Table of Contents

Special Section: Research and Applications of 3D Printing and Bioprinting for Covid-19












Regular Section

Perspective Articles

by Jia An, Chee Kai Chua, Vladimir Mironov
472 Views, 120 PDF Downloads

The application of machine learning (ML) in bioprinting has attracted considerable attention recently. Many have focused on the benefits and potential of ML, but a clear overview of how ML shapes the future of three-dimensional (3D) bioprinting is still lacking. Here, it is proposed that two missing links, Big Data and Digital Twin, are the key to articulate the vision of future 3D bioprinting. Creating training databases from Big Data curation and building digital twins of human organs with cellular resolution and properties are the most important and urgent challenges. With these missing links, it is envisioned that future 3D bioprinting will become more digital and in silico, and eventually strike a balance between virtual and physical experiments toward the most efficient utilization of bioprinting resources. Furthermore, the virtual component of bioprinting and biofabrication, namely, digital bioprinting, will become a new growth point for digital industry and information technology in future.

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Review Articles

by Yi Zhang, Bin Wang, Junchao Hu, Tianyuan Yin, Tao Yue, Na Liu, Yuanyuan Liu
424 Views, 97 PDF Downloads

Three-dimensional (3D) bioprinting is an important technology for fabricating artificial tissue. To effectively reconstruct the multiscale structure and multi-material gradient of natural tissues and organs, 3D bioprinting has been increasingly developed into multi-process composite mode. The current 3D composite bioprinting is a combination of two or more printing processes, and oftentimes, physical field regulation that can regulate filaments or cells during or after printing may be involved. Correspondingly, both path planning strategy and process control all become more complex. Hence, the computer-aided design and computer-aided manufacturing (CAD/CAM) system that is traditionally used in 3D printing system is now facing challenges. Thus, the scale information that cannot be modeled in the CAD process should be considered in the design of CAM by adding a process management module in the traditional CAD/CAM system and add more information reflecting component gradient in the path planning strategy.

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Review Articles

by Shokouh Attarilar, Mahmoud Ebrahimi, Faramarz Djavanroodi, Yuanfei Fu, Liqiang Wang, Junlin Yang
532 Views, 98 PDF Downloads

Additive manufacturing (AM) is among the most attractive methods to produce implants, the processes are very swift and it can be precisely controlled to meet patient’s requirement since they can be produced in exact shape, dimension, and even texture of different living tissues. Until now, lots of methods have emerged and used in this field with diverse characteristics. This review aims to comprehensively discuss 3D printing (3DP) technologies to manufacture metallic implants, especially on techniques and procedures. Various technologies based on their main properties are categorized, the effecting parameters are introduced, and
the history of AM technology is briefly analyzed. Subsequently, the utilization of these AM-manufactured components in medicine along with their effectual variables is discussed, and special attention is paid on to the production of porous scaffolds, taking pore size, density, etc., into consideration. Finally, 3DP of the popular metallic systems in medical applications such as titanium, Ti6Al4V, cobalt-chromium alloys, and shape memory alloys are studied. In general, AM manufactured implants need to comply with important requirements such as biocompatibility, suitable mechanical properties (strength and elastic modulus), surface conditions, custom-built designs, fast production, etc. This review aims to introduce the AM technologies in implant applications and find new ways to design more sophisticated methods and compatible implants that mimic the desired tissue functions.

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Review Articles

by Colin Sherborne, Frederik Claeyssens
306 Views, 60 PDF Downloads

This review paper explores the potential of combining emulsion-based inks with additive manufacturing (AM) to produce filters for respiratory protective equipment (RPE) in the fight against viral and bacterial infections of the respiratory tract. The value of these filters has been highlighted by the current severe acute respiratory syndrome coronavirus-2 crisis where the importance of protective equipment for health care workers cannot be overstated. Three-dimensional (3D) printing of emulsions is an emerging technology built on a well-established field of emulsion templating to produce porous materials such as polymerized high internal phase emulsions (polyHIPEs). PolyHIPE-based porous polymers have tailorable porosity from the submicron to 100 s of μm. Advances in 3D printing technology enables the control of the bulk shape while a micron porosity is controlled independently by the emulsion-based ink. Herein, we present an overview of the current polyHIPE-based filter applications. Then, we discuss the current use of emulsion templating combined with stereolithography and extrusion-based AM technologies. The benefits and limitation of various AM techniques are discussed, as well as considerations for a scalable manufacture of a polyHIPE-based RPE.

