Polycaprolactone-polymethyl methacrylate electrospun blends for biomedical applications

Electrospinning is one of most versatile process to fabricate porous scaffolds in biomedical field. Synthetic polymers such as polycaprolactone (PCL) and polymethyl methacrylate (PMMA) provide excellent properties for biomedical applications due to their biocompatibility and tunable mechanical properties. PCL-PMMA electrospun blends combine compressive/tensile properties of individual polymers as well as biocompatibility/biodegradability. Together with porosity of scaffold, drug/nutrient supply is required in tissue regeneration and healing. High pressure CO₂ has been investigated to plasticize many biopolymers and impregnate drugs in scaffolds. This study explores several compositions of PCL-PMMA electrospun scaffolds for morphological and mechanical properties. These scaffolds are impregnated with hydrophilic (Rhodamine B) and hydrophobic (Fluorescein) dyes using high pressure CO₂ and air plasma treatment. Furthermore, release profiles of dyes have been studied from thin films and porous scaffolds to understand several controlling factors for controlled release applications. Results show dye-polymer interactions, CO₂ impregnation and stress relaxation of electrospun fibers are key factors in release profile from electrospun fibers. This study is a step forward in developing PCL-PMMA based electrospun scaffolds for drug delivery and tissue engineering.     

In-Vitro Cytotoxicity Study: Cell Viability and Cell Morphology of Carbon Nanofibrous Scaffold/Hydroxyapatite Nanocomposites

Electrospun carbon nanofibers (CNFs), which were modified with hydroxyapatite, were fabricated to be used as a substrate for bone cell proliferation. The CNFs were derived from electrospun polyacrylonitrile (PAN) nanofibers after two steps of heat treatment: stabilization and carbonization. Carbon nanofibrous (CNF)/hydroxyapatite (HA) nanocomposites were prepared by two different methods; one of them being modification during electrospinning (CNF-8HA) and the second method being hydrothermal modification after carbonization (CNF-8HA; hydrothermally) to be used as a platform for bone tissue engineering. The biological investigations were performed using in-vitro cell counting, WST cell viability and cell morphology after three and seven days. L929 mouse fibroblasts were found to be more viable on the hydrothermally-modified CNF scaffolds than on the unmodified CNF scaffolds. The biological characterizations of the synthesized CNF/HA nanofibrous composites indicated higher capability of bone regeneration.     

Multilayered electrospun nanofibrous scaffolds for tailored controlled release of embelin

Polymeric electrospun meshes are highly attractive as versatile platforms for numerous biomedical applications, tissue engineering, biosensors, and controlled release of bioactive agents. Herein, we describe the preparation and characterization of multilayered nanofibrous poly(ε-caprolactone) scaffolds with different embelin content by electrospinning technique. In vitro release in physiological and acidic pH and kinetic analysis were performed. The results show that it is possible to modulate the release profile depending on the number and thickness of layers added to drug-loaded scaffold that acts as an embelin reservoir. Electrospun multilayered scaffolds present characteristics, morphology and release profiles that could be very attractive for use as embelin controlled release systems.     

Electrospun PDA‐CA Nanofibers toward Hydrophobic Coatings

Nowadays, encapsulated dyes in a polymeric matrix have opened up new perspectives in many applications such as filtration of subatomic particles, composite reinforcement, multifunctional membranes, tissue engineering scaffolds, wound dressing, coatings, medical purposes as well as sensors. In the presented work, we report on electrospinning neat peryelene dianhydride based thermoplastic elastomers. Perylene‐3, 4,9, 10‐tetracarboxylic dianhydride (PDA) is encapsulated into cellulose acetate (CA) electrospun fibers, which was prepared from 12 % cellulose acetate solution, at 20 kV with a distance of 10 cm. The flow rate was 0.2 ml · h^–1. These water repellent nanofibrous coatings are anticipated to serve as hydrophobic coatings. Scanning electron microscope is used to study the properties of the electrospun PDA‐CA nanofibers.     

