Porous Polycarbonate Membrane Research Articles

Direct deep UV lithography to micropattern PMMA for stem cell culture.

Microengineering is increasingly being used for controlling the microenvironment of stem cells. Here, a novel method for fabricating structures with subcellular dimensions in commonly available thermoplastic poly(methyl methacrylate) (PMMA) is shown. Microstructures are produced in PMMA substrates using Deep Ultraviolet lithography, and the effect of different developers is described. Microgrooves fabricated in PMMA are used for the neuronal differentiation of mouse embryonic stem cells (mESCs) directly on the polymer. The fabrication of 3D, curvilinear patterned surfaces is also highlighted. A 3D multilayered microfluidic chip is fabricated using this method, which includes a porous polycarbonate (PC) membrane as cell culture substrate. Besides directly manufacturing PMMA-based microfluidic devices, an application of the novel approach is shown where a reusable PMMA master is created for replicating microstructures with polydimethylsiloxane (PDMS). As an application example, microchannels fabricated in PDMS are used to selectively expose mESCs to soluble factors in a localized manner. The described microfabrication process offers a remarkably simple method to fabricate for example multifunctional topographical or microfluidic culture substrates outside cleanrooms, thereby using inexpensive and widely accessible equipment. The versatility of the underlying process could find various applications also in optical systems and surface modification of biomedical implants.

Synthesis of conducting water-dispersible polyaniline particles and its template-guided patterning

Organic conductors are a promising material for future electronics. Although, its processing is a big challenge. In this manuscript, we demonstrate micropatterning of polyaniline within the pores of a polycarbonate membrane to fabricate a device for a conductometric sensor. The aqueous dispersion of polyaniline particles was prepared by single pot oxidative polymerization of aniline monomer using dodecylbenzene sulfonic acid as a surfactant as well as a dopant, and the polyaniline from its aqueous dispersion was then precipitated within the pores of polycarbonate membrane by adding solvents of varying polarities. The phase diagram of precipitation was drawn by titrating the polyaniline dispersion with tetrahydrofuran solvent. The dispersion was characterized by Fourier transform infrared spectroscopy and UV-Vis spectroscopy, as well as a transmission electron microscope. The molecular weight of the synthesized polyaniline was measured by gel permission chromatography. The morphology of polyaniline has been compared through transmission electron microscopy in its dispersed form and after precipitation. Field emission scanning electron microscopy was used to see the growth of channel formation of precipitated polyaniline within the pores of the polycarbonate membrane. The electroactivity of the precipitated polyaniline was measured by in-situ conductance measurement as a function of the electrochemical state.

Nano porous polycarbonate membranes stimulating cell adhesion and promoting osteogenic differentiation and differential mRNA expression

Tissue engineering is thought to be the ideal therapy for bone defect reconstructive treatment. In this study, we present a method of utilizing micro/nano porous polycarbonate membranes (PCMs) as the extracellular matrix to cultivate the human periodontal ligament cells (hPDLCs) and investigate the osteogenic differentiation of those cells. We also compared the osteogenic enhancing abilities of different pore size PCMs. The pore diameters of the candidate membranes are 200 nm, 800 nm, 1200 nm, and 10 μm respectively, and their physical properties are identified. After seeding and cultivating on the PCMs, hPDLCs can be stimulated to undergo osteogenic differentiation, in which the 200 nm PCM is proved to have the most optimal osteo-induction ability. The results of in vivo experiments provide strong evidence suggesting that the hPDLCs stimulated by 200 nm PCM greatly accelerates the healing of bone reconstruction in mice skull defects, as well as promote the process of ectopic osteogenesis. RNA-sequencing was conducted to determine the differential mRNA expression profile during the osteogenesis process of hPDLCs on PCMs. GO and KEGG enrichment analysis were conducted to study the regulatory mechanisms, in which osteogenic marker expression such as Hippo, TGF-β, and PI3K-Akt signaling pathways were significantly up-regulated. The up-regulation indicates the promising potential of nano porous PCMs for promoting osteogenesis for bone regeneration applications. Ultimately, signaling pathways that promote osteogenesis warrants further exploration.

