Nanofibrous Poly Research Articles

Construction of nanofibrous scaffolds with interconnected perfusable microchannel networks for engineering of vascularized bone tissue

Vascularization and bone regeneration are two closely related processes during bone reconstruction. A three-dimensional (3D) scaffold with porous architecture provides a suitable microenvironment for vascular growth and bone formation. Here, we present a simple and general strategy to construct a nanofibrous poly(l-lactide)/poly(ε-caprolactone) (PLLA/PCL) scaffold with interconnected perfusable microchannel networks (IPMs) based on 3D printing technology by combining the phase separation and sacrificial template methods. The regular and customizable microchannel patterns within the scaffolds (spacings: 0.4 mm, 0.5 mm, and 0.6 mm; diameters: 0.8 mm, 1 mm, and 1.2 mm) were made to investigate the effect of microchannel structure on angiogenesis and osteogenesis. The results of subcutaneous embedding experiment showed that 0.5/0.8-IPMs (spacing/diameter = 0.5/0.8) and 0.5/1-IPMs (spacing/diameter = 0.5/1) scaffolds exhibited more vascular network formation as compared with other counterparts. After loading with vascular endothelial growth factor (VEGF), VEGF@IPMs-0.5/0.8 scaffold prompted better human umbilical vein endothelial cells (HUVECs) migration and neo-blood vessel formation, as determined by Transwell migration, scratch wound healing, and chorioallantoic membrane (CAM) assays. Furthermore, the microangiography and rat cranial bone defects experiments demonstrated that VEGF@IPMs-0.5/0.8 scaffold exhibited better performance in vascular network formation and new bone formation compared to VEGF@IPMs-0.5/1 scaffold. In summary, our results suggested that the microchannel structure within the scaffolds could be tailored by an adjustable caramel-based template strategy, and the combination of interconnected perfusion microchannel networks and angiogenic factors could significantly enhance vascularization and bone regeneration.

Fabrication of gelatin/sodium alginate-poly (3-hydroxybutyric acid) bilayer electrospun biosheet as wound healing material in nursing care on pediatric fracture surgery

Novel the bilayered electrospun biosheet with rapid cell mimiciking and proliferative efficacy will be suitable for wound healing application. The optimized concentration of gelatin (G) and sodium alginate (A) biosheet with nanofibrous Poly (3-hydroxybutyric acid) (P) as a bilayered elctrospun matrix through electrospinning. The engineered GAP bilayered biosheet involves tissue formation at extra cellular matrix (ECM) which further characterized its function in vitro and invivo. Here we fabricated GAP which exhibit better physiochemical properties, biological and mechanical properties with superior prosomes it enhance air passable at skin wounds. The Bilayered biosheet matrix possess better biocompatibility, cell adherence, fructuous and cell to cell interactions evaluated using cell lines. Furthermore, GAP bilayered matrix regulates growth factors to attain maximum wound closure efficiency during invivo. Thus, the fabricated GAP electrospun biosheet would be a possible wound dressing for skin wound applications.

Dual-functional superwettable nano-structured membrane: From ultra-effective separation of oil-water emulsion to seawater desalination

Freshwater contamination and scarcity have progressively exacerbated the worldwide water crisis. Developing a feasible method to remediate polluted water as well as converting the abundant seawater to freshwater has become a matter of urgency. Here we demonstrate a nanofibrous poly(vinyl alcohol) based membrane (NPM) with dual functions: oil/water separation and solar water desalination. Interconnected polypyrrole (PPY) nanoparticles were decorated on the NPM as solar light absorber as well as enabling the membrane with superwettability. The underwater superoleophobic property endows the NPM with excellent anti-fouling performance and capacity to treat surfactant-stabilized industrial wastewater containing oil or various non-polar organic solvents with a separation efficiency of more than 99%. Mechanical robustness of the membrane is enhanced by mixing graphene oxide (GO) into NPM. Meanwhile, the efficient solar thermal conversion enables NPM to further desalinize the seawater under one sun solar radiation with excellent efficiency and durability with an evaporation rate of 2.87 kg m−2h−1. In the on-site desalination test, the solar vapor system demonstrated a daily solar water purification yield of 14.3 L m−2 under natural sunlight irradiation, suggesting a promising “green” application as mass manufacture seawater purification system without extra energy source. The outstanding performances of NPM for oil-in-water emulsion separation and the high-rate seawater desalination suggest its great potential for industrial applications in the future.

