial insemination, yet only one method, single-layer centrifugation using commercial preparations like EquiPure, has been widely employed. In this study, we have introduced a novel approach for isolating spermatozoa and compared their quality to those isolated using EquiPure. The AI port system (Memphasys, Ltd. in Sydney, Australia) features a disposable cartridge with an inoculation chamber for depositing extended semen and a harvest chamber for extracting isolated spermatozoa. These chambers are separated by a 5 µm polyethylene terephthalate (PETE) membrane, allowing highly motile spermatozoa to migrate from the inoculation chamber to the harvest chamber over a 20-minute period. This migration effectively leaves behind seminal plasma and other cell types, such as leukocytes. Comparative analyses between spermatozoa isolated with the AI port and EquiPure demonstrated that, across all measured sperm parameters, including yield, vitality, motility, morphology, DNA fragmentation, and mitochondrial superoxide generation, the AI port-isolated cells exhibited comparable or superior performance, particularly in terms of DNA fragmentation. In summary, the AI port system demonstrates the potential to efficiently isolate high-quality spermatozoa, possibly offering a cost-effective and user-friendly alternative that may enhance the success rates of artificial insemination in breeding programs. This study aimed to create a new method for refining stallion semen to increase the likelihood of a successful pregnancy through artificial insemination. While there are existing techniques for isolating high-quality sperm, the most common involves a complicated process using a centrifuge, which spins the semen to separate it. This research introduces a new approach called the AI port system that uses a disposable cartridge with two separate chambers for putting in semen and getting out isolated sperm. A membrane between the chambers acts like a filter, letting highly motile sperm swim across, leaving behind unwanted substances like bacteria and blood cells. Compared to the centrifugation method, the AI port system effectively produces sperm with comparable or better quality in various aspects, including vitality, movement, shape, DNA integrity, and energy production. In summary, the AI port system is an easy-to-use alternative with the potential to improve the success of artificial insemination in horse breeding programs.

Scientific evaluation on biodegradable and biofunctional polyurethane incorporated chitosan/elastin electrospun membranes in compared with synthetic polymeric expanded polytetrafluoroethylene and polyethylene terephthalate vascular membranes

Cardiovascular disease is a life-threatening health problem. Employing vascular membranes is one of the treatment options in cardiovascular surgery to replace damaged vascular tissues. However, certain limitations associated with synthetic polymeric vascular membranes (expanded polytetrafluoroethylene (e-PTFE) and polyethylene terephthalate (PET)) such as low biodegradability and biofunctional, may lead to thrombosis, inflammatory response, and tissue necrosis. Polyurethane (PU) is commonly applied in vascular engineering, owing to its good biocompatibility and biodegradability. Incorporating chitosan (CS) and elastin (EL) into the PU matrix, specifically in the design of electrospun nanofibrous membrane, is expected to enhance the biological properties of PU. These improvements are crucial to overcome the limitations of synthetic vascular membranes. Previously, there was no scientific comparison between synthetic vascular membranes and the improved design of PU-based nanofibrous membranes. This scientific comparison is pivotal to allow more research exploration on biodegradable and biofunctional materials towards the fabrication of vascular membranes. Herein, the physicochemical, biodegradability, and biofunctional capability of the electrospun PU-based electrospun membranes and two synthetic membranes were compared. Both PU and PU/CS/ES electrospun membranes were annotated with N–H, C–H, and C–N groups with the appearance of elongated fibers. The –CF2 group was presented in the e-PTFE membranes with the view of expanded fibril structure and interconnecting nodes. Whereas for the PET membranes, C=C, C=O, and C–O groups were noticed with the appearance of homogeneous knitted morphology. The PU/CS/ES membranes were found to be more hydrophilic than the PU and the synthetic membranes. The incorporation of CS and EL in the matrix of electrospun PU has improved the PU's biodegradability up to 23.86 ± 5.86 % at 60 days of incubation with the view of swollen and degraded elongated fibers, following the degradation test. Both synthetic polymeric membranes were declared non-biodegradable with less than 7 % degradation at similar incubation timepoint. The PU/CS/ES membranes were also found biofunctional with the most 82 ± 0.49 % of cell viability, protruded cell filopodia, and 44.24 ± 13.99 % scratch cell closure within 24 h of incubation. The incorporation of CS and EL into the PU matrix has improved the biodegradability and biofunctionality compared to the pure PU and synthetic polymeric membranes. Thus, highlight the suitability of PU/CS/ES electrospun membranes to be applied in cardiovascular tissue engineering.

