Advanced 3D Magnetic Scaffolds for Tumor-Related Bone Defects

The need for bone substitutes is a major challenge as the incidence of serious bone disorders is massively increasing, mainly attributed to modern world problems, such as obesity, aging of the global population, and cancer incidence. Bone cancer represents one of the most significant causes of bone defects, with reserved prognosis regarding the effectiveness of treatments and survival rate. Modern therapies, such as hyperthermia, immunotherapy, targeted therapy, and magnetic therapy, seem to bring hope for cancer treatment in general, and bone cancer in particular. Mimicking the composition of bone to create advanced scaffolds, such as bone substitutes, proved to be insufficient for successful bone regeneration, and a special attention should be given to control the changes in the bone tissue micro-environment. The magnetic manipulation by an external field can be a promising technique to control this micro-environment, and to sustain the proliferation and differentiation of osteoblasts, promoting the expression of some growth factors, and, finally, accelerating new bone formation. By incorporating stimuli responsive nanocarriers in the scaffold’s architecture, such as magnetic nanoparticles functionalized with bioactive molecules, their behavior can be rigorously controlled under external magnetic driving, and stimulates the bone tissue formation.     

Cryo-3D Printing of Hierarchically Porous Polyhydroxymethylene Scaffolds for Hard Tissue Regeneration

High molecular weight polyhydroxymethylene (PHM) has a repeat unit identical to that of low molecular weight sugar alcohols and exhibits carbohydrate-like properties. Herein, cryogenic extrusion-based 3D printing is combined with a phase separation in water to fabricate hierarchically porous PHM scaffolds containing interconnected macro-, micro-, and nanopores. As PHM is infusible and insoluble in common solvents, its precursor polyvinylene carbonate (PVCA) dissolved in dimethylsulfoxide (DMSO) is used to 3D print hierarchically porous PVCA scaffolds that are converted into PHM by hydrolysis without impairing the pore architectures. Similar to low-temperature deposition manufacturing, the PVCA/DMSO freezes on a build platform at −78 °C. However, instead of removing the frozen solvent by sublimation, the frozen scaffold is immersed in water to recover DMSO and to effect phase separation by precipitation. However, the computer-guided printhead pathway controls macropore formation phase separation of frozen PVCA/DMSO upon contact with water accounts for simultaneous micro- and nanopore formation. Contrary to 3D printing of PVCA/DMSO at ambient temperature, this cryo-3D printing process does not require shear thinning additives and affords significantly improved build precision with macropore sizes variable between 200 and 1500 µm. Cryo-3D-printed PHM scaffolds are biocompatible and promote osteoblast proliferation.     

Solvent-Cast 3D Printing of Biodegradable Polymer Scaffolds

3D printing is a popular fabrication technique because of its ability to produce complex architectures. Melt-based 3D printing is widely used for thermoplastic polymers like poly(caprolactone) (PCL), poly(lactic acid) (PLA), and poly(lactic-co-glycolic acid) (PLGA) because of their low processing temperatures. However, traditional melt-based techniques require processing temperatures and pressures high enough to achieve continuous flow, limiting the type of polymer that can be printed. Solvent-cast printing (SCP) offers an alternative approach to print a wider range of polymers. Polymers are dissolved in a volatile solvent that evaporates during deposition to produce a solid polymer filament. SCP, therefore, requires optimizing polymer concentration in the ink, print pressure, and print speed to achieve desired print fidelity. Here, capillary flow analysis shows how print pressure affects the process-apparent viscosity of PCL, PLA, and PLGA inks. Ink viscosity is also measured using rheology, which is used to link a specific ink viscosity to a predicted set of print pressure and print speed for all three polymers. These results demonstrate how this approach can be used to accelerate optimization by significantly reducing the number of parameter combinations. This strategy can be applied to other polymers to expand the library of polymers printable with SCP.     

Cryogenic 3D Printing of w/o Pickering Emulsions Containing Bifunctional Drugs for Producing Hierarchically Porous Bone Tissue Engineering Scaffolds with Antibacterial Capability

