3D printing process of oxidized nanocellulose and gelatin scaffold

For tissue engineering applications tissue scaffolds need to have a porous structure to meet the needs of cell proliferation/differentiation, vascularisation and sufficient mechanical strength for the specific tissue. Here we report the results of a study of the 3D printing process for composite materials based on oxidized nanocellulose and gelatin, that was optimised through measuring rheological properties of different batches of materials after different crosslinking times, simulation of the pneumatic extrusion process and 3D scaffolds fabrication with Solidworks Flow Simulation, observation of its porous structure by SEM, measurement of pressure-pull performance, and experiments aimed at finding out the vitro cytotoxicity and cell morphology. The materials printed are highly porous scaffolds with good mechanical properties.     

大鼠脂肪源性干细胞与三维打印明胶支架的相容性

目的通过观察大鼠脂肪源性干细胞(ADSCs)与三维打印(3DP)及戊二醛交联的明胶支架的相容性,筛选出最适合细胞生长的支架孔径,为进一步构建组织工程化组织或器官提供实验依据。方法采用酶消化法分离提取大鼠ADSCs,并用流式细胞术和多向诱导分化的方法进行鉴定;然后与不同孔径的3DP明胶支架复合培养,并用扫描电子显微镜和透射电子显微镜观察其超微结构,细胞活力分析仪检测其存活率;用MTT法检测二维(2D)与三维(3D)培养对ADSCs细胞活力的影响。结果获得的ADSCs具有多向分化潜能,具备干细胞的基本特征。接种ADSCs到3DP明胶支架后,扫描电子显微镜可看到细胞呈椭圆形或纺锤形,区别于传统二维培养的梭形形态;透射电子显微镜可看到细胞在支架空隙内散在分布,细胞核、细胞器等结构清晰,表明其与支架的相容性良好;90μm孔径的支架细胞存活率最高;3D培养的方法更有利于维持ADSCs的活力。结论 ADSCs与3DP明胶支架的相容性良好,90μm孔径的支架最适合ADSCs的生长。     

3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration

Low temperature 3D printing of calcium phosphate scaffolds holds great promise for fabricating synthetic bone graft substitutes with enhanced performance over traditional techniques. Many design parameters, such as the binder solution properties, have yet to be optimized to ensure maximal biocompatibility and osteoconductivity with sufficient mechanical properties. This study tailored the phosphoric acid-based binder solution concentration to 8.75 wt% to maximize cytocompatibility and mechanical strength, with a supplementation of Tween 80 to improve printing. To further enhance the formulation, collagen was dissolved into the binder solution to fabricate collagen-calcium phosphate composites. Reducing the viscosity and surface tension through a physiologic heat treatment and Tween 80, respectively, enabled reliable thermal inkjet printing of the collagen solutions. Supplementing the binder solution with 1–2 wt% collagen significantly improved maximum flexural strength and cell viability. To assess the bone healing performance, we implanted 3D printed scaffolds into a critically sized murine femoral defect for 9 weeks. The implants were confirmed to be osteoconductive, with new bone growth incorporating the degrading scaffold materials. In conclusion, this study demonstrates optimization of material parameters for 3D printed calcium phosphate scaffolds and enhancement of material properties by volumetric collagen incorporation via inkjet printing.     

Friction of sodium alginate hydrogel scaffold fabricated by 3-D printing

A rapid prototyping technology, formed by three-dimensional (3-D) printing and then crosslinked by spraying Ca²⁺ solution, is developed to fabricate a sodium alginate (SA) hydrogel scaffold. The porosity, swelling ratio, and compression modulus of the scaffold are investigated. A friction mechanism is developed by studying the reproducible friction behavior. Our results show that the scaffold can have 3-D structure with a porosity of 52%. The degree of swelling of the SA hydrogel scaffold is 8.5, which is nearly the same as bulk SA hydrogel. SA hydrogel exhibits better compressive resilience than bulk hydrogel despite its lower compressive modulus compared to bulk hydrogel. The SA hydrogel scaffold exhibits a higher frictional force at low sliding velocity (10^?6 to 10^?3 m/s) compared to bulk SA hydrogel, and they are equal at high sliding velocity (10^?2 to 1 m/s). For a small pressure (0.3 kPa), the SA hydrogel scaffold shows good friction reproducibility. In contrast, bulk SA hydrogel shows poor reproducibility with respect to friction behavior. The differences in friction behaviors between the SA hydrogel scaffold and bulk SA hydrogel are related to the structure of the scaffold, which can keep a stable hydrated lubrication layer.     

