3D Bioprinting and Medical Applications

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Processing and Engineering".

Deadline for manuscript submissions: closed (20 February 2021) | Viewed by 24374

Special Issue Editors


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Guest Editor
i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
Interests: bioengineering; biomaterials; biofabrication; bioprinting; skin

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Guest Editor
i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-465 Porto, Portugal
Interests: biomaterials; tissue engineering; regenerative medicine; hydrogels; injectable materials

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Guest Editor
Department of Mechanical, Aerospace & Civil Engineering, University of Manchester, Manchester M1 3BB, UK
Interests: additive manufacturing; digital manufacturing; advanced materials
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Special Issue Information

Dear Colleagues,

Bioprinting is a core technology in the field of biofabrication that allows the automated positioning of cells, biomaterials and biological factors towards the production of complex and functional 3D constructs for several biomedical applications. In recent years, this emerging field of research has experienced significant scientific and technological developments, allowing the fabrication of hierarchical cell material constructs with increased complexity and biomimicry as transplantable grafts for tissue repair and in vitro biological models. Despite promising outcomes from pre-clinical studies, the clinical translation of bioprinted constructs, particularly those containing living cells, requires further innovative development of new biomaterials and crosslinking mechanisms, bioprinting strategies, vascularization, and a deep assessment of the biological function of bioprinted constructs both in vitro and in vivo.

For this Special Issue of Polymers, we aim to present a collection of papers detailing the most recent developments and trends in the research of 3D bioprinting for medical applications. This includes the design of novel bioinks and biomaterial inks, new crosslinking mechanisms, the development of integrated bioprinting strategies, bioprinting of 3D scaffolds with cell-instructive properties, bioprinting of in vitro tissue models to aid in drug screening and disease modelling, as well as advances in the application of bioprinting to precision medicine.

Dr. Rúben F. Pereira
Dr. Pedro L. Granja
Prof. Paulo J. Bártolo
Guest Editors

Manuscript Submission Information

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Keywords

  • biofabrication and bioprinting
  • bioengineered bioinks
  • 3d scaffolds
  • biological models
  • disease modelling
  • tissue engineering and regenerative medicine

Published Papers (6 papers)

