Porous Membrane Research Articles

Thin-film composite electro-nanofiltration membrane for one-step and efficient fractionation of dyes and salts in high-salinity textile wastewater

The key to achieve sustainable treatment of high-salinity dye-containing wastewater is effective fractionation of dyes and salts. In this study, a thin-film composite electro-nanofiltration membrane was successfully fabricated by co-deposition of levodopa and ε-polylysine onto a porous ultrafiltration membrane substrate. With the co-deposition of the polylevodopa/ε-polylysine composite coating on the substrate membrane, the surface properties were significantly regulated, resulting in decreased pore size, reduced surface negative charge density and lower specific electric resistance, thus enhancing their ion transfer and dye/salt fractionation efficacy. Specifically, the fabricated LDP-4 membrane (molecular weight cut-off of 408 Da) with a 4-h co-deposition experienced a 99.12 % reactive orange 16 dye rejection and 10.15 % NaCl rejection, indicating an impressive selectivity between dyes and salts. Additionally, the LDP-4 electro-nanofiltration membrane as anion conducting membrane exhibited a fast and efficient electro-driven transfer of Cl− ions. Notably, under an electric field, the fabricated LDP-4 electro-nanofiltration membrane can efficiently fractionate NaCl from the reactive orange 16/NaCl mixed solution, achieving a 98.89 % desalination efficiency and 99.79 % dye recovery. Furthermore, the LDP-4 membrane demonstrated remarkable anti-fouling property and long-term stability over an 8-cycle electro-nanofiltration operation. Therefore, the electro-nanofiltration membranes fabricated by co-deposition of levodopa and ε-polylysine show a promising potential in sustainable resource recovery from high-salinity dye-containing wastewater.

Cordierite ceramic membrane preparation using gas solid reaction growth for nanoparticles filtration

Mullite whiskers have been successfully grown on the surface of cordierite honeycomb ceramics by the gas-phase growth method. The cilia-like structure can significantly improve the filtration precision. The acicular mullite whiskers grew on the cordierite present nanometer-sized (200–300 nm) diameters and micrometer-sized (1–2 μm) lengths. Owing to mullite whiskers growth on surface of pores, the morphology of pores is changed and the microstructure change will lead to filtration precision increasing. The composites with the largest ratio of length/diameter mullite whiskers possess the highest filtration precision, which can reach 122.42 nm, 255.00 nm and 458.67 nm in intercepting different particle size of nano-SiO2, respectively. Moreover, the bending strength of the cordierites were enhanced due to the generation of mullite whiskers, these generated whiskers intersected with each other forming many unfixed lap-jointing points. The porous ceramics membrane with the unique microstructure has great potential application in gas-solid separation field and liquid-solid separation field.

A high-performance digital polymerase chain reaction chip integrated with nanorods-decorated microchannel plate

Abstract In this paper, we report on a digital PCR chip integrated with microchannel plate (MCP) for the quantification of DNA molecules. MCP, a highly porous glass membrane, is employed here as microreactors. The density of the microreactors reaches up to 1600 mm−2 with a total number of 40,000 chambers each in 100 pL volumes embedded in a 5 × 5 mm2 MCP, which is 100 times larger than that of the conventional microfabricated chips. In addition, the MCP is functionalized with ZnO nanorods to enhance the fluorescence signal. The dynamic range is noted as 105 and the detection limit of λDNA is determined to be 1.4 copies/μL.