Preparation and characterisation of vancomycin-impregnated gelatin microspheres/silk fibroin scaffold

A type of antibacterial silk fibroin (SF) scaffold was developed and characterised as a potential functional wound dressing for acute trauma treatment. To achieve this, SF solution was mixed with previously fabricated vancomycin (Vm)-loaded gelatin (G) microspheres, followed by a freeze-drying step. Some physical and antimicrobial properties of the prepared Vm/G/SF scaffolds were investigated and the results demonstrated that the average pore size and porosity of the composite scaffold were 60–80?μm and 75%, respectively. The compressive stress and compressive modulus of Vm/G/SF scaffold were 140 and 468?KPa, respectively. Compared with Vm/G microspheres and Vm/SF scaffold, the Vm/G/SF scaffold has slower release rate of Vm. In addition, the Vm release rate of Vm/G/SF scaffold matched well with the degradation rate of SF scaffold. With respect to the antimicrobial effect, the results showed that the Vm/G/SF scaffold had good antimicrobial activity against Staphylococcus aureus (gram-positive), which is a gram-positive bacteria commonly found in infected wounds.     

High-resolution 3D scaffold model for engineered tissue fabrication using a rapid prototyping technique

Rapid prototyping, automatic image processing (computer-aided design (CAD)) and computer-aided manufacturing techniques are opening new and interesting prospects for medical devices and tissue engineering, especially for hard tissues such as bone. The development of a bone high-resolution scaffold prototype using these techniques is described. The results testify to the fidelity existing between microtomographic reconstruction and CAD. Furthermore, stereolithographic manufacturing of this scaffold, which possesses a high degree of similarity to the starting model as monitored by morphological evaluations (mean diameter 569±147 μm), represents a promising result for regenerative medicine applications.     

3D bio-printing technology for body tissues and organs regeneration

In the last decade, the use of new technologies in the reconstruction of body tissues has greatly developed. Utilising stem cell technology, nanotechnology and scaffolding design has created new opportunities in tissue regeneration. The use of accurate engineering design in the creation of scaffolds, including 3D printers, has been widely considered. Three-dimensional printers, especially high precision bio-printers, have opened up a new way in the design of 3D tissue engineering scaffolds. In this article, a review of the latest applications of this technology in this promising area has been addressed.     

3D打印多孔钛支架微观孔隙结构和力学性能

目的研究3D打印技术制造的钻石分子结构多孔钛支架的微观孔隙结构和力学性能,指导3D打印多孔钛骨科植入物的开发。方法采用选择性激光熔化(selective laser melting,SLM)和电子束熔化(electron beam melting,EBM)两种金属3D打印制造工艺,制造钻石分子结构多孔Ti6Al4V支架。使用光学显微镜和扫描电镜观察其微观孔隙结构,并使用万能材料试验机对这些支架进行压缩测试。结果两种3D打印制造工艺都会存在加工误差,并且在表面存在半熔融金属颗粒。SLM工艺相对误差为20.9%~35.8%。EBM工艺相对误差为-9.1%~46.8%,且制造不出杆件宽度为0.2 mm的支架。SLM工艺制造的支架抗压强度为99.7~192.6 MPa,弹性模量为2.43~4.23 GPa。EBM工艺制造的支架抗压强度为39.5~96.9 MPa,弹性模量为1.44~2.83 GPa。结论 SLM工艺比EBM工艺制造精度高。支架的孔隙率是影响其抗压强度和弹性模量的主要因素,相同工艺的情况下,孔隙率越大,抗压强度越小,弹性模量也越小;相近孔隙率的情况下,SLM工艺比EBM工艺强度高,弹性模量也高。     