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Research

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14 pages, 4485 KiB  
Article
Investigating the Material Properties and Microstructural Changes of Fused Filament Fabricated PLA and Tough-PLA Parts
by Nida Naveed
Polymers 2021, 13(9), 1487; https://doi.org/10.3390/polym13091487 - 06 May 2021
Cited by 37 | Viewed by 4381
Abstract
Fused deposition modelling (FDM) is a popular but complex additive manufacturing process that works with many process parameters which are crucial to investigate. In this study, 3D parts were fabricated by placing each filament layer in opposite direction to the others; for this, [...] Read more.
Fused deposition modelling (FDM) is a popular but complex additive manufacturing process that works with many process parameters which are crucial to investigate. In this study, 3D parts were fabricated by placing each filament layer in opposite direction to the others; for this, two combinations of raster angles, (45° −45°) and (0° 90°), along with three different infill speeds were used. In this study, two 3D printing material types—Polylactic Acid (PLA) and tough-PLA were used. The material properties of each 3D part were investigated to identify the best combination of these parameters. A microstructural analysis was also performed on outer and inner surfaces along with fracture interface of the parts after tensile testing using a scanning-electron-microscopy (SEM) to explain material failure modes and reasons. The results suggest that for both the material types, a raster angle of 45° −45° produces stronger parts than to a raster angle of 0° 90°. This study also suggests that a slow infill speed improves tensile properties by providing a better inner-connection between two contiguous roasters. Thus, the detailed analysis of microstructural defects correlated with tensile test results provides insight into the optimisation of raster angle and infill speed, and scope for improvement of mechanical properties. Full article
(This article belongs to the Special Issue 3D Bioprinting and Medical Applications)
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12 pages, 2685 KiB  
Article
The Potential of Polyethylene Terephthalate Glycol as Biomaterial for Bone Tissue Engineering
by Mohamed H. Hassan, Abdalla M. Omar, Evangelos Daskalakis, Yanhao Hou, Boyang Huang, Ilya Strashnov, Bruce D. Grieve and Paulo Bártolo
Polymers 2020, 12(12), 3045; https://doi.org/10.3390/polym12123045 - 18 Dec 2020
Cited by 35 | Viewed by 4102
Abstract
The search for materials with improved mechanical and biological properties is a major challenge in tissue engineering. This paper investigates, for the first time, the use of Polyethylene Terephthalate Glycol (PETG), a glycol-modified class of Polyethylene Terephthalate (PET), as a potential material for [...] Read more.
The search for materials with improved mechanical and biological properties is a major challenge in tissue engineering. This paper investigates, for the first time, the use of Polyethylene Terephthalate Glycol (PETG), a glycol-modified class of Polyethylene Terephthalate (PET), as a potential material for the fabrication of bone scaffolds. PETG scaffolds with a 0/90 lay-dawn pattern and different pore sizes (300, 350 and 450 µm) were produced using a filament-based extrusion additive manufacturing system and mechanically and biologically characterized. The performance of PETG scaffolds with 300 µm of pore size was compared with polycaprolactone (PCL). Results show that PETG scaffolds present significantly higher mechanical properties than PCL scaffolds, providing a biomechanical environment that promotes high cell attachment and proliferation. Full article
(This article belongs to the Special Issue 3D Bioprinting and Medical Applications)
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14 pages, 36268 KiB  
Article
Cell-Laden Gelatin Methacryloyl Bioink for the Fabrication of Z-Stacked Hydrogel Scaffolds for Tissue Engineering
by Jeong Wook Seo, Joon Ho Moon, Goo Jang, Woo Kyung Jung, Yong Ho Park, Kun Taek Park, Su Ryon Shin, Yu-Shik Hwang and Hojae Bae
Polymers 2020, 12(12), 3027; https://doi.org/10.3390/polym12123027 - 17 Dec 2020
Cited by 7 | Viewed by 3561
Abstract
Hydrogel-based scaffolds have been widely used to fabricate artificial tissues capable of replacing tissues and organs. However, several challenges inherent in fabricating tissues of large size and complex morphology using such scaffolds while ensuring cell viability remain. To address this problem, we synthesized [...] Read more.
Hydrogel-based scaffolds have been widely used to fabricate artificial tissues capable of replacing tissues and organs. However, several challenges inherent in fabricating tissues of large size and complex morphology using such scaffolds while ensuring cell viability remain. To address this problem, we synthesized gelatin methacryloyl (GelMA) based bioink with cells for fabricating a scaffold with superior characteristics. The bioink was grafted onto a Z-stacking bioprinter that maintained the cells at physiological temperature during the printing process, without exerting any physical pressure on the cells. Various parameters, such as the bioink composition and light exposure time, were optimized. The printing accuracy of the scaffolds was evaluated using photorheological studies. The internal morphology of the scaffolds at different time points was analyzed using electron microscopy. The Z-stacked scaffolds were fabricated using high-speed printing, with the conditions optimized to achieve high model reproducibility. Stable adhesion and high proliferation of cells encapsulated within the scaffold were confirmed. We introduced various strategies to improve the accuracy and reproducibility of Z-stack GelMA bioprinting while ensuring that the scaffolds facilitated cell adhesion, encapsulation, and proliferation. Our results demonstrate the potential of the present method for various applications in tissue engineering. Full article
(This article belongs to the Special Issue 3D Bioprinting and Medical Applications)
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15 pages, 67114 KiB  
Article
Processing Conditions of a Medical Grade Poly(Methyl Methacrylate) with the Arburg Plastic Freeforming Additive Manufacturing Process
by Lukas Hentschel, Frank Kynast, Sandra Petersmann, Clemens Holzer and Joamin Gonzalez-Gutierrez
Polymers 2020, 12(11), 2677; https://doi.org/10.3390/polym12112677 - 12 Nov 2020
Cited by 18 | Viewed by 3423
Abstract
The Arburg Plastic Freeforming process (APF) is a unique additive manufacturing material jetting method. In APF, a thermoplastic material is supplied as pellets, melted and selectively deposited as droplets, enabling the use of commercial materials in their original shape instead of filaments. The [...] Read more.
The Arburg Plastic Freeforming process (APF) is a unique additive manufacturing material jetting method. In APF, a thermoplastic material is supplied as pellets, melted and selectively deposited as droplets, enabling the use of commercial materials in their original shape instead of filaments. The medical industry could significantly benefit from the use of additive manufacturing for the onsite fabrication of customized medical aids and therapeutic devices in a fast and economical way. In the medical field, the utilized materials need to be certified for such applications and cannot be altered in any way to make them printable, because modifications annul the certification. Therefore, it is necessary to modify the processing conditions rather than the materials for successful printing. In this research, a medical-grade poly(methyl methacrylate) was analyzed. The deposition parameters were kept constant, while the drop aspect ratio, discharge rate, melt temperatures, and build chamber temperature were varied to obtain specimens with different geometrical accuracy. Once satisfactory geometrical accuracy was obtained, tensile properties of specimens printed individually or in batches of five were tested in two different orientations. It was found that parts printed individually with an XY orientation showed the highest tensile properties; however, there is still room for improvement by optimizing the processing conditions to maximize the mechanical strength of printed specimens. Full article
(This article belongs to the Special Issue 3D Bioprinting and Medical Applications)
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13 pages, 1925 KiB  
Article
Fabrication of Second Skin from Keratin and Melanin
by Chen Nowogrodski, Ido Simon, Shlomo Magdassi and Oded Shoseyov
Polymers 2020, 12(11), 2568; https://doi.org/10.3390/polym12112568 - 02 Nov 2020
Cited by 4 | Viewed by 3439
Abstract
Second skin is a topically applied, skin-conforming material that mimics human skin properties and bears potential cosmetic and e-skin applications. To successfully integrate with natural skin, characteristics such as color and skin features must be matched. In this work, we prepared bio-based skin-like [...] Read more.
Second skin is a topically applied, skin-conforming material that mimics human skin properties and bears potential cosmetic and e-skin applications. To successfully integrate with natural skin, characteristics such as color and skin features must be matched. In this work, we prepared bio-based skin-like films from cross-linked keratin/melanin films (KMFs), using a simple fabrication method and non-toxic materials. The films retained their stability in aqueous solutions, showed skin-like mechanical properties, and were homogenous and handleable, with non-granular surfaces and a notable cross-linked structure as determined by attenuated total reflection (ATR). In addition, the combination of keratin and melanin allowed for adjustable tones similar to those of natural human skin. Furthermore, KMFs showed light transmittance and UV-blocking (up to 99%) as a function of melanin content. Finally, keratin/melanin ink (KMI) was used to inkjet-print high-resolution images with natural skin pigmented features. The KMFs and KMI may offer advanced solutions as e-skin or cosmetics platforms. Full article
(This article belongs to the Special Issue 3D Bioprinting and Medical Applications)
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Review

