Hydrophilicity Of Substrate Research Articles

Wetting and Dewetting Behaviors of Droplets on the Nanoring Surface

AbstractThis study uses molecular dynamics simulations to investigate the wetting behavior of water droplets on a gold substrate with annular grooves. The research finds that droplet size and substrate hydrophilicity similarly affect wetting behavior. Enhanced hydrophilicity changes the velocity trend of droplet contact line movement, while droplet size impacts the magnitude of velocity change. Contact angle fluctuations are observed and analyzed theoretically based on Young's equation. The results provide insights into the relationship between droplet dynamics and surface structure, contributing to a better understanding of wetting processes at the microscopic level.

Substrates with Tunable Hydrophobicity for Optimal Cell Adhesion.

Electrospinning is a technique used to create nano/micro-fibrous materials from various polymers for biomedical uses. Polymers like polycaprolactone (PCL) are commonly used, but their hydrophobic properties can limit their applications. To enhance hydrophilicity, nonionic surfactants such as sorbitane monooleate (Span80) and poloxamer (P188) can be added to the PCL electrospinning solution without altering its net charge density. These additions enable the successful production of PCL/P188 and PCL/Span80 fibrous substrates. In this study, P188 and Span80 are incorporated into the PCL solutions; they are successfully electrospun into PCL/P188 and PCL/Span80 substrates, respectively. PCL/P188 substrates show that until a specific P188 concentration, fiber and pore sizes are similar to PCL substrates. However, exceeding 0.30% P188 concentration enlarges fibers, impacting fiber uniformity at higher concentrations. Conversely, higher concentrations of Span80 result in thicker, less uniform fibers, indicating potential disruptions in the electrospinning process. Notably, both surfactants significantly improve substrate hydrophilicity, enhancing the adhesion and proliferation of fibroblasts, endothelial cells, and smooth muscle cells. P188, in particular, shows superior efficacy in promoting cell adhesion and growth at concentrations optimized for different cell types. Therefore, precise surfactant concentrations in the electrospinning solution can lead to the optimization of electrospun substrates for tissue engineering applications.

Substrate Induced van der Waals Force Effects on the Stability of Violet Phosphorus

AbstractSince the first isolation of graphene, the importance of van der Waals (vdW) interactions has become increasingly recognized in the burgeoning field of layered materials. In this work, infrared nanoimaging techniques and theoretical modeling are used to unravel the critical role played by interfacial vdW interactions in governing the stability of violet phosphorus (VP)—a recently rediscovered wide bandgap p‐type semiconductor—when exfoliated on different substrates. It is demonstrated that vdW interactions with the underlying substrate can have a profound influence on the stability of exfoliated VP flakes and investigate how these interactions are affected by flake thickness, substrate properties (e.g., substrate hydrophilicity, surface roughness), and the exfoliation process. These findings highlight the key role played by interfacial vdW interactions in governing the stability and physical properties of layered materials, and can be used to guide substrate selection in the preparation and study of this important class of materials.

The effect of PEG-content and molecular weight of PEG-PPG-PEG block copolymers on the structure and performance of polyphenylsulfone ultra- and nanofiltration membranes

