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![a Liver and inset of basic functional unit, the hepatic lobule. The liver consists of four lobes of unequal size and shape. The portal vein subdivides repeatedly, terminating into capillaries leading to a lobule (see labeled histologic features). Liver tissue is composed of thousands of lobules that are primarily comprised of parenchymal cells, the metabolic cells of the liver. Reprinted from [29], Copyright (2005), with permission from Elsevier. Porous chitosan/gelatin scaffold with specific external shape and predefined internal](profile/Peter-Goering/publication/259201917/figure/fig4/AS:667196573360130@1536083467105/a-Liver-and-inset-of-basic-functional-unit-the-hepatic-lobule-The-liver-consists-of.png)
a Liver and inset of basic functional unit, the hepatic lobule. The liver consists of four lobes of unequal size and shape. The portal vein subdivides repeatedly, terminating into capillaries leading to a lobule (see labeled histologic features). Liver tissue is composed of thousands of lobules that are primarily comprised of parenchymal cells, the metabolic cells of the liver. Reprinted from [29], Copyright (2005), with permission from Elsevier. Porous chitosan/gelatin scaffold with specific external shape and predefined internal
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Several recent research efforts have focused on use of computer-aided additive fabrication technologies, commonly referred to as additive manufacturing, rapid prototyping, solid freeform fabrication, or three-dimensional printing technologies, to create structures for tissue engineering. For example, scaffolds for tissue engineering may be processe...
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... In this process, stereolithography was used to prepare a resin mold that was subsequently utilized to produce a polydimethylsiloxane (PDMS) mold. The hybrid gelatin-chitosan resin was sub- sequently cast into the mold and lyophilized. Scaffolds were fabricated to mimic the internal unit structure of the liver, the hepatic lobule, as shown in Fig. 4 [28, 29]. The scaffold architecture included accurate branching angles of liver vasculature and a hepatocyte chamber [28]. Hepatocyte- scaffold interactions were analyzed with in vitro studies over 3 days; the hepatocytes exhibited greater attachment and ...
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The main aim of this work was to stimulate bone-forming cells to produce three-dimensional networks of mineralized proteins such as those occurring in bones. This was achieved by a novel approach using a specific type of mesenchymal progenitor cells (i.e., primary fibroblast cells from human hair roots) seeded onto polymer scaffolds. We wrote polym...
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... The same principle can be applied to the use of SLA for printing ceramic materials. However, in this case, ceramic particles suspended in a slurry system replace the resin-based system with micro/nanometer-sized, light-sensitive monomers and a photo initiator that solidifies via photo-polymerization mechanism once exposed to a UV laser [174,175]. To obtain a smooth flow for printing and homogeneity in the print, the ceramic resin is required to have a long shelf life and appropriate rheological behavior [176]. ...
... SLA is used to fabricate scaffolds for bone regenerative applications using materials such as HA, β-TCP, alumina, ZrO2, and bioactive glasses [175]. A primary difference between the traditional SLA and ceramic SLA methods is the contribution of scattering phenomena due to the addition of ceramic particles relative to the light-sensitive monomer [174]. ...
... The key components of this 3DP technique are a projector screen made up of pixels with digital light, a digital mirror device made of numerous micro-mirrors that navigate light from the projector, a conveyor and a resin tank that contains the feedstock (Figure 4) [157]. Speed and printing SLA is used to fabricate scaffolds for bone regenerative applications using materials such as HA, β-TCP, alumina, ZrO 2 , and bioactive glasses [175]. A primary difference between the traditional SLA and ceramic SLA methods is the contribution of scattering phenomena due to the addition of ceramic particles relative to the light-sensitive monomer [174]. ...