The robust design of PMIA braided tube reinforced PFA hollow fiber membranes with graphene doping for water-in-oil separation

In order to solve the problem of oily wastewater, the poly(m-phenyleneisophthalamide)(PMIA) braided tube reinforced (PBR) poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether)(PFA) hollow fiber membrane with thermal and solvent resistant property was prepared via no-solvent green method. The membrane surface and pore structure was optimized by changing the sintering temperature and graphene (GE) content. The morphologies showed that the spherical surface with good lipophilicity was formed, and the excellent mechanical strength with favorable interface bonding state could be obtained due to the PFA melts permeating into the supporting layer. The doping of GE produced synergistic effects with the sintering temperature owing to its good thermal conductivity and pore formation. The PBR-PFA/GE hollow fiber membrane exhibited good hydrophobicity and lipophilicity with more than 97% separation efficiency for different oil products at -0.02 MPa. With the addition of GE, the average pore size first increases and then decreases, and the porosity gradually decreases. In addition, the hollow fiber membrane showed high separation ability to the water-in-oil emulsion, and maintained stable flux recovery rate after recycling, making it possible to apply in the field of oily wastewater treatment.

The minimal membrane requirements for BAX-induced pore opening upon exposure to oxidative stress

Perforation of the outer mitochondrial membrane triggered by BAX and facilitated by its main activator cBID is a fundamental process in cell apoptosis. Here, we employ a newly designed correlative approach based on a combination of a fluorescence cross correlation binding with a calcein permeabilization assay to understand the involvement of BAX in pore formation under oxidative stress conditions. To mimic the oxidative stress, we enriched liposomal membranes by phosphatidylcholines with truncated sn-2 acyl chains terminated by a carboxyl or aldehyde moiety. Our observations revealed that oxidative stress enhances proapoptotic conditions involving accelerated pore-opening kinetics. This enhancement is achieved through increased recruitment of BAX to the membrane and facilitation of BAX membrane insertion. Despite these effects, the fundamental mechanism of pore formation remained unchanged, suggesting an all-or-none mechanism. In line with this mechanism, we demonstrated that the minimal number of BAX molecules at the membrane necessary for pore formation remains constant regardless of BAX activation by cBID or the presence of oxidized lipids. Overall, our findings give a comprehensive picture of the molecular mechanisms underlying apoptotic pore formation and highlight the selective amplifying role of oxidized lipids in triggering formation of membrane pores.

New 2D Metal-Organic Monoacid Framework (MOmAF): Realization of Extreme Water Repellence.

Metal-organic frameworks (MOFs) are normally moisture-sensitive and unstable in aqueous environments, which has considerably limited their practical applications because water/moisture is ubiquitous in many industrial processes. New materials with superior water stability are, therefore, in great demand and vital to their practical applications. Here, a novel oil/water interfacial assembly strategy is demonstrated for the synthesis of a new class of metal-organic monoacid framework (MOmAF) with exceptional water stability and chemical stability. Superhydrophobic 2D sheets are synthesized at room temperature, while 1D nanotubes are obtained via the self-scrolling of their 2D sheets for the first time. In addition, a simple sequential drop-casting method is developed to coat as-synthesized MOmAF structures onto porous membranes. This can potentially open up new avenues in the design of superhydrophobic self-cleaning MOmAF materials without tedious post-synthetic modifications and usher in a new class of materials meeting industrial needs.

INHIBITION OF METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (MRSA) BIOFILM: THE ESSENTIAL ROLE AND POTENTIAL USAGE OF BACTERIOCINS

Background: The potential of Methicillin-Resistant Staphylococcus aureus (MRSA) to develop biofilms and its resistance to antibiotics become major worldwide issue. Complementary anti-microbial strategies have been used recently, in particular for the treatment of MRSA biofilm-associated resistance. Purpose: To review the potential, essential role, and mechanism of bacteriocin that can inhibit MRSA biofilms. The review was conducted by searching and analyzing published articles from Elsevier, ProQuest and PubMed database. Review: Globally, the incidence of MRSA in 85 countries based on WHO surveillance reaches more than 20%. Biofilm, as one of the virulence factors of MRSA, can result in the failure of antibiotic therapy. According to reports, bacteriocins, such as peptides synthesized by Gram-negative and Gram-positive bacteria, have antimicrobial activity that has the potential to inhibit antibiotic-resistant pathogens and biofilms formed by MRSA. Result: The bacteriostatic and bactericidal activity of bacteriocins against MRSA has been shown through research across several countries on the usage of bacteriocins, which was isolated from different types of bacteria against MRSA biofilms. Bacteriocins contribute to the inhibition of MRSA biofilms by inhibiting the synthesis of cell walls, leading to pores in the cytoplasmic membranes of bacterial cells, interrupting the synthesis of extracellular membranes, disrupting cell membranes, and reducing the number of planktonic cells within MRSA biofilms. Conclusion: Bacteriocins have an effective mechanism for treating MRSA biofilms with low toxicity and risk of resistance, hence they are safe to be developed as complementary components to antibiotics in an effort to treat MRSA biofilms.

