Natural Polysaccharides as Multifunctional Components for One-Step 3D Printing Tough Hydrogels

Natural polysaccharides (NPS) are regarded as biomolecular and structural components for preparing high-performance tough hydrogels. But the one-step fabrication of NPS-containing hydrogels in seconds and the template-free design of complicated high-resolution structures are still significant challenges in this field. To meet these requirements, various NPS-containing tough hydrogels are fabricated and processed into 2D/3D structures via the combination of Ru(bpy)₃²⁺-mediated photochemistry and extrusion 3D printing technique. The whole fabrication process is one-step, completed in tens of seconds under visible light irradiation. It is found that the used NPS plays a key role in achieving the fabrication of high-performance structured tough hydrogels. The high reactivity of functional groups in the used NPS can shorten their gelation times. Long rigid chains of the used NPS, their hierarchical assemblies, and contrasting multinetworks benefit from the efficient dissipation of mechanical energy and enhancement of its operational stability. Strong supramolecular interactions enable hydrogel precursors to have high viscosities, therefore providing good controllability to design high-resolution and complicated tough hydrogel structures via extrusion 3D printing. It is anticipated that this straightforward fabrication strategy and findings will open new horizons for NPS-containing materials.     

3D打印塑料材料在汽车配件设计中的应用

近年来,汽车产业出现了以塑代钢的轻量化趋势,随着3D打印技术的不断发展,3D打印塑料材料在汽车配件设计中应用广泛,能够有效地节省汽车研发周期,削减成本。概述了3D打印塑料材料的现状,包括其种类、形态及改进技术,及其对于汽车配件设计的影响;介绍了3D打印塑料材料在汽车配件设计中的应用,并对其在汽车配件设计中的未来发展趋势进行了探讨。     

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.     

A Guide to Polysaccharide-Based Hydrogel Bioinks for 3D Bioprinting Applications

Three-dimensional (3D) bioprinting is an innovative technology in the biomedical field, allowing the fabrication of living constructs through an approach of layer-by-layer deposition of cell-laden inks, the so-called bioinks. An ideal bioink should possess proper mechanical, rheological, chemical, and biological characteristics to ensure high cell viability and the production of tissue constructs with dimensional stability and shape fidelity. Among the several types of bioinks, hydrogels are extremely appealing as they have many similarities with the extracellular matrix, providing a highly hydrated environment for cell proliferation and tunability in terms of mechanical and rheological properties. Hydrogels derived from natural polymers, and polysaccharides, in particular, are an excellent platform to mimic the extracellular matrix, given their low cytotoxicity, high hydrophilicity, and diversity of structures. In fact, polysaccharide-based hydrogels are trendy materials for 3D bioprinting since they are abundant and combine adequate physicochemical and biomimetic features for the development of novel bioinks. Thus, this review portrays the most relevant advances in polysaccharide-based hydrogel bioinks for 3D bioprinting, focusing on the last five years, with emphasis on their properties, advantages, and limitations, considering polysaccharide families classified according to their source, namely from seaweed, higher plants, microbial, and animal (particularly crustaceans) origin.     

4D Printing of Reversible Shape Morphing Hydrogel Structures

A series of hydrogel‐based inks are developed to print 3D structures capable of reversible shape deformation in response to hydration and temperature. The inks are made of large polymer chains and UV curable monomers which form interpenetrating polymer networks after polymerization. By taking advantage of the long polymer chains in the ink formulations, it is possible to adjust the rheological properties of the inks to enable 3D printing. Hydrogels produced from the inks exhibit robust mechanical performance with their mechanical properties controlled by the nature of the long polymer chains within their networks. In this paper, hydrogel hinges are made from various ink formulations and a simple model is developed to predict their bending characteristics, including the bending curvature and bending angle. This model can be used as a guide to determine optimal parameters for a wide range of materials combination to create all‐hydrogel structures that undergo desired shape transitions.

     

Novel Formulations Containing Fluorescent Sensors to Improve the Resolution of 3D Prints

Three-dimensional printing in SLA (stereolithography) and DLP (digital light processing) technologies has recently been experiencing a period of extremely rapid development. This is due to the fact that researchers recognise the many advantages of 3D printing, such as the high resolution and speed of the modelling and printing processes. However, there is still a search for new resin formulations dedicated to specific 3D printers allowing for high-resolution prints. Therefore, in the following paper, the effects of dyes such as BODIPY, europium complex, and Coumarin 1 added to light-cured compositions polymerised according to the radical mechanism on the photopolymerisation process speed, polymerisation shrinkage, and the final properties of the printouts were investigated. The kinetics of the photopolymerisation of light-cured materials using real-time FT-IR methods, as well as printouts that tangibly demonstrate the potential application of 3D printing technology in Industry 4.0, were examined. These studies showed that the addition of dyes has an effect on obtaining fluorescent prints with good resolution.     