Effect of external electric fields on the ionic conductivity of the PET ion-track membrane

Polymeric ion track-etched membranes with asymmetric pores have been the subject of increased interest in both the academia and industry in recent decades. This interest is related to the rectification behavior of the membranes and their possible applications. In this work, the polyethylene terephthalate (PET) membranes with conical ion tracks were investigated for different etching conditions. Thin PET membranes were prepared using irradiated foils etched in a NaOH bath with the help of external electric fields (AC/DC) of a specific polarity. After etching, the I-V characteristics of the membranes were examined in the KCl solutions with different molarities. The obtained results showed that the I-V relations are strongly non-linear, thus confirming the rectification behavior of the membranes. It turned out that the external AC and DC fields applied during etching play an important role. They make it possible to influence the pore etching process, and so the properties of the membranes, which is important for the intended applications. Keywords: polymeric membranes, asymmetric pores, polyethylene terephthalate, I-V characteristics, transport phenomena

Fabrication of Two-Layer Microfluidic Devices with Porous Electrodes Using Printed Sacrificial Layers.

Two-layer microfluidic devices with porous membranes have been widely used in bioapplications such as microphysiological systems (MPS). Porous electrodes, instead of membranes, have recently been incorporated into devices for electrochemical cell analysis. Generally, microfluidic channels are prepared using soft lithography and assembled into two-layer microfluidic devices. In addition to soft lithography, three-dimensional (3D) printing has been widely used for the direct fabrication of microfluidic devices because of its high flexibility. However, this technique has not yet been applied to the fabrication of two-layer microfluidic devices with porous electrodes. This paper proposes a novel fabrication process for this type of device. In brief, Pluronic F-127 ink was three-dimensionally printed in the form of sacrificial layers. A porous Au electrode, fabricated by sputtering Au on track-etched polyethylene terephthalate membranes, was placed between the top and bottom sacrificial layers. After covering with polydimethylsiloxane, the sacrificial layers were removed by flushing with a cold solution. To the best of our knowledge, this is the first report on the sacrificial approach-based fabrication of two-layer microfluidic devices with a porous electrode. Furthermore, the device was used for electrochemical assays of serotonin and could successfully measure concentrations up to 5 µM. In the future, this device can be used for MPS applications.

Nanocomposite-modified nanopores: A promising platform for selective detection of copper ions

This research introduces an innovative platform designed for the selective detection of copper (II) (Cu2+) ions, employing a singular nanopore embedded within a 12 μ m-thick polyethylene terephthalate (PET) membrane. The track-etched nanopore was subsequently modified with nanomaterials in an allylamine hydrochloride (PAH)-modified asymmetric nanopore through electrostatic interactions. The nanomaterials included copper oxide (CuO), graphene oxide (GO), and their composite (GO/CuO), were synthesized using wet chemistry, and their structures and optical properties were thoroughly investigated using x-ray diffraction and diffuse reflectance spectroscopy. In the distinctive feature of the platform, Cu2+ ions gain access to coordination sites across a broad surface covered by the immobilized nanomaterials, facilitating effective binding. The selective response of GO/CuO modified pores towards Cu2+ ions was notably observed through ion transportation (I –V) studies, surpassing the response of unmodified nanopores and those modified with CuO alone. This selective behavior was demonstrated in the presence of various monovalent and divalent competing ions. Quantitative assessment of I –V studies was conducted by evaluating the intrinsic rectification ratio of asymmetric nanopores, providing a robust measure of platform's efficacy. Furthermore, we identified the optimal pH for detecting Cu2+ ions as 7, enhancing the specificity and accuracy of our method.

Modification of Track-Etched Polyethylene Terephthalate Membranes with Functionalized Silanes for Immobilizing Silver Nanoparticles

Modification of Track-Etched Polyethylene Terephthalate Membranes with Functionalized Silanes for Immobilizing Silver Nanoparticles

Immunocompetent Alveolus-on-Chip Model for Studying Alveolar Mucosal Immune Responses.