基于三维打印技术的多药控释型载药人工骨生物学评价

目的 评价三维打印技术制备的多药控释型载药人工骨的生物相容性.方法 利用三维打印技术制备多药控释型载药人工骨,并进行急性毒性试验、热源试验、皮肤刺激试验、溶血试验、微核试验和肌肉埋植试验等检测评价其生物相容性.结果 该多药控释型载药人工骨无全身急性毒性反应、无热源效应;皮肤刺激实验局部皮肤未见红斑、水肿反应;溶血率为0.29%,有良好的血液相容性;微核实验未见致突变现象.无细胞遗传毒性作用;肌肉埋植实验未见局部组织变性、坏死或排斥现象.结论 三维打印技术制备的多药控释型载药人工骨具有良好的生物相容性,符合医用生物材料的性能要求. Abstract： Objective To evaluate the biocompatibility of porous drug implant scaffolds prepared by 3D printing technique. Methods Porous drug implant scaffolds were fabricated by 3D printing technique, and a series of tests were carried out to validate the biocompatibility, including acute systemic toxicity, hot source test, local irritation reaction, micronucleus test, muscle implant test and so on. Results The porous drug implant scaffolds showed no acute systemic toxicity, no pyrogenetic effect, no local erythema and edema in local irritation re-action, hemolysis rate of 0.29%, no cellular genetoxic. No local tissue denaturation, necrosis and exclusion were found in intramuscular implant test. Conclusion With good biocompatibility, the porous drug implant scaffold fabricated by 3D printing technique can meet the clinical requirement for biomaterial.     

3D打印成型纳米羟基磷灰石/壳聚糖/聚己内酯三元复合支架材料的构建及表征

文题释义： 组织工程骨：将体外培养的功能相关的种子细胞种植于天然的或人工合成的支架材料内,加入生长因子体外培养一段时间,将他们移植到体内,促进组织修复和骨再生的人工骨。组织工程骨形成的3要素为：支架材料、成骨细胞、生长因子。 生物陶瓷：生物表面活性陶瓷通常含有羟基,还可做成多孔性,生物组织可长入并同其表面发生牢固的键合;生物吸收性陶瓷的特点是能部分吸收或者全部吸收,在生物体内能诱发新生骨的生长。生物活性陶瓷具有骨传导性,它作为一个支架,成骨在其表面进行;还可作为多种物质的外壳或填充骨缺损。生物陶瓷有羟基磷灰石陶瓷、磷酸三钙陶瓷等。  背景：目前常用的骨缺损修复支架材料种类较多,但单一类型材料难以满足骨组织工程支架材料的要求,通过合适的方法将几种单一材料组合形成复合型材料,综合考虑各种材料优缺点,是近年来学者们的研究重点。 目的：构建纳米羟基磷灰石/壳聚糖/聚己内酯三元复合支架材料,并作表征分析研究。 方法：采用3D打印成型技术制备纳米羟基磷灰石/壳聚糖/聚己内酯多孔三元复合支架材料,从X射线衍射分析、吸水率、抗压强度、体外降解性能、孔径分析、扫描电镜分析等多个维度对支架材料进行表征研究。 结果与结论：①X射线衍射分析显示,纳米羟基磷灰石/壳聚糖/聚己内酯多孔三元复合支架的晶型峰图与羟基磷灰石粉末衍射标准卡片类似,表明该三元复合支架是通过物理作用相互结合的,不影响羟基磷灰石的生物学功能;②三元复合支架的吸水率为18.28%,亲水性好,支架可承受的最大压力为1 415 N,其体外降解速率与成骨速率相当;③显微镜下可见三元复合支架的内孔为方形,孔径250 µm,孔径大小均匀、分布有致;④扫描电镜下三元复合支架可见,壳聚糖和聚己内酯组成的纤维排列整齐有序,成网格状, 羟基磷灰石呈颗粒状在纤维表面均匀分布,三元复合材料呈现均匀、疏松的微孔结构;⑤结果表明,通过3D打印成型技术可成功制备纳米羟基磷灰石/壳聚糖/聚己内酯三元复合支架材料,其具有适度的抗压强度、一定的孔隙率、适宜的降解速度和吸水率,能为修复骨缺损的奠定基础。 ORCID: 0000-0002-6321-9160(余和东) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程       