3D Printing/Interfacial Polymerization Coupling for the Fabrication of Conductive Hydrogel

In this study, 3D printing is coupled with interfacial polymerization to obtain electroactive hydrogels with complex and defined geometry. Conductive hydrogels are created through a two‐step procedure: first a digital light processing 3D printing system is used to fabricate poly(ethylene glycol)diacrylate 3D structure and then pyrrole is oxidized to polypyrrole (PPY), exploiting an interfacial polymerization mechanism through which PPY can be formed in the poly(ethylene glycol) matrix, thus creating a conductive phase.     

高聚物的新型3D打印材料开发进展

综述了一般3D打印技术的概念、产业及其发展。重点介绍了高聚物在3D打印材料中的应用。持续跟踪结果表明:一批新型高聚物的3D打印材料推向市场,一批国际知名化工公司也在积极介入3D打印业务。     

3D打印在包装工业中的应用与前景

综述了3D打印技术中熔融沉积成型技术、激光选区烧结法技术、光固化立体成型技术、分层实体制造技术四种方法的特点和应用,介绍了应用于3D打印技术中常用的材料以及3D打印技术在包装工业中的应用。指出在包装工业中采用3D打印技术具有的优势是其它同类包装制造技术无法比拟的,3D打印技术在未来的包装工业中有着十分广阔的应用前景。     

A biopolymer‐based 3D printable hydrogel for toxic metal adsorption from water

Herein, we describe a 3D printable hydrogel that is capable of removing toxic metal pollutants from aqueous solution. To achieve this, shear‐thinning hydrogels were prepared by blending chitosan with diacrylated Pluronic F‐127 which allows for UV curing after printing. Several hydrogel compositions were tested for their ability to absorb common metal pollutants such as lead, copper, cadmium and mercury, as well as for their printability. These hydrogels displayed excellent metal adsorption with some examples capable of up to 95% metal removal within 30 min. We show that 3D printed hydrogel structures that would be difficult to fabricate by conventional manufacturing methods can adsorb metal ions significantly faster than solid objects, owing to their higher accessible surface areas. © 2019 Society of Chemical Industry     

自由基–阳离子混杂固化型3D打印光敏树脂研究

选择丙烯酸酯作为自由基型预聚物,3,4–环氧环己基甲基–3,4环氧环己基甲酸酯作为阳离子型预聚物,三丙二醇二丙烯酸酯为活性稀释剂,2,2–二甲基–α–羟基苯乙酮和三芳基硫鎓盐为光引发剂来制备一种混杂固化光敏树脂。将聚氨酯丙烯酸酯(PUA)加入到上述制备的光敏树脂中,探究PUA作为辅助预聚物对光敏树脂性能的影响,用超声分散法制备了纳米氧化石墨烯(GO)改性光敏树脂复合材料。当PUA的质量分数为20%时,力学性能最优;GO对光敏树脂的力学性能有改善的作用,拉伸强度从17.84 MPa最大增强至27.84 MPa,提高了56%;且该混合体系的体积收缩率在3%左右,线收缩率也很小。     

Silk Hydrogel Microfibers for Biomimetic Fibrous Material Design

Fiber units are conserved design motifs that bestow intrinsic stiffness to biological tissues. Collagen fibrils are the fundamental unit of fibrous tissues with controlled assembly and multiscale structure‐function properties. Characteristic non‐linear tissue response is afforded through energy dissipation at the stiff‐soft interfaces of fibril collagen and extrafibrillar matrix components. The goal of this research is to develop a 3D silk hydrogel microfiber platform with bioinspired toughening mechanisms. Batch fabrication and post‐processing renders fibers that can be handled and with tunable features, as well as loading of components to improve material responses. Matrix loading of a glycoprotein, bovine serum albumin (BSA), adds a primary defense mechanism to material failure in the form of sacrificial bonds. This enables nano‐ to micro‐scale rearrangement with strain and improved fiber toughness compared to silk‐only fibers. Further biomimicry is added via matrix loading of a biosilica precursor peptide, R5, enabling biomineralization in the form of silicification. Inorganic mineral deposition of Silk‐BSA‐R5 hydrogel microfibers provides a fibrous scaffold for applications that require fibril‐mineral interfaces for load transduction. This microfiber platform introduces a methodology for meticulous fibrous scaffold design with biomimetic fibril hierarchy, toughening mechanisms, and loading capabilities for systematic tissue engineering applications.     

3D打印用聚丙烯复合材料的制备及性能研究

将碳酸钙和滑石粉按质量比为1∶1混合,与聚丙烯(PP)共混,制备可用于熔融沉积法(FDM)打印的PP材料,研究填料用量对3D打印试样力学性能和微观结构的影响。结果表明,随着填料用量的增大,3D打印制品的力学性能下降,PP材料的收缩率显著降低,试样内部纤维之间无空隙。当碳酸钙和滑石粉质量各占配方总质量的20%时,3D打印的PP制品性能最好。     

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。     

3D gel printing of magnetic hydrogel scaffolds assisted by in-situ gelation in a water level-controlled crosslinker bath

