The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Barry J Doyle - One of the best experts on this subject based on the ideXlab platform.
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mechanical behaviour of alginate gelatin hydrogels for 3D Bioprinting
Journal of The Mechanical Behavior of Biomedical Materials, 2018Co-Authors: Michael Di Giuseppe, Nicholas Law, T B Sercombe, Lawrence J Liew, Rodney J Dilley, Barry J Doyle, Braeden Webb, Ryley A MacraeAbstract:Hydrogels comprised of alginate and gelatin have demonstrated potential as biomaterials in three dimensional (3D) Bioprinting applications. However, as with all hydrogel-based biomaterials used in extrusion-based Bioprinting, many parameters influence their performance and there is limited data characterising the behaviour of alginate-gelatin (Alg-Gel) hydrogels. Here we investigated nine Alg-Gel blends by varying the individual constituent concentrations. We tested samples for printability and print accuracy, compressive behaviour and change over time, and viability of encapsulated mesenchymal stem cells in bioprinted constructs. Printability tests showed a decrease in strand width with increasing concentrations of Alg-Gel. However due to the increased viscosity associated with the higher Alg-Gel concentrations, the minimum width was found to be 0.32mm before blends became too viscous to print. Similarly, printing accuracy was increased in higher concentrations, exceeding 90% in some blends. Mechanical properties were assessed through uniaxial compression testing and it was found that increasing concentrations of both Alg and Gel resulted in higher compressive modulus. We also deemed 15min crosslinking in calcium chloride to be sufficient. From our data, we propose a blend of 7%Alg-8%Gel that yields high printability, mechanical strength and stiffness, and cell viability. However, we found the compressive behaviour of Alg-Gel to reduce rapidly over time and especially when incubated at 37°C. Here we have reported relevant data on Alg-Gel hydrogels for Bioprinting. We tested for biomaterial properties and show that these hydrogels have many desirable characteristics that are highly tunable. Though further work is needed before practical use in vivo can be achieved.
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characterisation of hyaluronic acid methylcellulose hydrogels for 3D Bioprinting
Journal of The Mechanical Behavior of Biomedical Materials, 2018Co-Authors: Nicholas Law, Brandon Doney, Hayley Glover, Yahua Qin, Zachary M Aman, T B Sercombe, Lawrence J Liew, Rodney J Dilley, Barry J DoyleAbstract:Hydrogels containing hyaluronic acid (HA) and methylcellulose (MC) have shown promising results for three dimensional (3D) Bioprinting applications. However, several parameters influence the applicability Bioprinting and there is scarce data in the literature characterising HAMC. We assessed eight concentrations of HAMC for printability, swelling and stability over time, rheological and structural behaviour, and viability of mesenchymal stem cells. We show that HAMC blends behave as viscous solutions at 4°C and have faster gelation times at higher temperatures, typically gelling upon reaching 37°C. We found the storage, loss and compressive moduli to be dependent on HAMC concentration and incubation time at 37°C, and show the compressive modulus to be strain-rate dependent. Swelling and stability was influenced by time, more so than pH environment. We demonstrated that mesenchymal stem cell viability was above 75% in bioprinted structures and cells remain viable for at least one week after 3D Bioprinting. The mechanical properties of HAMC are highly tuneable and we show that higher concentrations of HAMC are particularly suited to cell-encapsulated 3D Bioprinting applications that require scaffold structure and delivery of cells.
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parameter optimization for 3D Bioprinting of hydrogels
Bioprinting, 2017Co-Authors: Barry J Doyle, Braeden WebbAbstract:Abstract Successful Bioprinting of hydrogels relies on geometric accuracy and cell viability, both of which are influenced by a number of variable printing parameters. Despite much research aimed at the resulting quality of bioprinted structures, there is no standard method of comparing bioprint results. In this study, we have developed a simple method of assessing the bioprint results from a range of printing parameters in a standardized manner applicable to extrusion-based bioinks. The purpose of the parameter optimization index (POI) is to minimize the shear stress acting on the bioink, and thus on the encapsulated cells, while ensuring the maximum geometric accuracy is obtained. Here we demonstrate the use of the POI on a blend of 7% alginate and 8% gelatin, and test the printing achieved through 25, 27, and 30 gauge print nozzles at 1–6 mm/s print speeds, and at 100–250 kPa print pressures. In total, we tested 72 printing configurations. Our data shows that for this particular hydrogel blend, the optimum print is obtained with a 30 gauge nozzle, 100 kPa print pressure and 4 mm/s print speed. The POI is intuitive and easy to assess, and could be a useful method across a wide range of 3D Bioprinting research and development applications.