Esaxerenone Attenuates Aldosterone-Induced Mitochondrial Damage-Mediated Pyroptosis in Mouse Aorta and Rat Vascular Smooth Muscle Cells.

Vascular smooth muscle cell (VSMC) injury caused by the inflammatory response plays a key role in cardiovascular disease (CVD), and the vasoprotective effects of mineralocorticoid receptor blockers (MRBs) support the role of mineralocorticoid receptor (MR) activation. C57BL/6 mice and VSMCs isolated from rats were treated with aldosterone and esaxerenone. Caspase-1, GSDMD-N, IL-1β, and NR3C2 expression and DNA damage in aortic VSMCs were detected using immunohistochemistry, Western blotting, and TUNEL staining. Mitochondrial changes were detected by transmission electron microscopy (TEM). Reactive oxygen species (ROS), MitoTracker, JC-I, mitochondrial respiratory chain complexes I-V, and NR3C2 were detected using immunofluorescence and flow cytometry. Pyroptosis was detected with scanning electron microscopy (SEM). After aldosterone treatment, the number of TUNEL-positive cells increased significantly, and the expression of caspase-1, GSDMD-N, and IL-1β increased. TEM revealed mitochondrial damage, and SEM revealed specific pyroptotic changes, such as cell membrane pore changes and cytoplasmic extravasation. Increased ROS levels and nuclear translocation of NR3C2 were also observed. These pyroptosis-related changes were reversed by esaxerenone. Aldosterone activates the MR and mediates mitochondrial damage, thereby inducing pyroptosis in VSMCs via the NLRP3/caspase-1 pathway. Esaxerenone inhibits MR activation and reduces mitochondrial damage and oxidative stress, thereby inhibiting pyroptosis.

Self-supporting and hierarchical porous membrane of bacterial nanocellulose@metal-organic framework for ultra-high adsorption of Congo red

The widespread use of synthetic dyes has serious implications for both the environment and human health. Therefore, there is an urgent need for the development of novel, high-efficiency adsorbents for these dyes. In this study, a Zirconium-based metal-organic framework (MOF) with controllable morphology was in-situ grown on bacterial nanocellulose (BC) via a solvothermal method. The resulting BC@MOF composite nanofibers have a high specific surface area of 651 m2/g and can be assembled into a self-supported porous membrane (BMMCa) through vacuum filtration with the assistance of calcium ions. The addition of Ca(II) significantly enhanced the mechanical properties of the membrane through dispersion effect and electrostatic interactions, as well as enhancing its adsorption performance through the salting-out effect. The BMMCa membrane, with its hierarchical porous structure and high flux, exhibits high selectivity for Congo red (CR) with an ultra-high adsorption capacity of 3518.6 mg/g. Furthermore, the self-supporting membrane achieved rapid and convenient removal of CR through circulating filtration adsorption. The adsorption mechanism and selectivity were verified through the molecular dynamics simulation calculations by Materials Studio (MS) software. This membrane-based adsorbent, with its ultra-high adsorption capacity, good selectivity, and recycling ability, has great potential for practical wastewater treatment applications.

