Biocompatible 3D printed polymers via fused deposition modelling direct C2C12 cellular phenotype in vitro

Bibliometric Analysis-Based Review of Fused Deposition Modeling 3D Printing Method (1994-2020)

This study aimed at the detailed bibliometric analysis (BA) of fused deposition modeling (FDM) to understand the trend and research area. Web of Science database was used for extracting data using keywords, and 2793 documents were analyzed. From the analysis, the most influential and productive authors, countries, sources, and so on were identified and corresponding interrelations were represented by a three-field plot. Lotka's law was derived for author productivity and its reliability was verified by the Kolmogorov-Smirnov (K-S) test. Bradford's law was used for identifying the core sources contributing to the field of FDM. From the trend topic analysis, it was found that initially the research was focused upon removing error related to deposition as well as part orientation, but with the course of time, it diversified to include topics such as optimization of printing parameters, materials, and applications. Based on the inferences from BA, the article also discusses on current research trend and highlights certain future areas for research work.

Cytotoxic assessment of 3D printed photoinitiated prosthodontic resins versus heat polymerized acrylic resin (In-Vitro Study).. [DOI: 10.21203/rs.3.rs-1948364/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background: Although 3D printed photoinitiated resins are among the many materials utilized in prosthetic appliances today, biocompatibility for photocuring 3D printing materials for direct and long-term contacting with living body remain scarce. The purpose of this in vitro study was to evaluate the cell viability of human gingival fibroblasts after the exposure to two different 3D printed photoinitiated resins and compare it to the traditionally used heat polymerized acrylic resin for up to 7 days.Methods: This comparative in vitro study of sample size (n= 96), where the 3D printed resin disc samples (n= 64), were divided into two test groups, test group 1 (TG1) for NextDent Base resin (n= 32) and test group 2 (TG2) for Dental LT clear resin (n= 32), to be compared to Heat polymerized acrylic resin samples (Reference group (RG)) (n= 32). Human gingival fibroblasts were extracted from attached keratinized gingival tissues collected from healthy patient undergoing clinical crown lengthening procedure, cellular viability using MTT assay in response to TG1, TG2 and RG samples was assessed throughout four-time intervals (24, 48, 72 and 168 hours). The One-Way ANOVA test followed by Tukey’s post hoc test and Repeated Measures ANOVA test were used for statistical analyses, statistically significant different at P value ≤ 0.05Results: Throughout time intervals, there was a decrease in cell viability of all groups but with favorable cell viability which was more that 90% denoting non cytotoxicity. It was found to be significant among RG (P< 0.0001). The highest cell viability was found after 24 hours among all groups; however, the least viability was found after 48 hours among TG1 and RG, and among TG2 after 72 hours. After 168 hours, there was a non-statistical significant change in cell viability between groups (P= 0.526). there was significant increase in optical density for all groups throughout time intervals (P< 0.0001).Conclusion: Photoinitiated resins are comparable to traditionally used heat polymerized acrylic resin with equivalent cytotoxic effect for long term use. 3D printed photoinitiated resins are biocompatible and suggested for long term intraoral use.

3D-printed graphene polylactic acid devices resistant to SARS-CoV-2: Sunlight-mediated sterilization of additive manufactured objects

Additive manufacturing has played a crucial role in the COVID-19 global emergency allowing for rapid production of medical devices, indispensable tools for hospitals, or personal protection equipment. However, medical devices, especially in nosocomial environments, represent high touch surfaces prone to viral infection and currently used filaments for 3D printing can't inhibit transmission of virus [1]. Graphene-family materials are capable of reinforcing mechanical, optical and thermal properties of 3D printed constructs. In particular, graphene can adsorb near-infrared light with high efficiency. Here we demonstrate that the addition of graphene nanoplatelets to PLA filaments (PLA-G) allows the creation of 3D-printed devices that can be sterilized by near-infrared light exposure at power density analog to sunlight. This method has been used to kill SARS-CoV-2 viral particles on the surface of 3D printed PLA-G by 3 min of exposure. 3D-printed PLA-G is highly biocompatible and can represent the ideal material for the production of sterilizable personal protective equipment and daily life objects intended for multiple users.

Hybprinting for musculoskeletal tissue engineering

This review presents bioprinting methods, biomaterials, and printing strategies that may be used for composite tissue constructs for musculoskeletal applications. The printing methods discussed include those that are suitable for acellular and cellular components, and the biomaterials include soft and rigid components that are suitable for soft and/or hard tissues. We also present strategies that focus on the integration of cell-laden soft and acellular rigid components under a single printing platform. Given the structural and functional complexity of native musculoskeletal tissue, we envision that hybrid bioprinting, referred to as hybprinting, could provide unprecedented potential by combining different materials and bioprinting techniques to engineer and assemble modular tissues.