Lijie Grace Zhang - One of the best experts on this subject based on the ideXlab platform.
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3D Bioprinting for cardiovascular regeneration and pharmacology
Advanced Drug Delivery Reviews, 2018Co-Authors: Haitao Cui, Xuan Zhou, Shida Miao, Timothy Esworthy, Sejun Lee, Chengyu Liu, J Fisher, Muhammad M Mohiuddin, Lijie Grace ZhangAbstract:Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide. Compared to traditional therapeutic strategies, three-dimensional (3D) Bioprinting is one of the most advanced techniques for creating complicated cardiovascular implants with biomimetic features, which are capable of recapitulating both the native physiochemical and biomechanical characteristics of the cardiovascular system. The present review provides an overview of the cardiovascular system, as well as describes the principles of, and recent advances in, 3D Bioprinting cardiovascular tissues and models. Moreover, this review will focus on the applications of 3D Bioprinting technology in cardiovascular repair/regeneration and pharmacological modeling, further discussing current challenges and perspectives.
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advances in 3D Bioprinting for neural tissue engineering
Advanced Biosystems, 2018Co-Authors: Timothy Esworthy, Shida Miao, Seth Stake, Brent T Harris, Lijie Grace ZhangAbstract:Current therapies for nerve regeneration within injured tissues have had limited success due to complicated neural anatomy and inhibitory barriers in situ. Recent advancements in 3D Bioprinting technologies have enabled researchers to develop novel 3D scaffolds with complex architectures in an effort to mitigate the challenges that beset reliable and defined neural tissue regeneration. Among several possible neuroregenerative treatment approaches that are being explored today, 3D bioprinted scaffolds have the unique advantage of being highly modifiable, which promotes greater resemblance to the native biological architecture of in vivo systems. This high architectural similarity between printed constructs and in vivo structures is thought to facilitate a greater capacity for repair of damaged nerve tissues. In this review, advances of several 3D Bioprinting methods are introduced, including laser Bioprinting, inkjet Bioprinting, and extrusion-based printing. In addition, the emergence of 4D printing is discussed, which adds a dimension of transformation over time to traditional 3D printing. Finally, an overview of emerging trends in advanced Bioprinting materials is provided and their therapeutic potential for application in neural tissue regeneration is evaluated in both the central nervous system and the peripheral nervous system.
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3D Bioprinting for Organ Regeneration
Advanced Healthcare Materials, 2017Co-Authors: Haitao Cui, John P. Fisher, Lijie Grace ZhangAbstract:Regenerative medicine holds the promise of engineering functional tissues or organs to heal or replace abnormal and necrotic tissues/organs, offering hope for filling the gap between organ shortage and transplantation needs. Three-dimensional (3D) Bioprinting is evolving into an unparalleled bio-manufacturing technology due to its high-integration potential for patient-specific designs, precise and rapid manufacturing capabilities with high resolution, and unprecedented versatility. It enables precise control over multiple compositions, spatial distributions, and architectural accuracy/complexity, therefore achieving effective recapitulation of microstructure, architecture, mechanical properties, and biological functions of target tissues and organs. Here we provide an overview of recent advances in 3D Bioprinting technology, as well as design concepts of bioinks suitable for the Bioprinting process. We focus on the applications of this technology for engineering living organs, focusing more specifically on vasculature, neural networks, the heart and liver. We conclude with current challenges and the technical perspective for further development of 3D organ Bioprinting.
