Fabrication and characterization of PCL/gelatin composite nanofibrous scaffold for tissue engineering applications by electrospinning method

In the present study, we have fabricated a ternary composite nanofibrous scaffold from PCL/gelatin/chitosan, by electrospinning technique, using a solvent system—chloroform/methanol for polycaprolactone (PCL) and acetic acid for gelatin and chitosan, for tissue engineering applications. Field emission scanning electron microscopy (FE-SEM) was used to investigate the fiber morphology of the scaffold and it was found that the fiber morphology was influenced by the concentrations of PCL, gelatin, and chitosan in polymer solution during electrospinning. X-ray diffraction, Fourier transform infrared, and thermogravimetric (TG) analysis results showed some interactions among the molecules of PCL, gelatin, and chitosan within the scaffold. In-vitro cell culture studies were done by seeding L929 mouse fibroblasts on fabricated composite scaffold, which confirmed the cell viability, high cell proliferation rate, and cell adhesion on composite scaffold as indicated by MTT assay, DNA quantification, and FE-SEM analysis of cell-scaffold construct. Thus, the ternary composite scaffold made from the combination of PCL (synthetic polymer), gelatin, and chitosan (natural polymer) may find potential application in tissue engineering.

Surface modification of nanofibrous polycaprolactone/gelatin composite scaffold by collagen type I grafting for skin tissue engineering

Facile fabrication of spongy nanofibrous scaffold for tissue engineering applications

Albumin-induced exfoliation of molybdenum disulfide nanosheets incorporated polycaprolactone/zein composite nanofibers for bone tissue regeneration.

Performance of polycaprolactone/polyethylene terephthalate nanofiber scaffolds in vascular tissue engineering: Structural, mechanical, in vitro, and in vivo evaluation

Multifunctional nanofibrous scaffolds for effective bone tissue engineering (BTE) application must incorporate factors to promote neovascularization and tissue regeneration. In this study, silica-coated gold nanoparticles Au(SiO2) were tested for their ability to promote differentiation of human mesenchymal stem cells (hMSCs) into osteoblasts. Biocompatible poly-ε-caprolactone (PCL), PCL/silk fibroin (SF) and PCL/SF/Au(SiO2) loaded nanofibrous scaffolds were first fabricated by an electrospinning method. Electrospun nanofibrous scaffolds were characterized for fiber architecture, porosity, pore size distribution, fiber wettability and the relevant mechanical properties using field emission scanning electron microscopy (FESEM), porosimetry, determination of water contact angle, measurements by a surface analyzer and tabletop tensile-tester measurements. FESEM images of the scaffolds revealed beadless, porous, uniform fibers with diameters in the range of 164 ± 18.65 nm to 215 ± 32.12 nm and porosity of around 88–92% and pore size distribution around 1.45–2.35 µm. Following hMSCs were cultured on the composite scaffolds. Cell-scaffold interaction, morphology and proliferation of were analyzed by FESEM analysis, MTS (3-(4,5-dimethyl thiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt) and CMFDA (5-choromethyl fluorescein acetate) dye assays. Osteogenic differentiation of MSCs into osteogenic cells were determined by alkaline phosphatase (ALP) activity, mineralization by alizarin red S (ARS) staining and osteocalcin expression by immunofluorescence staining. The results revealed that the addition of SF and Au(SiO2) to PCL scaffolds enhanced the mechanical strength, interconnecting porous structure and surface roughness of the scaffolds. This, in turn, led to successful osteogenic differentiation of hMSCs with improved cell adhesion, proliferation, differentiation, mineralization and expression of pro-osteogenic cellular proteins. This provides huge support for Au(SiO2) as a suitable material in BTE.

Nanofibrous composite scaffolds of poly(ester amides) with tunable physicochemical and degradation properties

Recently electrospun scaffolds show excellent response in cell adhesion, growth, and tissue healing in comparison with other techniques. So in this study, PCL and PCL/DCPD scaffolds were designed and prepared with electrospinning. The electrospun scaffolds were characterized by scanning electron microscope with X-ray elemental analysis, atomic force microcopy, differential scanning calorimetry, and contact angle analysis for optimizing the effective parameters. Fiber formation with uniform diameter and bead-free structure was obtained. Scaffold surface roughness increased from 100nm for PCL to 440nm for PCL/DCPD. DSC analysis showed the effects of DCPD on thermal stability of composite scaffold and the results of contact angle evaluation indicate improved hydrophilicity and ability of water absorption of PCL/DCPD composite fibers as compared to PCL fibers. MTT assay indicated lack of toxicity for human gingival fibroblast (HGF) cells after cell seeding on scaffold. Also, the composite scaffold can improve cell viability by helping their growth on its surface. So it can be concluded that by engineering the electrospinning parameters we can fabricate a PCL/DCPD composite scaffold for tissue engineering applications.