How to fabricate bone tissue engineering scaffolds with excellent antibacterial and bone regeneration ability has attracted increasing attention. Herein, we produced a hierarchical porous β-tricalcium phosphate (β-TCP)/poly(lactic-co-glycolic acid)-polycaprolactone composite bone tissue engineering scaffold containing tetracycline hydrochloride (TCH) through a micro-extrusion-based cryogenic 3D printing of Pickering emulsion inks, in which the hydrophobic silica (h-SiO₂) nanoparticles were used as emulsifiers to stabilize composite Pickering emulsion inks. Hierarchically porous scaffolds with desirable antibacterial properties and bone-forming ability were obtained. Grid scaffolds with a macroscopic pore size of 250.03 ± 75.88 μm and a large number of secondary micropores with a diameter of 24.70 ± 15.56 μm can be fabricated through cryogenic 3D printing, followed by freeze-drying treatment, whereas the grid structure of scaffolds printed or dried at room temperature was discontinuous, and fewer micropores could be observed on the strut surface. Moreover, the impartment of β-TCP in scaffolds changed the shape and density of the micropores but endowed the scaffold with better osteoconductivity. Scaffolds loaded with TCH had excellent antibacterial properties and could effectively promote the adhesion, expansion, proliferation, and osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells afterward. The scaffolds loaded with TCH could realize the strategy to “kill bacteria first, then induce osteogenesis”. Such hierarchically porous scaffolds with abundant micropores, excellent antibacterial property, and improved bone-forming ability display great prospects in treating bone defects with infection.     

聚己内酯材料的改性及在3D打印中的应用

主要综述了通过物理和化学方法制备改性聚己内酯(PCL)的方法和所制备的改性PCL的性能,并且对PCL材料在3D打印领域中的应用也进行了介绍。由于PCL具有较好的生物相容性和韧性,并且改性的PCL也具有较为理想的强度,相应的3D打印产品可用到组织工程领域。另外,化学改性的PCL还具有一定的功能性。     

基于3D打印的三维短纤维增强复合材料强度预测分析

针对目前短纤维增强树脂基复合材料强度仍以实验和二维平面预测为主,提出一种能真实反映纤维空间结构的三维短纤维增强复合材料强度预测模型.基于概率方法修正"混合律模型"对临界区域内纤维的作用进行详细的理论公式推导,建立基于纤维取向、长度和体积分数等因素的三维短纤维增强复合材料强度预测模型.以短碳纤维增强尼龙复合材料为例进行强...     

Evaluating Oxygen Tensions Related to Bone Marrow and Matrix for MSC Differentiation in 2D and 3D Biomimetic Lamellar Scaffolds

The physiological O₂ microenvironment of mesenchymal stem cells (MSCs) and osteoblasts and the dimensionality of a substrate are known to be important in regulating cell phenotype and function. By providing the physiologically normoxic environments of bone marrow (5%) and matrix (12%), we assessed their potential to maintain stemness, induce osteogenic differentiation, and enhance the material properties in the micropatterned collagen/silk fibroin scaffolds that were produced in 2D or 3D. Expression of osterix (OSX) and vascular endothelial growth factor A (VEGFA) was significantly enhanced in the 3D scaffold in all oxygen environments. At 21% O₂, OSX and VEGFA expressions in the 3D scaffold were respectively 13,200 and 270 times higher than those of the 2D scaffold. Markers for assessing stemness were significantly more pronounced on tissue culture polystyrene and 2D scaffold incubated at 5% O₂. At 21% O₂, we measured significant increases in ultimate tensile strength (p < 0.0001) and Young’s modulus (p = 0.003) of the 3D scaffold compared to the 2D scaffold, whilst 5% O₂ hindered the positive effect of cell seeding on tensile strength. In conclusion, we demonstrated that the 3D culture of MSCs in collagen/silk fibroin scaffolds provided biomimetic cues for bone progenitor cells toward differentiation and enhanced the tensile mechanical properties.     

3D打印PLA/CF便携式塑料挂钩

提出了一种区别于传统塑料挂钩的新型便携式挂钩研发思路,采用纤维增强聚乳酸复合材料并基于3D打印技术辅助完成了便携式挂钩的原理验证和零件设计。首先采用纤维增强聚乳酸复合材料3D打印弯曲试样进行了力学性能测试,结果表明纤维增强聚乳酸复合材料其力学性能满足用来辅助研发新型便携式挂钩的要求。其次利用3D打印技术对新型便携式挂钩进行了原理及原型的验证。     

混凝土3D打印材料及3D打印模板技术应用进展

混凝土3D打印是现代数字化制造的典型代表,因其智能化、个性化、绿色建造的工艺优势受到广泛关注。作为一种新型建造方式,3D打印为建筑业带来了颠覆性的影响,并对传统混凝土材料提出了全新的挑战。如何提升混凝土材料与3D打印技术的适应性,实现3D打印技术在建筑中的广泛应用是人们普遍关注的焦点。本文概述了混凝土3D打印技术的发展历程,系统论述了混凝土3D打印材料在流变性、可挤出性、可建造性以及力学性能方面的研究现状,同时,介绍了3D打印模板技术在装饰及异型构筑物上的典型应用,以期为混凝土3D打印的研究与未来工程发展提供一定的参考与借鉴。     

Bioactive and Biocompatible Macroporous Scaffolds with Tunable Performances Prepared Based on 3D Printing of the Pre‐Crosslinked Sodium Alginate/Hydroxyapatite Hydrogel Ink

