Biomineralization,strength and cytocompatibility improvement of bredigite scaffolds through doping/coating

Coprecipitation-derived, sacrificial polymeric (urethane) foam-fabricated bredigite (Ca₇MgSi₄O₁₆) scaffolds were processed by individual and combined treatments of fluoride doping and poly (lactic-co-glycolic acid) (PLGA) coating and then studied in terms of structure, mechanical strength, bioactivity and cell biocompatibility in vitro. According to scanning electron microscopy and Archimedes porosimetry, the geometrical characteristics of pores for all the scaffolds are in the appropriate range for hard tissue regeneration applications. The apatite-formation ability of the samples immersed in a simulated body fluid is improved by doping for both the bare and coated conditions, based on microscopic and energy-dispersive X-ray spectroscopic analyses. Both the treatments advantageously buffer physiological pH changes imposed due to the fast bioresorption of the ceramic. Also, the biodegradable PLGA coating typically enhances the compressive strength of the scaffolds, which is critical for bone tissue engineering. In accordance with the MTT assay on osteoblast-like cells (MG-63) cultures, both the processes individually enhance the cell viability, while the highest improvement is obtained for the combined application of them. It is finally concluded that fluoride doping and PLGA coating are impressive approaches to improve the bioperformance of bredigite-based scaffolds.     

Fabrication of bimodal porous PLGA scaffolds by supercritical CO2 foaming/particle leaching technique

Specific pore structure is a vital essential for scaffolds applied in tissue engineering. In this article, poly(lactide‐co‐glycolide) (PLGA) scaffolds with a bimodal pore structure including macropores and micropores to facilitate nutrient transfer and cell adhesion were fabricated by combining supercritical CO₂ (scCO₂) foaming with particle leaching technique. Three kinds of NaCl particles with different scales (i.e., 100–250, <75, <10 μm) were used as porogens, respectively. In particular, heterogeneous nucleation occurred to modify scCO₂ foaming/particle leaching process when NaCl submicron particles (<10 μm) were used as porogens. The observation of PLGA scaffolds gave a formation of micropores (pore size <10 μm) in the cellular walls of macropores (pore size around 100–300 μm) to present a bimodal pore structure. With different mass fractions of NaCl introduced, the porosity of PLGA scaffolds ranged from 68.4 ± 1.4 to 88.7 ± 0.4% for three NaCl porogens. The results of SEM, EDS, and in vitro cytotoxicity test of PLGA scaffolds showed that they had uniform structures and were compatible for cell proliferation with no toxicity. This novel scCO₂ foaming/particle leaching method was promising in tissue engineering due to its ability to fabricate scaffolds with precise pore structure and high porosity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43644.     

Fabrication,drug delivery kinetics and cell viability assay of PLGA-coated vancomycin-loaded silicate porous microspheres

Porous ceramic microspheres are a desirable substance for bone tissue reconstruction and delivery applications. This study focuses on Mg–Ca silicate microspheres encapsulated in biodegradable poly (lactic-co-glycolic acid) (PLGA) to serve as a biocompatible carrier for the controlled release of vancomycin hydrochloride. In this regard, diopside (MgCaSi₂O₆), bredigite (MgCa₇Si₄O₁₆), and akermanite (MgCa₂Si₂O₇) powders were synthesized by sol-gel and subsequent calcination methods. Then, porous akermanite, diopside and bredigite microspheres of 700–1000 μm in diameter were fabricated by using carbon porogen, droplet extrusion and sintering, then loaded with the drug and eventually coated with PLGA. The bare microspheres showed a considerable burst release mode of the drug into a physiological medium, whereas PLGA coating of the microspheres reduced the burst release level. To investigate effective mechanisms governing in the drug release from the carriers, the contribution of burst, degradation, and diffusion was analyzed by the sequential quadratic programming algorithm method. It was found that the relative contribution of diffusion to bioresorption is ranked as diopside > akermanite > bredigite, whereas PLGA coating dominates the diffusion mechanism. The dental pulp stem cells cytocompatibility MTT assay of the microspheres also showed that the drug loading deteriorates but PLGA coating improves the cell biocompatibility significantly. Comparatively, the biocompatibility of the PLGA-coated microspheres was ranked as akermanite > diopside > bredigite, as a result of a compromise between the release of the constituting ions of the ceramic carriers and vancomycin molecules. It was eventually concluded that PLGA-coated Mg–Ca silicate microspheres are promising candidates for drug-delivery bone tissue engineering and dental bone grafting applications.     