Three-dimensional printing (3DP) technology has revolutionized the field of the use of bioceramics for maxillofacial and periodontal applications, offering unprecedented control over the shape, size, and structure of bioceramic implants. In addition, bioceramics have become attractive materials for these applications due to their biocompatibility, biostability, and favorable mechanical properties. However, despite their advantages, bioceramic implants are still associated with inferior biological performance issues after implantation, such as slow osseointegration, inadequate tissue response, and an increased risk of implant failure. To address these challenges, researchers have been developing strategies to improve the biological performance of 3D-printed bioceramic implants. The purpose of this review is to provide an overview of 3DP techniques and strategies for bioceramic materials designed for bone regeneration. The review also addresses the use and incorporation of active biomolecules in 3D-printed bioceramic constructs to stimulate bone regeneration. By controlling the surface roughness and chemical composition of the implant, the construct can be tailored to promote osseointegration and reduce the risk of adverse tissue reactions. Additionally, growth factors, such as bone morphogenic proteins (rhBMP-2) and pharmacologic agent (dipyridamole), can be incorporated to promote the growth of new bone tissue. Incorporating porosity into bioceramic constructs can improve bone tissue formation and the overall biological response of the implant. As such, employing surface modification, combining with other materials, and incorporating the 3DP workflow can lead to better patient healing outcomes.
... Different from the extrusion-based AM processes and the powderbased AM processes, stereolithography apparatus (SLA) uses light energy to photocure liquid resin selectively and can achieve a printing resolution of ~20 μm [42]. Even though SLA is mainly limited to polymers, recent developments in photocurable functional materials, such as ceramic, hydrogel, composite, and biomaterial, have widened the scope of SLA techniques for more applications [43][44][45][46]. Guillaume et al. [47] fabricated biodegradable poly (trimethylene carbonate) (PTMC)/hydroxyapatite (HA) composite scaffolds with gyroid-shaped pores using SLA. ...
... However, in this case, ceramic particles suspended in a slurry system replace the resin-based system with micro/nanometer size, light-sensitive monomers, and a photo initiator which solidifies by via photo-polymerization mechanism once exposed to UV laser [141,142]. To obtain a smooth flow for printing and homogeneity of the print, the ceramic resin is required to have long shelf life, and appropriate rheological behavior [143]. ...
3D Printing (3DP) technology has revolutionized the field of the use of bioceramics for maxillofacial and periodontal applications, offering unprecedented control over the shape, size, and structure of bioceramic implants. In addition, bioceramics have become attractive materials for these applications due to their biocompatibility, biostability, and favorable mechanical properties. However, despite their advantages, bioceramic implants are still associated with inferior biological performance issues after implantation, such as slow osseointegration, inadequate tissue response, and increased risk of implant failure. To address these challenges, researchers have been developing strategies to improve the biological performance of 3D printed bioceramic implants. The purpose of this review is to provide an overview of 3DP techniques and strategies for bioceramic materials designed for bone regeneration. The review also addresses the use and incorporation of active biomolecules in 3D printed bioceramic constructs to stimulate bone regeneration. By controlling the surface roughness, and chemical composition of the implant, the construct can be tailored to promote osseointegration and reduce the risk of adverse tissue reactions. Additionally, growth factors, such as bone morphogenic proteins (rhBMP-2) and pharmacologic agent (dipyridamole), can be incorporated to promote the growth of new bone tissue. Incorporating porosity into bioceramic constructs can improve bone tissue formation and the overall biological response of the implant. As such, by employing surface modification, combining with other materials, and incorporation of 3DP workflow can lead to better patient healing outcomes.
... The additive manufacturing of conventional 3D printing grapples with several challenges when it comes to producing spherical particles, such as achieving precise control over size, maintaining uniformity, and retaining the structural integrity of the particles [28][29][30]. Droplet deposition, however, has been recently proposed to overcome said challenges and form beads [31][32][33][34][35]. Beads might be produced by extruding a DP ink manually through a nozzle into a crosslinking solution. This mean of production, however, is largely uncontrolled being susceptible to operator influence. ...