Engineering a cell-hydrogel-fibre composite to mimic the structure and function of the tendon synovial sheath

The repair of tendon injuries is often compromised by post-operative peritendinous adhesions. Placing a physical barrier at the interface between the tendon and the surrounding tissue could potentially solve this problem by reducing adhesion formation. At present, no such system is available for routine use in clinical practice. Here, we propose the development of a bilayer membrane combining a nanofibrous poly(ε-caprolactone) (PCL) electrospun mesh with a layer of self-assembling peptide hydrogel (SAPH) laden with type-B synoviocytes. This bilayer membrane would act as an anti-adhesion system capable of restoring tendon lubrication, while assisting with synovial sheath regeneration. The PCL mesh showed adequate mechanical properties (Young's modulus=19±4 MPa, ultimate tensile stress=9.6±1.7 MPa, failure load=0.5±0.1 N), indicating that the membrane is easy to handle and capable to withstand the frictional forces generated on the tendon's surface during movement (~0.3 N). Morphological analysis confirmed the generation of a mesh with nanosized PCL fibres and small pores (< 3 μm), which prevented fibroblast infiltration to impede extrinsic healing but still allowing diffusion of nutrients and waste. Rheological tests showed that incorporation of SAPH layer allows good lubrication properties when the membrane is articulated against porcine tendon or hypodermis, suggesting that restoration of tendon gliding is possible upon implantation. Moreover, viability and metabolic activity tests indicated that the SAPH was conducive to rabbit synoviocyte growth and proliferation over 28 days of 3D culture, sustaining cell production of specific matrix components, particularly hyaluronic acid. Synoviocyte-laden peptide hydrogel promoted a sustained endogenous production of hyaluronic acid, providing an anti-friction layer that potentially restores the tendon gliding environment.

Biomimetic Membranes of Methacrylated Gelatin/Nanohydroxyapatite/Poly(l-Lactic Acid) for Enhanced Bone Regeneration.

Nanofibrous poly(l-lactic acid) (PLLA) membrane-simulated extracellular matrices (ECMs) can be used in the biomedical field. However, the hydrophobic nature and poor osteoinductive property of PLLA limit its application in guided bone regeneration (GBR). In this work, a methacrylated gelatin/nano-HA (GelMA/nHA) complex was first synthesized in situ and then introduced into PLLA to fabricate biomimetic GelMA/nHA/PLLA membranes, mimicking the nanofibrous architecture and composition of ECMs by electrospinning and photocrosslinking. Compared to PLLA and GelMA/PLLA membranes, the novel GelMA/nHA/PLLA membranes demonstrated better tensile, hydrophilic, water sorption, and degradation properties. An in vitro biological evaluation indicated that the membranes promoted human bone marrow-derived mesenchymal stem cell (hBMSC) proliferation, adhesion, and osteogenic differentiation. Critical-sized defects in rat models were used to evaluate the bone regeneration performances of the three kinds of membranes in vivo, and the GelMA/nHA/PLLA membranes demonstrated excellent osteogenic regeneration potential. Therefore, GelMA/nHA/PLLA membranes have wide application prospects in bioengineering applications such as GBR treatment.

Codelivery of Sustainable Antimicrobial Agents and Platelet-Derived Growth Factor via Biodegradable Nanofibers for Repair of Diabetic Infectious Wounds.