Development of gelatin-chitosan-hydroxyapatite based bioactive bone scaffold with controlled pore size and mechanical strength

Hydroxyapatite–chitosan/gelatin (HA:Chi:Gel) nanocomposite scaffold has potential to serve as a template matrix to regenerate extra cellular matrix of human bone. Scaffolds with varying composition of hydroxyapatite, chitosan, and gelatin were prepared using lyophilization technique where glutaraldehyde (GTA) acted as a cross-linking agent for biopolymers. First, phase pure hydroxyapatite–chitosan nanocrystals were in situ synthesized by coprecipitation method using a solution of 2% acetic acid dissolved chitosan and aqueous solution of calcium nitrate tetrahydrate [Ca(NO₃)₂,4H₂O] and diammonium hydrogen phosphate [(NH₄)₂H PO₄]. Keeping solid loading constant at 30 wt% and changing the composition of the original slurry of gelatin, HA–chitosan allowed control of the pore size, its distribution, and mechanical properties of the scaffolds. Microstructural investigation by scanning electron microscopy revealed the formation of a well interconnected porous scaffold with a pore size in the range of 35–150 μm. The HA granules were uniformly dispersed in the gelatin–chitosan network. An optimal composition in terms of pore size and mechanical properties was obtained from the scaffold with an HA:Chi:Gel ratio of 21:49:30. The composite scaffold having 70% porosity with pore size distribution of 35–150 μm exhibited a compressive strength of 3.3–3.5 MPa, which is within the range of that exhibited by cancellous bone. The bioactivity of the scaffold was evaluated after conducting mesenchymal stem cell (MSC) – materials interaction and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay using MSCs. The scaffold found to be conducive to MSC’s adhesion as evident from lamellipodia, filopodia extensions from cell cytoskeleton, proliferation, and differentiation up to 14 days of cell culture.     

猪兔鼠肾生物支架制备及体外细胞共培养探究

目的　 灌注制备家猪、新西兰白兔、SD大鼠肾去细胞生物支架,探究三种肾支架对共培养种子细胞HEK的影响。 方法　取健康成年家猪10头、新西兰白兔28只、SD大鼠28只,分别将取出的肾脏随机均等分为正常组和支架组,支架组由肾动脉依次灌入肝素、1% Triton X-100和1% SDS溶液完成去细胞化。两组肾分别作组织形态学鉴定并检测机械力学性质。去细胞支架作组织爬片与人胚肾上皮细胞共培养,观察细胞在支架爬片上的生长状况,免疫荧光检测人胚肾上皮细胞PCNA及DAPI表达量作灰度分析。 结果　家猪、新西兰白兔、SD大鼠肾脏经灌注去细胞后HE核染色阴性, Masson染色显示胶原蛋白阳性,Collagen I和Collagen IV荧光染色阳性,电镜扫描可见去细胞支架内蜂窝状孔洞结构,并可见典型的肾小球龛样结构;支架组弹性模量与正常组肾弹性模量差异无显著性,支架组PCNA/DAPI值均高于空白对照组,而三种支架组之间PCNA/DAPI值无显著性差异。 结论　本研究灌注去细胞方法可去除家猪、新西兰白兔、SD大鼠肾内的细胞及细胞核,保留细胞外基质,维持细胞外基质的三维空间结构和机械力学强度,是一种可靠有效的制备三者肾去细胞生物支架方法,灌注制备的去细胞支架均可提高异种共培养人胚肾上皮细胞HEK的增殖活性,且这种提高作用在家猪、新西兰白兔和SD大鼠之间并无物种差异性。     