The peritoneal cavity offers an attractive administration route for challenging-to-treat diseases, such as peritoneal carcinomatosis, post-surgical adhesions, and peritoneal fibrosis. Achieving a uniform and prolonged drug distribution throughout the entire peritoneal space, though, is difficult due to high clearance rates, among others. To address such an unmet clinical need, alternative drug delivery approaches providing sustained drug release, reduced clearance rates, and a patient-centric strategy are required. Here, we describe the development of a 3D-printed composite platform for the sustained release of the tyrosine kinase inhibitor gefitinib (GEF), a small molecule drug with therapeutic applications for peritoneal metastasis and post-surgical adhesions. We present a robust method for the production of biodegradable liposome-loaded hydrogel microbeads that can overcome the pharmacokinetic limitations of small molecules with fast clearance rates, a current bottleneck for the intraperitoneal (IP) administration of these therapeutics. By means of an electromagnetic droplet printhead, we 3D printed microbeads employing an alginate-based ink loaded with GEF-containing multilamellar vesicles (MLVs). The sustained release of GEF from microbeads was demonstrated. In vitro studies on an immortalized human hepatic cancer cell line (Huh-7) proved concentration-dependent cell death. These findings demonstrate the potential of 3D-printed alginate microbeads containing liposomes for delivering small drug compounds into the peritoneum, overcoming previous limitations of IP drug delivery.
Graphical abstract
... When dealing with significant damage to the crown part of a tooth, necessitating added retention, insertion of a post into the root becomes essential to secure both the core and the restoration (Figure 9) [5,103]. The decision between utilizing a post that is tailormade or one that is pre-manufactured depends on several considerations, including the shape of the canal, the amount of tooth structure remaining, and the chosen method of restoration [27]. Custom-designed posts are predominantly crafted from materials such as metal, zirconia, and composite materials reinforced with fibers. ...
Contemporary mass media frequently depict 3D printing as a technology with
widespread utilization in the creation of dental prosthetics. This paper endeavors to provide an
evidence-based assessment of the current scope of 3D printing’s integration within dental
laboratories and practices. Its primary objective is to offer a systematic evaluation of the existing
applications of 3D-printing technology within the realm of dental prosthetic restorations.
Furthermore, this article delves into potential prospects, while also critically examining the
sustained relevance of conventional dental laboratory services and manufacturing procedures. The
central focus of this article is to expound upon the extent to which 3D printing is presently harnessed
for crafting dental prosthetic appliances. By presenting verifiable data and factual insights, this
article aspires to elucidate the actual implementation of 3D printing in prosthetic dentistry and its
seamless integration into dental practices. The aim of this narrative review is twofold: firstly, to
provide an informed and unbiased evaluation of the role that 3D printing currently plays within
dental laboratories and practices; and secondly, to instigate contemplation on the transformative
potential of this technology, both in terms of its contemporary impact and its future implications,
while maintaining a balanced consideration of traditional dental approaches.
... A light beam with a wavelength of (355-410 nm) interacts with the photopolymer resin to form a bond between the resin monomers and eventually print the solid part in the digital light processing method [2]. This method can be applied in a variety of fields, including dentistry, tissue engineering, microfluidics, microneedle injection, and drug delivery [3][4][5][6][7]. Various systems have been created and designed for manufacturing 3D resin parts using several production processes. ...
One of the most challenging issues in DLP 3D printing is separation. Thus, the capability to employ a variety of polymer membranes can considerably aid in the development of the DLP technology. The primary purpose of this study is to thoroughly explore the characteristics influencing separation force and time on the FEP industrial membrane and the proposed PP membrane. Therefore, the impact of image cross section geometry and separation speed on separation force and separation time is investigated. As a consequence, changing the percentage of surface porosity has a negligible effect on the amount of separation force. According to the findings, reducing the cross-sectional area by 1.36% reduced the separation force by 6.5 times. Moreover, the outcomes are consistent with the mathematical model given. the separation force rose by 230% in the FEP membrane with an increase of 96 times of the speed, whereas the separation time decreased by 18.8 times. For the proposed PP membrane, as the speed increases, the separation force rate increases by 175% and the separation time falls by 29.6 times. The aforementioned findings show that the PP film may be used as a practical and affordable solution with quick separation that can reduce printing time when producing three-dimensional lattice pieces at varying speeds.