Objective Poly(ε-caprolactone) (PCL) has considerable mechanical and biological properties that make it a good candidate for tissue engineering applications. PCL alongside proteins and polysaccharides, like gelatin (GEL) and chondroitin sulphate (CS), can be used to fabricate composite scaffolds that provide mechanical and biological requirements for skin tissue engineering scaffolds. The aim of this study was fabricating novel composite nanofibrous scaffold containing various ratios of GEL/CS and PCL using co-electrospinning process. Materials and Methods In this experimental study, PCL mixed with a GEL/CS blend has limitations in miscibility and the lack of a common solvent. Here, we electrospun PCL and GEL/CS coincide separately on the same drum by using different nozzles to create composite nanofibrous scaffolds with different ratios (2:1, 1:1 and 1:2) of GEL to CS- PCL, and we mixed them at the micro/nanoscale. Morphology, porosity, phosphate-buffered saline (PBS) absorption, chemical structure, mechanical property and in vitro bioactivity of the prepared composite scaffolds were analysed. Results Scanning electron microscopy (SEM) images showed beadless nanofibres at all ratios of GEL to CS-PCL. The composite scaffolds (2:1, 1:1 and 1:2) had increased porosity compared to the PCL nanofibrous scaffolds, in addition to a significant increase in PBS absorption. The mechanical properties of the composite scaffolds were investigated under different conditions. The results demonstrated that all of the composite specimens had better strength when compared with the GEL/CS nanofibres. The increase in PCL ratio led to an increase in tensile strength of the nanofibres. Human dermal fibroblasts (HDF) were cultured on the fabricated composite scaffolds and evaluated by 3-(4,5-dimethylthiazol- 2-yl)-5-(3 carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) analysis and SEM. The results showed the bioactivity of these nanofibres and the potential for these scaffolds to be used for skin tissue engineering applications. ConclusionThe fabricated co-electrospun composite scaffolds had higher porosity and PBS absorption in comparison with the PCL nanofibrous scaffolds, in addition to significant improvements in mechanical properties under wet and dry conditions compared to the GEL/CS scaffold.

Starch based nanofibrous scaffolds for wound healing applications

The development of tissue engineering provides a novel approach to restore bodily functions by seeding cells onto various scaffolds. Although chitosan is a non-toxic biomaterial, its cytocompatibility still needs to be improved. In this study, gamma-poly(glutamic acid) (γ-PGA) was blended with chitosan to prepare both dense and porous γ-PGA/chitosan composite scaffolds using the freeze-gelation method. This method saves time and energy, and there is less residual solvent. SEM micrographs demonstrated that an interconnected porous structure with a pore size of 30-100 micrometer was present in the scaffolds. The hydrophilicity of the scaffolds was significantly improved by γ-PGA. Further, the tensile strength of the porous γ-PGA-modified chitosan scaffolds was about 50% higher than that of the unmodified chitosan scaffolds. The number of osteosarcoma cells cultured on the γ-PGA-modified scaffolds was about double that on the unmodified chitosan scaffolds on day 7. Thus, the γ-PGA/chitosan composite scaffolds, due to their better hydrophilicity, cytocompatibility, and mechanical strength, are very promising biomaterials for tissue engineering applications. We further demonstrated the use of glutamic acid to enhance the tensile strength of chitosan-based composite porous scaffolds. The tensile strength of the chitosan/collagen composite scaffolds was increased by more than 2 times with the addition of glutamic acids as cross-linking bridges. We found that the hepatocytes attached and proliferated well on these composite scaffolds, demonstrating that the glutamic acid modified-chitosan composite scaffolds are also potential tissue engineering biomaterials.

Scaffolds for bone tissue engineering require considerable mechanical strength to repair damaged bone defects. In this study, we designed and developed mechanically competent composite shape memory triphasic bone scaffolds using fused filament fabrication (FFF) three dimensional (3D) printing. Wollastonite particles (WP) were incorporated into the poly lactic acid (PLA)/polycaprolactone (PCL) matrix as a reinforcing agent (up to 40 wt%) to harness osteoconductive and load-bearing properties from the 3D printed scaffolds. PCL as a minor phase (20 wt%) was added to enhance the toughening effect and induce the shape memory effect in the triphasic composite scaffolds. The 3D-printed composite scaffolds were studied for morphological, thermal, and mechanical properties, in vitro degradation, biocompatibility, and shape memory behaviour. The composite scaffold had interconnected pores of 550 μm, porosity of more than 50%, and appreciable compressive strength (∼50 MPa), which was over 90% greater than that of the pristine PLA scaffolds. The flexural strength was improved by 140% for 40 wt% of WP loading. The inclusion of WP did not affect the thermal property of the scaffolds; however, the inclusion of PCL reduced the thermal stability. An accelerated in vitro degradation was observed for WP incorporated composite scaffolds compared to pristine PLA scaffolds. The inclusion of WP improved the hydrophilic property of the scaffolds, and the result was significant for 40 wt% WP incorporated composite scaffolds having a water contact angle of 49.61°. The triphasic scaffold exhibited excellent shape recovery properties with a shape recovery ratio of ∼84%. These scaffolds were studied for their protein adsorption, cell proliferation, and bone mineralization potential. The incorporation of WP reduced the protein adsorption capacity of the composite scaffolds. The scaffold did not leach any toxic substance and demonstrated good cell viability, indicating its biocompatibility and growth-promoting behavior. The osteogenic potential of the WP incorporated scaffolds was observed in MC3T3-E1 cells, revealing early mineralization in pre-osteoblast cells cultured in different WP incorporated composite scaffolds. These results suggest that 3D-printed WP reinforced PLA/PCL composite bioactive scaffolds are promising for load bearing bone defect repair.