More than half of diabetic wounds demonstrate clinical signs of infection at presentation and lead to poor outcomes. This work develops coaxial sheath-core nanofibrous poly(lactide-co-glycolide) (PLGA) scaffolds that are loaded with bioactive antibiotics and platelet-derived growth factor (PDGF) for the repair of diabetic infectious wounds. PDGF and PLGA/antibiotic solutions were pumped, respectively, into two independent capillary tubings for coaxial electrospinning to prepare biodegradable sheath-core nanofibers. Spun nanofibrous scaffolds sustainably released PDGF, vancomycin, and gentamicin for 3 weeks. The scaffolds also reduced the phosphatase and tensin homologue content, enhanced the amount of angiogenesis marker (CD31) around the wound area, and accelerated healing in the early stage of infected diabetic wound repair. Antibiotic/biomolecule-loaded PLGA nanofibers may provide a very effective way to aid tissue regeneration at the sites of infected diabetic wounds.

Preparation of electrospun nanofibrous poly(vinyl alcohol)/cellulose nanocrystals air filter for efficient particulate matter removal with repetitive usage capability via facile heat treatment

Air pollution has become a global concern, and numerous studies have focused on developing filters for particulate matter (PM) removal. However, the reusability of air filters, which could lower resources consumption and waste discharge, is also necessary to be investigated. In this study, a water washable electrospun poly (vinyl alcohol) (PVA)/cellulose nanocrystals (CNCs) nanofibrous air filter for PM removal was prepared. The water-soluble polymer composite was converted to be completely water-resistant via a facile heat treatment without adding any crosslinking agent. Our results indicate the increased crystallinity is the key factor to improve the aqueous stability of PVA/CNCs fibers. The CNCs provided additional nucleation sites for PVA crystallization during electrospinning and heating process. By loading 20% CNCs and heating at 140 °C for 5 min, the crystallinity degree and crystal size of PVA were increased from 54.7% and 3.3 nm to 85.4% and 6.3 nm, respectively. The reusability of fabricated filters was tested by water washing over 5 cycles. The results show the heavily fouled filters (pressure drop > 1000 Pa) were regenerated effectively: the PM2.5 removal efficiency was maintained at above 95%, meanwhile the pressure drop remained less than 100 Pa after repetitive usage (PM2.5 mass concentration > 500 μg m−3). Considering the raw materials are nontoxic and biodegradable, the heating temperature is relatively low, and the process is short, it is a promising green method to manufacture long lifetime air filter.

In situ bone tissue engineering using gene delivery nanocomplexes

Gene delivery offers promising outcomes for functional recovery or regeneration of lost tissues at cellular and tissue levels. However, more efficient carriers are needed to safely and locally delivery of genetic materials. Herein, we demonstrate microfluidic-assisted synthesis of plasmid DNA (pDNA)-based nanocomplexe (NC) platforms for bone tissue regeneration. pDNA encoding human bone morphogenesis protein-2 (BMP-2) was used as a gene of interest. Formation and fine-tuning of nanocomplexes (NCs) between pDNA and chitosan (CS) as carriers were performed using a micromixer platform. Flow characteristics were adjusted to tune mixing time and consequently size, zeta potential, and compactness of assembled NCs. Subsequently, NCs were immobilized on a nanofibrous Poly(ε-caprolactone) (PCL) scaffold functionalized with metalloprotease-sensitive peptide (MMP-sensitive). This construct can provide an environmental-sensitive and localized gene delivery platform. Osteogenic differentiation of bone marrow-derived mesenchymal stem cells (MSCs) was studied using chemical and biological assays. The presented results converge to indicate a great potential of the developed methodology for in situ bone tissue engineering using immobilized microfluidic-synthesized gene delivery nanocomplexes, which is readily expandable in the field of regenerative nanomedicine. Statement of significanceIn this study, we demonstrate microfluidic-assisted synthesis of plasmid DNA (pDNA)-based nanocomplexes (NCs) platforms for bone tissue regeneration. We used pDNA encoding human bone morphogenesis protein-2 (BMP-2) as the gene of interest. Using micromixer platform nanocomplexes (NCs) between pDNA and chitosan (CS) were fabricated and optimized. NCs were immobilized on a nanofibrous polycaprolactone scaffold functionalized with metalloprotease-sensitive peptide. In vitro and in vivo assays confirmed the osteogenic differentiation of mesenchymal stem cells (MSCs). The obtained data indicated great potential of the developed methodology for in situ bone tissue engineering using immobilized microfluidic-synthesized gene delivery nanocomplexes, which is readily expandable in the field of regenerative nanomedicine.

