Gyroid polylactic acid (PLA) scaffolds with different unit cell sizes of 2 mm (G2), 2.5 mm (G25), and 3 mm (G3) were fabricated via fused deposition modeling for bone tissue engineering ...applications. The porosity of the PLA scaffolds ranged from 86% to 90%. The structural anisotropy value of the scaffolds was 3.80, 2.00, and 1.04 for G2, G25, and G3, respectively. Compressive test results indicated that both the dense PLA and porous PLA scaffolds showed elastic-plastic deformation behavior in both building and transverse directions. The compressive elastic modulus and yield strength of the scaffolds were 118–180 MPa and 2–8 MPa in the building direction and 106–138 MPa and 2.5–6.0 MPa in the transverse direction, respectively. The tensile elastic modulus and yield strength were 51–63 MPa and 1.5–4.5 MPa in the building direction and 11–17 MPa and 1–5 MPa in the transverse direction, respectively. The gyroid PLA scaffolds showed significantly higher values for compressive strength (up to three times) compared to other gyroid structures reported in the literature. The PLA scaffolds can be anticipated as promising scaffold biomaterials for bone tissue engineering applications by virtue of their bone-mimicking porous structure and good mechanical properties.
•PLA gyroid scaffolds with three different unit cell sizes were manufactured by fused deposition modeling.•A well-interconnected porous structure with an open porosity of ~90% was achieved.•Higher mechanical strength compared to other TPMS structures manufactured by fused deposition modeling.•The mechanical properties of the PLA scaffolds are close to those of natural cancellous bone.
The fabricated multifunctional composite PCMs possesses high energy storage density, excellent light-to-thermal conversion and electro-to-thermal conversion effect.
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•The HDPE/CNTs ...porous scaffolds were successfully fabricated via sacrificial template method.•HDPE/CNTs/PW-3:7 obtained possesses high melting enthalpy (153.95 J/g).•The thermal conductivity and electrical conductivity of HDPE/CNTs/PW-3:7 are increased greatly.•HDPE/CNTs/PW-3:7 possesses huge potential in the field of multifunctional thermal energy storage.
The risk of leakage and low thermal conductivity severely hinder the wide application of phase change materials (PCMs). In this work, the high-density polyethylene/carbon nanotubes (HDPE/CNTs) porous scaffolds were successfully fabricated via a sacrificial template method followed by the general melt blending and water solvent etching. Subsequently, a series of paraffin wax HDPE/CNTs/PW composite PCMs were obtained combined with the simple vacuum impregnation method. The obtained HDPE/CNTs porous scaffolds can effectively avoid the leakage of PW, meanwhile, the thermal conductivity and electrical conductivity of HDPE/CNTs/PW-3:7 are increased by 2.94 times and 13 orders of magnitude compared with the HDPE/PW-3:7 respectively, also, it exhibits high phase change enthalpy (153.95 J/g for melting enthalpy and 152.82 J/g for crystallization enthalpy). From the above perspectives, the HDPE/CNTs/PW-3:7 has promising potential value in the application of light-to-thermal conversion, electro-to-thermal conversion and thermal energy storage.
In this study, a conventional technique of porous preparation was used to improve the constructive capability of direct ink writing on microstructures, and the hierarchically porous scaffolds were ...successfully prepared by 3D gel printing (3DGP). Micron-sized hydroxyapatite (HA) was coated with tricalcium phosphate (TCP) nanopowders synthesized by chemical co-precipitation to form biphasic calcium phosphate (BCP). The random structure of concave micropores was achieved by filling the BCP slurry with PMMA microspheres while successfully controlling the internal porosity of printed filaments. The results showed that the three-stage porous structure was successfully constructed, i.e., macroscopic pores of 1.50–2.00 mm, spherical micropores of 100–200 µm, and inter-powder interstices of 1.00–10.00 µm. Nano-TCP coated micron-HA powders improved the sintering activity of BCP particles. The compressive strength and porosity of the scaffolds sintered at 1400 °C were 2.78 MPa and 84.98%. The hierarchically porous BCP scaffolds had bright applications in bone tissue engineering.