Study of Structural, Morphological and Electrochemical Properties of Multilayer Nanowires

Ni/Cu nanowires were fabricated by electrodeposition in potentiostatic mode, into the pores of polycarbonate membrane. In present work metallic multilayer nanowires were deposited in polycarbonate membrane having pore size of 400 nm. It is found that the growth of nanowires is not constant, it varies with the pH values of electrolyte used for the deposition. Scanning electron microscopy (SEM) confirmed formed nanowires are cylindrical in shapes, dense and homogeneous for low pH depostion. X-ray diffraction technique is used to study the morphology and structure of fabricated Ni/Cu nanowires and found nanowires have FCC structure. An energy dispersive X-ray spectroscopy (EDS) is used to study the composition of multilayer nanowires. The electrochemical impedance spectroscopy has been carried out to study the in-situ growth process of multilayer nanowires.
 HIGHLIGHTS
 
 Fabricated Ni/Cu nanowires using electrodeposition method in potentiostatic mode, into the pores of polycarbonate membrane
 Scanning electron microscopy (SEM) confirmed that the fabricated nanowires are cylindrical in shape, dense and homogeneous for low pH value
 XRD study reveals FCC structure of fabricated nanowires
 
 GRAPHICAL ABSTRACT

Nanostructure and Nanomechanics of Prorocentrum donghaiense and Their Changes Under Nitrogen Limitation by Atomic Force Microscopy

In this paper, atomic force microscopy was employed to study the harmful algal bloom species Prorocentrum donghaiense for the first time. Cells were immobilized in pores of polycarbonate membrane to keep moist and to acquire images of P. donghaiense at different scales. Typical ultrastructures, such as knob-like spines and valve pores, were observed on cell surfaces. These structures had similar characteristics to those observed on scanning electron microscopy images. Moreover, the height and spacing of typical nanostructure, and nanomechanical parameters such as adhesion and elasticity, were also quantified by AFM. Additionally, the changes in cell surface nanostructure and nanomechanical characteristics under nitrogen limitation were further studied. Compared with the cells under normal culture conditions, the cell surface roughness and adhesion decreased, and the elastic modulus increased for cells under nitrogen limitation. Potential changes in the ability of P. donghaiense cells to perform normal physiological functions are reflected by changes in cell surface parameters, including cell surface roughness, cell surface adhesion, and cell surface elasticity. The results of this study reveal how P. donghaiense responds to changes in the external environment under approximately physiological conditions from the perspective of changes in cell surface nanostructures and nanomechanical characteristics and provide a new understanding of its cell biology.

A well-designed polystyrene/polycarbonate membrane for highly saline water desalination using DCMD process

A novel porous polycarbonate (PC) membrane was fabricated using ethanol as non-solvent deploying immersion-precipitation process. To further increase surface hydrophobicity, polystyrene (PS) microbeads were sprayed on PC support using an air-assisted electrospraying process. Due to the micro/nano roughness of the PS layer, the formed dual-layer PS/PC membrane possessed outstanding wetting resistance over the neat PC membrane. The water contact angle (WCA) of the neat PC and PS/PC membranes was measured as 95.2 and 155.1°, respectively. Liquid entry pressure of water represented a considerable enhancement of 84.6% compared to the neat membrane. Direct contact membrane distillation (DCMD) evaluation was performed using the fabricated and commercially available polytetrafluoroethylene (PTFE) membranes. Using concentrated saline water as feed (150 g/L), only PS reinforced PC (PS/PC) membrane showed nonwetting capability with stable DCMD performance during continuous long-term DCMD evaluation. Superhydrophobicity of PS/PC not only diminished pore wetting but also increased permeate flux considerably (45.9%↑) to produce high-quality permeate flux (˂4.6 μS/cm). Considering these attributes, using the low-cost PC polymer along with the high-productive air-assisted electrospraying process is a facile route to fabricate decent membranes for the membrane distillation (MD) process.