Acceleration of osteogenic differentiation by sustained release of BMP2 in PLLA/graphene oxide nanofibrous scaffold

After about three decades of experience, tissue engineering has become one of the most important approaches in reconstructive medical research to treat non‐self‐healing bone injuries and lesions. Herein, nanofibrous composite scaffolds fabricated by electrospinning, which containing of poly(L‐lactic acid) (PLLA), graphene oxide (GO), and bone morphogenetic protein 2 (BMP2) for bone tissue engineering applications. After structural evaluations, adipose tissue derived mesenchymal stem cells (AT‐MSCs) were applied to monitor scaffold's biological behavior and osteoinductivity properties. All fabricated scaffolds had nanofibrous structure with interconnected pores, bead free, and well mechanical properties. But the best biological behavior including cell attachment, protein adsorption, and support cells proliferation was detected by PLLA‐GO‐BMP2 nanofibrous scaffold compared to the PLLA and PLLA‐GO. Moreover, detected ALP activity, calcium content and expression level of bone‐related gene markers in AT‐MSCs grown on PLLA‐GO‐BMP2 nanofibrous scaffold was also significantly promoted in compression with the cells grown on other scaffolds. In fact, the simultaneous presence of two factors, GO and BMP2, in the PLLA nanofibrous scaffold structure has a synergistic effect and therefore has a promising potential for tissue engineering applications in the repair of bone lesions.     

A nanofibrous composite membrane of PLGA-chitosan/PVA prepared by electrospinning

Tissue engineering scaffolds produced by electrospinning feature a structural similarity to the natural extracellular matrix. In this study, poly(lactide-co-glycolide) (PLGA) and chitosan/poly(vinyl alcohol) (PVA) were simultaneously electrospun from two different syringes and mixed on the rotating drum to prepare the nanofibrous composite membrane. The composite membrane was crosslinked by glutaraldehyde vapor to maintain its mechanical properties and fiber morphology in wet stage. Morphology, shrinkage, absorption in phosphate buffered solution (PBS) and mechanical properties of the electrospun membranes were characterized. Fibroblast viability on electrospun membranes was discussed by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay and cell morphology after 7 days of culture. Results indicated that the PBS absorption of the composite membranes, no matter crosslinked or not, was higher than the electrospun PLGA membrane due to the introduction of hydrophilic components, chitosan and PVA. After crosslinking, the composite membrane had a little shrinkage after incubating in PBS. The crosslinked composite membrane also showed moderate tensile properties. Cell culture suggested that electrospun PLGA-chitosan/PVA membrane tended to promote fibroblast attachment and proliferation. It was assumed that the nanofibrous composite membrane of electrospun PLGA-chitosan/PVA could be potentially used for skin reconstruction.     

In vitro and in vivo evaluation of silk fibroin-hardystonite-gentamicin nanofibrous scaffold for tissue engineering applications

Designing advanced biomaterials with regenerative and drug delivering functionalities remains a challenge in the field of tissue engineering. In this paper we present the design, development, and a use case of an electrospun nano-biocomposite scaffold composed of silk fibroin (SF), hardystonite (HT), and gentamicin (GEN). The fabricated SF nanofiber scaffolds provide mechanical support while HT acts as a bioactive and drug carrier, on which GEN is loaded as an antibacterial agent. Antibacterial zone of inhibition (ZOI) results indicate that the inclusion of 3–6 wt% GEN significantly improves the antibacterial performance of the scaffolds against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria, with an initial burst release of 10–20% and 72–85% total release over 7 days. The release rate of stimulatory silicon ions from SF-HT scaffolds reached 94.53±5 ppm after 7 days. Cell studies using osteoblasts show that the addition of HT significantly improved the cytocompatibility of the scaffolds. Angiogenesis, in vivo biocompatibility, tissue vascularization, and translatability of the scaffolds were studied via subcutaneous implantation in a rodent model over 4-weeks. When implanted subcutaneously, the GEN-loaded scaffold promoted angiogenesis and collagen formation, which suggests that the scaffold may be highly beneficial for further bone tissue engineering applications.     