Thin-film composite (TFC) membranes obtained by forming a selective polyamide (PA) layer on a surface of a porous membrane-substrate via interfacial polymerization (IP) technique are the most effective membranes for nanofiltration (NF). The idea of this study is that addition of polyethylene glycol-polypropylene glycol-polyethylene glycol (PEG-PPG-PEG) block copolymers to the polyphenylsulfone (PPSU) casting solution tunes the pore structure (pore size and porosity), water contact angle and topology of the selective layer of ultrafiltration (UF) membranes. This influences the formation of PA layer via IP since membrane-substrate significantly effects the first stage of IP reaction. For the first time the effect of PEG-PPG-PEG copolymer molecular weight, content of PEG blocks and copolymer concentration in the PPSU casting solution on the structure, hydrophilicity and performance of ultrafiltration and TFC NF membranes was revealed. It was found that increase in PEG block content and PEG-PPG-PEG molecular weight led to the increase in pore size, porosity and hydrophilicity of selective layer of ultrafiltration membranes which results in the formation of thinner and more uniform PA layer with higher cross-linking degree of NF membranes via IP. It was revealed that NF membrane flux increased with the rise in the content of PEG units from 10 to 80 wt% and increase in molecular weight of PEG-PPG-PEG block copolymer. Modification of PPSU membrane-substrate yielded the increase in selectivity of the corresponding TFC NF membranes due to the formation of more uniform and denser defect-free PA layer attributed to the rise in hydrophilicity of membrane-substrate. It was found that membrane-substrate modification by PEG-PPG-PEG results in the enhancement of antifouling performance toward bovine serum albumin (flux recovery ratio is 99–100 %) and long-term stability during 48 h operation compared to the reference membrane. Modification of PPSU membrane-substrate by F38 PEG-PPG-PEG block copolymer (Mn = 5000 g mol−1, PEG block content of 80 wt%) was found to yield the TFC NF membranes with the best combination of permeation, separation and antifouling performance and long-term stability.

Experimental investigations on polydopamine coated poly lactic acid based biomaterial fabricated using 3D printing for orthopedic applications

Polymer based implants provide excellent biocompatibility due to porous structure and minimum chances of stress shielding. However, 3D Printed PLA structures possess insufficient mechanical strength, restricting their utility in biomedical domain. This challenge can be addressed by enhancing their mechanical properties through surface modification. The one-step oxidative polymerization process transforms dopamine hydrochloride into biocompatible polydopamine coating, that facilitates adhesion to both hydrophilic and hydrophobic surfaces. The mechanical performance of these structures is influenced significantly by the printing and coating parameters. Thus, this study undertakes the fabrication of bone plates at varying printing parameters followed by investigating the effects of polydopamine coating on their tensile and flexural behavior across varying coating conditions. In the study, SEM/EDS analysis has been performed for examining the morphological characteristics, interaction of coating with PLA and assessing the elemental distribution on the coated surface. The study further explores the impact of coating on substrate roughness and hydrophilicity through AFM and water contact angle measurement techniques. The deposition of polydopamine coating on PLA bone plates was confirmed using XRD and Raman spectroscopy. Upon application of coating, the findings suggested enhancement in tensile strength and flexural strength in the ranges of 47.18%–94.47% and 8.5%–33.78% respectively, across varying printing parameters. Similarly, varying coating parameters resulted in improvement ranging from 38.68% to 93.03% for tensile strength and 2.8%–30.57% for flexural strength. Furthermore, the deposition of coating substantially enhanced the hydrophilicity of the bone plates, making them suitable for tissue engineering applications. Thus, the successful deposition of polydopamine coating not only enhanced the mechanical behavior but also improved the hydrophilicity of bone plates, thereby advancing their suitability for biomedical applications.

Characterising Hydroxyapatite Deposited from Solution onto Novel Substrates: Growth Mechanism and Physical Properties.

Whilst titanium, stainless steel, and cobalt-chrome alloys are the most common materials for use in orthopaedic implant devices, there are significant advantages in moving to alternative non-metallic substrates. Substrates such as polymers may have advantageous mechanical biological properties whilst other substrates may bring unique capability. A key challenge in the use of non-metal products is producing substrates which can be modified to allow the formation of well-adhered hydroxyapatite films which promote osteointegration and have other beneficial properties. In this work, we aim to develop methodology for the growth of hydroxyapatite films on surfaces other than bulk metallic parts using a wet chemical coating process, and we provide a detailed characterisation of the coatings. In this study, hydroxyapatite is grown from saturated solutions onto thin titanium films and silicon substrates and compared to results from titanium alloy substrates. The coating process efficacy is shown to be dependent on substrate roughness, hydrophilicity, and activation. The mechanism of the hydroxyapatite growth is investigated in terms of initial attachment and morphological development using SEM and XPS analysis. XPS analysis reveals the exact chemical state of the hydroxyapatite compositional elements of Ca, P, and O. The characterisation of grown hydroxyapatite layers by XRD reveals that the hydroxyapatite forms from amorphous phases, displaying preferential crystal growth along the [002] direction, with TEM imagery confirming polycrystalline pockets amid an amorphous matrix. SEM-EDX and FTIR confirmed the presence of hydroxyapatite phases through elemental atomic weight percentages and bond assignment. All data are collated and reviewed for the different substrates. The results demonstrate that once hydroxyapatite seeds, it crystallises in the same manner as bulk titanium whether that be on a titanium or silicon substrate. These data suggest that a range of substrates may be coated using this facile hydroxyapatite deposition technique, just broadening the choice of substrate for a particular function.