Nanofibrous poly(vinyl alcohol)/chitosan contained carbonated hydroxyapatite nanoparticles scaffold for bone tissue engineering.

A scaffold that mimics the physicochemical structure of bone at the nanoscale level is an attractive alternative to conventional bone grafts, but its development remains a main challenge in bone tissue engineering today. This work describes the fabrication of a nanofibrous poly(vinyl alcohol)/chitosan/carbonated hydroxyapatite (PVA/CS/CHAp) scaffold. CHAp nanoparticles were synthesized using a co-precipitation method, and nanofibrous PVA/CS/CHAp scaffolds were fabricated by electrospinning using CHAp concentrations of 0, 5, 10, 15, and 20 wt%. The physicochemical properties of the scaffolds were evaluated by SEM, XRD, FTIR, and EDS, and the mechanical properties were determined by tensile strength tests. Swelling behavior, protein adsorption onto the scaffold surfaces, surface biomineralization, and cells viability were also evaluated in vitro. The addition of CHAp to the composite decreased the fiber diameter from ∼160 nm at 0 wt% to ∼139 nm at 15 wt% and great agglomerations were evident at 20 wt%. XRD, FTIR, and EDS showed effective incorporation of CHAp into the nanofibrous structure. This CHAp incorporation significantly increased the modulus of the scaffold at PVA/CS/CHAp 15 wt%, with an average 103.86 MPa, but tensile strength was not significantly altered. However, the elongation at break was decreased as the CHAp concentration increased. Swelling capacity of scaffold increases due to CHAp addition. Protein adsorption onto the scaffold increased 2.3fold at 20 wt% when compared to 0 wt%. The PVA/CS/CHAp 15 wt% showed a better bioactivity when compared to PVA/CS/CHAp 0 wt% after immersion of the scaffolds in a simulated body fluid solution for 7 days. Cell viability and cell morphology results reveal that PVA/CS/CHAp able to facilitate osteoblast cells to attach and proliferate. Introducing higher CHAp into the scaffold could increase the cell viability of the scaffold. PVA/CS/CHAp has potential to serve as an alternative scaffold material for bone tissue engineering.

ZnO decorated anti-bacterial electrospun ABS nanocomposite membrane for oil-water separation

Abstract Here we report the fabrication and performance of a superoleophilic and anti-bacterial nonwoven nanofibrous poly(acrylonitrile-co-butadiene-co-styrene) [ABS]/ZnO electrospun nanocomposite membrane. The electrospun ABS membrane was decorated with floral ZnO nanoparticles (NPs) by a post-treatment method. The pristine ABS and nanocomposite membranes showed super oleophilic nature and could selectively separate different oils from the oil–water mixture by a gravity-driven technique. The ZnO NPs in the nanofiber could enhance the oil flux and also imparted anti-bacterial activity to electrospun ABS membrane against Escherichia coli and Staphylococcus aureus. The current nanofibrous system can be a good candidate for multi-functional oil-water separation.

Electrospun Nanofibrous Poly(3-Hydroxybutyrate-Co-3-Hydroxyvalerate) With Antibacterial Activity

Elaboration of electrospun nanofibrous poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV)-based mats was implemented through two routes to obtain antibacterial material containing carvacrol, a phenolic compound extracted from essential oils. The first strategy relied on a direct blend of PHBHV and carvacrol/-cyclodextrin inclusion complexes, PHBHV (carvCD-IC), while the second approach implied the elaboration of multilayered scaffold via the introduction of poly(β-CD-epichlorohydrin), PolyCD. The PolyCD/carv-based mat was electrospun between two hydrophobic PHBHV mats. Scanning Electron Microscopy analysis of mats showed uniform and beadless fibers. The three layered materials [PHBHV-(PolyCD/carv)-PHBHV] is sufficient to ensure optimal antiradical activity (RSA of 88.6%) and exhibit interesting antibacterial activities against E. coli and S. aureus.

