Porous poly(glycerol sebacate) (PGS) elastomer scaffolds for skin tissue engineering

Poly (glycerol sebacate) (PGS) elastomer scaffolds with different porosity for skin tissue engineering were fabricated via particulate leaching. The introduction of pores lowers the hydrophilicity but improves the water uptake capability of PGS. The gel content of PGS increases with the increase of salt mass ratio, but the degree of swelling goes the opposite way due to the existence of the porous structure. The degradation rate of PGS can be tailored and controlled by the porous structure, which is of great value for its applications in tissue engineering. The feasibility of these porous PGS scaffolds for skin tissue engineering was evaluated by seeding mouse dermal fibroblasts (MDFs) onto the scaffold. In vitro cell culture results indicate good attachment, proliferation and deep penetration of MDFs into porous PGS scaffolds, which confirms the excellent biocompatibility of these scaffolds.     

Silk fibroin microfibers and chitosan modified poly (glycerol sebacate) composite scaffolds for skin tissue engineering

Porous mSF/PGS and CS/PGS composite scaffolds were prepared by the combination of poly(glycerol sebacate) (PGS) with silk fibroin microfibers (mSF) and chitosan (CS) as modifiers through particulate leaching and freeze-drying techniques. Both mSF/PGS and CS/PGS scaffolds show highly interconnected and open porous structures, and the crosslink density and water absorption of PGS were obviously enhanced by the modifiers. Moreover, the silk fibroin microfiber and chitosan can slow down and control the degradation rate of PGS. The biocompatibility of these porous PGS based composite scaffolds for skin tissue engineering was evaluated by cell culture experiments, and the results indicate of the good attachment, proliferation and deep penetration of cells into these composite scaffolds.     

Electrospinning of Hyperbranched Poly-L-Lysine/Polyaniline Nanofibers for Application in Cardiac Tissue Engineering

Electrospun polyaniline nanofibers are one of the most promising materials for cardiac tissue engineering due to their tunable electroactive properties. Moreover, the biocompatibility of polyaniline nanofibes can be improved by grafting of adhesive peptides during the synthesis. In this paper, we describe the biocompatible properties and cardiomyocytes proliferation on polyaniline electrospun nanofibers modified by hyperbranched poly-L-lysine dendrimers (HPLys). The microstructure characterization of the HPLys/polyaniline nanofibers was carried out by scanning electron microscopy (SEM). It was observed that the application of electrical current stimulates the differentiation of cardiac cells cultured on the nanofiber scaffolds. Both electroactivity and biocompatibility of the HPLys based nanofibers suggest the use this material for culture of cardiac cells and opens the possibility of using this material as a biocompatible electroactive 3-D matrix in cardiac tissue engineering.     

Electrospinning nanofibers of microbial polyhydroxyalkanoates for applications in medical tissue engineering

Differently to most chemically synthesized medical materials, polyhydroxyalkanoates (PHAs) are intracellular carbon and energy storage granules, which is a family of natural bio-polymers synthesized by microorganism's materials. Due to excellent biocompatibility reasonable biodegradability and versatile material difference, PHAs are well medical biomaterials candidates for applications in tissue engineering and drug delivery, including commercial PHB, PHBV, PHBHHx, PHBVHHx, P34HB and few uncommercial PHAs. Electrospinning nanofibers with the size of 10–10,000 nm can improve the mechanical properties and decrease the crystallinity of PHA, meanwhile simulate the structure and function of native extracellular matrix of cells. Hence, PHAs electrospinning nanofibers as engineered scaffolds have been widely used for tissue engineering scaffolds in cardiovascular, vascular, nerve, bone, cartilage and skin; also, as carriers for application in drug delivery system. In this review, we highlight the extraction and properties of medical PHAs from natural or engineered microorganism, and microstructure, current manufacturing techniques and medical applications of electrospinning nanofibers of PHAs. Moreover, the current challenges and prospects of PHAs electrospinning nanofibers are discussed rationally, providing an insight into developing vibrant fields of PHAs electrospinning nanofibers-based biomedicine.     