We introduce an advanced immunocompetent lung-on-chip model designed to replicate the human alveolar structure and function. This innovative model employs a microfluidic-perfused biochip that supports an air-liquid interface mimicking the environment in the human alveoli. Tissue engineering is used to integrate key cellular components, including endothelial cells, macrophages, and epithelial cells, to create a representative tissue model of the alveolus. The model facilitates in-depth examinations of the mucosal immune responses to various pathogens, including viruses, bacteria, and fungi, thereby advancing our understanding of lung immunity. The primary goal of this protocol is to provide details for establishing this alveolus-on-chip model as a robust in vitro platform for infection studies, enabling researchers to closely observe and analyze the complex interactions between pathogens and the host's immune system within the pulmonary environment. This is achieved through the application of microfluidic-based techniques to simulate key physiological conditions of the human alveoli, including blood flow and biomechanical stimulation of endothelial cells, alongside maintaining an air-liquid interface crucial for the realistic exposure of epithelial cells to air. The model system is compatible with a range of standardized assays, such as immunofluorescence staining, cytokine profiling, and colony-forming unit (CFU)/plaque analysis, allowing for comprehensive insights into immune dynamics during infection. The Alveolus-on-chip is composed of essential cell types, including human distal lung epithelial cells (H441) and human umbilical vein endothelial cells (HUVECs) separated by porous polyethylene terephthalate (PET) membranes, with primary monocyte-derived macrophages strategically positioned between the epithelial and endothelial layers. The tissue model enhances the ability to dissect and analyze the nuanced factors involved in pulmonary immune responses in vitro. As a valuable tool, it should contribute to the advancement of lung research, providing a more accurate and dynamic in vitro model for studying the pathogenesis of respiratory infections and testing potential therapeutic interventions.

Static and dynamic guided bone regeneration using a shape-memory polyethylene terephthalate membrane: An experimental study in rabbit mandible.

Periosteal expansion (PEO) results in the formation of new bone in the space created between existing bone by expanding the periosteum. PEO has already been performed on rabbit parietal bone and effective new bone formation has been demonstrated. In this study, the utility of a polyethylene terephthalate (PET) membrane as an activator was evaluated in the more complex morphology of the mandible. A PET membrane coated with hydroxyapatite (HA)/gelatine was placed in the rabbit mandibular bone at lower margin of mandibular molar region underneath periosteum, and screw-fixed. In the experimental group, the membrane was bent and screw-fixed along the lateral surface of the bone, with removal of the outer screw after 7 days followed by activation of the membrane. The experimental group was divided into two subgroups: with and without a waiting period for activation. Three animals were euthanized at 3 weeks and another three at 5 weeks postoperatively. Bone formation was assessed using micro-CT as well as histomorphometric and histological methods. No PET membrane-related complications were observed. The area of newly formed bone and the percentage of new bone in the space created by the stretched periosteum did not significantly differ between the control and experimental groups. However, in the experimental group a greater volume was present after 5 weeks than after 3 weeks. Histologically, bone formation occurred close to the site of cortical bone perforation, with many sinusoidal vessels extending through the perforations in the new bone into the overlying fibrous tissue. Inflammatory cells were not seen in the bone.

One-step fabrication of robust Stenocara beetle-inspired membrane deriving from polyethylene terephthalate (PET) waste for enhancing emulsion separation

The purification of emulsified water from waste oil has become a major research topic. Stenocara beetle-inspired wettable membranes have emerged as separating-efficient designs for purification of oil due to surface energy difference and surface roughness driven demulsification, but they are still suffering from tedious preparation and low robustness. Herein, a one-step electrospinning/electrospraying process was employed to construct Stenocara beetle-like membrane using waste PET and tetrabutyl titanate (TBT) as raw materials for water-in-oil emulsion separation. Specifically, the synchronized deposition process combines electrospinning high-hydrophobic PET fiber membrane and electrospraying superhydrophilic TiO2 particles (superhydrophilic bumps) generated from hydrolysis of TBT on the PET membrane surface, leading to a similar structure to Stenocara beetle. During the separation process, the bumpy superhydrophilic TiO2 particles can capture and aggregate tiny water droplets even though the droplet size is smaller than the membrane pore size. Moreover, this Stenocara beetle-like structure exists both on the surface and interior of the samples, resulting in the boosted demulsification ability and excellent separation efficiency up to 99.8 % and flux as high as 6392 L m-2h−1. Stenocara beetle-like membrane also exhibits strong mechanical properties and strain of the membrane is up to 128.8 %. Even after the friction test, the membrane maintained cycling stability and abrasion resistance with separation flux higher than 3500 L m-2h−1. Overall, this efficient one-step strategy can open up new avenues to fabricate advanced superwetting membranes in the field of emulsion separation.

AlveoMPU: Bridging the Gap in Lung Model Interactions Using a Novel Alveolar Bilayer Film.