Nanofibrous poly(ethylene oxide)‐based structures incorporated with multi‐walled carbon nanotube and graphene oxide as all‐solid‐state electrolytes for lithium ion batteries

AbstractNanofibrous solid polymer electrolytes were prepared using the electrospinning method. These nanofibres were constructed from poly(ethylene oxide), lithium perchlorate and ethylene carbonate, which were incorporated with multi‐walled carbon nanotube (MWCNT) and graphene oxide (GO). The morphological properties of the as‐prepared electrolytes and the interaction between the components of the composites were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. X‐ray spectra and differential scanning calorimetry indicated an increase in amorphous regions of the nanofibrous electrolytes on addition of the fillers. However, the crystalline regions were increased on incorporation of fillers into polymeric film electrolytes. The conductivity values of the nanofibrous electrolytes reached 0.048 and 0.057 mS cm−1 when 0.35 wt% MWCNT and 0.21 wt % GO were introduced into the nanofibrous structures, respectively. The capacity and cycling stability of the nanofibrous electrolytes were improved by incorporation of MWCNT filler. Furthermore, stress and elongation modulus were improved at low MWCNT and GO filler contents. Results revealed that the nanofibrous structures could be promising candidates as solvent‐free electrolytes applicable in lithium ion batteries. © 2019 Society of Chemical Industry

Rapid mineralization of hierarchical poly(l-lactic acid)/poly(ε-caprolactone) nanofibrous scaffolds by electrodeposition for bone regeneration.

Introduction: Hierarchical nanofibrous scaffolds are emerging as a promising bone repair material due to their high cell adhesion activity and nutrient permeability. However, the existing method for hierarchical nanofibrous scaffolds fabrication is complicated and not perfectly suitable for further biomedical application in view of both structure and function. In this study, we constructed a hierarchical nanofibrous poly (l-lactic acid)/poly(ε-caprolactone) (PLLA/PCL) scaffold and further evaluated its bone healing ability.Methods: The hierarchical PLLA/PCL nanofibrous scaffold (PLLA/PCL) was prepared by one-pot TIPS and then rapidly mineralized at room temperature by an electrochemical deposition technique. After electrode-positioning at 2 V for 2 hrs, a scaffold coated with hydroxyapatite (M-PLLA/PCL) could be obtained.Results: The pore size of the M-PLLA/PCL scaffold was hierarchically distributed so as to match the biophysical structure for osteoblast growth. The M-PLLA/PCL scaffold showed better cell proliferation and osteogenesis activity compared to the PLLA/PCL scaffold. Further in vivo bone repair studies indicated that the M-PLLA/PCL scaffold could accelerate defect healing in 12 weeks.Conclusion: The results of this study implied that the as-prepared hydroxyapatite coated hierarchical PLLA/PCL nanofibrous scaffolds could be developed as a promising material for efficient bone tissue repair after carefully tuning the TIPS and electrodeposition parameters.

Thermo-responsive nanofibrous composite membranes for efficient self-cleaning of protein foulants