Magnesium (Mg) plays an important role in controlling bone apatite structure and density and is a potential bioactive material in repairing critical‐sized bone defects. In this study, we aimed to ...evaluate the effect of adding NanoMgO to polycaprolactone/beta‐tricalcium phosphate (PCL/β‐TCP) scaffolds on bone regeneration. Novel 3D‐printed porous PCL/β‐TCP composite scaffolds containing 10% nanoMgO were fabricated by fused deposition modeling (FDM) and compared with PCL/β‐TCP (1:1) scaffolds (control). The morphology and physicochemical properties of the scaffolds were characterized by ATR‐FTIR, XRD, scanning electron microscope‐energy dispersive X‐ray analysis (SEM–EDX), transmission‐electron‐microscopy (TEM), water contact angle, and compressive strength tests and correlated to its cytocompatibility and osteogenic capacity in‐vitro. To evaluate in‐vivo osteogenic capacity, bone‐marrow‐derived stem cell (BMSC)‐loaded scaffolds were implanted into 8 mm rat critical‐sized calvarial defects for 12 weeks. The hydrophilic scaffolds showed 50% porosity (pore size = 504 μm). MgO nanoparticles (91.5 ± 27.6 nm) were homogenously dispersed and did not adversely affect BMSCs' viability and differentiation. Magnesium significantly increased elastic modulus, pH, and degradation. New bone formation (NBF) in Micro‐CT was 30.16 ± 0.31% and 23.56 ± 1.76% in PCL/β‐TCP/nanoMgO scaffolds with and without BMSCs respectively, and 19.38 ± 2.15% and 15.75 ± 2.24% in PCL/β‐TCP scaffolds with and without BMSCs respectively. Angiogenesis was least remarkable in PCL/β‐TCP compared with other groups (p < .05). Our results suggest that the PCL/β‐TCP/nanoMgO scaffold is a more suitable bone substitute compared to PCL/β‐TCP in critical‐sized calvarial defects.
A series of porous scaffolds of piezoelectric ceramic barium titanate (BaTiO3) were successfully fabricated by Digital Light Processing (DLP) 3D printing technology in this work. To obtain a ...high-precision and high-purity sample, the debinding sintering profile was explored and the optimal parameters were determined as 1425 °C for 2h. With the increase of scaffolds porosity from 10% to 90%, the compressive strength and piezoelectric coefficient (d33) decreased gradually. The empirical formulas about the mechanical and piezoelectric properties were obtained by adjusting BaTiO3 ceramics with different porosity. In addition, the distribution of potential and stress under 100 MPa pressure were studied by the finite element method (FEM).
In this study, three types of porous gelatin/HAp composite-based scaffolds were prepared and their microstructure, mechanical property, and in vitro biocompatibility were evaluated. FD-gelatin/HAp ...scaffolds were prepared via a conventional freeze-drying (FD) method, while DCPD-bound gelatin/HAp (DCPD-gelatin/HAp) microsphere scaffolds and HAp-bound gelatin/HAp (HAp-gelatin/HAp) microsphere scaffolds were prepared via the combined method of emulsion technique and novel microsphere-packing method. It was found that the microstructure and mechanical property of porous gelatin/HAp scaffolds were highly dependent on the preparation method and type of scaffolds. FD-gelatin/HAp scaffolds had few pores with a comparatively flat surface and had a compressive strength was 24 ± 1 MPa. DCPD-gelatin/HAp microsphere scaffolds had a porous structure with the average pore size of 121 ± 12 μm and had the compressive strength of 50 ± 3 MPa. HAp-gelatin/HAp microsphere scaffolds also had a porous structure with the average pore size of 190 ± 26 μm and had the compressive strength of 17 ± 4 MPa. In vitro biocompatibility was performed by culturing the osteoblast-like MC3T3-E1 cells with all types of scaffolds. The results showed that all types of scaffolds were biocompatible to support cell attachment and proliferation. However, a significant difference in cell behavior was clearly observed. Most cells were grown on the surface of FD-gelatin/HAp scaffolds due to the lack of the porous structure, while those were grown on the surface and inside the pore of both DCPD-gelatin/HAp microsphere scaffolds and HAp-gelatin/HAp microsphere scaffolds due to the presence of the porous structure. Thus, the porous gelatin/HAp microsphere-based scaffolds have a potential as novel bone tissue regenerative materials.
