In vitro blood compatibility and bone mineralization aspects of polymeric scaffold laden with essential oil and metallic particles for bone tissue engineering

Bone tissue engineering scaffolds necessities appropriate physicochemical and mechanical properties to support its renewal. Electrospun scaffolds have been used unequivocally in bone tissue restoration. The main intention of this research is to develop electrospun polyurethane (PU) scaffold decorated with metallic particles and essential oil with advanced properties to make them as a putative candidate. The nanocomposite scaffold exhibited appropriate wettability and suitable fiber diameter compared to the polyurethane scaffold. Interaction of the added constituents with the polyurethane was corroborated through hydrogen bonding formation. Tensile strength of the composites was enhanced compared to the polyurethane scaffold. Thermal analysis depicted the lower weight loss of the composite scaffold than the pristine PU. Blood coagulation was significantly delayed and also the composite surface rendered safe interaction with red blood cells. In vitro toxicity testing using fibroblast cells portrayed the nontoxic behavior of the fabricated material. The above-said advanced properties of the composite scaffold can be warranted for bone tissue engineering application.     

Fabrication and characterization of a novel wound scaffold based on polyurethane added with Channa striatus for wound dressing applications

Abstract

Wound healing is a complex process and it involves restoration of damaged skin tissues. Several wound dressings comprising naturally made substances are constantly investigated to assist wound healing. In this research, a new wound dressing based on polyurethane (PU) supplemented with essence of Channa striatus (CS) fish oil was made by electrospinning. Morphological study depicted the reduction in fiber diameter than PU with the addition of fish oil (0.552?±?0.109?μm for 8:1 v/v% and 0.519?±?0.196?μm 7:2 v/v%) than the pristine PU (0.971?±?0.205?µm). Fourier transform infrared spectroscopy (FTIR) analysis revealed the presence of fish oil in the composite as identified through increasing peak intensity. Fish oil resulted in the hydrophilic behavior (88?±?3 (8:1 v/v) and 70?±?6 (7:2 v/v)) as revealed in the contact angle analysis. Thermal gravimetric analysis (TGA) showed the superior thermal behavior of the wound dressing patch compared to the PU. Atomic force microscopy (AFM) analysis insinuated a decrease in the surface roughness of the pristine polyurethane with the added fish oil. Coagulation assays signified the delay in the blood clotting time portraying its anti-thrombogenic behavior. Hemolytic assay revealed the less toxic nature of the developed nanocomposites with the red blood cells (RBC’s) depicting its safety with blood. Hence, polyurethane nanofibers supplemented with fish oil made them as deserving candidates for wound dressing application.     

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.     

Green synthesis of nickel oxide particles and its integration into polyurethane scaffold matrix ornamented with groundnut oil for bone tissue engineering

Physiochemical properties of the fabricated scaffolds play a crucial role in influencing the cellular response for the new tissue growth. In this study, electrospun polyurethane (PU) scaffolds incorporated with green synthesized nickel oxide nanoparticles and groundnut oil (GO) were fabricated using electrospinning technique. First, synthesis of nickel oxide (NiO) was done using leaf extract of Plectranthus amboinicus (PA) via microwave-assisted technique. Synthesized nanoparticles were confirmed through Energy-dispersive X-ray spectroscopy (EDX) analysis and size of the particles were in the range of 800–950?nm. Fiber morphology of the fabricated scaffolds was analyzed using scanning electron microscope (SEM) which showed decrease in fiber diameter for the fabricated composites compared to the pristine PU. The wettability studies showed an increase in contact angle for developed composites than the pure PU. Thermal analysis depicted an increase in thermal behavior for the PU/GO/NiO compared to the pristine PU. Surface roughness values were obtained through atomic force microscopy (AFM) which showed a decrease in roughness while adding GO and NiO to the PU. Finally, the fabricated composites showed enhanced deposition of calcium content than the pristine PU. These results corroborated that the developed composites have a significant effect on the fiber morphology, wettability, thermal behavior, surface roughness, and mineral deposition depicting its versatility for bone regeneration.     