骨科个体化治疗与3D打印技术

个体化治疗是骨科发展的一个重要方向,无论是个体化假体的应用还是常规假体的个体化植入,理论上均可改善骨关节假体与邻近骨性结构的匹配,从而改善病患功能状态。个体化治疗理论上的优越性无法代偿其在术前规划、设计、制造等方面程序上复杂及时限上滞后的缺陷,因而,个体化治疗常常停留在一种曲高和寡的概念。伴随图像技术的发展及3D打印技术的成熟,个体化设计及制造的生产效率有望显著提高,从而弥补传统个体化治疗效率上的不足,将个体化从概念落地为治疗理念。     

3D打印羊椎骨粉/聚乙烯醇支架、纳米级羟基磷灰石/聚乙烯醇支架、羊椎骨粉/聚乙烯醇无孔骨板的性能比较

BACKGROUND: With the promotion of 3D printing technology, 3D printing scaffolds for bone tissue engineering have become the new ideas for jaw bone repair. OBJECTIVE: To compare the physical and biological properties of sheep vertebral bone meal/polyvinyl alcohol (PVA) scaffold, nano-hydroxyapatite (nHA)/PVA scaffold, and sheep vertebral bone meal/PVA nonporous bone plate. METHODS: 3D printing technology was used to print sheep vertebral bone meal/PVA scaffold, nHA/PVA scaffold, and sheep vertebral bone meal/PVA nonporous bone plate. Porosity, morphology, water absorption rate and mechanical properties of different scaffolds were detected. Three kinds of scaffolds were all used to culture bone marrow mesenchymal stem cells, and cell proliferation ability was detected using cell counting kit-8 at 1, 4, 7 days of culture. RESULTS AND CONCLUSION: Under scanning electron microscope, the sheep vertebral bone meal/PVA scaffold and nHA/PVA scaffold exhibited regular and interconnected pores with good continuity and clear network structure; the sheep vertebral bone meal/PVA nonporous bone plate had no obvious pores; however, it had dense and evenly distributed micropores with different sizes on its surface. The porosity of nHA/PVA scaffold was lower than that of the sheep vertebral bone meal/PVA scaffold (P < 0.05). The water absorption rate was highest for the nHA/PVA scaffold followed by the sheep vertebral bone meal/PVA scaffold and the sheep vertebral bone meal/PVA nonporous bone plate (P < 0.05). In contrast, the scaffold toughness was highest for the sheep vertebral bone meal/PVA nonporous bone plate, followed by the sheep vertebral bone meal/PVA scaffold and nHA/PVA scaffold. In addition, the cell proliferation activity of cells cultured on the sheep vertebral bone meal/PVA scaffold was significantly higher than that cultured on the other two kinds of scaffolds. Taken together, the 3D printing sheep vertebral bone/PVA scaffold has good physical and chemical performance.     