In vitro biocompatibility of electrospun hexanoyl chitosan fibrous scaffolds towards human keratinocytes and fibroblasts

With the ability to form a submicron-sized fibrous structure with interconnected pores mimicking the extracellular matrix (ECM) for tissue formation, electrospinning was used to fabricate ultra-fine fiber mats of hexanoyl chitosan (H-chitosan) for potential use as skin tissue scaffolds. In the present communication, the in vitro biocompatibility of the electrospun fiber mats was evaluated. Indirect cytotoxicity evaluation of the fiber mats with mouse fibroblasts (L929) revealed that the materials were non-toxic and did not release substances harmful to living cells. The potential for use of the fiber mats as skin tissue scaffolds was further assessed in terms of the attachment and the proliferation of human keratinocytes (HaCaT) and human foreskin fibroblasts (HFF) that were seeded or cultured on the scaffolds at different times. The results showed that the electrospun fibrous scaffolds could support the attachment and the proliferation of both types of cells, especially for HaCaT. In addition, the cells cultured on the fibrous scaffolds exhibited normal cell shapes and integrated well with surrounding fibers. The obtained results confirmed the potential for use of the electrospun H-chitosan fiber mats as scaffolds for skin tissue engineering.     

Release Profiles of Tricalcium Phosphate Nanoparticles from Poly(L‐lactic acid) Electrospun Scaffolds with Single Component,Core–Sheath,or Porous Fiber Morphologies: Effects on hASC Viability and Osteogenic Differentiation

Functional PLA scaffolds are created with single component, core–sheath, or porous fiber morphology and doped with TCP nanoparticles to study the release profiles for use in bone tissue engineering applications. Pharmacokinetic analyses are performed for the three different nanofibrous structures after doping with TCP. Results indicate that single component and porous fiber scaffolds exhibit an initial‐burst release profile whereas core–sheath fibers show a steady release. All scaffolds are then seeded with human adipose‐derived stem cells (hASC), which remain viable and continue proliferation on all nanofibrous morphologies for up to 21 d. Osteogenic differentiation of hASC and cell‐mediated calcium accretion are largest on porous fibers.

     

Bioactive Applications for Electrospun Fibers

Electrospinning is a versatile technique providing highly tunable nanofibrous nonwovens. Many biomedical applications have been developed for nanofibers, among which the production of antimicrobial mats stands out. The production of scaffolds for tissue engineering, fibers for controlled drug release, or active wound dressings are active fields of research exploiting the possibilities offered by electrospun materials. The fabrication of materials for active food packaging or membranes for environmental applications is also reviewed. We attempted to give an overview of the most recent literature related with applications in which nanofibers get in contact with living cells and develop a nano-bio interface.     

Calix[4]arene-based fluorescent probe and the adsorption capacity of its electrospun nanofibrous film for the cesium cation as an adsorbent

Calix[4]arene-based cation receptor 1 has been synthesised by following a multi-step synthetic procedure. The fluorescence properties of 1 upon the addition of various metal ions were investigated by fluorescence spectroscopy. As a result, it was revealed that 1 displayed dramatic quenching effect upon the exposure to Cs⁺. In contrast, no significant quenching effects were observed upon the addition of other metal ions such as Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ag⁺, Zn²⁺ and Ni²⁺. Compound 1 was also found by Job plot to form a 1:1 complex with Cs⁺. In addition, we also prepared 1-embedded electrospun nanofibrous film (NF-1) as an adsorbent for Cs⁺. NF-1 is proved to adsorb Cs⁺ effectively from an aqueous solution, indicating that it would be usefully utilised as an adsorbent to remove Cs⁺.     