Sustained release of dexamethasone from drug‐loading PLGA scaffolds with specific pore structure fabricated by supercritical CO2 foaming

Inducing differentiation of bone marrow stem cells to generate new bone tissue is highly desirable by controlling the release of some osteoinductive or osteoconductive factors from porous scaffolds. In this study, dexamethasone was selected as a representative of small molecule drugs and dexamethasone‐loading porous poly(lactide‐co‐glycolide) (PLGA) scaffolds were successfully fabricated by supercritical CO₂ foaming. Scanning electron microscopy images showed that scaffolds had rough and relatively interconnected pores facilitating cells adhesion and growth. Specially, dexamethasone which was incorporated into PLGA matrix in a molecularly dispersed state could serve as a nucleation agent to be helpful for the formation of interconnected pores. Dexamethasone‐loading porous PLGA scaffolds exhibited sustained release profile, and the delivery of dexamethasone from porous scaffolds could last for up to 2 months. The cumulative released amount of dexamethasone was relevant with drug loading capacity (1.66%–2.95%) and pore structure of scaffolds; while the release behavior was anomalous (non‐Fickian) transport by fitting with the simple exponential equation, which had a diffusional exponent n higher than 0.5. It is feasible to fabricate drug‐loading porous scaffolds by supercritical CO₂ foaming with specific pore structure and sustained release profile, which can be well applied in bone tissue engineering. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46207.     

Formation of porous PLGA scaffolds by a combining method of thermally induced phase separation and porogen leaching

A novel method for the fabrication of porous poly(L -lactide-co-glycolide) (PLGA) scaffolds by combining thermally induced phase separation and porogen leaching is presented in this article. Big pores with about 75–400 μm diameters in the obtained scaffolds were generated by the porogen, sucrose particles, while small pores with diameters less than 20 μm induced via phase separation. Extraction of the solvent, chloroform by ethanol at cool temperatures could reduce the scaffold toxicity. Effects of PLGA concentration, freezing temperature, volume fraction of porogen, and introduction of β-tricalcium phosphate (β-TCP) on morphology, porosity, and compressive properties of the scaffolds were systematically discussed. Results showed that the size of small pores decreased by decreasing the polymer concentration and reducing the freezing temperature, whereas the interconnectivity of the scaffolds was improved by increasing the porogen fraction. The compressive modulus and strength were significantly lowered by increasing the scaffold porosity, that is, by increasing porogen fraction, or decreasing the polymer concentration, or reducing the freezing temperature. Addition of β-TCP into the scaffolds did not influence the compressive modulus significantly but tended to decrease the compressive strength. The obtained scaffolds with diverse pore sizes would be potentially used in bone tissue engineering. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of Fe3O4 concentration on 3D gel-printed Fe3O4/CaSiO3 composite scaffolds for bone engineering

