The majority of synthetic polymers used in 3 D printing are not designed to promote specific cellular interactions and hence possess limited bioactivity. Most of the strategies proposed to overcome this limitation demand multiple and expensive processing steps. This study aimed to evaluate the surface modification of 3D-printed poly(lactic acid) (PLA) scaffolds with polydopamine (PDA) coating as an alternative strategy to enhance their bioactivity and to facilitate the immobilization of type I collagen (COL I) onto the implant surface. Physical and chemical properties of PLA scaffolds coated with PDA, COL I or both were evaluated. The response of porcine bone marrow stem cells (MSCs) to the coatings was also investigated. The PDA layer improved COL immobilization onto the surface of the PLA scaffolds by 92%. The combination of PDA and COL functionalizations provided the best conditions for early-stage (<7 days) cell response. In addition, the PDA plus COL surface facilitated the robust deposition of extracellular matrix in the first 14 days of cell culture. Although the behavior of the MSCs appeared to be similar for both uncoated PLA and PDA plus COL-coated scaffolds by day 21, cells seeded onto PDA plus COL scaffolds produced substantially higher amounts of alkaline phosphatase. These results indicate that the osteoinductivity of 3D-printed PLA scaffolds can be enhanced by PDA and type I collagen coatings. This surface modification of polymeric scaffolds represents a promising strategy for bone tissue engineering. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018.
This study aimed to assess the response of 3D printed PLA scaffolds biomimetically coated with apatite on human primary osteoblast spheroids and evaluate the biological response to its association with Bone Morphogenetic Protein 2 (rhBMP-2) in rat calvaria. PLA scaffolds were produced via 3D printing, soaked in simulated body fluid (SBF) solution, and characterized by physical-chemical, morphological, and mechanical properties. The in vitro biological response was assessed with human primary osteoblast (HOb) spheroids. The in vivo analysis was conducted through the implantation of 3D printed PLA scaffolds either alone, covered by apatite (PLA-CaP) or PLA-CaP loaded with rhBMP-2 (PLA-CaP+rhBMP-2) on critical-sized defects (8 mm) of rat calvaria. Increased cell adhesion and in vitro release of growth factors (PDGF, bFGF, VEGF) was observed for PLA-CaP scaffolds when pre-treated with FBS. PLA-CaP+BMP2 presented higher values of newly formed bone (NFB) than other groups at all experimental periods (p&lt;0.05), attaining 44.85% of NFB after 6 months. These findings indicate that functionalization of PLA scaffolds with biomimetic apatite can improve its biological properties in the presence of complex biological media. Its association with BMP2 may enhance bone repair, suggesting this strategy as a promising candidate for bone tissue engineering.
This study aimed to assess the response of 3D printed polylactic acid (PLA) scaffolds biomimetically coated with apatite on human primary osteoblast (HOb) spheroids and evaluate the biological response to its association with Bone Morphogenetic Protein 2 (rhBMP-2) in rat calvaria. PLA scaffolds were produced via 3D printing, soaked in simulated body fluid (SBF) solution to promote apatite deposition, and characterized by physical-chemical, morphological, and mechanical properties. PLA-CaP scaffolds with interconnected porous and mechanical properties suitable for bone repairing were produced with reproducibility. The in vitro biological response was assessed with human primary osteoblast spheroids. Increased cell adhesion and the rise of in vitro release of growth factors (Platelet-Derived Growth Factor (PDGF), Basic Fibroblast Growth Factor (bFGF), Vascular Endothelial Growth Factor (VEGF) was observed for PLA-CaP scaffolds, when pre-treated with fetal bovine serum (FBS). This pre-treatment with FBS was done in a way to enhance the adsorption of serum proteins, increasing the number of bioactive sites on the surface of scaffolds, and to partially mimic in vivo interactions. The in vivo analysis was conducted through the implantation of 3D printed PLA scaffolds either alone, coated with apatite (PLA-CaP) or PLA-CaP loaded with rhBMP-2 on critical-sized defects (8 mm) of rat calvaria. PLA-CaP+rhBMP2 presented higher values of newly formed bone (NFB) than other groups at all in vivo experimental periods (p < 0.05), attaining 44.85% of NFB after six months. These findings indicated two new potential candidates as alternatives to autogenous bone grafts for long-term treatment: (i) 3D-printed PLA-CaP scaffold associated with spheroids, since it can reduce the time of repair in situ by expression of biomolecules and growth factors; and (ii) 3D-printed PLA-CaP functionalized rhBMP2 scaffold, a biocompatible, bioactive biomaterial, with osteoconductivity and osteoinductivity.
Polyhydroxybutyrate and chitosan have been studied as materials for drug delivery systems (DDSs) due to their biodegradability and biocompatibility. The aim of this work was to produce amphiphilic polyhydroxybutyrate/chitosan matrices that form porous structures (scaffolds) after swelling in water and arnica extract. The matrices were analyzed by TGA, SEM, XDR, DSC, and FTIR. Thin plate spline interpolation method (TPSIM) was used to predict the swelling of the matrices generating three‐dimensional data fitted, showing the influence of time and concentration variables on both fluids absorption. Polyhydroxybutyrate/chitosan samples containing 60 wt % (weight percent) of chitosan formed a porous structure as they were submitted to arnica loading, and the obtained device was able to deliver arnica in physiological medium. Thus, the produced matrices have a strong potential to perform both as scaffolds and DDS © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47838.
In additive manufacturing, determining the correct deposition parameters is very important as this can affect the final properties of printed parts. Since there is no agreement on the optimal level of the different printing parameters in reported results, this work evaluated the influences of layer thickness (LT), deposition speed (DS) and printing direction (PD) on tensile properties and dimensional accuracy of poly(lactic acid) 3D parts evaluating the possibility of using thin plate spline interpolation method (TPSIM) of data, a new approach, in determination of optimized fused deposition modeling process parameters. It was observed that the use of low levels of LT (0.10 mm), DS (40 mm/s), and PD (0°) provided parts with higher mechanical strength and dimensional performance. Denser parts showed lower anisotropy effect and, consequently, best tensile properties were obtained. TPSIM was an efficient mathematical analysis and well fitted results of predicted and experimental results.
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