Joint experimental-computational: Revealing the role of sodium poly(heptazineimide) in the selective separation of CO2 in PEBAX-based mixed matrix membranes

Mixed matrix membranes (MMMs) with the dual properties of porous materials and polymer matrix membranes have become one of the most optimal solutions to the gas separation problem. However, the adapted porous material and the explicit transport mechanism of gases within the mixed matrix membrane hinder its further commercialization. Thanks to their porous nature and tunable gas adsorption properties, heteroatom-doped porous materials, especially nitrogen-doped porous materials, are widely used to design and prepare advanced CO2 separation membranes. Herein, a layered two-dimensional nano-sheet with a nitrogen content of 44.7 % was successfully synthesized via thermal polymerization. And nano-sheets were homogeneously dispersed in a Pebax matrix to make a composite film. Since the CO2 affinity of the nitrogen functional site and the PEO flexible chain, realizing the synergistic improvement of CO2 permeability and selectivity. A comprehensive combined permeation experimental/simulation characterization reveals the CO2 transport pathway within the membrane, indicating the mechanism of action of nitrogen-doped porous packing on CO2 diffusion. Among these, the CO2 permeability of the mixed matrix film containing 5 wt% sodium poly(heptazine imide) (NaPHI) reached 153 Barrer at a feed gas pressure of 9 bar, nearly 149 % compared to the pure Pebax film. The selectivity of CO2/N2 was enhanced to 105, exhibiting a remarkable increase of 159 % and exceeding the 2019 Robeson limit. Importantly, the present work further reveals and demonstrates the gas separation mechanism of nitrogen-doped porous filler/polymer hybrid matrix membranes, which provides new ideas for the design and application of heteroatom-doped porous fillers in the field of gas separation.

Enzyme-Free In-Situ Electrochemical Measurement Using a Porous Membrane Electrode for Glucose Transport into Cell Spheroids.

Microphysiological systems have attracted attention because of their use in drug screening. However, it is challenging to measure cell functions in real time using a device. In this study, we developed a cell culture device using a porous membrane electrode for in situ electrochemical glucose measurements for cell analysis. First, a porous membrane electrode was fabricated and electrochemically evaluated for enzyme-free glucose measurement. Subsequently, the glucose uptake of MCF-7 spheroids was evaluated using living spheroids, fixed spheroids, supernatants, and glucose transporter inhibitor-treated spheroids. Conventionally, the direct optical measurement of glucose uptake requires fluorescence-labeled glucose derivatives. In addition, the glucose uptake can be evaluated by measuring the glucose concentration in the medium by optical or electrochemical measurements. However, glucose needs to be consumed in the entire cell culture medium, which needs a long culture time. In contrast, our system can measure glucose in approximately 5 min without any labels because of in situ electrochemical measurements. This system can be used for in situ measurements in in vitro cell culture systems, including organ-on-a-chip for drug screening.

Investigation of performance and entropy generation rate of Direct Contact Membrane Distillation (DCMD) with Static Mixer (SM): 3D CFD study

This study investigated the performance of Direct Contact Membrane Distillation (DCMD) with a Static Mixer (DCMDSM) and compared it to conventional DCMD using 3D Computational Fluid Dynamics (CFD) under steady-state conditions. The permeate flux and total entropy generation rate (TEGR) were explored as functions of various parameters, including temperature differences between feed and permeate flow, inlet velocity, salt mass fraction, membrane porosity, membrane thermal conductivity, and membrane pore radius. The study revealed that the maximum permeate flux of DCMDSM was 79 % higher than DCMD. Additionally, the average TEGR of DCMDSM was 67 % lower than that of DCMD. Furthermore, increasing the inlet velocity led to higher permeate flux in both DCMD and DCMDSM. The results showed that the performance of the DCMDSM at lower velocities was better than at higher inlet velocities. Moreover, increasing the temperature difference between feed and permeate, salt mole fraction, and porosity showed similar effects on permeate flux for both DCMD and DCMDSM, with the permeate flux of DCMDSM consistently exhibiting 60 % higher permeate flux than DCMD across all parameter ranges. Finally, the analysis of membrane thermal conductivity indicated that higher thermal conductivity of the membrane resulted in better permeate flux for DCMDSM than DCMD. Additionally, the TEGR analysis revealed that it was minimized at lower temperature differences, higher inlet velocities, and lower membrane thermal conductivities for both DCMD and DCMDSM.