In this study, porous calcium silicate (CaSiO₃) scaffolds were prepared by 3D gel-printing (3DGP) method and Fe₃O₄ water-based magnetic fluids (WMFs) were prepared by phacoemulsification compound chemical coprecipitation method. Fe₃O₄ WMFs were coated on CaSiO₃ scaffolds surface to prepare Fe₃O₄/CaSiO₃ composite scaffolds. The effect of WMFs with different Fe₃O₄ concentrations on porous CaSiO₃ scaffolds was studied. The composition and morphological characteristics of porous scaffolds were analyzed by using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis. The magnetic properties were tested by vibrating sample magnetometer (VSM). The stability of Fe₃O₄ WMFs coatings and the degradability of composite scaffolds were tested by immersing them in simulated body fluid (SBF). The results show that when Fe₃O₄ concentration was 5.4% (w/v), the composite scaffolds had the highest saturation magnetization of 69.6 emu/g and the best stability in dynamic SBF. It is obviously that Fe₃O₄ WMFs coatings can be used for bone tissue engineering scaffolds repairing.     

PLGA/SF blend scaffolds modified with plasmid complexes for enhancing proliferation of endothelial cells

Biomimetic scaffolds have been investigated for vascular tissue engineering for many years. However, the design of an ideal biodegradable vascular scaffold is still in progress. The optimization of poly(lactide-co-glycolide)/silk fibroin (PLGA/SF) blend composition was performed to provide the designed scaffolds with adequate mechanical properties and favorable biocompatibility for the intended application. By systematically varying the weight ratio of PLGA and SF, we could control fiber diameter and hydrophilicity as well as mechanical properties of the fibrous scaffolds. These scaffolds with a weight ratio of PLGA/SF at 70/30 exhibited excellent performance, such as tensile strength of 1.5 ± 0.1 MPa, and elongation at break of 77.4 ± 6.4%. Therefore, PLGA/SF scaffold with a weight ratio of 70/30 was chose as the matrix because it matches at best the mechanical demands for application in vascular tissue engineering. In order to promote the endothelialization of electrospun scaffolds, we used pEGFP-ZNF580 plasmid (pZNF580) complexes to modify the electrospun scaffolds by electrospraying technique. pZNF580 complexes were prepared from pZNF580 and microparticles (MPs) of amphiphilic copolymer methoxy-poly(ethylene glycol)-block-poly(3(S)-methyl-2,5-morpholinedione-co-glycolide)-graft-polyethyleneimine. Negatively charged PLGA/SF fibers adsorbed the positively charged MPs via physical deposition and electrostatic force. Scanning electron microscope image indicated the forming of composite scaffold and MPs did not change fiber’s shape and 3-D structure. Cell culture experiments demonstrated that the scaffolds modified with MPs/pZNF580 complexes could promote human umbilical vein endothelial cell growth and inhibit human umbilical artery smooth muscle cell proliferation. Our results indicated that the composite scaffolds with MPs/pZNF580 complexes could be used as a potential scaffold for vascular tissue engineering.     

Fabrication and characterization of electrospun fibrous nanocomposite scaffolds based on poly(lactide‐co‐glycolide)/poly(vinyl alcohol) blends

Tissue engineering involves the fabrication of three‐dimensional scaffolds to support cellular in‐growth and proliferation. Ideally, the scaffolds should be similar to the native extracellular matrix (ECM). Electrospun polymer nanofibrous scaffolds are appropriate candidates for ECM mimetic materials since they mimic the nanoscale properties of ECM. Electrospun polymer nanocomposites based on poly(lactide‐co‐glycolide) (PLGA)/poly(vinyl alcohol) (PVA) and organically modified montmorillonite (OMMT) were prepared by a solution intercalation technique followed by electrospinning. The morphology of fibrous scaffolds based on these nanocomposites was investigated using scanning electron microscopy. The scaffolds showed highly porous structure within the nanofibres of diameters ranging from 400 to 700 nm. X‐ray diffractometry gave evidence of good dispersion of the OMMT in the blends with exfoliated morphology. Measurements of the water uptake and water contact angle of the fibrous scaffolds indicated significant improvement in the hydrophilicity of the scaffolds. Evaluations of the mechanical properties and unrestricted somatic stem cell culture of the electrospun fibrous nanocomposite scaffolds revealed that the PLGA90/PVA10/1.5% OMMT and PLGA90/PVA10/3% OMMT samples are the most useful from the tissue engineering application viewpoint. Copyright © 2010 Society of Chemical Industry     