Direct Writing of Silver Nanowire Patterns with Line Width down to 50 μm and Ultrahigh Conductivity.

Direct writing of one-dimensional nanomaterials with large aspect ratios into customized, highly conductive, and high-resolution patterns is a challenging task. In this work, thin silver nanowires (AgNWs) with a length-to-diameter ratio of 730 are employed as a representative example to demonstrate a potent direct ink writing (DIW) strategy, in which aqueous inks using a natural polymer, sodium alginate, as the thickening agent can be easily patterned with arbitrary geometries and controllable structural features on a variety of planar substrates. With the aid of a quick spray-and-dry postprinting treatment at room temperature, the electrical conductivity and substrate adhesion of the written AgNWs-patterns improve simultaneously. This simple, environment benign, and low-temperature DIW strategy is effective for depositing AgNWs into patterns that are high-resolution (with line width down to 50 μm), highly conductive (up to 1.26 × 105 S/cm), and mechanically robust and have a large alignment order of NWs, regardless of the substrate's hardness, smoothness, and hydrophilicity. Soft electroadhesion grippers utilizing as-manufactured interdigitated AgNWs-electrodes exhibit an increased shear adhesion force of up to 15.5 kPa at a driving voltage of 3 kV, indicating the strategy is very promising for the decentralized and customized manufacturing of soft electrodes for future soft electronics and robotics.

Surface hydrophilicity-mediated migration of nano/microparticles under temperature gradient in a confined space

HypothesisParticle transport by a temperature gradient is prospective in many biomedical applications. However, the prevalence of boundary confinement in practical use introduces synergistic effects of thermophoresis and thermo-osmosis, causing controversial phenomena and great difficulty in understanding the mechanisms. ExperimentsWe developed a microfluidic chip with a uniform temperature gradient and switchable substrate hydrophilicity to measure the migrations of various particles (d = 200 nm − 2 μm), through which the effects of particle thermophoresis and thermo-osmotic flow from the substrate surface were decoupled. The contribution of substrate hydrophilicity on thermo-osmosis was examined. Thermophoresis was measured to clarify its dependence on particle size and hydrophilicity. FindingsThis paper reports the first experimental evidence of a large enthalpy-dependent thermo-osmotic mobility χ ∼ ΔH on a hydrophobic polymer surface, which is 1–2 orders of magnitude larger than that on hydrophilic surfaces. The normalized Soret coefficient for polystyrene particles, ST/d = 18.0 K-1µm−1, is confirmed to be constant, which helps clarify the controversy of the size dependence. Besides, the Soret coefficient of hydrophobic proteins is approximately-four times larger than that of hydrophilic extracellular vesicles. These findings suggest that the intrinsic slip on the hydrophobic surface could enhance both surface thermo-osmosis and particle thermophoresis.