Porous-conductive chitosan scaffolds for tissue engineering, 1. Preparation and characterization

Novel porous-conductive chitosan scaffolds were fabricated by incorporating conductive polypyrrole (PPy) particles into a chitosan matrix and employing a phase separation technique to build pores inside the scaffolds. Conductive polypyrrole particles were prepared with a microemulsion method using FeCl3 as a dopant. The preparation conditions were optimized to obtain scaffolds with controlled pore size and porosity. The conductivity of the scaffolds was investigated using a standard four-point probe technique. It was found that several kinds of scaffolds showed a conductivity close to 10(-3) S.cm(-1) with a low polypyrrole loading of around 2 wt.-%. The main mechanical properties, such as tensile strength, breaking elongation and Young's modulus of the scaffolds, were examined both in the dry and in the hydrated states. The results indicated that a few different kinds of scaffolds exhibited the desired mechanical strength for some tissue engineering applications. The miscibility of polypyrrole and chitosan was also evaluated using a dynamic mechanical method. The presence of significant phase separation was detected in non-porous PPy/chitosan scaffolds but enhanced miscibility in porous PPy/chitosan scaffolds was observed.     

Fabrication and characterization of chitosan-gelatin/single-walled carbon nanotubes electrospun composite scaffolds for cartilage tissue engineering applications

Cartilage is a connective tissue with a slow healing rate due to lack in blood circulation and slow metabolism. Designing tissue engineering scaffolds modified based on its specific features can assist its natural regeneration process. In this study, the chitosan-gelatin/single-walled carbon nanotubes functionalized by COOH (SWNTs-COOH) nanocomposite scaffolds were fabricated through electrospinning. The effect of each component and different duration of cross-linking were assessed in terms of morphology, porosity, chemical structure, thermal behavior, mechanical properties, wettability, biodegradability, and in vitro cell culture study. Adding SWNTs-COOH decreased fiber diameter, water contact angle and degradation rate while increased tensile strength, hydrophilicity, stability and cell viability, due to their high intrinsic electrical conductivity, and mechanical properties and the presence of COOH functional groups in its structure. All the sample presented a porosity percentage of more than 80%, which is essential for tissue engineering scaffolds. The presence SWNTs-COOH did not have any adverse effect on cytocompatibility. The optimal cross-linking time increased the stability of the scaffolds in PBS. It can be concluded that the chitosan-gelatin/1wt% SWNTs-COOH scaffold can be appropriate for cartilage tissue engineering applications.     

Fabrication and enhanced mechanical properties of porous PLA/PEG copolymer reinforced with bacterial cellulose nanofibers for soft tissue engineering applications

A new class of polylactic acid (PLA)/polyethylene glycol (PEG) copolymer reinforced with bacterial cellulose nanofibers (BC) was prepared using a solvent casting and particulate leaching methods. Four weight fractions of BC (1, 2.5, 5, and 10 wt%) were incorporated into copolymer via silane coupling agent. Mechanical properties were evaluated using response surface method (RSM) to optimize the impact of pore size, porosity, and BC contents. Compressive strength obtained for PLA/PEG-5 BC wt% was 9.8 MPa, which significantly dropped after developing a porous structure to 4.9 MPa. Nielson model was applied to investigate the BC stress concentration on the PLA/PEG. Likewise, krenche and Hapli-Tasi model were employed to investigate the BC nanofiber reinforcement and BC orientation into PLA/PEG chains. The optimal parameters of the experiment results found to be 5 wt% for BC, 230 μm for pore size, and 80% for porosity. Scanning electron microscopy (SEM) micrograph indicates that uniform pore size and regular pore shape were achieved after an addition of BC-5% into PLA/PEG. The weight loss of copolymer-BC with scaffolds enhanced to the double values, compared with PLA/PEG-BC % without scaffolds. Differential Scanning Calorimetric (DSC) results revealed that the BC nanofiber improved glass transition temperature (T_g) 57 °C, melting temperature (T_m) 171 °C, and crystallinity (χ %) 43% of PLA/PEG reinforced-BC-5%.     