PH-responsive polyaryl sulfide sulfone amide membrane containing tertiary amine unit: Oxidation and reversible acid-base treatment

Developing functional membranes with switchable pores for the separation of contaminants with different sizes has been challenging due to the lack of novel materials with adaptable and adjustable structures. Polymers containing the tertiary amine (TA) unit can be transformed via oxidation into amine oxide (AO) structure that can modulate the membrane pore size. In this study, new monomers containing pH-responsive TA units and diacyl chloride containing reducible thioether (-S-) groups were used to yield pore-size-adjustable membrane resin polyarylene sulfide sulfone amide/amide tertiary amine (PASSA/ATA) at room temperature. By varying the polymerization ratio of the reaction solution, membranes could be prepared directly through non-solvent induce phase separation (NIPS) method without extra treatment. By oxidizing the TA units to AO through acid condition (H2O2/H2SO4/CH3COOH), the PASSA/ATA membrane can be switched from ultrafiltration to loose-nanofiltration with the rejection of RO16 and rhodamine B increased from 18.4% to 34.3 % (pristine membrane) to 91.7 % and 98.5 %. The permeance and rejection rate of the oxidized membrane were found to recover to the initial state after alkali-treatment. The mechanism of the switchable pore size was elucidated by dissipative particle dynamics (DPD) simulations. Interestingly, the oxidized PASSA/ATA membrane showed good organic solvent resistance and in nanofiltration performance, as it was capable of retaining about 95 % of Congo red in N,N-dimethylformamide (DMF) with permeance of about 10 L m−2 h−1 bar−1. This work presents a facile and low-carbon approach to develop novel membranes with multiple filtration capabilities, potentially applicable in various separation processes.

Fabrication and manipulation of hierarchically porous PEEK membranes based on crystallization‐induced phase segregation and sea‐island structures

AbstractPoly ether ether ketone (PEEK) is a premier engineering plastic, which has gained considerable attention in recent years. Our prior research investigated crystallization template techniques and pore formation mechanisms within the PEEK/poly (ether imide) system, paving the way for the development of hierarchically porous membranes (HPMs). Compared to single‐porous membranes, HPMs demonstrate enhanced flux and high mass transfer efficiency simultaneously, effectively mitigating the trade‐off effects. In this study, we focused on fabricating PEEK HPMs through precise manipulation of a polymer ternary blend system. The meticulous tuning enables intricate control of the hierarchical pore morphology of PEEK at two distinct scales. The finite element simulations not only underscored the crucial role of hierarchical pores in bolstering separation efficiency, but also exhibited strong concordance with the experimental findings. This study provides guidance for future optimization of HPMs with superior separation performance.

Process for integrating multiple porous silicon membranes with variable characteristics into planar microfluidics

We present a fabrication process based on selective ion implantation to monolithically integrate several porous silicon membranes with different morphologies in the same planar fluidic chip through a single anodization step. By manipulating the dopant concentration of specific zones of a silicon on insulator wafer, the porous silicon elements formed through electrochemical anodization present different characteristics in terms of pore size and porosity. Using this technique, we are able to fabricate both lateral porous silicon membranes and standard porous silicon membranes with vertical pores that can be used in flow-through and flow-over configurations. Achieved mean pore sizes and porosities for the various membranes integrated in the same chip range from 25 nm to 50 nm, and 65–90 %, respectively. Because porous silicon membranes have been used for biosensing and for sample preparation in microfluidics devices, this method is foreseen to enable the use of porous silicon membranes to achieve all the functions involved in the analytical process on a single chip.