Effect of PCL concentration on PCL/CaSiO3 porous composite scaffolds for bone engineering

Porous polycaprolactone (PCL)-coated calcium silicate (CaSiO₃) composite scaffolds were successfully prepared by 3D gel-printing (3DGP) and vacuum impregnation technology in this study. The effect of different PCL concentration on porous CaSiO₃ scaffolds prepared by 3DGP technology was studied. The composition and morphological characteristics of PCL/CaSiO₃ scaffolds were tested by using fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS) analysis. PCL coating amount on the scaffolds surface was calculated by thermogravimetric analysis (TGA). Compressive strength was tested by a universal testing machine, and degradability was tested by immersing the scaffolds in a simulated body fluid (SBF). The results show that PCL coating thickness increased from 7.29 μm to 12.2 μm, and the compressive strength of the corresponding composite scaffolds increased from 17.15 MPa to 24.12 MPa following with PCL concentration increasing from 7.5% to 12.5%. When the porous composite scaffolds were immersed in SBF for 28 days, the degradation ratio was 1.06% (CaSiO₃), 1.63% (CaSiO₃-7.5PCL), 1.81% (CaSiO₃-10PCL) and 1.55% (CaSiO₃-12.5PCL), respectively. It is obviously that PCL/CaSiO₃ composite scaffolds, which are suitable for bone growth in bone repair engineering, are beneficial to improve the mechanical properties and biodegradability of pure CaSiO₃ scaffolds.     

Preparation and characterization of Chitosan and PLGA‐based scaffolds for tissue engineering applications

Three dimensional (3D) biodegradable porous scaffolds play a crucial role in bone tissue repair. In this study, four types of 3D polymer/hydroxyapatite (HAp) composite scaffolds were prepared by freeze drying technique in order to mimic the organic/inorganic nature of the bone. Chitosan (CH) and poly(lactic acid‐co‐glycolic acid) (PLGA) were used as the polymeric part and HAp as the inorganic component. Properties of the resultant scaffolds, such as morphology, porosity, degradation, water uptake, mechanical and thermal stabilities were examined. 3D scaffolds having interconnected macroporous structure and 77–89% porosity were produced. The pore diameters were in the range of 6 and 200 µm. PLGA and HAp containing scaffolds had the highest compressive modulus. PLGA maintained the strength by decreasing water uptake but increased the degradation rate. Scaffolds seeded with SaOs‐2 osteoblast cells showed that all scaffolds were capable of encouraging cell adhesion and proliferation. The presence of HAp particles caused an increase in cell number on CH‐HAp scaffolds compared to CH scaffolds, while cell number decreased when PLGA was incorporated in the structure. CH‐PLGA scaffolds showed highest cell number on days 7 and 14 compared to others. Based on the properties such as interconnected porosity, high mechanical strength, and in vitro cell proliferation, blend scaffolds have the potential to be applied in hard tissue treatments. POLYM. COMPOS., 36:1917–1930, 2015. © 2014 Society of Plastics Engineers     

Additive Manufacturing of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/Poly(D,L-lactide-co-glycolide) Biphasic Scaffolds for Bone Tissue Regeneration