Altering substrate properties of thin film nanocomposite membrane by Al2O3 nanoparticles for engineered osmosis process

ABSTRACT The scarcity of energy and water resources is a major challenge for humanity in the twenty-first century. Engineered osmosis (EO) technologies are extensively researched as a means of producing sustainable water and energy. This study focuses on the modification of substrate properties of thin film nanocomposite (TFN) membrane using aluminium oxide (Al2O3) nanoparticles and further evaluates the performance of resultant membranes for EO process. Different Al2O3 loading ranging from zero to 0.10 wt% was incorporated into the substrate and the results showed that the hydrophilicity of substrate was increased with contact angle reduced from 74.81° to 66.17° upon the Al2O3 incorporation. Furthermore, the addition of Al2O3 resulted in the formation of larger porous structure on the bottom part of substrate which reduced water transport resistance. Using the substrate modified by 0.02 wt% Al2O3, we could produce the TFN membrane that exhibited the highest water permeability (1.32 L/m2.h.bar, DI water as a feed solution at 15 bar), decent salt rejection (96.89%), low structural parameter (532.44 μm) and relatively good pressure withstandability (>25 bar).

Distinct impact of substrate hydrophilicity on performance and structure of TFC NF and RO polyamide membranes

Substrate properties have profound impacts on the structure and performance of both thin-film composite (TFC) nanofiltration (NF) and reverse osmosis (RO) polyamide (PA) membranes. Some studies have previously investigated the impact of substrate hydrophilicity on PA formation and TFC membrane performance. However, the observed phenomena and explanations remain contradictory in literature. Herein, we performed interfacial polymerization (IP) reactions of both piperazine (PIP)-trimesoyl chloride (TMC) and m-phenylenediamine (MPD)-TMC systems on substrates with different hydrophilicity. We found that the TFC RO membrane showed higher water permeance and NaCl rejection on the relatively hydrophobic substrate, while the TFC NF membrane favored the relatively hydrophilic substrate. The critical importance of interfacial degassing and local monomer concentration was highlighted to dissect the distinct impact of substrate hydrophilicity. For the MPD-TMC system, interfacial nanobubble generation was inhibited because of the decreased local MPD concentration and heat production for the more hydrophilic substrates, resulting in a decrease in the roughness feature and compromised water permeance of RO membranes. In contrast, interfacial degassing was not a dominant mechanism in the PIP-TMC system due to the slower reaction rate of PIP-TMC than MPD-TMC. Consequently, the PA layer of NF membrane became thinner and looser when the substrate became more hydrophilic, resulting from the diluted local PIP concentration. Our study unveils the fundamental relationship among substrate hydrophilicity, PA structure, and separation performance of both TFC NF and RO PA membranes, providing important guides on their design and synthesis.

Integration of Biofunctional Molecules into 3D-Printed Polymeric Micro-/Nanostructures.

Three-dimensional printing at the micro-/nanoscale represents a new challenge in research and development to achieve direct printing down to nanometre-sized objects. Here, FluidFM, a combination of microfluidics with atomic force microscopy, offers attractive options to fabricate hierarchical polymer structures at different scales. However, little is known about the effect of the substrate on the printed structures and the integration of (bio)functional groups into the polymer inks. In this study, we printed micro-/nanostructures on surfaces with different wetting properties, and integrated molecules with different functional groups (rhodamine as a fluorescent label and biotin as a binding tag for proteins) into the base polymer ink. The substrate wetting properties strongly affected the printing results, in that the lateral feature sizes increased with increasing substrate hydrophilicity. Overall, ink modification only caused minor changes in the stiffness of the printed structures. This shows the generality of the approach, as significant changes in the mechanical properties on chemical functionalization could be confounders in bioapplications. The retained functionality of the obtained structures after UV curing was demonstrated by selective binding of streptavidin to the printed structures. The ability to incorporate binding tags to achieve specific interactions between relevant proteins and the fabricated micro-/nanostructures, without compromising the mechanical properties, paves a way for numerous bio and sensing applications. Additional flexibility is obtained by tuning the substrate properties for feature size control, and the option to obtain functionalized printed structures without post-processing procedures will contribute to the development of 3D printing for biological applications, using FluidFM and similar dispensing techniques.

Influence of Substrate Hydrophilicity on Structural Properties of Supported Lipid Systems on Graphene, Graphene Oxides, and Silica.