IRRADIATION-ENHANCED PHYTOCHROME PELLETABILITY IN AVENA: PIGMENT RELEASE BY Mg2+-GRADIENT ELUTION

Abstract— Gradient elution is used to facilitate controlled withdrawal of Mg²⁺ from phytochrome-rich particulate fractions from irradiated Avena sativa L. shoots. The bound pigment from red-irradiated tissue is released in a discrete band when the Mg²⁺ falls to just below 1 mM. This phytochrome has an apparent molecular weight of ?300 kilodaltons upon gel filtration, indistinguishable from that of the unbound pigment in the same extract and from that in the 50,000 × g supernatant from non-irradiated Avena. This indicates that the bound phytochrome is released as a soluble molecule at a Mg²⁺ concentration above that which permits release of the particulate binding partner from other particulate components. These findings appear to preclude the possibility that the phytochrome-binding partner association can be selectively preserved at a Mg²⁺ level that would permit separation and analysis of phytochrome-bearing particles without the complication of Mg²⁺-induced membrane and RNP aggregation. “Cycled” P_fr (that from tissue irradiated with a red-far red sequence prior to homogenization) is released at 0.1 to 0.2 mM Mg²⁺. This indicates that “cycled P_r is more tenaciously bound by the particulate fraction than is P_fr. This effect is photoreversible both by further in vivo and subsequent in vitro irradiations, suggesting that the state of the pigment, rather than of the binding partner, directly controls the tenacity of the interaction. Increasing concentrations of KCl release the pigment from the particulate fraction in the presence of 10 mM Mg²⁺; increasing Triton X100 concentrations do not. This confirms the ionic nature of the pigment-particulate fraction interaction and indicates strongly that the phytochrome is located external to any membrane vesicles present (although not necessarily that it is bound directly to such vesicles). The data further suggest that phospholipid polar head groups are not primarily responsible for the binding.     

Fabrication of nanocomposite PAN nanofibers containing MgO and Al2O3 nanoparticles

This paper describes the effect of embedding MgO and Al₂O₃ nanoparticles on the diameter of electrospun composite polyacrylonitrile (PAN) nanofibers. Diameter of nanofibers determines the important properties of the nanofibrous mats used in a variety of developed applications such as tissue engineering scaffolds, drug delivery, catalysis, ultra filtration, sensors, and nanoelectronics. The results showed that the type and amount of nanoparticles dispersed in PAN solutions affect the conductivity as well as the viscosity of the electrospinning solutions. Increasing the amount of MgO and Al₂O₃ leads to higher conductivity and higher viscosity of the electrospinning solution and ultimately to a smaller nanofiber diameter. Moreover, the results showed that higher conductivity of the electrospinning solution overcomes the effect of higher viscosity. Finally, no interaction was detected between metal oxide nanoparticles and PAN macromolecules.     

Improved cellular response on multiwalled carbon nanotube-incorporated electrospun polyvinyl alcohol/chitosan nanofibrous scaffolds

We report the fabrication of multiwalled carbon nanotube (MWCNT)-incorporated electrospun polyvinyl alcohol (PVA)/chitosan (CS) nanofibers with improved cellular response for potential tissue engineering applications. In this study, smooth and uniform PVA/CS and PVA/CS/MWCNTs nanofibers with water stability were formed by electrospinning, followed by crosslinking with glutaraldehyde vapor. The morphology, structure, and mechanical properties of the formed electrospun fibrous mats were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and mechanical testing, respectively. We showed that the incorporation of MWCNTs did not appreciably affect the morphology of the PVA/CS nanofibers; importantly the protein adsorption ability of the nanofibers was significantly improved. In vitro cell culture of mouse fibroblasts (L929) seeded onto the electrospun scaffolds showed that the incorporation of MWCNTs into the PVA/CS nanofibers significantly promoted cell proliferation. Results from this study hence suggest that MWCNT-incorporated PVA/CS nanofibrous scaffolds with small diameters (around 160 nm) and high porosity can mimic the natural extracellular matrix well, and potentially provide many possibilities for applications in the fields of tissue engineering and regenerative medicine.     