... However, there are still some drawbacks that need to be improved, such as high cost and the wide-ranging requirements of the materials used in 3D printing applications (Ozbolat and Hospodiuk, 2016). In addition, the thickness of the material in each layer is determined by the energy generated by the light source and the exposure time of the material; this means that this technology is associated with complex dynamics and reaction processes (Skoog et al., 2014). ...
Spinal cord injury is considered one of the most difficult injuries to repair and has one of the worst prognoses for injuries to the nervous system. Following surgery, the poor regenerative capacity of nerve cells and the generation of new scars can make it very difficult for the impaired nervous system to restore its neural functionality. Traditional treatments can only alleviate secondary injuries but cannot fundamentally repair the spinal cord. Consequently, there is a critical need to develop new treatments to promote functional repair after spinal cord injury. Over recent years, there have been several developments in the use of stem cell therapy for the treatment of spinal cord injury. Alongside significant developments in the field of tissue engineering, three-dimensional bioprinting technology has become a hot research topic due to its ability to accurately print complex structures. This led to the loading of three-dimensional bioprinting scaffolds which provided precise cell localization. These three-dimensional bioprinting scaffolds could repair damaged neural circuits and had the potential to repair the damaged spinal cord. In this review, we discuss the mechanisms underlying simple stem cell therapy, the application of different types of stem cells for the treatment of spinal cord injury, and the different manufacturing methods for three-dimensional bioprinting scaffolds. In particular, we focus on the development of three-dimensional bioprinting scaffolds for the treatment of spinal cord injury.
... Layer-by-layer stacking and additive manufacturing techniques are alternate terms for 3D printing, whereas 3D bioprinting implies the printing process used for printing cells [25,28,29]. Existing bioprinting techniques include extrusion bioprinting which is dependent on the molding principles and printing materials (including piston-driven, pneumatic, and spiral) [30], inkjet bioprinting (piezoelectric and temperature-controlled) [31], laser-assisted bioprinting [32], and light-cured bioprinting [33]. Human tissues and organs can be created with biological 3D printing methods using cells, biomaterials, and/or cytokines as bioinks (Table 1). ...
Three-dimensional (3D) tumor models prepared from patient-derived cells have been reported to imitate some of the biological development processes of in situ tumors in vitro. These 3D tumor models share several important characteristics with their in vivo tumor counterparts. Accordingly, their applications in tumor modeling, drug screening, and precision-targeted treatment are promising. However, the establishment of tumor models is subject to several challenges, including advancements in scale size, repeatability, structural precision in time and space, vascularization, and the tumor microenvironment. Recently, bioprinting technologies enabling the editorial arrangement of cells, factors, and materials have improved the simulation of tumor models in vitro. Among the 3D bioprinted tumor models, the organoid model has been widely appreciated for its advantages of maintaining high heterogeneity and capacity for simulating the developmental process of tumor tissues. In this review, we outline approaches and potential prospects for tumor model bioprinting and discuss the existing bioprinting technologies and bioinks in tumor model construction. The multidisciplinary combination of tumor pathology, molecular biology, material science, and additive manufacturing will help overcome the barriers to tumor model construction by allowing consideration of the structural and functional characteristics of in vitro models and promoting the development of heterogeneous tumor precision therapies.Graphic abstract
... The quick and easy fabrication afforded by 3D printing has contributed to the large push in additive manufacturing research, [37][38][39][40] and the photoactivate resins continue to be studied leading to a plethora of amalgamate resins with enhanced properties or novel functionalities. [41][42][43][44][45][46] The tumbler photochemistry sample stick was used on the VISION spectrometer to measure the in situ photo-polymerization of a 405 nm 3D printer photoresin (used as purchased, ANYCU-BIC). A quartz sample holder was fabricated out of an 18 mm outer diameter, 16 mm inner diameter, and 1.5 cm height quartz tube. ...