This study developed a self-clean thermo-responsive nanofibrous poly(vinylidene fluoride) (PVDF)/nylon-6,6/poly(N-isopropylacrylamide) (PNIPAAm) composite ultrafiltration membrane consisting of a nylon-6,6/PNIPAAm functional nanofibre layer integrated into a PVDF substrate. The morphological analysis showed the presence of electrospun nano-nets branching out from the main nanofibres as PNIPAAm concentration increased, affecting the pore size distribution and solute rejection. The PVDF/nylon-6,6/PNIPAAm membranes showed improved surface hydrophilicity below the low critical solution temperature (LCST) and strong thermo-switchability. With bovine serum albumin (BSA) as the model foulant, the rejection of the 4 wt% PNIPAAm membranes was greatly improved to above 96%. Through a two-cycle ultrafiltration study using feed solution containing BSA and CaCl2, the membrane with 4 wt% PNIPAAm showed superior recovery of water permeance up to 97% assisted with temperature-change cleaning, compared to the control membrane that only recovered 56%. Filtration experiments with and without intermediate temperature-change cleaning proved that the anti-fouling mechanism of the PNIPAAm membranes was strongly associated with surface wettability and rapid conformation of PNIPAAm polymer chains induced by volume-phase transition, resulting in reduced protein adsorption and ‘shaking-off’ of the absorbed proteins from the membrane surface. Such smart responsive membranes have great potential for the development of easy-to-clean membranes for food and wastewater treatment.

Macroporous nanofibrous vascular scaffold with improved biodegradability and smooth muscle cells infiltration prepared by dual phase separation technique.

IntroductionThe fast degradation of vascular graft and the infiltration of smooth muscle cells (SMCs) into the vascular graft are considered to be critical for the regeneration of functional neo-vessels. In our previous study, a novel dual phase separation technique was developed to one-pot prepare macroporous nanofibrous poly(L-lactic acid) (PLLA)/poly(ε-caprolactone) (PCL) vascular scaffold by phase separating the immiscible polymer blend. However, the slow degradation of PLLA/PCL limited cell infiltration. Herein, we hypothesized that poly(lactic-co-glycolic acid) (PLGA) would be miscible with PLLA but immiscible with PCL. Then, PLGA can be introduced into the PLLA/PCL blend to fabricate macroporous nanofibrous scaffold with improved biodegradability by using dual phase separation technique.Materials and methodsThe miscibility of PLGA with PLLA and PCL was evaluated. Then, the PLLA/PLGA/PCL scaffold was prepared by dual phase separation technique. The prepared scaffolds were characterized in terms of the morphology, in vitro degradation, mechanical properties, and cells’ infiltration and viability for human vascular SMCs (HVSMCs). Finally, platelet-derived growth factor-BB (PDGF-BB) was immobilized on the scaffold and its effect on the bioactivity of HVSMCs was studied.ResultsPLGA is miscible with PLLA but immiscible with PCL as hypothesized. The addition of PLGA enlarged the pore size and improved the biodegradability of composite scaffold. Notably, PLLA/PLGA/PCL scaffold with the blend ratio of 30:40:30 possessed improved pore interconnectivity for cells’ infiltration and enough mechanical properties. Moreover, HVSMCs could grow and infiltrate into this scaffold, and surface modification with PDGF-BB on the nanofibrous scaffold enhanced HVSMCs migration and proliferation.ConclusionThis study provides a strategy to expand dual phase separation technique into utilizing ternary even multinary polymer blend to fabricate macroporous nanofibrous scaffold with improved physicochemical properties. The prepared PLLA/PLGA/PCL scaffold would be promising for the regeneration of functional tunica media in vascular tissue engineering.

Pore size directs bone marrow stromal cell fate and tissue regeneration in nanofibrous macroporous scaffolds by mediating vascularization