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3D Bioprinting a cell laden bone matrix for breast cancer metastasis study
ACS Applied Materials & Interfaces, 2016Co-Authors: Xuan Zhou, Wei Zhu, Margaret Nowicki, Shida Miao, Haitao Cui, Benjamin Holmes, Robert I Glazer, Lijie Grace ZhangAbstract:Metastasis is one of the deadliest consequences of breast cancer, with bone being one of the primary sites of occurrence. Insufficient 3D biomimetic models currently exist to replicate this process in vitro. In this study, we developed a biomimetic bone matrix using 3D Bioprinting technology to investigate the interaction between breast cancer (BrCa) cells and bone stromal cells (fetal osteoblasts and human bone marrow mesenchymal stem cells (MSCs)). A tabletop stereolithography 3D bioprinter was employed to fabricate a series of bone matrices consisting of osteoblasts or MSCs encapsulated in gelatin methacrylate (GelMA) hydrogel with nanocrystalline hydroxyapatite (nHA). When BrCa cells were introduced into the stromal cell-laden bioprinted matrices, we found that the growth of BrCa cells was enhanced by the presence of osteoblasts or MSCs, whereas the proliferation of the osteoblasts or MSCs was inhibited by the BrCa cells. The BrCa cells co-cultured with MSCs or osteoblasts presented increased vascular...
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Hierarchical Fabrication of Engineered Vascularized Bone Biphasic Constructs via Dual 3D Bioprinting: Integrating Regional Bioactive Factors into Architectural Design
Advanced Healthcare Materials, 2016Co-Authors: Haitao Cui, Ali Khademhosseini, Wei Zhu, Xuan Zhou, Lijie Grace ZhangAbstract:A biphasic artificial vascularized bone construct with regional bioactive factors is presented using dual 3D Bioprinting platform technique, thereby forming a large functional bone grafts with organized vascular networks. Biocompatible mussel-inspired chemistry and "thiol-ene" click reaction are used to regionally immobilize bioactive factors during construct fabrication for modulating or improving cellular events.
Wai Yee Yeong - One of the best experts on this subject based on the ideXlab platform.
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3D Bioprinting processes a perspective on classification and terminology
International Journal of Bioprinting, 2018Co-Authors: Jia Min Lee, Swee Leong Sing, Miaomiao Zhou, Wai Yee YeongAbstract:This article aims to provide further classification of cell-compatible Bioprinting processes and examine the concept of 3D Bioprinting within the general technology field of 3D printing. These technologies are categorized into four distinct process categories, namely material jetting, vat photopolymerization, material extrusion and free-form spatial printing. Discussion will be presented on the definition of classification with example of techniques grouped under the same category. The objective of this article is to establish a basic framework for standardization of process terminology in order to accelerate the implementation of Bioprinting technologies in research and commercial landscape.
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proof of concept 3D Bioprinting of pigmented human skin constructs
Biofabrication, 2018Co-Authors: Wai Yee Yeong, May Win NaingAbstract:Three-dimensional (3D) pigmented human skin constructs have been fabricated using a 3D Bioprinting approach. The 3D pigmented human skin constructs are obtained from using three different types of skin cells (keratinocytes, melanocytes and fibroblasts from three different skin donors) and they exhibit similar constitutive pigmentation (pale pigmentation) as the skin donors. A two-step drop-on-demand Bioprinting strategy facilitates the deposition of cell droplets to emulate the epidermal melanin units (pre-defined patterning of keratinocytes and melanocytes at the desired positions) and manipulation of the microenvironment to fabricate 3D biomimetic hierarchical porous structures found in native skin tissue. The 3D bioprinted pigmented skin constructs are compared to the pigmented skin constructs fabricated by conventional a manual-casting approach; in-depth characterization of both the 3D pigmented skin constructs has indicated that the 3D bioprinted skin constructs have a higher degree of resemblance to native skin tissue in term of the presence of well-developed stratified epidermal layers and the presence of a continuous layer of basement membrane proteins as compared to the manually-cast samples. The 3D Bioprinting approach facilitates the development of 3D in vitro pigmented human skin constructs for potential toxicology testing and fundamental cell biology research.