Characterization of neuronal viability and network activity under microfluidic flow

BackgroundMicrofluidics technology has the potential to allow precise control of the temporal and spatial aspects of solute concentration, making it highly relevant for the study of volume transmission mechanisms in neural tissue. However, full utilization of this technology depends on understanding how microfluidic flow at the rates needed for rapid solution exchange affects neuronal viability and network activity. New methodWe designed a tape-based pressurized microfluidic flow system that is simple to fabricate and can be attached to commercial microelectrode arrays. The device is multi-layered, allowing the inclusion of a porous polycarbonate membrane to isolate neuronal cultures from shear forces while maintaining diffusive exchange of solutes. We used this system to investigate how flow affected survival and spiking patterns of cultured hippocampal neurons. ResultsViability and network activity of the cultures were reduced in proportion to flow rate. However, shear reduction measures did not improve survival or spiking activity; media conditioning in conjunction with culture age proved to be the critical factors for network stability. Diffusion simulations indicate that dilution of a small molecule accounts for the deleterious effects of flow on neuronal cultures. Comparison with existing methodsThis work establishes the experimental conditions for real time measurement of network activity during rapid solution exchange, using multi-layered chambers with reversible bonding that allow for reuse of microelectrode arrays. ConclusionsWith correct media conditioning, the microfluidic flow system allows drug delivery on a subsecond timescale without disruption of network activity or viability, enabling in vitro reproduction of volume transmission mechanisms.

Electrodeposited Ni-Rich Ni-Pt Mesoporous Nanowires for Selective and Efficient Formic Acid-Assisted Hydrogenation of Levulinic Acid to γ-Valerolactone.

In pursuit of friendlier conditions for the preparation of high-value biochemicals, we developed catalytic synthesis of γ-valerolactone by levulinic acid hydrogenation with formic acid as the hydrogen source. Both levulinic and formic acid are intermediate products in the biomass transformation processes. The objective of the work is twofold: the development of a novel approach for milder synthesis conditions to produce γ-valerolactone and the reduction of the economic cost of the catalyst. Ni-rich Ni–Pt mesoporous nanowires were synthesized in an aqueous medium using a combined hard–soft-template-assisted electrodeposition method, in which porous polycarbonate membranes controlled the shape and the Pluronic P-123 copolymer served as the porogen agent. The electrodeposition conditions selected favored nickel deposition and generated nanowires with nickel percentages above 75 atom %. The increase in deposition potential favored nickel deposition. However, it was detrimental for the porous diameter because the mesoporous structure is promoted by the presence of the platinum-rich micelles near the substrate, which is not favored at more negative potentials. The prepared catalysts promoted the complete transformation to γ-valerolactone in a yield of around 99% and proceeded with the absence of byproducts. The coupling temperature and reaction time were optimized considering the energy cost. The threshold operational temperature was established at 140 °C, at which, 120 min was sufficient for attaining the complete transformation. Working temperatures below 140 °C rendered the reaction completion difficult. The Ni78Pt22 nanowires exhibited excellent reusability, with minimal nickel leaching into the reaction mixture, whereas those with higher nickel contents showed corrosion.

A comprehensive review of template-synthesized multi-component nanowires: From interfacial design to sensing and actuation applications

Nanowires are one of the most promising nano-building blocks for many applications, including sensors/biosensors, electronics, photonics, energy conversion and storage devices, MEMS and NEMS, biotechnology and nanomedicine. With the growing demands of multi-purpose and multi-functional materials in these fields, different types of multi-component nanowires with complex structures have been designed and fabricated. Among various fabrication methods, porous anodic aluminum oxide (AAO) and polycarbonate (PC) membranes are well-established hard templates that have been used for synthesizing a variety of nanowires and nanowire structures. In this article, a comprehensive review of template-synthesized multi-component nanowire structures has been given, including multi-segmented, core-shell and multi-element nanowires, which can be synthesized by using these hard templates in a sequential or parallel way. Besides, the assembly and integration of different functions and properties into smaller and lighter devices require careful interfacial design and synthesis of multi-component nanowires. The interfacial structure and properties, such as interface uniformity, intermetallic compound formation and surface oxidation, have significant impact on the electrical and thermal conductivity, mechanical strength, functionality, stability and reliability of nanowire-based electronics and devices. A rational interfacial design is crucially important to improve these properties of nanowire devices for emerging multi-functional sensors and actuators, due in fact that sensors and actuators are among the most important components in many electronics and products. Multi-component nanowire based sensors and actuators have potential applications in a wide range of mechanical, electrical, thermal, and biomedical devices.