Tantalum nanoparticles enhance the osteoinductivity of multiscale composites based on poly(lactide-co-glycolide) electrospun fibers embedded in a gelatin hydrogel

Bioresorbable polymeric materials have risen great interest as implants for bone tissue regeneration, since they show substantial advantages with respect to conventional metal devices, including biodegradability, flexibility, and the possibility to be easily modified to introduce specific functionalities. In the present work, an innovative nanocomposite scaffold, properly designed to show biomimetic and osteoinductive properties for potential application in bone tissue engineering, was developed. The scaffold is characterized by a multi-layer structure, completely different with respect to the so far employed polymeric implants, consisting in a poly(d,l-lactide-co-glycolide)/polyethylene glycol electrospun nanofibrous mat sandwiched between two hydrogel gelatin layers enriched with tantalum nanoparticles (NPs). The composition of the electrospun fibers, containing 10 wt% of polyethylene glycol, was selected to ensure a proper integration of the fibers in the gel phase, essential to endow the composite with flexibility and to prevent delamination between the layers. The scaffold maintained its structural integrity after six weeks of soaking in physiological solutions, albeit the gelatin phase was partially released. The combined use of gelatin, bioresorbable electrospun fibers and tantalum NPs endows the final device with biomimetic and osteoinductive properties. Indeed, results of the in vitro tests demonstrate that the obtained scaffolds clearly represent a favorable milieu for normal human bone-marrow derived mesenchymal stem cells viability and osteoblastic differentiation; moreover, inclusion of tantalum NPs in the scaffold improves cell performance with particular regard to early and late markers of osteoblastic differentiation.     

含低聚醚链共价有机骨架薄膜材料的制备及其离子分离性能

用2,5-二(2-甲氧基-乙氧基)对苯二甲酰肼(BMTH)和1,3,5-三甲氧基-2,4,6-三甲酰基苯(TpOMe)缩聚,基于界面聚合法,在多孔三氧化二铝(AAO)基底上制备出一种二维共价有机骨架(COF)膜TpOMe-BMTH,并研究了所得膜材料对锂、镁离子的分离性能。结果显示,TpOMe-BMTH/AAO膜具有高的结晶性和良好的稳定性,并表现出优异的金属离子选择性,在LiCl(0.1 mol·L^-1)和MgCl₂(0.1 mol·L^-1)组成的二元混合离子体系中,对Li⁺/Mg²⁺的分离因子高达258。基于密度泛函理论的平面波赝势方法计算表明,材料孔道中的富氧低聚醚链对 Li⁺和 Mg²⁺的结合能分别为-282.69和-13.46 kJ·mol^-1,使材料表现出强的亲锂特性,促进了Li⁺沿着COF膜的一维孔道进行吸附扩散,最终实现锂、镁离子的高效分离。     

Electrospun Nylon6 Nanofibrous Membrane as SPE Adsorbent for the Enrichment and Determination of Three Estrogens in Environmental Water Samples

In this paper, electrospun Nylon6 nanofibrous membrane was firstly used as adsorbent for solid membrane extraction (SME). The membrane was arranged as a disk in a home-made device, three estrogens-estradiol (E2), ethinylestradiol (EE2) and estrone (E1) in environmental water were extracted and then determined by liquid chromatography–ultraviolet detector (LC–UV). The important parameters affecting extraction efficiency were completely studied and optimized. The experimental results showed that only 1.5 mg Nylon6 nanofibrous membrane could make the maximum sample loading volume up to 50 mL and the target analytes were adsorbed effectively. Under the optimized conditions, the limits of detection (LOD) for E2, EE2, E1 were up to 0.05, 0.08, 0.17 ng mL^?1 respectively and the repeatabilities (RSD%) of intra-membrane and inter-membrane were below 6.0% about spiked samples. The proposed method was subsequently applied to studying water samples from river, rain, pond and tap. Satisfactory spiked recoveries in the range of 85.3–95.9% at 0.25 ng mL^?1 spiked level for the three estrogens were obtained. A comparison with commercial nylon microporous membrane and octadecylsilica (ODS) cartridges was also carried out. All the results showed that electrospun Nylon6 nanofibrous membrane, as a new adsorbent material has great potential for the enrichment of steroid estrogens in the water samples with satisfactory recovery and repeatability.     