Pristine graphene, a range of graphene oxides, and silica substrates were used to investigate the effect of surface hydrophilicity on supported lipid bilayers by means of all-atom molecular dynamics simulations. Supported 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid bilayers were found in close-contact conformations with hydrophilic substrates with as low as 5% oxidation level, while self-assembled monolayers occur on pure hydrophobic graphene only. Lipids and water at the surface undergo large redistribution to maintain the stability of the supported bilayers. Deposition of bicelles on increasingly hydrophilic substrates shows the continuous process of reshaping of the supported system and makes intermediate stages between self-assembled monolayers and supported bilayers. The bilayer thickness changes with hydrophilicity in a complex manner, while the number of water molecules per lipid in the hydration layer increases together with hydrophilicity.

Targeting of GLUT5 for Transporter-Mediated Drug-Delivery Is Contingent upon Substrate Hydrophilicity.

Specific link between high fructose uptake and cancer development and progression highlighted fructose transporters as potential means to achieve GLUT-mediated discrimination between normal and cancer cells. The gained expression of fructose-specific transporter GLUT5 in various cancers offers a possibility for developing cancer-specific imaging and bioactive agents. Herein, we explore the feasibility of delivering a bioactive agent through cancer-relevant fructose-specific transporter GLUT5. We employed specific targeting of GLUT5 by 2,5-anhydro-D-mannitol and investigated several drug conjugates for their ability to induce cancer-specific cytotoxicity. The proof-of-concept analysis was carried out for conjugates of chlorambucil (CLB) in GLUT5-positive breast cancer cells and normal breast cells. The cytotoxicity of conjugates was assessed over 24 h and 48 h, and significant dependence between cancer-selectivity and conjugate size was observed. The differences were found to relate to the loss of GLUT5-mediated uptake upon increased conjugate size and hydrophobicity. The findings provide information on the substrate tolerance of GLUT5 and highlight the importance of maintaining appropriate hydrophilicity for GLUT-mediated delivery.

Polyethyleneimine‐Mediated Polyamide Composite Membrane with High Perm‐Selectivity for Forward Osmosis

AbstractThin‐film composite (TFC) membranes comprised of a polyamide (PA) selective layer upon a porous substrate dominate the forward osmosis (FO) membrane market. However, further improvement of perm‐selectivity still remains a great challenge. Herein, a polyethyleneimine (PEI) interlayer is intentionally designed prior to interfacial polymerization (IP) to tailor the PA layer, which thus improves the separation performance. The PEI interlayer not only improves the substrate hydrophilicity for adsorbing more diamine monomer and controlling its release rate, but also participates in IP reaction by crosslinking with acyl chloride (TMC). Furthermore, it can decrease the electronegativity of the substrate for decreasing reverse salt diffusion. Consequently, a denser, thinner and smoother PA layer is formed due to the uniform distribution, controllable release of diamine monomer and the extra crosslinking between PEI and TMC. Furthermore, the PA layer becomes more hydrophilic with PEI involvement. As a result, the asprepared TFC membrane exhibits a favorable water flux of 16.1 L m−2 h−1 and an extremely low reverse salt flux (1.25 g m−2 h−1). Meanwhile, it achieves an excellent perm‐selectivity with a ratio of water to salt permeability coefficient of 8.25 bar−1. Moreover, it exhibits an outstanding antifouling capacity. The work sheds light on fabricating high perm‐selective membranes for desalination.

Bias Stress Stability of Solution-Processed Nano Indium Oxide Thin Film Transistor.

In this paper, the effects of annealing temperature and other process parameters on spin-coated indium oxide thin film transistors (In2O3-TFTs) were studied. The research shows that plasma pretreatment of glass substrate can improve the hydrophilicity of glass substrate and stability of the spin-coating process. With Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) analysis, it is found that In2O3 thin films prepared by the spin coating method are amorphous, and have little organic residue when the annealing temperature ranges from 200 to 300 °C. After optimizing process conditions with the spin-coated rotating speed of 4000 rpm and the annealing temperature of 275 °C, the performance of In2O3-TFTs is best (average mobility of 1.288 cm2·V−1·s−1, Ion/Ioff of 5.93 × 106, and SS of 0.84 V·dec−1). Finally, the stability of In2O3-TFTs prepared at different annealing temperatures was analyzed by energy band theory, and we identified that the elimination of residual hydroxyl groups was the key influencing factor. Our results provide a useful reference for high-performance metal oxide semiconductor TFTs prepared by the solution method.