Pillar[5]arene-functionalized nanochannel platform for detecting chiral drugs

Chirality is a fascinating and essential feature of life and highly associated with many significant pharmaceutical, chemical, and biological processes. The construction of chiral recognition platform is a hot research topic and challenging assignment. Herein, we report an electrochemical method by differential pulse voltammetry (DPV) for the enantioselective recognition of chiral drug propranolol (R/S-PPL) through a nanochannel platform based on the N-acetyl-l-cysteine functionalized pillar[5]arenes derivative NALC-P5 and the porous polycarbonate membrane. The chiral discrimination depends on the difference in the supramolecular host-guest interaction between the chiral NALC-P5 and the R/S-PPL. The transmission rate of the R/S-PPL can be regulated in the nanochannel and we can achieve the selective transport of the chiral drugs. This simple electrochemical technique has potential applications as a general platform for the recognition of chiral molecules.

Development of an Organ-on-a-Chip-Device for Study of Placental Pathologies.

The human placenta plays a key role in reproduction and serves as a major interface for maternofetal exchange of nutrients. Study of human placenta pathology presents a great experimental challenge because it is not easily accessible. In this paper, a 3D placenta-on-a-chip model is developed by bioengineering techniques to simulate the placental interface between maternal and fetal blood in vitro. In this model, trophoblasts cells and human umbilical vein endothelial cells are cultured on the opposite sides of a porous polycarbonate membrane, which is sandwiched between two microfluidic channels. Glucose diffusion across this barrier is analyzed under shear flow conditions. Meanwhile, a numerical model of the 3D placenta-on-a-chip model is developed. Numerical results of concentration distributions and the convection–diffusion mass transport is compared to the results obtained from the experiments for validation. Finally, effects of flow rate and membrane porosity on glucose diffusion across the placental barrier are studied using the validated numerical model. The placental model developed here provides a potentially helpful tool to study a variety of other processes at the maternal–fetal interface, for example, effects of drugs or infections like malaria on transport of various substances across the placental barrier.

Gas sensing behavior of Cu2O and CuO/Cu2O composite nanowires synthesized by template-assisted electrodeposition

Metal oxide-based conductometric gas sensors are one of the promising candidates for highly sensitive, harsh environment resilient, low cost and nontoxic sensors for industrial applications. Here we present conductometric gas sensors based on Cu2O and CuO/Cu2O composite nanowires investigated towards few VOCs and CO gases. The Cu2O nanowires with an average length of 8 µm and diameter of 180 nm were synthesized through template-assisted electrodeposition of Cu2O into a polycarbonate membrane pores, from an aqueous solution. The CuO/Cu2O composite nanowires were obtained by annealing the synthesized Cu2O nanowires in an oxygen environment. The morphology, dimension, and crystallography of the synthesized nanowires are studied using scanning electron microscopy and X-ray diffraction measurements before and after annealing process. Our proposed sensor based on Cu2O nanowires showed a fast response in sensing ethanol gas at 250 °C response values of 178 and 15% towards 50 and 1 ppm of ethanol, respectively. CuO/Cu2O nanowires behaved selective and sensitive at 150 °C with a response value of 55% towards 500 ppm of CO.

Rapid Fabrication of Membrane-Integrated Thermoplastic Elastomer Microfluidic Devices.

Leveraging the advantageous material properties of recently developed soft thermoplastic elastomer materials, this work presents the facile and rapid fabrication of composite membrane-integrated microfluidic devices consisting of FlexdymTM polymer and commercially available porous polycarbonate membranes. The three-layer devices can be fabricated in under 2.5 h, consisting of a 2-min hot embossing cycle, conformal contact between device layers and a low-temperature baking step. The strength of the FlexdymTM-polycarbonate seal was characterized using a specialized microfluidic delamination device and an automated pressure controller configuration, offering a standardized and high-throughput method of microfluidic burst testing. Given a minimum bonding distance of 200 μm, the materials showed bonding that reliably withstood pressures of 500 mbar and above, which is sufficient for most microfluidic cell culture applications. Bonding was also stable when subjected to long term pressurization (10 h) and repeated use (10,000 pressure cycles). Cell culture trials confirmed good cell adhesion and sustained culture of human dermal fibroblasts on a polycarbonate membrane inside the device channels over the course of one week. In comparison to existing porous membrane-based microfluidic platforms of this configuration, most often made of polydimethylsiloxane (PDMS), these devices offer a streamlined fabrication methodology with materials having favourable properties for cell culture applications and the potential for implementation in barrier model organ-on-chips.