The alveoli, critical sites for gas exchange in the lungs, comprise alveolar epithelial cells and pulmonary capillary endothelial cells. Traditional experimental models rely on porous polyethylene terephthalate or polycarbonate membranes, which restrict direct cell-to-cell contact. To address this limitation, we developed AlveoMPU, a new foam-based mortar-like polyurethane-formed alveolar model that facilitates direct cell-cell interactions. AlveoMPU features a unique anisotropic mortar-shaped configuration with larger pores at the top and smaller pores at the bottom, allowing the alveolar epithelial cells to gradually extend toward the bottom. The underside of the film is remarkably thin, enabling seeded pulmonary microvascular endothelial cells to interact with alveolar epithelial cells. Using AlveoMPU, it is possible to construct a bilayer structure mimicking the alveoli, potentially serving as a model that accurately simulates the actual alveoli. This innovative model can be utilized as a drug-screening tool for measuring transepithelial electrical resistance, assessing substance permeability, observing cytokine secretion during inflammation, and evaluating drug efficacy and pharmacokinetics.

Crown-Ether Crystal Channel Membranes with Subnanometer Pores for Selective Na+ Transport.

Emulating biological sodium ion channels to achieve high selectivity and rapid Na+ transport is important for water desalination, energy conversion, and separation processes. However, the development of artificial ion channels, especially multichannels, to achieve high ion selectivity, remains a challenge. In this work, we demonstrate the fabrication of ion channel membranes utilizing crown-ether crystals (DA18C6-nitrate crystals), which feature extremely consistent subnanometer pores. The polyethylene terephthalate (PET) membranes were initially subjected to amination, followed by the in situ growth of DA18C6-nitrate crystals to establish ordered multichannels aimed at facilitating selective Na+ conductance. These channels allow rapid Na+ transport while inhibiting the migration of other ions (K+ and Ca2+). The Na+ transport rate was 2.15 mol m-2 h-1, resulting in the Na+/K+ and Na+/Ca2+ selectivity ratios of 6.53 and 12.56, respectively. Due to the immobilization of the crown-ether ring, when the size of the transmembrane ion exceeded that of the crown-ether ring's cavity, the ions had to undergo a dehydration process to pass through the channel. This resulted in the ions encountering a higher energy barrier upon entering the channel, making it more difficult for them to permeate. However, the size of Na+ was compatible with the cavity of the crown-ether ring and was able to displace the hydrated layer effectively, facilitating selective Na+ translocation. In summary, this research offers a promising approach for the future development of functionalized ion channels and efficient membrane materials tailored for high-performance Na+ separation.

Pyrolysis behaviour of ultrafiltration polymer composite membranes (PSF/PET): Kinetic, thermodynamic, prediction modelling using artificial neural network and volatile product analysis

This study aims to explore the feasibility of managing ultrafiltration polymer composite membranes (UPCM) waste and converting it into valuable chemicals and energy products using a pyrolysis process. The thermal decomposition experiments were performed on polysulfone (PSF)/polyethylene terephthalate (PET) membranes using thermogravimetric analysis (TG). The vapors generated during the thermochemical process were analyzed under different heating rate conditions using TG-FTIR and GC/MS. In addition, the kinetic and thermodynamic parameters of the pyrolysis process were determined using conventional modeling methods and artificial neural network (ANN) method. The results demonstrated that the PSF/PET feedstock exhibits ahigh volatile matter content (77 % wt.%), which can be completely decomposed up to 600 °C by 79 wt%. While TG-FTIR analysis showed that the released vapors contained aromatic groups and benzoic acid (89.21 wt% at 15˚C/min) as the main GC/MS compound. Moreover, the kinetic analysis demonstrated complete decomposition of the membranes at a lower activation energy (151 kJ/mol). Meanwhile, the ANN model exhibited high performance in predicting the degradation stages of PSF/PET membranes under unknown heating conditions. This approach shows potential for modeling the thermal decomposition of ultrafiltration composite membranes more broadly.