HiViPore: a highly viable in-flow compression for a one-step cell mechanoporation in microfluidics to induce a free delivery of nano- macro-cargoes

BackgroundAmong mechanoporation techniques for intracellular delivery, microfluidic approaches succeed in high delivery efficiency and throughput. However, especially the entry of large cargoes (e.g. DNA origami, mRNAs, organic/inorganic nanoparticles) is currently impaired since it requires large cell membrane pores with the need to apply multi-step processes and high forces, dramatically reducing cell viability.ResultsHere, HiViPore presents as a microfluidic viscoelastic contactless compression for one-step cell mechanoporation to produce large pores while preserving high cell viability. Inducing an increase of curvature at the equatorial region of cells, formation of a pore with a size of ~ 1 μm is obtained. The poration is coupled to an increase of membrane tension, measured as a raised fluorescence lifetime of 12% of a planarizable push-pull fluorescent probe (Flipper-TR) labelling the cell plasma membrane. Importantly, the local disruptions of cell membrane are transient and non-invasive, with a complete recovery of cell integrity and functions in ~ 10 min. As result, HiViPore guarantees cell viability as high as ~ 90%. In such conditions, an endocytic-free diffusion of large nanoparticles is obtained with typical size up to 500 nm and with a delivery efficiency up to 12 times higher than not-treated cells.ConclusionsThe proposed one-step contactless mechanoporation results in an efficient and safe approach for advancing intracellular delivery strategies. In detail, HiViPore solves the issues of low cell viability when multiple steps of poration are required to obtain large pores across the cell plasma membrane. Moreover, the compression uses a versatile, low-cost, biocompatible viscoelastic fluid, thus also optimizing the operational costs. With HiViPore, we aim to propose an easy-to-use microfluidic device to a wide range of users, involved in biomedical research, imaging techniques and nanotechnology for intracellular delivery applications in cell engineering.

Covalent Organic Framework Membranes with Patterned High-Density Through-Pores for Ultrafast Molecular Sieving.

The creation of uniformly molecular-sized through-pores within polymeric membranes and the direct evidence of these pores are essential for fundamentally understanding the transport mechanism and improving separation efficiency. Herein, we report an electric-field-assisted interface synthesis approach to fabricating large-area covalent organic framework (COF) membranes that consist of preferentially oriented single-crystalline COF domains. These single-crystalline frameworks were translated into high-density, vertically aligned through-pores across the entire membrane, enabling the direct visualization of membrane pores with an ultrahigh resolution of 2 Å using the low-dose high-resolution transmission electron microscopy technique (HRTEM). The density of directly visualized through-pores was quantified to be 1.2 × 1017 m-2, approaching theoretical predictions. These COF membranes demonstrate ultrahigh solvent permeability, which is 10 times higher than that of state-of-the-art organic solvent nanofiltration membranes. When applied to high-value pharmaceutical separations, their COF membranes exhibit 2 orders of magnitude higher methanol permeance and 20-fold greater enrichment efficiency than their commercial counterparts.

Enhanced anti-biochemical fouling properties of the polyacrylonitrile membranes assisted by the d-amino acid surface-modified halloysite nanotubes