3D打印技术制备β-磷酸三钙仿生骨支架在兔股骨髁部骨缺损修复中的应用

目的 探讨采用3D打印技术制备的β-磷酸三钙(β-TCP)仿生骨支架的形态结构特点及其相关生物性能,并观察其修复新西兰兔股骨髁部骨缺损的效果。方法 选取5～6月龄新西兰大白兔20只,随机分为支架组和空白组,每组10只;两组大白兔按造模术后采集标本的时间不同又分为两个亚组,每组5只。两组大白兔均于左侧股骨用环钻钻取直径约5 mm、长约10 mm的圆柱形松质骨块,建立股骨髁骨缺损模型。空白组截取的10个松质骨标本,使用微计算机断层扫描技术进行扫描,获得骨缺损标本的结构影像学数据,通过3D生物打印系统设计出相应的仿生骨支架模型,再以β-TCP作为打印材料,打印出20枚仿生骨支架。取10枚β-TCP支架测量高度、直径,电子显微镜下观察β-TCP支架孔道形态结构特点,测量大孔的直径和孔隙率,使用电子力学测试机测定β-TCP支架的弹性模量与抗压强度。空白组10只大白兔造模后不植入任何材料。支架组10只大白兔在造模后,将制备的10枚β-TCP支架植入骨缺损处。分别于术后第6、12周使用耳缘静脉推注空气方法处死空白组和支架组的各亚组大白兔,于骨缺损部位或植骨部位上下离断、截取长约10 mm骨段,制备切片,HE染色,观察骨组织生长情况;采用Lane-Sandhu组织学评分标准对骨组织修复情况进行评价。结果 使用3D生物打印技术制备的20枚圆柱体β-TCP支架,与松质骨标本结构形态相似。支架高度(9.97±0.08)mm、直径(5.09±0.07)mm,松质骨标本高度(9.96±0.39)mm、直径(5.01±0.22)mm,支架与松质骨标本比较差异均无统计学意义(P值均＞0.05)。扫描电镜观察到支架表面及内部呈均匀多孔状,孔径相互连通,大小相仿,孔隙分布较均匀,在大孔侧壁布满了微孔,外形多为近似圆形;其中大孔直径为(223.02±18.20)μm,孔隙率为74.02%±1.38%。松质骨标本大孔直径(227.02±31.20)μm,孔隙率为76.02%±3.29%,支架与松质骨标本比较差异均无统计学意义(P值均＞0.05)。使用电子力学测试机测定支架的抗压强度为(2.93±0.65)MPa,弹性模量为95～190 MPa。骨组织切片HE染色:术后第6周,支架组植骨处可见较成熟的骨组织,骨小梁和骨髓组织增多,新生骨正在逐渐覆盖植骨材料,周围可见少量成骨细胞,出现少量新生骨并向材料内长入;空白组的骨缺损处周围有少量类骨组织形成,大量成纤维细胞和脂肪组织生长,未见明显成骨细胞及骨小梁结构。术后12周,支架组植骨处出现成熟的骨小梁和骨髓组织,有编织骨形成,新生骨量较多,部分材料已被吸收降解,材料存留较少;空白组的骨缺损处见少量骨组织从缺损边缘向内长入,大部分被成纤维细胞和脂肪组织填充。Lane-Sandhu组织学评分,术后6周、12周支架组分别为(5.2±0.3)、(8.1±1.2)分,空白组分别为(1.3±0.5)、(4.5±0.6)分,支架组评分均大于空白组,差异有统计学意义(t=7.341、12.672, P值均＜0.05)。结论 3D生物打印技术制备的β-TCP仿生骨支架,与松质骨标本的骨组织解剖结构形态相似,且具有良好的生物力学性能,可以提供个体化的仿生骨支架,修复新西兰兔股骨髁部骨缺损的效果良好。     

The 3D printing of gelatin methacrylamide cell-laden tissue-engineered constructs with high cell viability

In the present study, we report on the combined efforts of material chemistry, engineering and biology as a systemic approach for the fabrication of high viability 3D printed macroporous gelatin methacrylamide constructs. First, we propose the use and optimization of VA-086 as a photo-initiator with enhanced biocompatibility compared to the conventional Irgacure 2959. Second, a parametric study on the printing of gelatins was performed in order to characterize and compare construct architectures. Hereby, the influence of the hydrogel building block concentration, the printing temperature, the printing pressure, the printing speed, and the cell density were analyzed in depth. As a result, scaffolds could be designed having a 100% interconnected pore network in the gelatin concentration range of 10–20 w/v%. In the last part, the fabrication of cell-laden scaffolds was studied, whereby the application for tissue engineering was tested by encapsulation of the hepatocarcinoma cell line (HepG2). Printing pressure and needle shape was revealed to impact the overall cell viability. Mechanically stable cell-laden gelatin methacrylamide scaffolds with high cell viability (>97%) could be printed.     