Every material experiences atomic and molecular motions that are generally termed vibrations in gases and liquids or phonons in solid state materials. Optical spectroscopy techniques, such as Raman, infrared absorption spectroscopy, or inelastic neutron scattering (INS), can be used to measure the vibrational/phonon spectrum of ground state materials properties. A variety of optical pump probe spectroscopies enable the measurement of excited states or elucidate photochemical reaction pathways and kinetics. So far, it has not been possible to study photoactive materials or processes in situ using INS due to the mismatch between neutron and photon penetration depths, differences between the flux density of photons and neutrons, cryogenic temperatures for INS measurements, vacuum conditions, and a lack of optical access to the sample space. These experimental hurdles have resulted in very limited photochemistry studies using INS. Here we report on the design of two different photochemistry sample sticks that overcome these experimental hurdles to enable in situ photochemical studies using INS, specifically at the VISION instrument at Oak Ridge National Laboratory. We demonstrate the use of these new measurement capabilities through (1) the in situ photodimerization of anthracene and (2) the in situ photopolymerization of a 405 nm photoresin using 405 nm excitation as simple test cases. These new measurement apparatus broaden the science enabled by INS to include photoactive materials, optically excited states, and photoinitiated reactions.
... Three-dimensional printing works by laying down successive layers of material until the entire object is created. There are several types of 3D printing technologies that have been used for bone tissue engineering, such as fused deposition modeling (FDM) [46], two types of stereolithography (SLA) [47] (laser-based stereolithography [48] and digital light processing-based stereolithography (DLP)) [49], selective laser sintering (SLS) [50], Inkjet 3D printing (3DP) [51], laser-assisted bioprinting (LAB) [52] and 3D bioprinting [53]. The schematic diagram of these technologies is shown in Figure 5, and the working principle and the pros and cons of these technologies are described in Table 2. ...
Immobilization using external or internal splints is a standard and effective procedure to treat minor skeletal fractures. In the case of major skeletal defects caused by extreme trauma, infectious diseases or tumors, the surgical implantation of a bone graft from external sources is required for a complete cure. Practical disadvantages, such as the risk of immune rejection and infection at the implant site, are high in xenografts and allografts. Currently, an autograft from the iliac crest of a patient is considered the “gold standard” method for treating large-scale skeletal defects. However, this method is not an ideal solution due to its limited availability and significant reports of morbidity in the harvest site (30%) as well as the implanted site (5–35%). Tissue-engineered bone grafts aim to create a mechanically strong, biologically viable and degradable bone graft by combining a three-dimensional porous scaffold with osteoblast or progenitor cells. The materials used for such tissue-engineered bone grafts can be broadly divided into ceramic materials (calcium phosphates) and biocompatible/bioactive synthetic polymers. This review summarizes the types of materials used to make scaffolds for cryo-preservable tissue-engineered bone grafts as well as the distinct methods adopted to create the scaffolds, including traditional scaffold fabrication methods (solvent-casting, gas-foaming, electrospinning, thermally induced phase separation) and more recent fabrication methods (fused deposition molding, stereolithography, selective laser sintering, Inkjet 3D printing, laser-assisted bioprinting and 3D bioprinting). This is followed by a short summation of the current osteochondrogenic models along with the required scaffold mechanical properties for in vivo applications. We then present a few results of the effects of freezing and thawing on the structural and mechanical integrity of PLLA scaffolds prepared by the thermally induced phase separation method and conclude this review article by summarizing the current regulatory requirements for tissue-engineered products.