Polyhydroxyalkanoates are biopolyesters whose biocompatibility, biodegradability, environmental sustainability, processing versatility, and mechanical properties make them unique scaffolding polymer candidates for tissue engineering. The development of innovative biomaterials suitable for advanced Additive Manufacturing (AM) offers new opportunities for the fabrication of customizable tissue engineering scaffolds. In particular, the blending of polymers represents a useful strategy to develop AM scaffolding materials tailored to bone tissue engineering. In this study, scaffolds from polymeric blends consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(D,L-lactide-co-glycolide) (PLGA) were fabricated employing a solution-extrusion AM technique, referred to as Computer-Aided Wet-Spinning (CAWS). The scaffold fibers were constituted by a biphasic system composed of a continuous PHBV matrix and a dispersed PLGA phase which established a microfibrillar morphology. The influence of the blend composition on the scaffold morphological, physicochemical, and biological properties was demonstrated by means of different characterization techniques. In particular, increasing the content of PLGA in the starting solution resulted in an increase in the pore size, the wettability, and the thermal stability of the scaffolds. Overall, in vitro biological experiments indicated the suitability of the scaffolds to support murine preosteoblast cell colonization and differentiation towards an osteoblastic phenotype, highlighting higher proliferation for scaffolds richer in PLGA.     

Preparation and characterization of new nano-composite scaffolds loaded with vascular stents

In this study, vascular stents were fabricated from poly (lactide-ɛ-caprolactone)/collagen/nano-hydroxyapatite (PLCL/Col/nHA) by electrospinning, and the surface morphology and breaking strength were observed or measured through scanning electron microscopy and tensile tests. The anti-clotting properties of stents were evaluated for anticoagulation surfaces modified by the electrostatic layer-by-layer self-assembly technique. In addition, nano-composite scaffolds of poly (lactic-co-glycolic acid)/polycaprolactone/nano-hydroxyapatite (PLGA/PCL/nHA) loaded with the vascular stents were prepared by thermoforming-particle leaching and their basic performance and osteogenesis were tested in vitro and in vivo. The results show that the PLCL/Col/nHA stents and PLGA/PCL/nHA nano-composite scaffolds had good surface structures, mechanical properties, biocompatibility and could guide bone regeneration. These may provide a new way to build vascularized-tissue engineered bone to repair large bone defects in bone tissue engineering.     

Compressive properties and creep resistance of a novel,porous, semidegradable poly(vinyl alcohol)/poly(lactic‐co‐glycolic acid) scaffold for articular cartilage repair

Tissue engineering for articular cartilage repair has shown success in ensuring the integration of neocartilage with surrounding natural tissue, but the rapid restoration of biomechanical functions remains a significant challenge. The poly(vinyl alcohol) (PVA) hydrogel is regarded as a potential articular cartilage replacement for its fair mechanical strength, whereas its lack of bioactivity limits its utility. To obtain a scaffold possessing expected bioactivity and initial mechanical properties, we herein report a novel salt‐leaching technique to fabricate a porous PVA hydrogel simultaneously embedded with poly(lactic‐co‐glycolic acid) (PLGA) microspheres. Through the investigation of environmental scanning electron microscopy, we found that the porous PVA/PLGA scaffold was successfully manufactured. The compression and creep properties were also comprehensively studied before and after cell culturing. The relationship between the compressive modulus and strain ratio of the porous PVA/PLGA scaffold showed significant nonlinear behavior. The elastic compressive modulus was influenced a little by the porogen content, whereas it went higher with a higher PLGA microsphere content. The cell‐cultured scaffolds presented higher compressive moduli than the initial ones. The creep resistance of the cell‐cultured scaffolds was much better than that of the initial ones. In all, this new scaffold is a promising material for articular cartilage repair. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40311.     

I‐Optimal design of poly(lactic‐co‐glycolic) acid/hydroxyapatite three‐dimensional scaffolds produced by thermally induced phase separation