Bioactive and biocompatible porous scaffold materials with adjustable pore structures and drug delivery capability are one of the key elements in bone tissue engineering. In this work, bioactive and biocompatible sodium alginate (SA)/hydroxyapatite (HAP) macroporous scaffolds are facilely and effectively fabricated based on 3D printing of the pre‐crosslinked SA/HAP hydrogels followed by further crosslinking to improve the mechanical properties of scaffolds. The pore structures and porosity (>80%) of the porous scaffolds can be readily tailored by varying the formation conditions. Furthermore, the in vitro biomineralization tests show that the bioactivity of the porous scaffolds is effectively enhanced by the addition of HAP nanoparticles into the scaffold matrix. Furthermore, the anti‐inflammatory drug curcumin is loaded into the porous scaffolds and the in vitro release study shows the sustainable drug release function of the porous scaffolds. Moreover, mouse bone mesenchymal stem cells (mBMSCs) are cultured on the porous scaffolds, and the results of the in vitro biocompatibility experiment show that the mBMSCs can be adhered well on the porous scaffolds. All of the results suggest that the bioactive and biocompatible SA/HAP porous scaffolds have great application potential in bone tissue engineering.     

生物玻璃陶瓷骨支架光固化3D打印及降解性能

利用光固化技术制备的生物玻璃陶瓷骨植入物在骨修复领域具有许多优势,然而生物玻璃陶瓷受粉体粒度的影响,在光固化打印工艺、结构、力学性能和生物性能等方面存在较大的差异。本文以光固化3D打印过程中粒度的变化为切入点,制备了两种不同粒度粉体的生物玻璃陶瓷浆料,分别对生物玻璃陶瓷浆料的稳定性、流变特性和固化特性进行了表征,根据TG-DSC曲线绘制了脱脂烧结曲线并对骨支架的表面质量、结构和力学性能进行了评价,最后通过颅骨修复试验对降解性能进行了分析。结果表明:小粒度粉体的浆料稳定性较好,黏度较高,对应的固化厚度和过固化宽度也较小;小粒度粉体制备的骨支架表面质量、结构致密化程度和弯曲强度均优于大粒度粉体制备的骨支架,但降解速率较低,植入体内2个月后有新骨长入骨支架孔隙。本研究对不同粒度粉体的生物玻璃陶瓷骨支架制备具有指导意义,有助于推动基于粒度分布的梯度可控降解骨支架的开发和应用。     

Effect of Morphological Characteristics and Biomineralization of 3D-Printed Gelatin/Hyaluronic Acid/Hydroxyapatite Composite Scaffolds on Bone Tissue Regeneration

The use of porous three-dimensional (3D) composite scaffolds has attracted great attention in bone tissue engineering applications because they closely simulate the major features of the natural extracellular matrix (ECM) of bone. This study aimed to prepare biomimetic composite scaffolds via a simple 3D printing of gelatin/hyaluronic acid (HA)/hydroxyapatite (HAp) and subsequent biomineralization for improved bone tissue regeneration. The resulting scaffolds exhibited uniform structure and homogeneous pore distribution. In addition, the microstructures of the composite scaffolds showed an ECM-mimetic structure with a wrinkled internal surface and a porous hierarchical architecture. The results of bioactivity assays proved that the morphological characteristics and biomineralization of the composite scaffolds influenced cell proliferation and osteogenic differentiation. In particular, the biomineralized gelatin/HA/HAp composite scaffolds with double-layer staggered orthogonal (GEHA20-ZZS) and double-layer alternative structure (GEHA20-45S) showed higher bioactivity than other scaffolds. According to these results, biomineralization has a great influence on the biological activity of cells. Hence, the biomineralized composite scaffolds can be used as new bone scaffolds in bone regeneration.     

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.     

三维打印珍珠粉-硫酸钙/聚己内酯复合支架及性能研究

具有生物相容性的支架可以作为可控的细胞外环境,供细胞附着、增殖、分化以及组织生成,在组织工程中有着重要的作用。本研究运用三维打印技术制备了珍珠粉-硫酸钙/聚己内酯(Pearl-CaSO_4/PCL)复合支架,详细研究了珍珠粉含量对复合支架的理化性能和生物学性能的影响。结果表明,复合支架具有350mm左右的三维连通大孔,其孔隙率约60%,支架强度可达8 MPa。珍珠粉的复合能够有效调节复合支架的降解速率并稳定支架周围的体液环境。细胞实验结果表明,Pearl-CaSO_4/PCL复合支架能够促进骨髓间充质干细胞的增殖与分化,且与珍珠粉的含量呈正相关。因此,Pearl-CaSO_4/PCL复合支架在骨缺损修复领域具有应用前景。     