Production,blood compatibility and cytotoxicity evaluation of a single stage non-woven multicomponent electrospun scaffold mixed with sesame oil,honey and propolis for skin tissue engineering

Scaffolds used in skin tissue engineering must mimic the native function of the extracellular matrix (ECM) and facilitate the fibroblast cell response for new tissue growth. In this study, a novel dressing scaffold based on polyurethane (PU) with sesame oil, honey, and propolis was fabricated by electrospinning. Scanning electron microscopy (SEM) images showed that the diameter of the electrospun scaffolds decreased by blending sesame oil (784?±?125.46?nm) and sesame oil/honey/propolis (576?±?133.72?nm) into the PU matrix (890?±?116.911?nm). Fourier infrared (FT-IR) and thermogravimetric (TGA) analysis demonstrated the formation of hydrogen bonds and interaction between PU and sesame oil, honey, and propolis. Contact-angle measurement indicated reduced wettability of PU/sesame oil scaffold (114?±?1.732) and improved wettability (54.33?±?1.528) in the PU/sesame oil/honey/propolis scaffold. Further, tensile tests and atomic force microscopy (AFM) analysis indicated that the fabricated composite membrane exhibited enhanced mechanical strength and reduced surface roughness compared to the pristine PU. The developed composite displayed less toxicity to the red blood cells (RBC’s) compared to the pristine PU. Cytotoxicity assay showed enhanced cell viability of HDF in electrospun scaffolds than pristine PU after 72?h culture. These enhanced properties of the developed scaffolds suggest the potential of utilizing them in skin tissue engineering.     

Fabrication of tri-polymers composite film with high cyclic stability and rapid degradation for cardiac tissue engineering

In this communication, biodegradable and highly elastic silk fibroin/poly(lactide-co-ε-caprolactone)/polyethylene oxide (SF/PLCL/PEO) tri-polymers composite film was fabricated by sol–gel casting technology. The tri-polymers composite film exhibited a high cycle performance and rapid degradation rate by regulating the content of blending of the three polymer contents. The viability of cardiomyocyte cells was demonstrated for both SF/PLCL and SF/PLCL/PEO composite films after 1 day of culture, although the tri-polymers composite film demonstrated superior cell growth, attachment and spreading after culturing for 7 days. Study findings support the potential application of this biocompatible tri-polymers composite film as a heart patch substitute with multi-functionalities.     

Novel photopolymerizable biodegradable triblock polymers for tissue engineering scaffolds: synthesis and characterization

For use in micro-patterned scaffolds in tissue engineering, novel diacrylated triblock macromers (PLA-b-PCL-b-PLA, PGA-b-PCL-b-PGA and PCL-b-PEO-b-PCL) were synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). All diacrylated polymers were designed as triblock copolymers and involved biodegradable blocks of relatively non-polar epsilon-caprolactone (CL) and polar monomers such as glycolide (GA), lactide (LA) or ethylene oxide (EO). All triblock polymers were prepared in molecular weights of a few kilo daltons via the anionic ring-opening polymerization (ROP) of the corresponding lactide, glycolide or caprolactone using stannous octoate [Sn(Oct)(2)] as catalyst. The polymers had low polydispersity indices, ranging from 1.23 to 1.56. Biodegradable polymeric networks were prepared with conversions of 72-84% via photopolymerization of the triblock diacrylated polymers with 2,2-dimethoxy-2-phenylacetophenone (DMPA) as photoinitiator. PLA-b-PCL-b-PLA copolymers crumbled easily and were not suitable for micro-patterning. PGA-b-PCL-b-PGA copolymers had higher water contact angles than PCL-b-PEO-b-PCL and were also cytocompatible with Fibroblasts 3T3.     

Production and characterization of chitosan fibers and 3-D fiber mesh scaffolds for tissue engineering applications