Effect of l-Arginine treatment on the in vitro stability of electrospun aligned chitosan nanofiber mats

Chitosan (Cs) mats obtained by electrospinning are potentially ideal scaffolds for tissue engineering. This technique allows obtaining nanometric fibrous structures with preferred orientation, which in turn enable cells to align themselves and produce extracellular matrix along desired orientations. In this study, we fabricated aligned Cs electrospun nanofiber mats and investigated the role of the amino acid l-Arginine (L-Arg) as stabilizing agent. Morphological, chemical, mechanical and biological characterizations were performed on untreated and L-Arg treated nanofibrous mats showing the role of L-Arg as biomimetic stabilizer. L-Arg acts as chemical stabilizer of nanofibrous mats, providing improved wettability behavior, mechanical properties and stability even after 60 days in aqueous medium in comparison to untreated mats. Moreover, preliminary biological tests demonstrated favorable cell-material interactions implying physiological responses in terms of viability and proliferation. The proposed L-Arg-treated Cs mats can be considered as potential scaffolds for highly oriented tissue patterning.     

Controlled release of doxorubicin from electrospun MWCNTs/PLGA hybrid nanofibers

In this study, multiwalled carbon nanotubes (MWCNTs) were used to encapsulate a model anticancer drug, doxorubicin (Dox). Then, the drug-loaded MWCNTs (Dox/MWCNTs) with an optimized drug encapsulation percentage were mixed with poly(lactide-co-glycolide) (PLGA) polymer solution for subsequent electrospinning to form drug-loaded composite nanofibrous mats. The structure, morphology, and mechanical properties of the formed electrospun Dox/PLGA, MWCNTs/PLGA, and Dox/MWCNTs/PLGA composite nanofibrous mats were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and tensile testing. In vitro viability assay and SEM morphology observation of mouse fibroblast cells cultured onto the MWCNTs/PLGA fibrous scaffolds demonstrate that the developed MWCNTs/PLGA composite nanofibers are cytocompatible. The incorporation of Dox-loaded MWCNTs within the PLGA nanofibers is able to improve the mechanical durability and maintain the three-dimensional structure of the nanofibrous mats. More importantly, our results indicate that this double-container drug delivery system (both PLGA polymer and MWCNTs are drug carriers) is beneficial to avoid the burst release of the drug and able to release the antitumor drug Dox in a sustained manner for 42 days. The developed composite electrospun nanofibrous drug delivery system may be used as therapeutic scaffold materials for post-operative local chemotherapy.     

Improved efficacy of bio‐mineralization of human mesenchymal stem cells on modified PLLA nanofibers coated with bioactive materials via enhanced expression of integrin α2β1

Current therapeutic interventions in bone defects are mainly focused on finding the best bioactive materials for inducing bone regeneration via activating the related intracellular signaling pathways. Integrins are trans‐membrane receptors that facilitate cell‐extracellular matrix (ECM) interactions and activate signal transduction. To develop a suitable platform for supporting human bone marrow mesenchymal stem cells (hBM‐MSCs) differentiation into bone tissue, electrospun poly L‐lactide (PLLA) nanofiber scaffolds were coated with nano‐hydroxyapatite (PLLA/nHa group), gelatin nanoparticles (PLLA/Gel group), and nHa/Gel nanoparticles (PLLA/nHa/Gel group) and their impacts on cell proliferation, expression of osteoblastic biomarkers, and bone differentiation were examined and compared. MTT data showed that proliferation of hBM‐MSCs on PLLA/nHa/Gel scaffolds was significantly higher than other groups (P < .05). Alkaline phosphatase activity was also more increased in hBM‐MSCs cultured under osteogenic media on PLLA/nHa/Gel scaffolds compared to others. Gene expression evaluation confirmed up‐regulation of integrin α2β1 as well as the osteogenic genes BGLAP, COL1A1, and RUNX2. Following use of integrin α2β1 blocker antibody, the protein level of integrin α2β1 in cells seeded on PLLA/nHa/Gel scaffolds was decreased compared to control, which confirmed that most of the integrin receptors were bound to gelatin molecules on scaffolds and could activate the integrin α2β1/ERK axis. Collectively, PLLA/nHa/Gel scaffold is a suitable platform for hBM‐MSCs adhesion, proliferation, and osteogenic differentiation in less time via activating integrin α2β1/ERK axis, and thus it might be applicable in bone tissue engineering.