连续碳纤维增强热固性酚醛树脂复合材料的3D打印工艺及性能研究

针对连续碳纤维增强热固性酚醛树脂复合材料3D打印成型工艺的技术难题,本文提出了浸渍-原位预固化-后固化的3D打印成型方案,实现了连续碳纤维增强热固性酚醛树脂复合材料的3D打印成型,并研究浸渍温度对酚醛树脂接触角与表面张力,以及打印工艺对样件形貌和力学性能的影响规律。结果表明:当浸渍温度为40 ℃,预固化温度为180 ℃时,纤维-树脂界面结合效果最佳,原料具备成型条件;当打印间距为0.5 mm时,样件的弯曲强度及模量达到最大值,分别为660.00 MPa和57.99 GPa,层间剪切强度达到20.14 MPa。此连续碳纤维增强热固性酚醛树脂复合材料一体化制备工艺解决了3D打印热固性树脂原位成型难的问题,为制备具有复杂结构的连续纤维增强热固性树脂复合材料提供了参考。     

3D打印PLA/麦秸粉复合材料的力学性能优化

将聚乳酸(PLA)作为基体,麦秸粉作为增强体,通过挤出成型工艺制备用于熔融沉积成型3D打印的木塑复合材料。采用正交试验设计的方法,通过对复合材料的力学性能进行测试,探索最佳的制备工艺。结果表明,随着麦秸粉平均粒径的增加,复合材料的弯曲强度与冲击强度出现先上升后下降的趋势,当平均粒径为120μm时,弯曲强度与冲击强度分别达到60.51 MPa,12.84 k J/m~2;麦秸粉的含量在1%时,复合材料的弯曲强度与冲击强度达到最大值,分别为62.87 MPa,12.72 k J/m~2;硅烷偶联剂KH550的加入会提高复合材料的力学性能,对冲击强度的作用效果强于弯曲强度,当KH550的添加量为8%时,冲击强度达到12.90 k J/m~2;马来酸酐接枝聚丙烯相容剂(MAPP)的添加会使复合材料的弯曲强度与冲击强度先上升后下降,当MAPP含量为1%时,复合材料的弯曲强度与冲击强度分别为62.68 MPa,11.91 k J/m~2,达到最大值。     

3D Printing for Biological Scaffolds using Poly(Ionic Liquid)/Gelatin/Sodium Alginate Ink

The poly(ionic liquid)s (PILs) have attracted a wide range of applications in thermo-responsive materials, carbon materials, catalysis, porous polymers, separation and absorption materials, and biological field due to their favorable tunability and biological functions. However, the applications of PILs in bio-scaffold are rarely studied. In the present work, the ionic liquid (IL) monomer (1-vinyl-3-butylimidazolium chloride, [VBIM]Cl) is cross-linked with other three compounds, respectively, to synthesize three kinds of PILs (PIL1, PIL2, and PIL3). Furthermore, individually cross-linked PILs are added into gelatin (Gel)/sodium alginate (SA) solution aiming to prepare biological inks (bio-inks) for 3D printing. The water absorption, degradation rate, and porosity of the bio-scaffolds are measured to evaluate the physicochemical characteristics, while the PC12 cell line is used to evaluate the biocompatibility of the bio-scaffolds through cell proliferation. These results demonstrate that the biological activity of the bio-scaffold can be varied at the tendency of PIL1 < PIL3 < PIL2, providing a potential prospect for the application of PILs in tissue-engineered bio-scaffolds.     

芳纶增强复合材料波纹夹层3D打印与力学性能研究

为解决波纹夹层结构传统制备方法存在的问题,采用熔融沉积(FDM)3D打印技术制备芳纶增强聚乳酸复合材料波纹夹层结构,并研究切片层高与打印温度对波纹夹层结构力学性能的影响。结果表明:当试样的切片层高为0.1 mm,打印温度为210℃时,复合材料波纹夹层结构的力学性能最好;试样的弯曲强度和冲击强度与切片层高呈负相关;随着打印温度的升高,试样的弯曲强度和冲击强度呈现先增大后减小的趋势。通过分析复合材料电镜图发现,切片层高的降低,有利于芳纶与聚乳酸基体的结合。     

聚丙烯荧光材料制备及其3D打印测试

通过配位反应合成了三种荧光配合物:铕配合物[Eu(DBM)3phen],8-羟基喹啉铝配合物(AlQ3)和8-羟基喹啉锌配合物(ZnQ2),然后通过熔融共混的方式在聚丙烯(PP)材料中分别掺杂这三种荧光配合物,制得三种PP/荧光配合物复合材料,以提高PP发光性能.对这三种复合材料进行了一系列的荧光和力学性能测试.结果表...