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hybrid microscaffold based 3D Bioprinting of multi cellular constructs with high compressive strength a new biofabrication strategy
Scientific Reports, 2016Co-Authors: Yu Jun Tan, Wai Yee Yeong, Xipeng Tan, Shu Beng TorAbstract:A hybrid 3D Bioprinting approach using porous microscaffolds and extrusion-based printing method is presented. Bioink constitutes of cell-laden poly(D,L-lactic-co-glycolic acid) (PLGA) porous microspheres with thin encapsulation of agarose-collagen composite hydrogel (AC hydrogel). Highly porous microspheres enable cells to adhere and proliferate before printing. Meanwhile, AC hydrogel allows a smooth delivery of cell-laden microspheres (CLMs), with immediate gelation of construct upon printing on cold build platform. Collagen fibrils were formed in the AC hydrogel during culture at body temperature, improving the cell affinity and spreading compared to pure agarose hydrogel. Cells were proven to proliferate in the bioink and the bioprinted construct. High cell viability up to 14 days was observed. The compressive strength of the bioink is more than 100 times superior to those of pure AC hydrogel. A potential alternative in tissue engineering of tissue replacements and biological models is made possible by combining the advantages of the conventional solid scaffolds with the new 3D Bioprinting technology.
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Smart hydrogels for 3D Bioprinting
International Journal of Bioprinting, 2015Co-Authors: Shuai Wang, Wai-Yee Y Yeong, Jia Min Lee, Wai Yee YeongAbstract:Hydrogels are 3D networks that have a high water content. They have been widely used as cell carriers and scaffolds in tissue engineering due to their structural similarities to the natural extracellular matrix. Among these, “Smart” hydrogels refer to a group of hydrogels that is responsive to various external stimuli such as pH, temperature, light, electric, and magnetic field. Combining the potential of 3D printing and smart hydrogels is an exciting new para- digm in the fabrication of a functional 3D tissue. In this article, we provide a state-of-the-art review on smart hydrogels and Bioprinting. We identify the critical material properties needed for the most commonly used Bioprinting techniques, namely extrusion-based, inkjet-based, and laser-based techniques. The latest progress in different smart hydrogel sys- tems and their applications in Bioprinting are presented. The challenges of printing these hydrogel systems are also highlighted. Lastly, we present the potentials and the future perspectives of smart hydrogels in 3D Bioprinting.
Qing Gao - One of the best experts on this subject based on the ideXlab platform.
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3D Bioprinting of vessel like structures with multilevel fluidic channels
ACS Biomaterials Science & Engineering, 2017Co-Authors: Qing Gao, An Liu, Zhenjie Liu, Zhiwei Lin, Jingjiang Qiu, Yu Liu, Yidong Wang, Meixiang Xiang, Bing ChenAbstract:In this study, 3D hydrogel-based vascular structures with multilevel fluidic channels (macro-channel for mechanical stimulation and microchannel for nutrient delivery and chemical stimulation) were fabricated by extrusion-based three-dimensional (3D) Bioprinting, which could be integrated into organ-on-chip devices that would better simulate the microenvironment of blood vessels. In this approach, partially cross-linked hollow alginate filaments loading fibroblasts and smooth muscle cells were extruded through a coaxial nozzle and then printed along a rotated rod template, and endothelial cells were seeded into the inner wall. Because of the fusion of adjacent hollow filaments, two-level fluidic channels, including a macro-channel in the middle formed from the cylindrical template and a microchannel around the wall resulted from the hollow filaments were formed. By this method, different shapes of vessellike structures of millimeter diameter were printed. The structures printed using 4% alginate exhibited...