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Original Articles

by Linzhi Jing, Jie Sun, Hang Liu, Xiang Wang, Dejian Huang
435 Views, 173 PDF Downloads

Electrohydrodynamic printing (EHDP) is capable of fabricating micro- to nano-scale fibrous scaffolds for three-dimensional (3D) cell cultures and tissue engineering applications. One of the major bottlenecks that limits the widespread EHDP is the lack of biomaterial ink solutions with tunable mechanical, chemical, and biological properties. In this work, we blend plant protein nanoparticles with synthetic polymer poly(ε-caprolactone) (PCL) to develop composite biomaterial inks, such as PCL/gliadin and PCL/zein for EHDP scaffold fabrication. The tensile test results showed that the composite materials with a relatively small amount of plant protein nanoparticles, such as PCL/gliadin-10, PCL/zein-10 can significantly increase both Young’s modulus and yield stress of the fabricated scaffolds. These scaffolds are further evaluated by culturing mouse embryonic fibroblasts (NIH/3T3) cells, and proven to enhance cell adhesion and proliferation, apart from temporary inhibition effects for PCL/gliadin-20 scaffold at the initial growth stage. After these plant protein nanoparticles are gradually released into culture medium, the generated nanoporous structures on the scaffolds are also favorable to cellular attachment, migration, and proliferation. As competent candidates to upregulate cell biological behaviors in 3D microenvironment, such composite scaffolds manifest a great potential in drug screening and 3D in vitro model development.     

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Original Articles

by Bin Xie, Ming-Chun Zhao, Rong Xu, Ying-Chao Zhao, Deng-Feng Yin, Chengde Gao, Andrej Atrens
394 Views, 88 PDF Downloads

An antibacterial biomedical Mg alloy was designed to have a low biodegradation rate. ZK30-0.2Cu-xMn (x = 0, 0.4, 0.8, 1.2, and 1.6 wt.%) was produced by selective laser melting (SLM). Alloying with Mn had a significant influence on the grain size, hardness, and biodegradation rate. Increasing Mg content to 0.8 wt% decreased the biodegradation rate, attributed to the decreased grain size and the relatively protective manganese surface oxide layer. Higher Mn contents increased the biodegradation rate attributed to the presence of the Mn-rich particles. ZK30-0.2Cu-0.8Mn exhibited the lowest biodegradation rate, strong antibacterial performance and good cytocompatibility.

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Original Articles

by Marlon Wesley Machado Cunico
319 Views, 58 PDF Downloads

Dental prosthesis and restoration technologies have been developed in the past years. Despite the advantages of additive manufacturing, computer-aided design, and computer-aided manufacturing technologies are still the dominant type of method for fabricating prostheses. Therefore, the main goal of this study is to assess the feasibility of using indirect fused deposition modeling to fabricate dental prosthesis made of ZrSiO4-glass composites. To achieve this goal, filaments were filled by 90% of ZrSiO4 and 50 μm glass spheres to fabricate prosthesis. Multivariable approach was applied to evaluate the feasibility of the proposed method. Holding temperature, holding time, heating rate, and cooling rate were considered the control factors, while shrinkage, flexural strength, and process feasibility were the study responses. In addition, the flexural strength of materials was found between 25 and 85 MPa, while shrinkage fluctuated between 10 and 25%.

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Original Articles

by Chuanchuan Zheng, Shokouh Attarilar, Kai Li, Chong Wang, Jia Liu, Liqiang Wang, Junlin Yang, Yujin Tang
256 Views, 41 PDF Downloads

In this study, a β-tricalcium phosphate (β-TCP)/poly (lactic-co-glycolic acid) (PLGA) bone tissue scaffold was loaded with osteogenesis-promoting drug HA15 and constructed by three-dimensional (3D) printing technology. This drug delivery system with favorable biomechanical properties, bone conduction function, and local release of osteogenic drugs could provide the basis for the treatment of bone defects. The biomechanical properties of the scaffold were investigated by compressive testing, showing comparable biomechanical properties with cancellous bone tissue. Furthermore, the microstructure, pore morphology, and condition were studied. Moreover, the drug release concentration, the effect of anti-tuberculosis drugs in vitro and in rabbit radial defects, and the ability of the scaffold to repair the defects were studied. The results show that the scaffold loaded with HA15 can promote cell differentiation into osteoblasts in vitro, targeting HSPA5. The micro-computed tomography scans showed that after 12 weeks of scaffold implantation, the defect of the rabbit radius was repaired and the peripheral blood vessels were regenerated. Thus, HA15 can target HSPA5 to inhibit endoplasmic reticulum stress which finally leads to promotion of osteogenesis, bone regeneration, and angiogenesis in the rabbit bone defect model. Overall, the 3D-printed β-TCP/PLGA-loaded HA15 bone tissue scaffold can be used as a substitute material for the treatment of bone defects because of its unique biomechanical properties and bone conductivity.