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•Melatonin albumin nanoparticle (MNP) embedded polycaprolactone scaffold fabricated.•Controlled release observed for 22 days.•MNP concentration modulated melatonin release from ...scaffolds.•Significant elevation in Glycosaminoglycans - Human chondrocytes.•Diffusion & dissolution mechanism of drug release – mathematical models.
The therapeutic potential of an engineered cartilage construct can be enhanced by sustained delivery of chondrogenic drug like melatonin from 3D porous scaffolds embedded with melatonin loaded bovine serum albumin nanoparticles (MNP). In this study, MNP was synthesized and loaded into polycaprolactone (PCL) scaffolds. 12 % (w/v) and 10 % (w/v) PCL scaffolds were fabricated with different concentrations of MNP. X- ray diffraction and Raman analysis of MNP and scaffolds revealed amorphization of melatonin which is highly desired in drug delivery applications. Additionally, Fourier Transform Infrared spectroscopic analysis confirmed the drug to be chemically inert to fabrication process. Field emission scanning electron microscopic analysis suggested highly interlinked porous scaffold (diameter 50 μm – 300 μm) and MNP diameters in the range of 110−200 nm. Importantly, UV spectrophotometric analysis showed that all groups of scaffolds showed sustained release for 21 days, wherein MNP concentration had an influence on release behaviour of melatonin from scaffolds. Drug release kinetics studied using mathematical models revealed, diffusion and dissolution mechanism of release. Furthermore, in vitro evaluation of MNP loaded scaffolds with Human chondrocytes for 21 days increased glycosaminoglycans deposition significantly. In brief, sustained release of melatonin from polycaprolactone scaffolds increased the therapeutic potential of the engineered construct.
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•Novel enhanced porous scaffolds based on triply periodic minimal surface are designed and fabricated.•The manufacturability, mechanical and biological properties of fabricated ...scaffolds are investigated.•Mechanical properties and permeability of scaffolds are in the range of human bones.•The designed scaffolds exhibit good biocompatibility according to in vitro studies.
Triply periodic minimal surfaces (TPMS) - based porous structures have been universally adopted for mimicking the properties of bone scaffolds due to their interconnected geometries with smooth surfaces and controllable pores. To further increase the versatility and controllability, an enhanced porous scaffold based on TPMS is proposed. The enhanced pores with different sizes are designed onto three types of TPMS-based scaffolds and then additively manufactured through laser powder bed fusion (LPBF). To investigate the manufacturability, various approaches are used and the results confirm that morphological features of printed samples are identical to the designed ones. As for mechanical properties, the results from the compression tests show that the elastic modulus and compressive strength of enhanced porous scaffolds are 2.0 GPa to 5.1 GPa and 86.7 MPa to 264.2 MPa respectively, which are all in the range of human bones. In terms of permeability, both experiments and simulation indicate that the designed scaffolds have 40%−150% improvement compared to scaffolds without enhanced pores. The biocompatibility of the scaffolds is further verified by in vitro studies. The results demonstrate the suitability of the proposed enhanced porous scaffolds for bone implants, and it will facilitate the design of more effective porous materials.
Hierarchical structures with tailored macro/micro-porosity architecture play an important role in bone tissue regeneration. In 3D printing process, the printing ink formulation will influence on the ...ceramic macro and micro porous architectures. In this paper, HA powders of nano-sized grains (NP) with diameters of 30–50 nm, air jet milling powders (AP) with diameters of 10–30 μm, and spherical powder (SP) with diameters of 10–50 μm, were used as the initial printing materials in the printing ink formulations. The viscosity and the rheological behavior of printing inks were studied. The microstructure and morphology of the printed scaffold were observed and the mechanical properties of different types of scaffolds were tested. The results showed that the initial printing materials would influence on printing performance, both of the AP and SP inks may print porous scaffolds successfully. However, NP printing inks exhibited dramatic shrinkage and it is not suitable for 3D printing of bioceramics. The printing ink formulation also have effects on the ceramic macro and micro porous architectures and mechanical properties. The maximum compressive strength of SPS were 5.5 MPa, 3.2 MPa and 0.9 MPa with porosities of 60%, 70% and 80%, respectively. As the macroporosity decreases, the mechanical properties of the material would drop dramatically. With the same porosities, the compressive strength of APS were slightly higher than that of the SPS specimens.
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