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3D Bioprinting of Vessel-like Structures with Multilevel Fluidic Channels
2017Co-Authors: Qing Gao, An Liu, Zhenjie Liu, Zhiwei Lin, Jingjiang Qiu, Yu Liu, Yidong Wang, Meixiang Xiang, Bing ChenAbstract:In this study, 3D hydrogel-based vascular structures with multilevel fluidic channels (macro-channel for mechanical stimulation and microchannel for nutrient delivery and chemical stimulation) were fabricated by extrusion-based three-dimensional (3D) Bioprinting, which could be integrated into organ-on-chip devices that would better simulate the microenvironment of blood vessels. In this approach, partially cross-linked hollow alginate filaments loading fibroblasts and smooth muscle cells were extruded through a coaxial nozzle and then printed along a rotated rod template, and endothelial cells were seeded into the inner wall. Because of the fusion of adjacent hollow filaments, two-level fluidic channels, including a macro-channel in the middle formed from the cylindrical template and a microchannel around the wall resulted from the hollow filaments were formed. By this method, different shapes of vessellike structures of millimeter diameter were printed. The structures printed using 4% alginate exhibited ultimate strength of 0.184 MPa, and L929 mouse fibroblasts encapsulated in the structures showed over 90% survival within 1 week. As a proof of concept, an envisioned load system of both mechanical and chemical stimulation was demonstrated. In addition, a vascular circulation flow system, a cerebral artery surgery simulator, and a cell coculture model were fabricated to demonstrate potential tissue engineering applications of these printed structures
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Research on the printability of hydrogels in 3D Bioprinting
Scientific Reports, 2016Co-Authors: Yong He, Haiming Zhao, Feifei Yang, Qing Gao, Bing Xia, Jian-zhong FuAbstract:As the biocompatible materials, hydrogels have been widely used in three- dimensional (3D) Bioprinting/organ printing to load cell for tissue engineering. It is important to precisely control hydrogels deposition during printing the mimic organ structures. However, the printability of hydrogels about printing parameters is seldom addressed. In this paper, we systemically investigated the printability of hydrogels from printing lines (one dimensional, 1D structures) to printing lattices/films (two dimensional, 2D structures) and printing 3D structures with a special attention to the accurate printing. After a series of experiments, we discovered the relationships between the important factors such as air pressure, feedrate, or even printing distance and the printing quality of the expected structures. Dumbbell shape was observed in the lattice structures printing due to the hydrogel diffuses at the intersection. Collapses and fusion of adjacent layer would result in the error accumulation at Z direction which was an important fact that could cause printing failure. Finally, we successfully demonstrated a 3D printing hydrogel scaffold through harmonize with all the parameters. The cell viability after printing was compared with the casting and the results showed that our Bioprinting method almost had no extra damage to the cells.
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Coaxial nozzle-assisted 3D Bioprinting with built-in microchannels for nutrients delivery
Biomaterials, 2015Co-Authors: Qing Gao, Jian-zhong Fu, Yong He, An Liu, Liang MaAbstract:This study offers a novel 3D Bioprinting method based on hollow calcium alginate filaments by using a coaxial nozzle, in which high strength cell-laden hydrogel 3D structures with built-in microchannels can be fabricated by controlling the crosslinking time to realize fusion of adjacent hollow filaments. A 3D Bioprinting system with a Z-shape platform was used to realize layer-by-layer fabrication of cell-laden hydrogel structures. Curving, straight, stretched or fractured filaments can be formed by changes to the filament extrusion speed or the platform movement speed. To print a 3D structure, we first adjusted the concentration and flow rate of the sodium alginate and calcium chloride solution in the crosslinking process to get partially crosslinked filaments. Next, a motorized XY stages with the coaxial nozzle attached was used to control adjacent hollow filament deposition in the precise location for fusion. Then the Z stage attached with a Z-shape platform moved down sequentially to print layers of structure. And the printing process always kept the top two layers fusing and the below layers solidifying. Finally, the Z stage moved down to keep the printed structure immersed in the CaCl2 solution for complete crosslinking. The mechanical properties of the resulting fused structures were investigated. High-strength structures can be formed using higher concentrations of sodium alginate solution with smaller distance between adjacent hollow filaments. In addition, cell viability of this method was investigated, and the findings show that the viability of L929 mouse fibroblasts in the hollow constructs was higher than that in alginate structures without built-in microchannels. Compared with other Bioprinting methods, this study is an important technique to allow easy fabrication of lager-scale organs with built-in microchannels.
Bing Chen - One of the best experts on this subject based on the ideXlab platform.