Multilayer spin-valve CoFeP/Cu nanowires with giant magnetoresistance

Multilayer CoFeP/Cu spin-valve nanowires with period of four {FMs/Cu/FMh/Cu}n and five {FMs/Cu/FMs/FMh/Cu}n layers were synthesized by the electrodeposition in the pores of polycarbonate membranes from single electrolyte where FMs are magnetically soft and FMh are magnetically hard layers. The results of magnetic measurements showed that the field dependence of the magnetoresistance of nanowires obtained in the work are typical for multilayer structures with a giant magnetoresistance, the maximum of which reaches ∼9%. Multilayered nanowires based on the giant magnetoresistive effect are interesting objects from fundamental point of view as model objects for explanation of the nature of magnetic ordering in strongly coupled bias magnetic multilayers. These materials are promising for practical applications as sensitive elements in magnetic field sensors, biomedical applications and functional spintronic materials.

Fabrication of self-supported Ni(OH)2@nickel nanowire coreshell arrays with enhanced electrochemical performance for supercapacitor applications

A self-supported nickel nanowire array coated with Ni(OH)2 (Ni(OH)2@SNWA) with enhanced electrochemical performance was successfully fabricated by template-directed electrodeposition and oxidation treatment. Porous polycarbonate membrane was used as the template for the preparation of self-supported nickel nanowire array with a small wire diameter and high wire density. The Ni(OH)2 on the surface formed through oxidation treatment is in close contact with the inside nickel wire. Due to its self-supported and integrated core–shell structure, the Ni(OH)2@SNWA has excellent ionic and electrical conductivities, and shows enhanced electrochemical performance at high current densities.

Imidazolium functionalized poly(vinyl alcohol) membranes for direct methanol alkaline fuel cell applications

AbstractIn this study, imidazolium functionalized poly(vinyl alcohol) (PVA) was synthesized by acetalization and direct quaternization reaction. Afterwards, composite anion exchange membranes based on imidazolium‐ and quaternary ammonium‐ functionalized PVA were used for direct methanol alkaline fuel cell applications. 1H NMR and Fourier transform infrared spectroscopy data indicated that imidazole functionalized PVA was successfully synthesized. Inductively coupled plasma mass spectrometry data demonstrated that the imidazolium structure was efficiently obtained by direct quaternization of the imidazole group. Composite anion exchange membranes were fabricated by application of the functionalized PVA solution on the surface of porous polycarbonate (PC) membranes. Fuel cell related properties of all prepared membranes were investigated systematically. The imidazolium functionalized composite membrane (PVA‐Im/PC) exhibited higher ionic conductivity (7.8 mS cm−1 at 30 °C) despite a lower water uptake and ion exchange capacity value compared to that of quaternary ammonium. In addition, PVA‐Im/PC showed the lowest methanol permeation rate and the highest membrane selectivity as well as high alkaline and oxidative stability. Dynamic mechanical analysis results reveal that both composite membranes were mechanically resistant up to 107 Pa at 140 °C. The superior performance of imidazolium functionalized PVA composite membrane compared to quaternary ammonium functionalized membrane makes it a promising candidate for direct methanol alkaline fuel cell applications. © 2020 Society of Chemical Industry

Synthesis of SnO2 nanowires as a reusable and flexible electrode for electrochemical detection of riboflavin

The fabrication and testing of a riboflavin (RF) sensor based on the use of tin oxide (SnO2) nanowires was successfully attained. Template directed electrodeposition was used to produce one-dimensional nanostructures of SnO2. SnO2 nanowires were achieved by the electrodeposition of tin(ii) chloride into the nanochannels of the porous polycarbonate membrane by applying potential of −0.75 V. Various techniques such as XRD, FESEM, EDS and FTIR were used to characterize the synthesized nanowires. All electrochemical studies were carried out in phosphate buffer pH 7.0 and 0.1 Vs−1 scan rate. The fabricated sensor showed excellent anti-interference ability against electroactive species and metal ions. It also proved its long-term stability and good reproducibility with RSD values 1.90% and 1.30% respectively. The voltammetric signal increases linearly in the 0–13 μM concentrations range with a lower detection limit of 0.6 µM. Rs and Rct values decreased significantly with increasing concentration. The synthesized electrode is proved to be useful for the estimation of the RF content in pharmaceutical samples with 98% recovery.