In bone tissue engineering, three‐dimensional (3D) scaffolds are often designed to have adequate modulus while taking into consideration the requirement for a highly porous network for cell seeding and tissue growth. This article presents the design optimization of 3D scaffolds made of poly(lactic‐co‐glycolic) acid (PLGA) and nanohydroxyapatite (nHA), produced by thermally induced phase separation (TIPS). Slow cooling at a rate of 1°C/min enabled a uniform temperature and produced porous scaffolds with a relatively uniform pore size. An I‐optimal design of experiments (DoE) with 18 experimental runs was used to relate four responses (scaffold thickness, density, porosity, and modulus) to three experimental factors, namely the TIPS temperature (?20, ?10, and 0°C), PLGA concentration (7%, 10%, and 13% w/v), and nHA content (0%, 15%, and 30% w/w). The response surface analysis using JMP® software predicted a temperature of ?18.3°C, a PLGA concentration of 10.3% w/v, and a nHA content of 30% w/w to achieve a thickness of 3 mm, a porosity of 83%, and a modulus of ~4 MPa. The set of validation scaffolds prepared using the predicted factor levels had a thickness of 3.05 ± 0.37 mm, a porosity of 86.8 ± 0.9%, and a modulus of 3.57 ± 2.28 MPa. POLYM. ENG. SCI., 59:1146–1157 2019. © 2019 Society of Plastics Engineers     

Improvement of mechanical properties of macroporous β-tricalcium phosphate bioceramic scaffolds with uniform and interconnected pore structures

The biocompatible and degradable macroporous bioceramic scaffolds with high mechanical properties and interconnected porous structures play an important role in hard tissue regeneration and bone tissue engineering applications. In this study, the improvement of mechanical properties of macroporous β-tricalcium phosphate [β-Ca₃(PO₄)₂, β-TCP] bioceramic scaffolds with uniform macropore size and interconnected pores were fabricated by impregnation of the synthesized β-TCP nano-powder slurry into polymeric frames. The microstructures, mechanical properties and in vitro degradation of the fabricated samples were investigated. For a comparison, β-TCP scaffolds were also fabricated from commercial micro-size powders under the same conditions. The resultant scaffolds showed porosities ∼65% with uniform macropore size ranging from 400 to 550 μm and interconnected pore size ∼100 μm. The compressive strength of the samples fabricated from nano-size powders reached 10.87 MPa, which was almost twice as high as those fabricated from commercial micro-size powders, and was comparable to the high-end value (2–10 MPa) of human cancellous bone. Furthermore, the degradation of the β-TCP bioceramics fabricated from nano-size powders was apparently lower than those fabricated from commercial micro-size powders, suggesting the possible control of the degradation of the scaffolds by regulating initial powder size. Regarding the excellent mechanical properties and porous structures, the obtained macroporous β-TCP bioceramic scaffolds can be used in hard tissue regeneration and bone tissue engineering applications.     

Surface hydrophilization of electrospun PLGA micro-/nano-fibers by blending with Pluronic F-108

Poly(lactide-co-glycolide) (PLGA) has been widely explored as scaffolds in tissue engineering. However, its hydrophobicity can adversely affect events such as protein adsorption and downstream cell adhesion in tissue engineering applications. Although surface modification techniques (high energy radiation/chemical treatment) to modify the hydrophobicity of PLGA can be useful at the macroscopic scale, their usefulness for micro-/nano-meter scale objects can be limited due to adverse affects on physical properties. Therefore, in this study we report the surface hydrophilization of electrospun micro-/nano-fiber meshes of PLGA (85:15) by blending with small quantities (0.5-2%) of a non-ionic surfactant Pluronic^® F-108 (PF-108). The blended fiber meshes showed a decrease in surface contact angle when compared to pure PLGA fiber meshes demonstrating an improvement in surface hydrophilicity due to blending. This was corroborated by XPS analysis that demonstrated surface enrichment of PF-108. Thermal and mechanical studies demonstrated that blending with small quantities of PF-108 do not compromise the bulk properties of PLGA. Therefore these studies demonstrated the feasibility of hydrophilization of electrospun PLGA micro-/nano-fibers, without compromising the bulk properties (thermal and mechanical) of native PLGA.     