Photoluminescent polypropylene nanofiber-supported polyethylene terephthalate integrated with strontium aluminate phosphor

In order to develop photochromic materials with persistent afterglow emission, such as concrete and smart windows, electrospun polypropylene nanofibers (PPNF) were incorporated into polyethylene terephthalate (PET) for reinforcement. Nanoparticles of lanthanide-activated strontium aluminum oxide (NLSA) were physically embedded into polyethylene terephthalate films to produce transparent PPNF@PET smart membranes. Electrospinning was utilized to create PPNF, which were subsequently included as a roughening agent into PET membranes. The green coloration detected upon exposing the PPNF@PET film to ultraviolet light was verified by CIE Lab coordinates and photoluminescence analysis. The PPNF@PET hybrids with low quantities of NLSA were found to immediately reverse this emission activity after removing the ultraviolet source, which suggest fluorescence emission. Afterglow photoluminescence was detected at higher phosphor concentrations in PPNF@PET by slow reversibility of the light emission, which suggests glow in the dark emission. After 365 nm of excitation, a 517 nm emission band could be monitored from the PPNF@PET hybrids. The chemical structure and morphology of LSA nanoparticles and PPNF were studied, showing diameters of 80–120 nm and 75–180 nm, respectively. Different analysis methods were employed to examine the morphologies of PPNF@PET membranes. As compared to a NLSA-free polyethylene terephthalate control sample, the PPNF@PET smart membranes demonstrated improved scratch resistance. The hydrophobicity and UV resistance of the PPNF@PET smart membranes were improved with an increase in the concentration of NLSA.

Nonlinear vibrations of fractional viscoelastic PET membranes subjected to tangential follower force

Nonlinear forced vibrations of simply supported viscoelastic Polyethylene Terephthalate (PET) membranes subjected to a harmonic excitation and tangential follower force are investigated in this paper. The consideration of vibration systems under follower force requires special attention to the modeling of non-conservative force and its influence on nonlinear analysis. Herein, a fractional Kelvin-Voigt Hamilton-based framework accounting for the viscoelastic PET membrane is developed. Based on the Hamilton principle for the non-conservative system, the mathematical modeling of viscoelastic PET membrane taking into account non-conservative force and geometric nonlinearity is formulated, and the derived equations are discretized via the Galerkin schemes. A technique of multiple scales is employed to numerically acquire the frequency–response curves with different system configurations. Numerical investigations are conducted to analyze the effects of tangential follower force, viscous coefficient, as well as fractional order on the dynamic stability of the considered structure. Further ramifications of the present study point to the paramount importance of tangential follower force and an accurate viscoelasticity model on the dynamic behaviors of the viscoelastic structures.

Tuning of ion current rectification and ion current saturation of multiple nanochannels in polymeric membrane

The present study gives an insight into ion flow dynamics of aqueous electrolytes via functionalized multiple nanochannels in polyethylene terephthalate (PET) membrane. The selectivity of certain ions (anions/cations) of various electrolyte combinations KCl- KClO4 (S1), KBr-KCl (S2), KBr-KClO4 (S3) over their counter-ions by the nanochannels (generated via swift heavy ion irradiation followed by chemical etching) has been studied. Tuning of the ion transport and ion current rectification has been done using different functionalized nanochannels (with charged carboxyl and protonated amino groups). The impact of ion selectivity of the nanochannels is reflected in the short circuit current and ion current saturation of different systems. The collection of counter ions outside the channels along with the in-built potential due to the flow of ions inside the channels play a crucial role in the ion transport behaviour of the collective system. The cation-selective channels (with charged carboxyl groups) show low rectification ratio compared to the anion-selective channels. The functionalized nanochannels with two -OH polar charge groups (generated through the amino-silane based reagent (3-aminopropyl) trimethoxysilane (APTMS)) exhibit higher current saturation values (S1AP∼31 μA, S2AP∼30 μA and S3AP ∼ 30.5 μA) and higher short circuit current values (S1AP ∼32.3μA, S2AP ∼ 29.6μA and S3AP ∼31.3μA) due to the overlapping of electric double layer (EDL). Systematic study of tuning of ion transport through nanochannels helps to understand the nanofluidic flow and has imminent application in the fabrication of nanoelectronic and bioinspired nanodevices.

Survival and hormone production of isolated mouse follicles in three-dimensional artificial scaffolds after stimulation with bpV(HOpic)