Silk Fibroin Combined with Electrospinning as a Promising Strategy for Tissue Regeneration

The development of tissue engineering scaffolds is of great significance for the repair and regeneration of damaged tissues and organs. Silk fibroin (SF) is a natural protein polymer with good biocompatibility, biodegradability, excellent physical and mechanical properties and processability, making it an ideal universal tissue engineering scaffold material. Nanofibers prepared by electrospinning have attracted extensive attention in the field of tissue engineering due to their excellent mechanical properties, high specific surface area, and similar morphology as to extracellular matrix (ECM). The combination of silk fibroin and electrospinning is a promising strategy for the preparation of tissue engineering scaffolds. In this review, the research progress of electrospun silk fibroin nanofibers in the regeneration of skin, vascular, bone, neural, tendons, cardiac, periodontal, ocular and other tissues is discussed in detail.     

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.     

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.     

Design and fabrication of poly (glycerol sebacate)‐based fibers for neural tissue engineering: Synthesis,electrospinning, and characterization

Poly (glycerol sebacate) (PGS) is a thermoset biodegradable elastomer considered as a promising candidate material for nerve applications. However, PGS synthesis is very time and energy consuming. In this study, the PGS pre‐polymer (pPGS) was synthesized using three synthesis times of 3, 5, and 7 hours at 170°C. Fourier transform infrared (FTIR), nuclear magnetic resonance spectroscopy, X‐ray diffraction analysis, and differential scanning calorimetry thermogram were utilized to study the pPGS behavior. Poly (vinyl alcohol) was used as a carrier to fabricate aligned poly (vinyl alcohol)‐poly (glycerol sebacate) (PVA‐PGS) fibers with various ratios (60:40, 50:50, and 40:60) using electrospinning and crosslinked through the thermal crosslinking method. Morphology of the fibers was studied before and after crosslinking using scanning electron microscopy (SEM). FTIR, mechanical properties in the dry and wet state, water contact angle, in vitro degradation, and water uptake behavior of crosslinked scaffolds were also investigated. 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay, SEM analysis, and 4′, 6‐diamidino‐2‐phenylindole (DAPI) staining were utilized to determine the biocompatibility of scaffolds. The results show the synthesized pPGS in 3 hours at 170°C is the optimized sample in the terms of chemical reaction. All scaffolds have bead‐free and a uniform fiber diameter. The Young's modulus of crosslinked PVA‐PGS (50:50 and 40:60) fibers is shown to be in the expected range for nerve applications. The cell culture studies reveal PVA‐PGS (50:50 and 40:60) fibers could lead to better cell adhesion and proliferation. The results suggest that PVA‐PGS (50:50 and 40:60) is a suitable and promising biodegradable material in the fabrication of scaffolds for nerve regeneration.     

Fabrication of graphene‐silver/polyurethane nanofibrous scaffolds for cardiac tissue engineering

The graphene‐based nanocomposites are considered as great candidates for enhancing electrical and mechanical properties of nonconductive scaffolds in cardiac tissue engineering. In this study, reduced graphene oxide‐silver (rGO‐Ag) nanocomposites (1 and 2 wt%) were synthesized and incorporated into polyurethane (PU) nanofibers via electrospinning technique. Next, the human cardiac progenitor cells (hCPCs) were seed on these scaffolds for in vitro studies. The rGO‐Ag nanocomposites were studied by X‐ray diffraction (XRD), Raman spectroscopy, and transmission electron microscope (TEM). After incorporation of rGO‐Ag into PU nanofibers, the related characterizations were carried out including scanning electron microscope (SEM), TEM, water contact angle, and mechanical properties. Furthermore, PU and PU/nanocomposites scaffolds were used for in vitro studies, wherein hCPCs showed good cytocompatibility via 3‐(4, 5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) assay and considerable attachment on the scaffold using SEM studies. Real‐time polymerase chain reaction (PCR) and immunostaining studies confirmed the upregulation of cardiac specific genes including GATA‐4, T‐box 18 (TBX 18), cardiac troponin T (cTnT), and alpha‐myosin heavy chain (α‐MHC) in the PU/rGO‐Ag scaffolds in comparison with neat PU ones. Therefore, these nanofibrous rGO‐Ag–reinforced PU scaffolds can be considered as suitable candidates in cardiac tissue engineering.     