This study reports on the production of chitosan fibers and 3-D fiber meshes for the use as tissue engineering scaffolds. Both structures were produced by means of a wet spinning technique. Maximum strain at break and tensile strength of the developed fibers were found to be 8.5% and 204.9 MPa, respectively. After 14 d of immersion in simulated body fluid (SBF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and inductively coupled plasma emission (ICP) spectroscopy analyses showed that a bioactive Ca-P layer was formed on the surface of the fibers, meaning that they exhibit a bioactive behavior. The samples showed around 120% max. swelling in physiological conditions. The pore sizes of 3-D chitosan fiber mesh scaffolds were observed to be in the range of 100-500 microm by SEM. The equilibrium-swelling ratio of the developed scaffolds was found to be around 170% (w/w) in NaCl solution at 37 degrees C. Besides that, the limit swelling strain was less than 30%, as obtained by mechanical spectroscopy measurements in the same conditions. The viscoelastic properties of the scaffolds were also evaluated by both creep and dynamic mechanical tests. By means of using short-term MEM extraction test, both types of structures (fibers and scaffolds) were found to be non-cytotoxic to fibroblasts. Furthermore, osteoblasts directly cultured over chitosan fiber mesh scaffolds presented good morphology and no inhibition of cell proliferation could be observed.Osteoblast-like cells proliferating over chitosan based fibers after 7 d of culture.     

Fabrication of open‐porous PCL/PLA tissue engineering scaffolds and the relationship of foaming process,morphology, and mechanical behavior

Tissue engineering scaffolds should provide a suitable porous structure and proper mechanical strength, which is beneficial for the delivery of growth factor and regulation of cells. In this study, the open‐porous polycaprolactone (PCL)/poly (lactic acid) (PLA) tissue engineering scaffolds with suitable porous scale were fabricated using different ratios of PCL/PLA blends. At the same time, the relationship of foaming process, morphology, and mechanical behavior in the optimized batch microcellular foaming process were studied based on the single‐factor experiment method. The porous structures and mechanical strength of the scaffolds were optimized by adjusting foaming parameters, including the temperature, pressure, and CO₂ dissolution time. The results indicated that the foaming parameters influence the cell morphology, further determine the mechanical behavior of PCL/PLA blends. When the PCL content is high, with the increase of temperature and time, the cell diameter and the elastic modulus increased, and the tensile strength and elastic modulus increased with the increase of the average cell size, and decreased as the increase of the cell density. While when the PLA content was high, the cell diameter showed the same trend, and the tensile strength and elastic modulus were higher, and the elongation at break was lower, and tensile strength and elastic modulus decreased with the increase of the average cell size and increased with the increase of cell density. This work successfully fabricated optimized porous PCL/PLA scaffolds with excellent suitable mechanical properties, pore sizes, and high interconnectivity, indicating the effectiveness of modulating the batch foaming process parameters.     

Fabrication of biodegradable poly(trimethylene carbonate) networks for potential tissue engineering scaffold applications

Biodegradable poly(trimethylene carbonate) (PTMC) networks were prepared by photopolymerization of linear (L)‐ and star (S)‐shaped PTMC macromonomers for potential tissue engineering scaffold applications. The L‐ (M_n, 6400) and S‐shaped (M_n, 5880) PTMC macromonomers were synthesized using 1,4‐butane diol and 2‐ethyl‐ 2‐hydroxyl‐propane‐1,3‐diol co‐initiated ring‐opening polymerization of trimethylene carbonate (TMC) in the presence of stannous octoate and subsequent acrylation with acryloyl chloride. Chemical structures of the PTMC macromonomers and their corresponding networks were characterized by ¹H NMR and ¹³C NMR spectroscopy. The human endothelial cell line, EA.hy926 was used to test the biocompatibility, cell adhesion, and proliferation behavior of both PTMC networks. The PTMC networks made from the S‐shaped macromonomers exhibited superior cell adhesion and proliferation behavior than those made of the linear macromonomers. Copyright © 2008 John Wiley & Sons, Ltd.     

Fabrication and characterization of chitosan-silk fibroin/hydroxyapatite composites via in situ precipitation for bone tissue engineering