PurposeTo preserve fertility before gonadotoxic therapy, ovarian tissue can be removed, cryopreserved, and transplanted back again after treatment. An alternative is the artificial ovary, in which the ovarian follicles are extracted from the tissue, which reduces the risk of reimplantation of potentially remaining malignant cells. The PTEN inhibitor bpV(HOpic) has been shown to activate human, bovine and alpacas ovarian follicles, and it is therefore considered a promising substance for developing the artificial ovary. The purpose of this study was to examine the impact of different scaffolds and the vanadate derivative bpV(HOpic) on mice follicle survival and hormone secretion over 10 days.MethodsA comparative analysis was performed, studying the survival rates (SR) of isolated mice follicle in four different groups that differed either in the scaffold (polycaprolactone scaffold versus polyethylene terephthalate membrane) or in the medium—bpV(HOpic) versus control medium. The observation period of the follicles was 10 days. On days 2, 6, and 10, the viability and morphology of the follicles were checked using fluorescence or confocal microscopy. Furthermore, hormone levels of estrogen (pmol/L) and progesterone (nmol/L) were determined.ResultsWhen comparing the SR of follicles among the four groups, it was observed that on day 6, the study groups utilizing the polycaprolactone scaffold with bpV(HOpic) in the medium (SR: 0.48 ± 0.18; p = 0.004) or functionalized in the scaffold (SR: 0.50 ± 0.20; p = 0.003) exhibited significantly higher survival rates compared to the group using only the polyethylene terephthalate membrane (SR: 0). On day 10, a significantly higher survival rate was only noted when comparing the polycaprolactone scaffold with bpV(HOpic) in the medium to the polyethylene terephthalate membrane group (SR: 0.38 ± 0.20 versus 0; p = 0.007). Higher levels of progesterone were only significantly associated with better survival rates in the group with the polycaprolactone scaffold functionalized with bpV(HOpic) (p = 0.017).ConclusionThis study demonstrates that three-dimensional polycaprolactone scaffolds improve the survival rates of isolated mice follicles in comparison with a conventional polyethylene terephthalate membrane. The survival rates slightly improve with added bpV(HOpic). Furthermore, higher rates of progesterone were also partly associated with improved survival.

Enhanced SERS-based vertical flow assay for high sensitivity multiplex analysis of antibiotics

Vertical flow assay (VFA) is of great significance in food safety and environmental monitoring for rapid and highly sensitive detection of a variety of antibiotics. Herein, an enhanced surface-enhanced Raman scattering (SERS)-based VFA (eSERS-VFA) was proposed for multiplex determination of avermectin (AVM) and streptomycin (STR) through SERS nanotag recognition, and gold-core silver-shell nanocube was employed as the enhanced substrate of nanotag. A polyethylene terephthalate (PET) membrane with the hydrophobic property was inserted into the interface of nitrocellulose (NC) membrane and absorbent pad to increase immunoreaction time of SERS nanotags and antigens fixed on the NC membrane. The experimental results indicate that the as-developed eSERS-VFA possessed extraordinary properties for antibiotics analysis with excellent sensitivity, wide quantitative detection range, and short analysis time less than 15 min. The limits of detection (LODs) for AVM and STR reached 38.9 and 29.1 fg mL−1, respectively, and the linear dynamic detection ranges (LDRs) were all from 1 pg mL−1 to 100 ng mL−1. We believe that this eSERS-VFA will open a bright window for VFA-based scheme design, and support potential application prospects in the detection of trace antibiotics.

Development of Triboelectric Nanogenerators Using Novel 3D Printed Polymer Materials

Triboelectric nanogenerators (TENGs) are becoming attractive devices for harvesting mechanical energy. 3D printing (3DP) is a newly reported technique for the development of this device. This technique is not fully explored for the fabrication of triboelectric materials and compatible printing processes. Herein, three main 3DP techniques including powder‐based multijet fusion, resin‐based polyjet fusion, and filament‐based fused deposition modeling are utilized to investigate new sets of 3DP triboelectric materials. Mechanical to electrical conversion efficiency of 3D printed and commercially available negative and positive triboelectric materials are compared and investigated. Polyamide ‐12 (PA12), Veroclear, acrylonitrile‐styrene‐acrylate (ASA), copper‐coated polylactic acid (Cu‐PLA), polycarbonate (PC), and polyethylene terephthalate glycol (PETG) are fabricated using compatible 3D printing techniques. 3D‐printed PA12 is considered as a reference positive triboelectric layer. Meanwhile, 3D‐printed Veroclear, ASA, Cu‐PLA, PC, PETG, and commercial materials like Teflon sheets, PA6,6 conductive sheets, indium tin oxide‐coated polyethylene terephthalate, conductive‐nylon sheets, and PVDF membrane are selected as negative triboelectric materials. The maximum AC voltage of 80 V and maximum instantaneous current of 0.9 μA are produced by pairing 3DP‐PA12 and 3DP‐Veroclear under open circuit condition. This AC output is further converted to DC output using brdige rectifier circuitry to efficiently charge up the capacitor and glow series of 16 LEDs.