In the U.S., 30% of adults suffer joint pain, most commonly in the knee, which severely limits mobility and is often attributed to injury of cartilage and underlying bone in the joint. Current treatment methods such as microfracture result in less resilient fibrocartilage with eventual failure; autografting can cause donor site morbidity and poor integration. To overcome drawbacks in treatment, tissue engineers can design cell-instructive biomimetic scaffolds using biocompatible materials as alternate therapies for osteochondral defects. Nanofibrous poly (l-lactic acid) (PLLA) scaffolds of uniform, spherical, interconnected and well-defined pore sizes that are fabricated using a thermally-induced phase separation and sugar porogen template method create an extracellular matrix-like environment which facilitates cell adhesion and proliferation. Herein we report that chondrogenesis and endochondral ossification of rabbit and human bone marrow stromal cells (BMSCs) can be controlled by scaffold pore architecture, particularly pore size. Small-pore scaffolds support enhanced chondrogenic differentiation in vitro and cartilage formation in vivo compared to large-pore scaffolds. Endochondral ossification is prevented in scaffolds with very small pore sizes; pore interconnectivity is critical to promote capillary ingrowth for mature bone formation. These results provide a novel strategy to control tissue regenerative processes by tunable architecture of macroporous nanofibrous scaffolds. Statement of significanceProgress in understanding the relationship between cell fate and architectural features of tissue engineering scaffolds is critical for engineering physiologically functional tissues. Sugar porogen template scaffolds have uniform, spherical, highly interconnected macropores. Tunable pore-size guides the fate of bone marrow stromal cells (BMSCs) towards chondrogenesis and endochondral ossification, and is a critical design parameter to mediate neotissue vascularization. Preventing vascularization favors a chondrogenic cell fate while allowing vascularization results in endochondral ossification and mineralized bone formation. These results provide a novel strategy to control tissue regenerative processes by tunable architecture of macroporous nanofibrous scaffolds.

An Optimized Covalent Immobilization of Glucamine on Electrospun Nanofibrous Poly(vinylidene fluoride) Sheets Grafted with Oxirane Groups for Higher Boron Adsorption

Nanofibrous poly(vinylidene fluoride) (PVDF) sheets were produced by electrospinning and grafted with oxirane groups using radiation induced grafting of glycidyl methacrylate (GMA) followed by treatment with N-methyl-D-glucamine (NMDG). The NMDG density in the nanofibers was tuned by optimization of the immobilisation reaction variables using response surface methodology (RSM). The various properties of NMDG-containing nanofibers were evaluated using Fourier-transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The NMDG-containing nanofibers were tested for boron selective removal from solutions. A maximum glucamine density yield of 2.2 mmol/g was obtained at 15 wt%, 87 oC, 64.7 min and 150 % for NMDG concentration, temperature, time and degree of grafting (DG), respectively. The applied procedure incorporating RSM was found to be highly effective in the optimization of covalently immobilised glucamine on the oxirane modified PVDF based-nanofibrous structure and in imparting an excellent combination of physico-chemical and boron retention properties. A complete boron removal was achieved in 100 mg/l boron solution adsorbent with a dosage of 0.6 g at pH 7 in 2 h time. This was accompanied by a promising reusability suitable for boron removal from solutions.

Suppressing mesenchymal stem cell hypertrophy and endochondral ossification in 3D cartilage regeneration with nanofibrous poly(l-lactic acid) scaffold and matrilin-3

Articular cartilage has a very limited ability to self-heal after injury or degeneration due to its low cellularity, poor proliferative activity, and avascular nature. Current clinical options are able to alleviate patient suffering, but cannot sufficiently regenerate the lost tissue. Biomimetic scaffolds that recapitulate the important features of the extracellular matrix (ECM) of cartilage are hypothesized to be advantageous in supporting cell growth, chondrogenic differentiation, and integration of regenerated cartilage with native cartilage, ultimately restoring the injured tissue to its normal function. It remains a challenge to support and maintain articular cartilage regenerated by bone marrow-derived mesenchymal stem cells (BMSCs), which are prone to hypertrophy and endochondral ossification after implantation in vivo. In the present work, a nanofibrous poly(l-lactic acid) (NF PLLA) scaffold developed by our group was utilized because of the desired highly porous structure, high interconnectivity, and collagen-like NF architecture to support rabbit BMSCs for articular cartilage regeneration. We further hypothesized that matrilin-3 (MATN3), a non-collagenous, cartilage-specific ECM protein, would enhance the microenvironment of the NF PLLA scaffold for cartilage regeneration and maintain the cartilage property. To test this hypothesis, we seeded BMSCs on the NF PLLA scaffold with or without MATN3. We found that MATN3 suppresses hypertrophy in this 3D culture system in vitro. Subcutaneous implantation of the chondrogenic cell/scaffold constructs in a nude mouse model showed that pretreatment with MATN3 was able to maintain chondrogenesis and prevent hypertrophy and endochondral ossification in vivo. These results demonstrate that the porous NF PLLA scaffold treated with MATN3 represents an advantageous 3D microenvironment for cartilage regeneration and phenotype maintenance, and is a promising strategy for articular cartilage repair. Statement of SignificanceArticular cartilage defects, caused by trauma, inflammation, or joint instability, may ultimately lead to debilitating pain and disability. Bone marrow-derived mesenchymal stem cells (BMSCs) are an attractive cell source for articular cartilage tissue engineering. However, chondrogenic induction of BMSCs is often accompanied by undesired hypertrophy, which can lead to calcification and ultimately damage the cartilage. Therefore, a therapy to prevent hypertrophy and endochondral ossification is of paramount importance to adequately regenerate articular cartilage. We hypothesized that MATN3 (a non-collagenous ECM protein expressed exclusively in cartilage) may improve regeneration of articular cartilage with BMSCs by maintaining chondrogenesis and preventing hypertrophic transition in an ECM mimicking nanofibrous scaffold. Our results showed that the administration of MATN3 to the cell/nanofibrous scaffold constructs favorably maintained chondrogenesis and prevented hypertrophy/endochondral ossification in the chondrogenic constructs in vitro and in vivo. The combination of nanofibrous PLLA scaffolds and MATN3 treatment provides a very promising strategy to generate chondrogenic grafts with phenotypic stability for articular cartilage repair.