Paclitaxel-Loaded Macrophage Membrane Camouflaged Albumin Nanoparticles for Targeted Cancer Therapy.

BackgroundMelanoma is the most common symptom of aggressive skin cancer, and it has become a serious health concern worldwide in recent years. The metastasis rate of malignant melanoma remains high, and it is highly difficult to cure with the currently available treatment options. Effective yet safe therapeutic options are still lacking. Alternative treatment options are in great demand to improve the therapeutic outcome against advanced melanoma. This study aimed to develop albumin nanoparticles (ANPs) coated with macrophage plasma membranes (RANPs) loaded with paclitaxel (PTX) to achieve targeted therapy against malignant melanoma.MethodsMembrane derivations were achieved by using a combination of hypotonic lysis, mechanical membrane fragmentation, and differential centrifugation to empty the harvested cells of their intracellular contents. The collected membrane was then physically extruded through a 400 nm porous polycarbonate membrane to form macrophage cell membrane vesicles. Albumin nanoparticles were prepared through a well-studied nanoprecipitation process. At last, the two components were then coextruded through a 200 nm porous polycarbonate membrane.ResultsUsing paclitaxel as the model drug, PTX-loaded RANPs displayed significantly enhanced cytotoxicity and apoptosis rates compared to albumin nanoparticles without membrane coating in the murine melanoma cell line B16F10. RANPs also exhibited significantly higher internalization efficiency in B16F10 cells than albumin nanoparticles without a membrane coating. Next, a B16F10 tumor xenograft mouse model was established to explore the biodistribution profiles of RANPs, which showed prolonged blood circulation and selective accumulation at the tumor site. PTX-loaded RANPs also demonstrated greatly improved antitumor efficacy in B16F10 tumor-bearing mouse xenografts.ConclusionAlbumin-based nanoscale delivery systems coated with macrophage plasma membranes offer a highly promising approach to achieve tumor-targeted therapy following systemic administration.

Scale ratio modulated magnetic anisotropy of 3D [formula omitted][formula omitted] crossed nanowire networks

In this work, three dimensional (3D) interconnected Ni1-xCox (0⩽x⩽100%) crossed nanowire (CNW) networks with different scale ratios have been fabricated in order to investigate the influence of size reduction of the whole 3D networks structure on their crystal orientation and magnetic properties. Interconnected porous polycarbonate membranes, each one with different nanopore diameters but with the same porosity, have been designed to obtain porous architectures with different scale ratios. Using these membranes, CNW networks with the same packing fraction of about 22%, but different nanowires (NWs) diameters have been grown by electrodeposition. As a result, the magnetostatic (MS) anisotropy in the saturated state is the same for all the 3D networks, which allows identifying size dependent magnetic anisotropies. Reducing the diameter of the nanowires leads to changes on their magnetic properties, so that Co-rich CNW networks show a magnetocrystalline (MC) anisotropy contribution originated by a preferential hexagonal close packed orientation that competes with the MS anisotropy field. In turn, low diameter Ni-rich CNW networks show an anisotropy contribution of different nature than the MS and MC fields. The strategy presented in this work to accurately separate magnetic contributions leads to a better understanding of the magnetic behavior of complex 3D nanoarchitectures and to their potential use in the development of magnetic, sensing and spintronic applications.

ELECTROCHEMICAL PREPARATION OF BISMUTH NANOWIRES USING ION-ETCHED POROUS POLYCARBONATE MEMBRANE

Bismuth as “environmentally friendly” metal represents a promising electrode material for different electrochemical techniques. In this study, we prepared bismuth nanowires by chronoamperometry using ion-etched porous polycarbonate membrane. According to SEM- EDX analysis, obtained bismuth nanowires show uniform growth with a high aspect ratio. Due to its large surface, these nanowires have the potential to greatly improve sensor properties for the detection of a variety of inorganic and organic compounds (pollutants, drugs, etc.). Key words: electrodeposition, bismuth, nanowires, SEM-EDX.