Membrane fouling has always been one of the key problems to be solved in the liquid–liquid separation process of biomacromolecules, proteins, bacteria, etc. Here, halloysite nanotubes (HNTs) surface-modified with D-Amino acid (D-Aa) is synthesized in one step and introduced into the polyacrylonitrile (PAN) ultrafiltration membrane matrix to obtain a PAN mixed matrix membrane (MMM). D-Aas with three different R groups are selected to modify the HNTs. The results show that the carboxyl and amino groups of the D-Aa molecules interact with the surface of HNTs through hydrogen bonds, while the R groups are oriented towards the outside of the tube, thereby becoming the main factor affecting the surface chemical structure of the HNTs. Therefore, due to the low polarity of isobutyl and the good affinity with PAN and DMAc molecules, D-leucine-modified halloysite nanotubes (D-Leu@HNTs) can be evenly dispersed in the PAN membrane matrix and segregate to the membrane top-surface and pore wall during the non-solvent induced phase separation (NIPS) process with the solvent exchange between water and DMAc, thereby significantly improving the pore structure and hydrophilicity of the polyacrylonitrile membrane, and ultimately giving the PAN/D-Leu membrane ultra-high pure water permeability (PWP) of 1334 L·m−2·h−1·bar−1, rejection of 100 %, and excellent anti-biochemical fouling performances. The prepared PAN/D-Leu membrane maintains stable and efficient filtration performances in the 300-hour cross-flow experiment, and the membrane after testing still has excellent anti-biofilm fouling performance, showing a promising industrial application prospect.

Distinct Efficacies of Interlayers in Tailoring Polyamide Nanofiltration Membrane Performance for Organic Micropollutant Removal: Dependent on Substrate Characteristics.

Interlayered thin-film nanocomposite (TFN) membranes have shown the potential to boost nanofiltration performance for water treatment applications including the removal of organic micropollutants (OMPs). However, the effects of substrates have been overlooked when exploiting and evaluating the efficacy of certain kinds of interlayers in tailoring membrane performance. Herein, a series of TFN membranes were synthesized on different porous substrates with identical interlayers of metal-organic framework nanosheets. It was revealed that the interlayer introduction could narrow but not fully eliminate the difference in the properties among the polyamide layers formed on different substrates, and the membrane performance variation was prominent in distinct aspects. For substrates with small pore sizes exerting severe water transport hindrance, the introduced interlayer mainly enhanced membrane water permeance by affording the gutter effect, while it could be more effective in reducing membrane pore size by improving the interfacial polymerization platform and avoiding PA defects when using a large-pore-size substrate. By matching the selected substrates and interlayers well, superior TFN membranes were obtained with simultaneously higher water permeance and OMP rejections compared to three commercial membranes. This study helps us to objectively understand interlayer efficacies and attain performance breakthroughs of TFN membranes for more efficient water treatment.

An Integrated and Modular Compartmentalized Microfluidic System with Tunable Electrospun Porous Membranes for Epithelialized Organs-on-a-Chip.

A modular and 3D compartmentalized microfluidic system with electrospun porous membranes (PMs) for epithelialized organ-on-a-chip systems is presented. Our novel approach involves direct deposition of polymer nanofibers onto a patterned poly(methyl methacrylate) (PMMA) substrate using electrospinning, resulting in an integrated PM within the microfluidic chip. The in situ deposition of the PM eliminates the need for additional assembly processes. To demonstrate the high throughput membrane integration capability of our approach, we successfully deposited nanofibers onto various chip designs with complex microfluidic planar structures and expanded dimensions. We characterized and tested the fully PMMA chip by growing an epithelial monolayer using the Caco-2 cell line to study drug permeability. A comprehensive analysis of the bulk and surface properties of the membrane's fibers made of PMMA and polystyrene (PS) was conducted to determine the polymer with the best performance for cell culture and drug transport applications. The PMMA-based membrane, with a PMMA/PVP ratio of 5:1, allowed for the fabrication of a uniform membrane structure along the aligned nanofibers. By modulating the fiber diameter and total thickness of the membrane, we could adjust the membrane's porosity for specific cell culture applications. The PMMA-PVP nanofibers exhibited a low polydispersity index value, indicating monodispersed nanofibers and a more homogeneous and uniform fiber network. Both types of membranes demonstrated excellent mechanical integrity under medium perfusion flow rates. However, the PMMA-PVP composition offered a tailored porous structure with modulable porosity based on the fiber diameter and thickness. Our developed platform enables dynamic in vitro modeling of the epithelial barrier and has applications in drug transport and in vitro microphysiological systems.