Electrospinning superhydrophobic nanofibrous poly(vinylidene fluoride)/stearic acid coatings with excellent corrosion resistance

Due to the unique micro/nanoscale rough surface structures and water-repellency, the superhydrophobic surfaces hold great potential of anti-corrosive protection. This study reported a facile and controllable electrospinning technology to fabricate polyvinylidenefluoride (PVDF)/stearic acid (SA) nanofibers onto metal substrates for long-time anti-corrosive protection. Moreover, the anti-corrosion performances of the superhydrophobic nanofibers coated metal substrates were characterized by the Tafel polarization curve and electrochemical impedance spectroscopy (EIS). In addition, the electrochemical corrosion test results demonstrated the superhydrophobic PVDF/SA nanofibrous coatings possessed superior anti-corrosion performances for long-term metal substrates preservation, even after being immersed in a 3.5 wt% NaCl aqueous solutions up to 30 days. Therefore, we deeply believe the superhydrophobic PVDF/SA nanofibrous coatings could present a superior application prospect in anti-corrosive protection.

In vitro degradation and in vivo toxicity of NanoMatrix3D® polycaprolactone and poly(lactic acid) nanofibrous scaffolds.

Nanofibrous materials present unique properties favorable in many biomedicine and industrial applications. In this research we evaluated biodegradation, tissue response and general toxicity of nanofibrous poly(lactic acid) (PLA) and polycaprolactone (PCL) scaffolds produced by conventional method of electrospinning and using NanoMatrix3D® (NM3D® ) technology. Mass density, scanning electron microscopy and in vitro degradation (static and dynamic) were used for material characterization, and subcutaneous, intramuscular and intraperitoneal implantation - for in vivo tests. Biochemical blood analysis and histology were used to assess toxicity and tissue response. Pore size and fiber diameter did not differ in conventional and NM3D® PLA and PCL materials, but mass density was significantly lower in NM3D® ones. Scaffolds made by conventional method showed toxic effect during the in-vivo tests due to residual concentration of chloroform that released with material degradation. NM3D® method allowed cleaning scaffolds from residual solutions that made them nontoxic and biocompatible. Subcutaneous, intramuscular and intraperitoneal implantation of PCL and PLA NM3D® electrospun nanofibrous scaffolds showed their appropriate cell conductive properties, tissue and vessels formation in all sites. Thus, NM3D® PCL and PLA nanofibrous electrospun scaffolds can be used in the field of tissue engineering, surgery, wound healing, drug delivery, and so forth, due to their unique properties, nontoxicity and biocompatibility. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2200-2212, 2018.