To address the slow degradation rate of polycaprolactone (PCL)-based scaffolds for tissue engineering applications, particularly when rapid removal is needed to mitigate unwanted immune reactions, lipase has been employed to accelerate scaffold degradation. However, it remains unclear whether the presence of other polymeric materials in PCL composites, particularly those that are hydrophilic, would affect the degradation process. In this study, discs of composite materials composed of PCL blended with selected commonly used additives (gelatin, collagen, and poly(lactic-co-glycolic acid)) (PLGA) at two weight ratios (3:1 and 2:1, w/w) were prepared and then studied for their degradation kinetics in response to exogenously added lipase. Time-dependent degradation of composite discs was closely monitored by mass loss and morphology change. Notably, the inclusion of gelatin, collagen, or PLGA into PCL affects PCL degradation, showing different degradation rate constants. During exposure to lipase, the composite materials exhibited distinct morphology changes, which were closely correlated with their wettability due to the hydrophilic additives. Furthermore, lipase-enabled PCL degradation of cell-laden composite scaffolds also affected prolonged cell adhesion to the scaffolds in a concentration-dependent manner. In summary, a detailed understanding of lipase-aided degradation of PCL composite materials would offer the opportunity to better design scaffolds for applications in tissue regeneration.

Tissue engineering scaffolds as three-dimensional substrates may serve as ideal templates for tissue regeneration by simulating the structure of the extracellular matrix (ECM). Many biodegradable synthetic polymers, either hydrophobic, like Poly-ε-caprolactone (PCL), or hydrophilic, like Poly(Vinyl Alcohol) (PVA), are widely used as candidate bioactive materials for fabricating tissue engineering scaffolds. However, a combination of good cytocompatibility of hydrophilic polymers with good biomechanical performance of hydrophobic polymers could be beneficial for the in vivo performance of the scaffolds. In this study, we aimed to fabricate biodegradable fibrous scaffolds by combining the properties of hydrophobic PCL with those of hydrophilic PVA and evaluate their properties in comparison with pristine PCL scaffolds. Therefore, single-layered PCL scaffolds, sequential tri-layered (PVA/PCL/PVA), and core-shell (PVA as shell and PCL as core) composite scaffolds were developed utilizing the electrospinning technique. The material structural and biomechanical properties of the electrospun scaffolds, before and after their hydrolytic degradation over a seven-month period following storage in phosphate-buffered saline (PBS) at 37 °C, were comprehensively compared. In addition, human embryonic kidney cells (HEK-293) were cultured on the scaffolds to investigate potential cell attachment, infiltration, and proliferation. The results demonstrated the long-term efficacy of core-shell biodegradable fibrous scaffolds in comparison to single-layers PCL and tri-layers PVA/PCL/PVA, not only due to its superior morphological characteristics and mechanical properties, but also due to its ability to promote homogeneous cell distribution and proliferation, without any external chemical or physical stimuli.Graphical

Synthetic polymers used in tissue engineering require functionalization with bioactive molecules to elicit specific physiological reactions. These additives must be homogeneously dispersed in order to achieve enhanced composite mechanical performance and uniform cellular response. This work demonstrates the use of a solvent-free powder processing technique to form osteoinductive scaffolds from cryomilled polycaprolactone (PCL) and tricalcium phosphate (TCP). Cryomilling is performed to achieve micrometer-sized distribution of PCL and reduce melt viscosity, thus improving TCP distribution and improving structural integrity. A breakthrough is achieved in the successful fabrication of 70 weight percentage of TCP into a continuous film structure. Following compaction and melting, PCL/TCP composite scaffolds are found to display uniform distribution of TCP throughout the PCL matrix regardless of composition. Homogeneous spatial distribution is also achieved in fabricated 3D scaffolds. When seeded onto powder-processed PCL/TCP films, mesenchymal stem cells are found to undergo robust and uniform osteogenic differentiation, indicating the potential application of this approach to biofunctionalize scaffolds for tissue engineering applications.