Fabrication of collagen immobilized electrospun poly (vinyl alcohol) scaffolds

In the development of tissue engineering scaffolds, the interactions between material surface and cells play crucial roles. The biomimetic 3‐D scaffolds absolutely provide better results for fulfilling requirements such as porosity, interconnectivity, cell attachment and proliferation. In this study, 3‐D electrospun scaffolds were prepared by using an electrospinning technique. Photo cross‐linkable polyvinyl alcohol was used as a polymeric matrix. During the electrospinning, the nanofibers were cross‐linked with in situ ultraviolet radiation. The crosslinked polymer fibers were achieved in a simple process at a single step. Nanofiber surface was modified with collagen by a chemical approach. The chemical structures were proven by attentuated total reflectance Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. The surface morphology of the nanofibers was characterized by scanning electron microscope (SEM). Morphological investigations show that the resulting nanofibrous matrix has uniform morphology with a diameter of 220–250 nm. In vitro attachment and growth of 3T3 mouse fibroblasts and human umbilical vein endothelial cells (ECV304) cells on polyvinyl alcohol‐based nanofiber mats were also investigated. Cell attachment, proliferation, and methylthiazole tetrazolium cytotoxicity assays indicated good cell viability throughout the culture time, which was also confirmed by SEM analysis. Copyright © 2015 John Wiley & Sons, Ltd.     

Incorporation of two‐dimensional nanomaterials into silk fibroin nanofibers for cardiac tissue engineering

Mimicking the extracellular matrix to have a similar nanofibrous structure regarding electrical conductivity and mechanical properties would be highly beneficial for cardiac tissue engineering. The molybdenum disulfide, MoS₂, and reduced graphene oxide, rGO, nanosheets are two‐dimensional nanomaterials which can be considered as great candidates for enhancing the electrical and mechanical properties of biological scaffolds for cardiac tissue engineering applications. In this study, MoS₂ and rGO nanosheets were synthesized and incorporated into silk fibroin nanofibers, SF, via electrospinning method. Then, the human iPSCs transfected with TBX‐18 gene, TBX18‐hiPSCs, were seeded on these scaffolds for in vitro studies. The MoS₂ and rGO nanosheets were studied by Raman spectroscopy. After incorporation of the nanosheets into SF nanofibers, the associated characterizations were carried out including scanning electron microscopy, transmission electron microscopy, water contact angle, and mechanical test. Furthermore, SF, SF/MoS₂, and SF/rGO scaffolds were used for in vitro studies. Herein, the scaffolds exhibited acceptable biocompatibility and considerable attachment to TBX18‐hiPSCs confirmed by 3‐(4, 5‐dimethylthiazol‐2‐yl)‐2, 5‐diphenyl tetrazolium bromide, MTT, assay, and scanning electron microscopy. Also, the real‐time PCR and immunostaining studies confirmed the maturity and upregulation of cardiac functional genes, including GATA‐4, c‐TnT, and α‐MHC in the SF/MoS₂ and SF/rGO scaffolds compared with the bare SF one. Therefore, the reinforcement of these SF‐based scaffolds with MoS₂ and rGO endues them as a suitable candidate for cardiac tissue engineering.     