3D打印技术应用于关节置换术的现状及问题对策探讨

近年来,个体化、精确化成为骨科发展的一个重要方向。3D打印技术是材料领域中出现的一项快速成型的新技术,能够将抽象的三维数字模型转变为直观、立体的实物模型。目前该技术已广泛应用于骨科手术中,不仅协助医师进行术前规划,并且能降低术中及术后并发症的发生。本文主要探讨3D打印技术应用于人工关节置换术中的现状、存在的问题并提出对策分析,进一步对其应用前景进行展望。     

数字化设计结合3D打印技术在拇指再造中的应用

目的　通过数字化设计,结合3D打印技术实现拇指缺损再造供区面积准确、个性化及优化的选择。 方法　采集7例拇指受伤缺损患者双手及双足CT扫描数据,在Mimics软件中重建双手模型,根据左右手互为镜面投影的原理,利用Mimics软件自带“Mirror”功能生成健侧手的镜像,利用生成的镜像实现对拇指缺损的部分的虚拟形态学上的恢复,再进行数字化模拟对比和切割等操作,可以得到缺损拇指部分的三维形态模型;利用3D打印技术将生成的缺损模型打印出来,在缺损部分实物模型上贴上医用胶布包裹修剪,制作好的样布可以准确地指导供区的选择。 结果　7例拇指缺损患者均采用数字化设计结合3D打印技术进行拇指再造供区面积的选择,再造后拇指外观形态高度接近未受伤前,功能恢复快、效果好,患者反映良好。 结论　数字化设计结合3D打印技术可以实现拇指缺损供区面积准确、个性化及优化的选择。     

Bone regeneration and infiltration of an anisotropic composite scaffold: an experimental study of rabbit cranial defect repair

Tissue formation on scaffold outer edges after implantation may restrict cell infiltration and mass transfer to/from the scaffold center due to insufficient interconnectivity, leading to incidence of a necrotic core. Herein, a nano-hydroxyapatite/polyamide66 (n-HA/PA66) anisotropic scaffold with axially aligned channels was prepared with the aim to enhance pore interconnectivity. Bone tissue regeneration and infiltration inside of scaffold were assessed by rabbit cranial defect repair experiments. The amount of newly formed bone inside of anisotropic scaffold was much higher than isotropic scaffold, e.g., after 12 weeks, the new bone volume in the inner pores was greater in the anisotropic scaffolds (>50%) than the isotropic scaffolds (<30%). The results suggested that anisotropic scaffolds could accelerate the inducement of bone ingrowth into the inner pores in the non-load-bearing bone defects compared to isotropic scaffolds. Thus, anisotropic scaffolds hold promise for the application in bone tissue engineering.     

3D打印技术在牙科制造领域中的应用及未来

文题释义： 熔融沉积成型：是将热熔性材料加工成丝状,经过送丝机构到达热熔喷嘴上,之后热熔性材料被加热装置加热融化,沿着打印机已经设定好的路径进行运动,同时加热融化的丝状材料在成型平台上凝固成型,层层粘接堆积,最终形成产品模型。 光固化立体成型技术：能够在微米级的精细分辨率下制造高表面质量的零件,其成型过程就是树脂材料进行光固化聚合的过程,一般是以点成线、以线成面,然后成型平台根据打印参数决定的打印层厚进行升降。 背景：对于牙齿缺损或缺失的病例,需通过个性化制作修复物达到治疗目的。传统的制作工艺耗时长、费用高、精准度差。3D打印技术引入牙科制造后,能一定程度提高制作效率和品质。 目的：介绍 3D 打印技术在牙科制造中的应用现状,讨论目前应用中存在的技术瓶颈,展望未来3D打印技术在牙科制造应用的发展方向。 方法：作者以“3D printing,metal implant,dental manufacturing,dental restorations,3D 打印,骨缺损,金属内植物,牙科制造,牙科修复”等为关键词,检索1980至2019年期间的Web of Science、万方、CNKI 数据库中的相关文献。初检文章 261 篇,筛选后对60篇文章进行参考总结。 结果与结论：3D 打印牙模、数字化种植导板、蜡型等已在牙科制造中得到应用和推广,3D打印技术在牙科制造已得到较广泛的应用,使用最为广泛的6种工艺分别是树脂光固化成型、叠层实体制造、熔融沉积成型、选择性激光烧结、选择性激光熔化、立体喷墨技术。目前3D打印技术在牙科制造领域的应用存在着一定的技术瓶颈,突破技术瓶颈后,3D打印技术在未来的牙科制造领域将能发挥更大作用。 ORCID: 0000-0002-0781-7537(姚路) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程