Polyvinylalcohol/chitosan (PVA/CS) is an excellent dual-network hydrogel material, but some significant challenges remain in fabricating composites with specific structures. In this study, 3D gel printing (3DGP) combined with a water-level controlled crosslinker bath was proposed for the rapid in-situ prototyping of PVA/CS/Fe₃O₄ magnetic hydrogel scaffolds. Specifically, the PVA/CS/Fe₃O₄ hydrogels were extruded into the crosslinker water to achieve rapid in-situ gelation, improving the printability of hydrogel scaffolds. The effect of the PVA/CS ratio on the rheological and mechanical properties of dual-network magnetic hydrogels was evaluated. The printing parameters were systematically optimized to facilitate the coordination between the crosslinking water bath and printer. The different crosslinking water baths were investigated to improve the printability of PVA/CS/Fe₃O₄ hydrogels. The results showed that the printability of the sodium hydroxide (NaOH) crosslinker was significantly better than that of sodium tripolyphosphate (TPP). The magnetic hydrogels (PVA: CS= 1: 1) crosslinked by NaOH had better compressive strength, swelling rate, and saturation magnetization of 1.17 MPa, 92.43%, and 22.19 emu/g, respectively. The MC3T3-E1 cell culture results showed that the PVA/CS/Fe₃O₄ scaffolds promoted cell adhesion and proliferation, and the scaffolds crosslinked by NaOH had superior cytocompatibility. 3DGP combined with a water-level controlled crosslinker bath offers a promising approach to preparing magnetic hydrogel materials.     

3D打印制备三维石墨烯及其在水处理中的应用

石墨烯作为一类新型纳米材料,具有对水中各类污染物良好的吸附去除性能,但石墨烯纳米粉末态的性状使其在使用后难以从溶液中分离出来而造成二次污染。因此构建大体积的三维石墨烯结构,可以有效弥补水处理中纳米材料难以分离的问题。本文介绍了如今常用的三维结构制备方法,如模板法、自组装法等,但这些方法通常步骤烦琐、影响因素及所需条件较多等,在过程中易产生结构缺陷,从而影响制得的三维结构的力学性能。文中指出,3D打印法通过计算机数据调控,具有操作简便、结构设计精准、批量制备的优点,可制备出优良的三维结构体,并可通过对浆料组分的灵活调控进行改性或增加其力学性能。综上所述,配置满足3D打印黏度要求的浆料,并使制得的三维结构具备一定要求的力学性能,充分利用其精密的规模化生产,是使3D打印三维石墨烯适用于水处理的关键所在。     

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。     

Naturally Derived Maleic Chitosan/Thiolated Sodium Hyaluronate Hydrogels as Potential 3D Printing Tissue Engineering Materials

3D printing is an attractive method to accurately construct artificial organs or alternative materials with complicated structures and functional performance. Naturally derived hydrogels have emerged as promising materials for the preparation of biomimetic 3D organization or scaffolds by 3D printing due to their good biocompatibility, high water content, and fascinating 3D network. However, the poor printing properties and weak structural stability of naturally derived hydrogels limit their applications. In this study, photopolymerizable hydrogels are designed based on maleic chitosan (MCS) and thiolated sodium hyaluronate (SHHA). The Michael addition between MCS and SHHA improves the viscosity of the mixed solution. Moreover, it benefits the 3D printing process, followed by photopolymerization (acrylate-thiol step-chain polymerization and acrylate–acrylate chain polymerization) to form a stable covalent network rapidly. The rheological property, swelling behaviors, microstructure, and in vitro degradation are tuned by adjusting the molar ratio of the thiol group and acrylate group. In addition, MCS/SHHA hydrogel scaffolds with good accuracy and enhanced structural stability are prepared using extrusion-based 3D printing and photopolymerization technology. The hydrogels display excellent cytocompatibility and can support adherence of L929 cells, which can be used as prospective materials for tissue engineering applications.     

Active Materials for 3D Printing in Small Animals: Current Modalities and Future Directions for Orthopedic Applications

The successful clinical application of bone tissue engineering requires customized implants based on the receiver’s bone anatomy and defect characteristics. Three-dimensional (3D) printing in small animal orthopedics has recently emerged as a valuable approach in fabricating individualized implants for receiver-specific needs. In veterinary medicine, because of the wide range of dimensions and anatomical variances, receiver-specific diagnosis and therapy are even more critical. The ability to generate 3D anatomical models and customize orthopedic instruments, implants, and scaffolds are advantages of 3D printing in small animal orthopedics. Furthermore, this technology provides veterinary medicine with a powerful tool that improves performance, precision, and cost-effectiveness. Nonetheless, the individualized 3D-printed implants have benefited several complex orthopedic procedures in small animals, including joint replacement surgeries, critical size bone defects, tibial tuberosity advancement, patellar groove replacement, limb-sparing surgeries, and other complex orthopedic procedures. The main purpose of this review is to discuss the application of 3D printing in small animal orthopedics based on already published papers as well as the techniques and materials used to fabricate 3D-printed objects. Finally, the advantages, current limitations, and future directions of 3D printing in small animal orthopedics have been addressed.     

三维设计方法在水泥工厂设计中的应用

主要介绍三维设计方法和设计工具,以及三维设计的应用特征和优势,探讨三维设计技术在水泥工程设计中的应用前景和应用方法。