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Original Articles

by Cyron Lego Custodio, Phoebeliza Jane M. Broñola, Sharyjel R.Cayabyab, Vivian U. Lagura, Josefina R. Celorico, Blessie A. Basilia
200 Views, 36 PDF Downloads
This study presents the physicochemical and mechanical behavior of incorporating hydroxyapatite (HAp) with polylactic acid (PLA) matrix in 3D printed PLA/HAp composite materials. Effects of powder loading to the composition, crystallinity, morphology, and mechanical properties were observed. HAp was synthesized from locally sourced nanoprecipitated calcium carbonate and served as the filler for the PLA matrix. The 0, 5, 10, and 15 wt. % HAp biocomposite filaments were formed using a twin-screw extruder. The resulting filaments were 3D printed in an Ultimaker S5 machine utilizing a fused deposition modeling technology. Successful incorporation of HAp and PLA was observed using infrared spectroscopy and X-ray diffraction (XRD). The mechanical properties of pure PLA had improved on the incorporation of 15% HAp; from 32.7 to 47.3 MPa in terms of tensile strength; and 2.3 to 3.5 GPa for stiffness. Moreover, the preliminary in vitro bioactivity test of the 3D printed PLA/HAp biocomposite samples in simulated body fluid (SBF) indicated varying weight gains and the presence of apatite species’ XRD peaks. The HAp particles embedded in the PLA matrix acted as nucleation sites for the deposition of salts and apatite species from the SBF solution
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Original Articles

by Lung Chow, Kit-lun Yick, Yue Sun, Matthew S.H. Leung, Mei-ying Kwan, Sun-pui Ng, Annie Yu, Joanne Yip, Ying-fan Chan
269 Views, 33 PDF Downloads, 5 Supp.File Downloads

The treatment of hypertrophic scars (HSs) is considered to be the most challenging task in wound rehabilitation. Conventional silicone sheet therapy has a positive effect on the healing process of HSs. However, the dimensions of the silicone sheet are typically larger than those of the HS itself which may negatively impact the healthy skin that surrounds the HS. Furthermore, the debonding and displacement of the silicone sheet from the skin are critical problems that affect treatment compliance. Herein, we propose a bespoke HS treatment design that integrates pressure sleeve with a silicone sheet and use of silicone gel using a workflow of three-dimensional (3D) printing, 3D scanning and computer-aided design, and manufacturing software. A finite element analysis (FEA) is used to optimize the control of the pressure distribution and investigate the effects of the silicone elastomer. The result shows that the silicone elastomer increases the amount of exerted pressure on the HS and minimizes unnecessary pressure to other parts of the wrist. Based on this treatment design, a silicone elastomer that perfectly conforms to an HS is printed and attached onto a customized pressure sleeve. Most importantly, unlimited scar treating gel can be applied as the means to optimize treatment of HSs while the silicone sheet is firmly affixed and secured by the pressure sleeve.

Original Articles

by Marisela Rodriguez-Salvador, Baruc Emet Perez-Benitez, Karen Marcela Padilla-Aguirre
187 Views, 41 PDF Downloads

Tissue spheroids consist of a three-dimensional model of cells which is capable of imitating the complicated composition of healthy and unhealthy human tissue. Due to their unique properties, they can bring innovative solutions to tissue engineering and regenerative medicine, where they can be used as building blocks for the formation of organ and tissue models used in drug experimentation. Considering the rapid transformation of the health industry, it is crucial to assess the research dynamics of this field to support the development of innovative applications. In this research, a scientometric analysis was performed as part of a Competitive Technology Intelligence methodology, to determine the main applications of tissue spheroids. Papers from Scopus and Web of Science published between 2000 and 2019 were organized and analyzed. In total, 868 scientific publications were identified, and four main categories of application were determined. Main subject areas, countries, cities, authors, journals, and institutions were established. In addition, a cluster analysis was performed to determine networks of collaborations between institutions and authors. This article provides insights into the applications of cell aggregates and the research dynamics of this field, which can help in the decision-making process to incorporate emerging and innovative technologies in the health industry.

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