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3D Bioprinting of vessel like structures with multilevel fluidic channels
ACS Biomaterials Science & Engineering, 2017Co-Authors: Qing Gao, An Liu, Zhenjie Liu, Zhiwei Lin, Jingjiang Qiu, Yu Liu, Yidong Wang, Meixiang Xiang, Bing ChenAbstract:In this study, 3D hydrogel-based vascular structures with multilevel fluidic channels (macro-channel for mechanical stimulation and microchannel for nutrient delivery and chemical stimulation) were fabricated by extrusion-based three-dimensional (3D) Bioprinting, which could be integrated into organ-on-chip devices that would better simulate the microenvironment of blood vessels. In this approach, partially cross-linked hollow alginate filaments loading fibroblasts and smooth muscle cells were extruded through a coaxial nozzle and then printed along a rotated rod template, and endothelial cells were seeded into the inner wall. Because of the fusion of adjacent hollow filaments, two-level fluidic channels, including a macro-channel in the middle formed from the cylindrical template and a microchannel around the wall resulted from the hollow filaments were formed. By this method, different shapes of vessellike structures of millimeter diameter were printed. The structures printed using 4% alginate exhibited...
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3D Bioprinting of Vessel-like Structures with Multilevel Fluidic Channels
2017Co-Authors: Qing Gao, An Liu, Zhenjie Liu, Zhiwei Lin, Jingjiang Qiu, Yu Liu, Yidong Wang, Meixiang Xiang, Bing ChenAbstract:In this study, 3D hydrogel-based vascular structures with multilevel fluidic channels (macro-channel for mechanical stimulation and microchannel for nutrient delivery and chemical stimulation) were fabricated by extrusion-based three-dimensional (3D) Bioprinting, which could be integrated into organ-on-chip devices that would better simulate the microenvironment of blood vessels. In this approach, partially cross-linked hollow alginate filaments loading fibroblasts and smooth muscle cells were extruded through a coaxial nozzle and then printed along a rotated rod template, and endothelial cells were seeded into the inner wall. Because of the fusion of adjacent hollow filaments, two-level fluidic channels, including a macro-channel in the middle formed from the cylindrical template and a microchannel around the wall resulted from the hollow filaments were formed. By this method, different shapes of vessellike structures of millimeter diameter were printed. The structures printed using 4% alginate exhibited ultimate strength of 0.184 MPa, and L929 mouse fibroblasts encapsulated in the structures showed over 90% survival within 1 week. As a proof of concept, an envisioned load system of both mechanical and chemical stimulation was demonstrated. In addition, a vascular circulation flow system, a cerebral artery surgery simulator, and a cell coculture model were fabricated to demonstrate potential tissue engineering applications of these printed structures
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3D Bioprinting of BMSC-laden methacrylamide gelatin scaffolds with CBD-BMP2-collagen microfibers.
Biofabrication, 2015Co-Authors: Bing Chen, Qingyuan Meng, Sumei Liu, Xiongfei Zheng, Cheng Zhang, Heran Wang, Nuo Wang, Jianwu DaiAbstract:Three-dimensional (3D) Bioprinting combines biomaterials, cells and functional components into complex living tissues. Herein, we assembled function-control modules into cell-laden scaffolds using 3D Bioprinting. A customized 3D printer was able to tune the microstructure of printed bone mesenchymal stem cell (BMSC)-laden methacrylamide gelatin scaffolds at the micrometer scale. For example, the pore size was adjusted to 282 ± 32 μm and 363 ± 60 μm. To match the requirements of the printing nozzle, collagen microfibers with a length of 22 ± 13 μm were prepared with a high-speed crusher. Collagen microfibers bound bone morphogenetic protein 2 (BMP2) with a collagen binding domain (CBD) as differentiation-control module, from which BMP2 was able to be controllably released. The differentiation behaviors of BMSCs in the printed scaffolds were compared in three microenvironments: samples without CBD-BMP2-collagen microfibers in the growth medium, samples without microfibers in the osteogenic medium and samples with microfibers in the growth medium. The results indicated that BMSCs showed high cell viability (>90%) during printing; CBD-BMP2-collagen microfibers induced BMSC differentiation into osteocytes within 14 days more efficiently than the osteogenic medium. Our studies suggest that these function-control modules are attractive biomaterials and have potential applications in 3D Bioprinting.