Homogeneous chitosan-silk fibroin/hydroxyapatite(CS-SF/HA) composites were prepared by in situ precipitation method driven by a multiple-order template. The morphology of the composites was investigated by scanning electron microscope(SEM) and transmission electron microscope(TEM). The compositional analysis was carried out by X-ray diffraction analysis(XRD) and Fourier transformed infrared spectroscopy(FTIR). The mechanical properties and biocompatibility of the composites were also determined. The results indicated that the inorganic particles of uniform size(50 nm) were well-dispersed among the CS-SF matrices. The compressive modulus of the CS-SF/HA composites was enhanced with the increasing amount of SF. The in vitro results suggested that the MC3T3-E1 osteoblast-like cells on CS-SF/HA composite disks displayed strong bonding and spreading, and the cell proliferation cultured on each composite disk increased throughout the culture period for up to 7 days. Especially, the samples with higher content of SF had much better biological properties. The evidences proved that the CS-SF/HA composites possessed excellent biocompatibility. By using the freeze-drying technique, hierarchical porous scaffolds with pores ranging from 50 μm to 200 μm were obtained. This work presented the advantages of in situ precipitation method to prepare the organic/inorganic composites, and a multiple-order template was introduced in the system to improve the properties of the composites by combining the merits of each organic template.     

Synthesis and characterization of a nano‐hydroxyapatite/chitosan/polyethylene glycol nanocomposite for bone tissue engineering

A novel nanocomposite involving nano‐hydroxyapatite/chitosan/polyethylene glycol (n‐HAP/CS/PEG) has been successfully synthesized via co‐precipitation approach at room temperature. The purpose to synthesize such nanocomposite is to search for an ideal analogue which may mimick the composition of natural bone for bone tissue engineering with respect to suitable biocompatibility, cytotoxicity and mechanical properties. The FTIR spectra of n‐HAP/CS and n‐HAP/CS/PEG scaffolds indicated significant intermolecular interaction between the various components of both the nanocomposites. The results of XRD, TEM and TGA/DTA suggested that the crystallinity and thermal stability of the n‐HAP/CS/PEG scaffold have decreased and increased respectively, relative to n‐HAP/CS scaffold. The comparison of SEM images of both the scaffolds indicated that the incorporation of PEG influenced the surface morphology while a better in‐vitro bioactivity has been observed in n‐HAP/CS/PEG than in n‐HAP/CS based on SBF study, referring a greater possibility for making direct bond to living bone if implanted. Furthermore, MTT assay revealed superior non‐toxic nature of n‐HAP/CS/PEG to murine fibroblast L929 cells as compared to n‐HAP/CS. The comparative swelling studies of n‐HAP/CS/PEG and n‐HAP/CS scaffolds revealed a better swelling rate for n‐HAP/CS/PEG. Also n‐HAP/CS/PEG showed higher mechanical strength relative to n‐HAP/CS supportive of bone tissue ingrowths. Copyright © 2014 John Wiley & Sons, Ltd.     

Injectable hydrogels for targeted delivering of therapeutic molecules for tissue engineering and disease treatment

Hydrogels are cross‐linked three‐dimensional polymeric networks that play a vital role in solving the pharmacological and clinical limitations of the existing systems due to their unique physical properties such as affinity for biological fluids, tunable porous nature, high water content, ease of preparation, flexibility, and biocompatibility. Hydrogel also mimics the living natural tissue, which opens several opportunities for its use in biomedical areas. Injectable hydrogel allows temporal control and exceptional spatial arrangements and can offset hitches with established hydrogel‐based drug delivery systems. Here, we review the recent development of injectable hydrogels and their significance in the delivery of therapeutics such as cells, genes, and drug molecules and how these innovatory systems can complement the current delivery systems.     

Rheological properties of cross-linked hyaluronan-gelatin hydrogels for tissue engineering

Hydrogels that mimic the natural extracellular matrix (ECM) are used in three-dimensional cell culture, cell therapy, and tissue engineering. A semi-synthetic ECM based on cross-linked hyaluronana offers experimental control of both composition and gel stiffness. The mechanical properties of the ECM in part determine the ultimate cell phenotype. We now describe a rheological study of synthetic ECM hydrogels with storage shear moduli that span three orders of magnitude, from 11 to 3 500 Pa, a range important for engineering of soft tissues. The concentration of the chemically modified HA and the cross-linking density were the main determinants of gel stiffness. Increase in the ratio of thiol-modified gelatin reduced gel stiffness by diluting the effective concentration of the HA component.     