Self-organization of a chiral D-EAK16 designer peptide into a 3D nanofiber scaffold

Self-assembling peptide nanofiber scaffolds are an excellent material for applications such as tissue repair, tissue regeneration, instant stopping of bleeding, and slow drug release. We report a new self-assembling peptide D-EAK16 consisting purely of D-amino acids. D-EAK16 and L-EAK16 display mirror-image CD spectra at 20 degrees C. Like L-EAK16, D-EAK16 self-assembles into nanofibers, thus demonstrating that chiral self-assembling peptide nanofiber scaffolds can be made from both L- and D-amino acids. We also show that D-peptide nanofibers are resistant to natural proteases and may thus be useful in biotechnology, nanobiotechnology, tissue repair and tissue regeneration as well as other medical applications.     

Nanofibers for Biomedical and Healthcare Applications

Unique features of nanofibers provide enormous potential in the field of biomedical and healthcare applications. Many studies have proven the extreme potential of nanofibers in front of current challenges in the medical and healthcare field. This review highlights the nanofiber technologies, unique properties, fabrication techniques (i.e., physical, chemical, and biological methods), and emerging applications in biomedical and healthcare fields. It summarizes the recent researches on nanofibers for drug delivery systems and controlled drug release, tissue‐engineered scaffolds, dressings for wound healing, biosensors, biomedical devices, medical implants, skin care, as well as air, water, and blood purification systems. Attention is given to different types of fibers (e.g., mesoporous, hollow, core‐shell nanofibers) fabricated from various materials and their potential biomedical applications.     

A review on electrospun nanofibers for multiple biomedical applications

Electrospinning is a well-known technique since 1544 to fabricate nanofibers using different materials like polymers, metals oxides, proteins, and many more. In recent years, electrospinning has become the most popular technique for manufacturing nanofibers due to its ease of use and economic viability. Nanofibers have remarkable properties like high surface-to-volume ratio, variable pore size distribution (10–100 nm), high porosity, low density, and are suitable for surface functionalization. Therefore, electrospun nanofibers have been utilized for numerous applications in the pharmaceutical and biomedical field like tissue engineering, scaffolds, grafts, drug delivery, and so on. In this review article, we will be focusing on the versatility, current scenario, and future endeavors of electrospun nanofibers for various biomedical applications. This review discusses the properties of nanofibers, the background of the electrospinning technique, and its emergence in chronological order. It also covers the various types of electrospinning methods and their mechanism, further elaborating the factors affecting the properties of nanofibers, and applications in tissue engineering, drug delivery, nanofibers as biosensor, skin cancer treatment, and magnetic nanofibers.     

Immobilization of gelatin onto natural nanofibers for tissue engineering scaffold applications without utilization of any crosslinking agent

Bacterial cellulose was oxidized by periodate oxidation to give rise to 2,3-dialdehyde bacterial cellulose (DABC) with 60.3 ± 0.5 % aldehyde content, which was further reacted with gelatin (Gel) for the immobilization of Gel to form DABC/Gel nanocomposites. The scanning electron microscopy and transmission electron microscopy revealed that DABC/Gel exhibited the refined 3D nano-network structures and the average thickness of Gel coatings in the composites was about 75 nm. FTIR and XPS were utilized to analyze the functional groups and chemical states of DABC/Gel nanocomposites. The results inferred that Gel was fixed on DABC nanofibers via the Schiff base reaction between –NH₂ in Gel and –CHO in DABC backbone. NIH3T3 mice fibroblast cells were used for determining the cytocompatibility of the scaffolds. The morphology of the cells was observed through optical inverted microscopy. The results show that DABC/Gel can be used as scaffold material in tissue engineering.     

Personalized hydrogels for individual health care: preparation,features, and applications in tissue engineering

Biomaterials-based tissue engineering scaffolds play an essential role as an independent therapy or with the combination of cellular or biological active constituents in tissue regeneration applications. However, synthetic grafts, xenografts, and allografts are recognized as foreign materials in human body, resulting in suboptimal clinical outcomes. Recently, autologous materials from a patient's body have drawn great attention in clinical treatment and tissue engineering. Moreover, the autologous scaffolds equipped with the advantages of tissue-like hydrogels have great potential to become a highly versatile tool as personalized hydrogels (PHs) for applications in 3D cell culture and tissue engineering. PHs may feature excellent biocompatibility, tailorable mechanical properties, regenerative capability, non-rejection of grafts/transplants on immunological responses, and customizable properties which could be suitable to meet the personal and clinical care. Here, we present a scoping review of recent progress of PHs with a focus on detailed preparation methods, material properties, and tissue engineering applications along with their challenges and opportunities. It is expected that PHs will circumvent the limitations of current tissue engineering therapies and will be used as next-generation scaffolds for tissue engineering and translational research.     