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38 pages, 15400 KiB  
Review
Carbon Nanomaterials for Electro-Active Structures: A Review
by Weiguang Wang, Yanhao Hou, Dean Martinez, Darwin Kurniawan, Wei-Hung Chiang and Paulo Bartolo
Polymers 2020, 12(12), 2946; https://doi.org/10.3390/polym12122946 - 09 Dec 2020
Cited by 20 | Viewed by 4624
Abstract
The use of electrically conductive materials to impart electrical properties to substrates for cell attachment proliferation and differentiation represents an important strategy in the field of tissue engineering. This paper discusses the concept of electro-active structures and their roles in tissue engineering, accelerating [...] Read more.
The use of electrically conductive materials to impart electrical properties to substrates for cell attachment proliferation and differentiation represents an important strategy in the field of tissue engineering. This paper discusses the concept of electro-active structures and their roles in tissue engineering, accelerating cell proliferation and differentiation, consequently leading to tissue regeneration. The most relevant carbon-based materials used to produce electro-active structures are presented, and their main advantages and limitations are discussed in detail. Particular emphasis is put on the electrically conductive property, material synthesis and their applications on tissue engineering. Different technologies, allowing the fabrication of two-dimensional and three-dimensional structures in a controlled way, are also presented. Finally, challenges for future research are highlighted. This review shows that electrical stimulation plays an important role in modulating the growth of different types of cells. As highlighted, carbon nanomaterials, especially graphene and carbon nanotubes, have great potential for fabricating electro-active structures due to their exceptional electrical and surface properties, opening new routes for more efficient tissue engineering approaches. Full article
(This article belongs to the Special Issue 3D Bioprinting and Medical Applications)
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