Preparation and modification of collagen-based porous scaffold for tissue engineering

In the effort to generate cartilage tissues using mesenchymal stem cells, porous scaffolds with prescribed biomechanical properties were prepared. Scaffolds with interconnected pores were prepared via lyophilisation of frozen hydrogels made from collagen modified with chitosan nanofibres, hyaluronic acid, copolymers based on poly(ethylene glycol) (PEG), poly(lactic-co-glycolic acid) (PLGA), and itaconic acid (ITA), and hydroxyapatite nanoparticles. The modified collagen compositions were cross-linked using N-(3-dimethylamino propyl)-N′-ethylcarbodiimide hydrochloride (EDC) combined with N-hydroxysuccinimide (NHS) in water solution. Basic physicochemical and mechanical properties were measured and an attempt to relate these properties to the molecular and supermolecular structure of the modified collagen compositions was carried out. Scaffolds containing hydrophilic chitosan nanofibres showed the highest swelling ratio (SR = 20–25) of all the materials investigated, while collagen modified with an amphiphilic PLGA-PEG-PLGA copolymer or functionalised with ITA exhibited the lowest swelling ratio (SR = 5–8). The best resistance to hydrolytic degradation was obtained for hydroxyapatite containing scaffolds. On the other hand, the fastest degradation rate was observed for synthetic copolymer-containing scaffolds. The results showed that the addition of hydroxyapatite or hyaluronic acid to the collagen matrix increases the rigidity in comparison to the collagen-chitosan scaffold. Collagen scaffold modified with hyaluronic acid presented reduced deformation at break while the presence of hydroxypatatite enhanced the scaffold deformation under tensile loading. The tensile elastic modulus of chitosan nanofibre collagen scaffold was the lowest but closest to the articular cartilage; however, the strength and deformation to failure increased up to 200 %. Presented at the 1st Bratislava Young Polymer Scientists Workshop, Bratislava, 20–23 August 2007.     

A reinforced nanofibrous patch with biomimetic mechanical properties and chondroinductive effect for rotator cuff tissue engineering

Patch augmented surgery has been a feasible technique for rotator cuff repair. An ideal rotator cuff tissue engineering patch should have proper mechanical properties to match the native tendons and sufficient biological effect to promote tendon-bone healing. In this study, kartogenin (KGN)-grafted poly (ether-ester-urethane)urea/gelatin composite nanofibrous patches (PEEUU-GEL-KGN) were fabricated via electrospinning process followed by crosslinking of GEL and covalent grafting of KGN. The optimized PEEUU-GEL-KGN nanofibrous patches exhibited biomimetic mechanical properties, including sufficient tensile strength, non-linear stress-strain profiles, and remarkable elasticity and cyclical properties. In vitro investigations revealed that the patches possessed outstanding biocompatibility and performed a sustained release of KGN for a long time. Modification with GEL and KGN significantly improved hydrophilicity of the patches, promoted the adhesion, spreading, and proliferation of mesenchymal stem cells and upregulated the expression of cartilage-related genes. In vivo studies demonstrated that the implanted PEEUU-GEL-KGN patches effectively improved the tissue cellularity and collagen alignment, accelerated the fibrocartilage regeneration, augmented the biomechanical strength of the repaired enthesis, and reinforced the fixing of the tendon to the bone. Overall, the PEEUU-GEL-KGN patches enhanced tendon-bone healing and resisted rotator cuff re-tear. Therefore, the PEEUU-GEL-KGN patch is a highly promising candidate for rotator cuff tissue engineering.     

Microrobotics and MEMS-based fabrication techniques for scaffold-based tissue engineering

Scaffold based tissue engineering strategies use cells, biomolecules and a scaffold to promote the repair and regeneration of tissues. Although scaffold-based tissue engineering approaches are being actively developed, most are still experimental, and it is not yet clear what defines an ideal scaffold/cell construct. Solid free form fabrication (SFF) techniques can precisely control matrix architecture (size, shape, interconnectivity, branching, geometry and orientation). The SFF methods enable the fabrication of scaffolds with various designs and material compositions, thus providing a control of mechanical properties, biological effects and degradation kinetics. This paper reviews the application of micro-robotics and MEMS-based fabrication techniques for scaffold design and fabrication. It also presents a novel robotic technique to fabricate scaffold/cell constructs for tissue engineering by the assembly of microscopic building blocks.