Efficient heavy metal removal by thin film nanocomposite forward osmosis membrane modified with geometrically different bimetallic oxide

A novel thin film nanocomposite (TFN) forward osmosis (FO) membrane with a positively charged and nanofunctional substrate layer has been developed for effective heavy metal ions removal. The substrate layer is constructed by adding titania nanotubes and magnetite oxide hybrid nanoparticles (TNT–Fe3O4) in the polysulfone (PSf) matrix. The introduction of nanoparticles endowed the substrate layer with improved hydrophilicity and loose structure. The modified substrate layer also improved the affinity between the nanofillers and polymer matrix, hence maintaining the selectivity of membrane. Compared to pristine thin film composite (TFC) membrane, the TFN with 0.5 wt.% nanofillers loading showed enhanced water flux from 1.63 to 2.82 L m−2 h−1 without losing its selectivity in terms of Js/Jv ratio when operated in FO mode. The enhancement was mainly attributed to the improved substrate hydrophilicity which has effectively reduced the internal polarization concentration (ICP). The best performing TFN-0.5 membrane increased the water flux with 73% compared to TFC and exhibited a high Cd2+ and Pb2+ heavy metal ion rejection of >98%. By designing the substrate layer, this study demonstrated the feasibility of enhancing the performance of FO membrane for treating heavy metal wastewater through a simple and efficient method.

Molecular Dynamics Study of Bubble Nucleation on a Substrate with Nonuniform Wettability.

In the present study, the molecular dynamics simulation method is adopted to study bubble nucleation on a platinum substrate with nonuniform wettability. The central region of the substrate has strong hydrophilicity and both sides have weak hydrophobicity. It is interesting that the bubble nucleation happens in the hydrophobic region when the substrate temperature is low, and the nucleation position moves to the hydrophilic region with the increase of the substrate temperature. The intrinsic regime for the change of nucleation position with the substrate temperature is fully illustrated based on the competition between the suffered potential restriction and the absorbed thermal energy of liquid atoms. When the liquid atoms on one region obtain enough thermal energy to break their potential barrier, they convert into a bubble nucleus. Both the potential barrier for liquid atoms clinging to the substrate surface and the solid-liquid heat transfer efficiency improve with the enhancement of substrate hydrophilicity. The potential barrier is decided only by the atomic distribution and interatomic interaction. However, the substrate temperature changes the absorbed thermal energy of the liquid atoms within a specific time, causing the movement of the nucleation position. Furthermore, a hydrophilic nanostructure is introduced to replace the central smooth hydrophilic region and promote lateral heat transfer to the liquid on the hydrophobic region, leading to the improvement of the bubble nucleation efficiency.

Effect of Hydrothermal (Sr)-Hydroxyapatite Coatings on the Corrosion Resistance and Mg2+ Ion Release to Enhance Osteoblastic Cell Responses of AZ91D Alloy.

The biomedical applications of Mg-based alloys are limited by their rapid corrosion rate in the body fluid. In this study, the hydrothermal synthesis is employed to produce protective bioactive hydroxyapatite coating (HAC) and strontium-substituted hydroxyapatite coating (Sr-HAC) to further enhance the corrosion resistance and in vitro biocompatibility of biodegradable AZ91D Mg alloy in physiological environments. For comparison, the brucite Mg(OH)2 prepared by the alkaline pre-treatment is designated as a control group. Experimental evidences of XRD and XPS analysis confirm that Sr2+ ions can be incorporated into HA crystal structure. It is noted that the hydrothermally synthesized Sr-HAC conversion coating composed of a specific surface topography with the nanoscaled flake-like fine crystallites is constructed on the AZ91D Mg alloy. The hydrophilicity of Mg substrate is effectively enhanced with the decrease in static contact angles after performing alkaline and hydrothermal treatments. Potentiodynamic polarization measurements reveal that the nanostructured Sr-HAC-coated specimens exhibit superior corrosion resistance than HAC and alkaline pre-treated Mg(OH)2. Moreover, immersion tests demonstrate that Sr-HAC provides favorable long-term stability for the Mg alloy with decreasing concentration of released Mg2+ ions in the SBF and the reduced corrosion rate during the immersion length of 30 days. The cells cultured on Sr-HAC specimens exhibit higher viability than those on the alkaline-pre-treated Mg(OH)2 and HAC specimens. The Sr-substituted HA coating with a nanostructured surface topography can help to stimulate the cell viability of osteoblastic cells.