Fabrication of forsterite scaffolds with photothermal-induced antibacterial activity by 3D printing and polymer-derived ceramics strategy

Bacterial infection of the implanting materials is one of the greatest challenges in bone tissue engineering. In this study, porous forsterite scaffolds with antibacterial activity have been fabricated by combining 3D printing and polymer-derived ceramics (PDCs) strategy, which effectively avoided the generation of MgSiO₃ and MgO impurities. Forsterite scaffolds sintered in an argon atmosphere can generate free carbon in the scaffolds, which exhibited excellent photothermal effect and could inhibit the growth of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in vitro. In addition, forsterite scaffolds have uniform macroporous structure, high compressive strength (>30 MPa) and low degradation rate. Hence, forsterite scaffolds fabricated by combining 3D printing and PDCs strategy would be a promising candidate for bone tissue engineering.     

Fabrication and characterization of 3-dimensional PLGA nanofiber/microfiber composite scaffolds

Novel three-dimensional (3-D) nano-/microfibrous poly(lactic-co-glycolic acid) (PLGA) scaffolds were fabricated by hybrid electrospinning, involving a combination of solution electrospinning and melt electrospinning. The scaffolds consisted of a randomly oriented structure of PLGA microfibers (average fiber diameter = 28 μm) and PLGA nanofibers (average fiber diameter = 530 nm). From mercury porosimetry, the PLGA nano-/microfiber (10/90) scaffolds were found to have similar pore parameters to the PLGA microfiber scaffolds. PLGA nano-/microfibrous scaffolds were examined and compared with the PLGA microfiber scaffolds in terms of the attachment, spreading and infiltration of normal human epidermal keratinocytes (NHEK) and fibroblasts (NHEF). The cell attachment and spreading of both cell types were several times higher in the nano-/microfiber composite scaffolds than in the microfibrous scaffolds without nanofibers. This shows that the presence of nanofibers enhanced the attachment and spreading of the cells on the nano-/microfiber composite scaffolds. Moreover, the nanofibers helped the cells infiltrate easily into the scaffolds. Overall, this novel nano-/microfiber structures has great potential for the 3-D organization and guidance of cells provided for tissue engineering.     

Highly interconnected macroporous MBG/PLGA scaffolds with enhanced mechanical and biological properties via green foaming strategy

In this study, mesoporous bioactive glass particles (MBGs) are incorporated into poly(lactic-co-glycolic acid) (PLGA) to fabricate highly interconnected macroporous composite scaffolds with enhanced mechanical and biological properties via a developed supercritical carbon dioxide (scCO₂) foaming method. Scaffolds show favorable highly interconnected and macroporous structure through a high foaming pressure and long venting time foaming strategy. Specifically, scaffolds with porosity from 73% to 85%, pore size from 120 μm to 320 μm and interconnectivity of over 95% are controllably fabricated at MBG content from 0 wt% to 20 wt%. In comparison with neat PLGA scaffolds, composite scaffolds perform improved strength (up to 1.5 folds) and Young's modulus (up to 3 folds). The interconnected macroporous structure is beneficial to the ingrowth of cells. More importantly, composite scaffolds also provide a more promising microenvironment for cellular proliferation and adhesion with the release of bioactive ions. Hopefully, MBG/PLGA scaffolds developed by the green foaming strategy in this work show promising morphological, mechanical and biological features for tissue regeneration.     

静电纺PLGA管状支架的构建及其生物力学性能

以具有良好生物相容性、生物可降解性的聚丙交乙交酯(PLGA)为原料,以高速旋转的滚轴为收集装置,通过静电纺丝法,制备PLGA管状支架(d=6mm)。研究不同工艺及乙醇处理对PLGA管状支架形貌结构、微细结构和生物力学性能的影响。结果表明:当纺丝液质量分数为7%,滚轴转速为1500r/min时,可制得纤维形貌规整、分布均匀,直径为(1660±218)nm,孔隙率为80.6%的PLGA管状支架;经乙醇处理后,其孔隙率减小,玻璃化温度和热分解温度提高,热稳定性增强;断裂强度、爆破强度及缝合强力均显著提高。