Improved survival of cardiac cells on surface modified electrospun nanofibers

Polycaprolactone (PCL) is a popular synthetic polymer used in the field of cardiac tissue engineering (CTE) due to its non-toxic degraded by products and low cost manufacturing method. However, hydrophobic nature of this material limits its wide spread application in different cell interaction processes. Therefore, current study aims to chemically modify PCL made random and aligned nanofibers with collagen coating mimicking the oriented matrix of the cardiac cells. Morphological and chemical properties of the electrospun PCL nanofibers were evaluated by SEM, FTIR, XRD and water contact angle measurement. Results indicated that the anisotropic characteristics of aligned nanofibers promoted cell attachment and alignment, which closely match the requirements of native cardiac cells. Thus, aligned nanofibers could be preferred for cardiac tissue regeneration and defects over random nanofibers.     

药物和蛋白质与聚己内酯分层复合纳米纤维的微观结构与力学特性

应用同轴共纺技术制得芯质和表层为两种不同材料的分层复合纳米纤维.分别以乙酰螺旋酶素片剂和明胶蛋白质为芯质材料,以可生物降解的聚己内酯作为表层材料,研究了这种分层复合纳米纤维的微观结构与力学特性.结果表明,尽管药物与表层聚合物材料的溶解溶剂互不相同,但仍可以将药物包覆在壁厚小于100nm的超细纤维中.这种纤维可用作体内手术伤口缝合线或大面积创伤如烧伤伤口的敷布.在实验范围内,纤维膜的力学性能随芯质内溶质含量的提高而降低.     

Synthesis of multifunctional Fe3O4 core/hydroxyapatite shell nanocomposites by biomineralization

Superparamagnetic nanoparticles with surface functional groups (-OH, -COOH and -NH(2)) were modified by in situ deposition of hydroxyapatite (HA) on the materials' surface through the biomineralization process to form Fe(3)O(4) core/hydroxyapatite shell nanocomposites. They possess potential applications as targeted carriers for antitumor drugs and as bone tissue engineering scaffolds by integrating multiple functions into a single nanosystem.     

Nanofiber Configuration of Electrospun Scaffolds Dictating Cell Behaviors and Cell-scaffold Interactions

Electrospun nanofibers are of the same length scale as the native extracellular matrix and have been extensively reported to facilitate adhesion and proliferation of cells and to promote tissue repair and regeneration. With a primary focus on tissue repair and regeneration using electrospun scaffolds, only a few studies involved electrospun nanofiber scaffolds directing cell behaviors have been reported. In this study, we prepared electrospun nanofiber scaffolds with distinct fiber configurations, namely, random and aligned orientations of nanofibers, as well as oriented yarns, and investigated their effects on cell behaviors. Our results showed that these scaffolds supported good proliferation and viability of murine fibroblasts. Fiber configuration profoundly influenced cell morpho-logy and orientation but showed no effects on cell proliferation rate. The yarn scaffold had comparable total protein accumulation with the random and aligned scaffolds, but it supported a greater pro-liferation rate of fibroblasts with significantly elevated collagen de-position due to its porous fibrous configuration. Cell-seeded yarn scaffolds showed a greater Young's modulus compared with cell-free controls as early as 1 week. Together with its unique fiber configuration similar to the native extracellular matrix of the myocardium, the yarn scaffold might be a suitable matrix material for modeling cardiac fibrotic disorders.