Differentiation of bMSCs on Biocompatible, Biodegradable, and Biomimetic Scaffolds for Largely Defected Tissue Repair.

Biocompatible, biodegradable, and biomimetic scaffolds in combination with stem cells are of great importance for tissue engineering, especially the repairing and regeneration of defected organs. As a case in point, esophageal diseases have become serious clinical problems because of the poor self-repairing ability of the organ. It is crucial to prepare artificial replacements with biological function for serious lesions of the esophagus. However, the pH value, mechanical strength, thickness, and other physical conditions are very different in different organs or different parts of the same organ, which pose high difficulty for successful tissue engineering. In this work, bone marrow mesenchymal stem cells (bMSCs) were isolated from rabbits and transfected with green fluorescent protein (GFP) to follow their capabilities of growth, stemness, and differentiation in ex vivo culture. These bMSCs were seeded on biocompatible, biodegradable, and biomimetic scaffolds to detect the tissue regenerative capability of the esophagus with multilayer hierarchical structure. According to the esophageal bilayer muscle architecture, we designed discontinuous and continuous microchannel patterned scaffolds with medical level polyurethane (PU) as the matrix to guide the inner-circular and outer-longitudinal muscle growth. The gap on the discontinuous walls not only helped cells to communicate with each other but also assisted cells to infiltrate through the gap and grew into the inner circular muscle. The graft of silk fibroin on the scaffold surface using the aminolysis and glutaraldehyde cross-linking method enhanced the substrate's hydrophilicity and biocompatibility. Mucosa-submucosa tissue of rabbit's esophagus was decellularized to obtain the extracellular matrix (ECM) and implanted in situ after recellularizing with bMSCs to repair the partially defected rabbits' esophagus. On the basis of both in vitro and in vivo results, we concluded that esophagus regeneration was promoted by the differentiation of bMSCs on the biocompatible, biodegradable, and biomimetic scaffolds, starting from tissue "niches", to repair the largely defected esophagus, which paves the way for tissue engineering and defected organ treatments.

Organic solvent supported fabrication of transparent free standing graphene oxide membranes

Free standing graphene oxide membranes (FSGOMs) were prepared by evaporation of GO-methanol/GO-water-methanol dispersions on silicon substrate and, subsequent delamination using 2-propanol or by mechanical exfoliation. SEM and XRD studies indicated the influence of methanol-water composition on morphological features and interlayer spacings of FSGOMs. Methanol provides superior surface coverage and fast drying conditions as compared to water-methanol and, surface morphology of FSGOMs can be tuned by providing sufficient duration for the settlement and stacking of GO sheets. Delamination of membranes is largely determined by dispersion composition, hydrophilicity of substrate and thickness of membrane. FSGOMs prepared in this work displayed considerable transmittance in visible region, mechanical flexibility and thermal stability of chemical composition up to 250 °C. These membranes are remarkably stable in 2-propanol, attributed to unimpeded permeation of propanol molecules through intra-layer spacings and introduction of fresh interactions. FSGOMs showed ~63% of methylene blue (MB) removal efficiency from MB-propanol solutions through multiple filtration cycles and the filtration ability may be ascribed to intra-layer entrapment of MB molecules through chemisorption at functional groups of GO. Present work provides quick, facile and economical method for damage-free FSGOM preparation, which has potential applications in the development of membranes for organic solvent filtration.