Influence of Multiple Thermomechanical Processing of 3D Filaments Based on Polylactic Acid and Polyhydroxybutyrate on Their Rheological and Utility Properties

This study focused on material recycling of a biodegradable blend based on PLA and PHB for multiple applications of biodegradable polymeric material under real conditions. In this study, we investigated the effect of multiple processing of a biodegradable polymer blend under the trade name NONOILEN^®, which was processed under laboratory as well as industrial conditions. In this article, we report on testing the effect of blending and multiple processing on thermomechanical stability, molecular characteristics, as well as thermophysical and mechanical properties of experimental- and industrial-type tested material suitable for FDM 3D technology. The results showed that the studied material degraded during blending and subsequently during multiple processing. Even after partial degradation, which was demonstrated by a decrease in average molecular weight and a decrease in complex viscosity in the process of multiple reprocessing, there was no significant change in the material’s thermophysical properties, either in laboratory or industrial conditions. There was also no negative impact on the strength characteristics of multiple processed samples. The results of this work show that a biodegradable polymer blend based on PLA and PHB is a suitable candidate for material recycling even in industrial processing conditions. In addition, the results suggest that the biodegradable polymeric material NONOILEN^® 3D 3056-2 is suitable for multiple uses in FDM technology.

Replace and repair: Biomimetic bioprinting for effective muscle engineering

The debilitating effects of muscle damage, either through ischemic injury or volumetric muscle loss (VML), can have significant impacts on patients, and yet there are few effective treatments. This challenge arises when function is degraded due to significant amounts of skeletal muscle loss, beyond the regenerative ability of endogenous repair mechanisms. Currently available surgical interventions for VML are quite invasive and cannot typically restore function adequately. In response to this, many new bioengineering studies implicate 3D bioprinting as a viable option. Bioprinting for VML repair includes three distinct phases: printing and seeding, growth and maturation, and implantation and application. Although this 3D bioprinting technology has existed for several decades, the advent of more advanced and novel printing techniques has brought us closer to clinical applications. Recent studies have overcome previous limitations in diffusion distance with novel microchannel construct architectures and improved myotubule alignment with highly biomimetic nanostructures. These structures may also enhance angiogenic and nervous ingrowth post-implantation, though further research to improve these parameters has been limited. Inclusion of neural cells has also shown to improve myoblast maturation and development of neuromuscular junctions, bringing us one step closer to functional, implantable skeletal muscle constructs. Given the current state of skeletal muscle 3D bioprinting, the most pressing future avenues of research include furthering our understanding of the physical and biochemical mechanisms of myotube development and expanding our control over macroscopic and microscopic construct structures. Further to this, current investigation needs to be expanded from immunocompromised rodent and murine myoblast models to more clinically applicable human cell lines as we move closer to viable therapeutic implementation.

Modeling the Mechanobiology of Cancer Cell Migration Using 3D Biomimetic Hydrogels

Understanding how cancer cells migrate, and how this migration is affected by the mechanical and chemical composition of the extracellular matrix (ECM) is critical to investigate and possibly interfere with the metastatic process, which is responsible for most cancer-related deaths. In this article we review the state of the art about the use of hydrogel-based three-dimensional (3D) scaffolds as artificial platforms to model the mechanobiology of cancer cell migration. We start by briefly reviewing the concept and composition of the extracellular matrix (ECM) and the materials commonly used to recreate the cancerous ECM. Then we summarize the most relevant knowledge about the mechanobiology of cancer cell migration that has been obtained using 3D hydrogel scaffolds, and relate those discoveries to what has been observed in the clinical management of solid tumors. Finally, we review some recent methodological developments, specifically the use of novel bioprinting techniques and microfluidics to create realistic hydrogel-based models of the cancer ECM, and some of their applications in the context of the study of cancer cell migration.

Bioengineered human skeletal muscle capable of functional regeneration

BACKGROUND

Skeletal muscle (SkM) regenerates following injury, replacing damaged tissue with high fidelity. However, in serious injuries, non-regenerative defects leave patients with loss of function, increased re-injury risk and often chronic pain. Progress in treating these non-regenerative defects has been slow, with advances only occurring where a comprehensive understanding of regeneration has been gained. Tissue engineering has allowed the development of bioengineered models of SkM which regenerate following injury to support research in regenerative physiology. To date, however, no studies have utilised human myogenic precursor cells (hMPCs) to closely mimic functional human regenerative physiology.

RESULTS

Here we address some of the difficulties associated with cell number and hMPC mitogenicity using magnetic association cell sorting (MACS), for the marker CD56, and media supplementation with fibroblast growth factor 2 (FGF-2) and B-27 supplement. Cell sorting allowed extended expansion of myogenic cells and supplementation was shown to improve myogenesis within engineered tissues and force generation at maturity. In addition, these engineered human SkM regenerated following barium chloride (BaCl2) injury. Following injury, reductions in function (87.5%) and myotube number (33.3%) were observed, followed by a proliferative phase with increased MyoD+ cells and a subsequent recovery of function and myotube number. An expansion of the Pax7+ cell population was observed across recovery suggesting an ability to generate Pax7+ cells within the tissue, similar to the self-renewal of satellite cells seen in vivo.

CONCLUSIONS

This work outlines an engineered human SkM capable of functional regeneration following injury, built upon an open source system adding to the pre-clinical testing toolbox to improve the understanding of basic regenerative physiology.

3D Graphene Scaffolds for Skeletal Muscle Regeneration: Future Perspectives

Although skeletal muscle can regenerate after injury, in chronic damages or in traumatic injuries its endogenous self-regeneration is impaired. Consequently, tissue engineering approaches are promising tools for improving skeletal muscle cells proliferation and engraftment. In the last decade, graphene and its derivates are being explored as novel biomaterials for scaffolds production for skeletal muscle repair. This review describes 3D graphene-based materials that are currently used to generate complex structures able not only to guide cell alignment and fusion but also to stimulate muscle contraction thanks to their electrical conductivity. Graphene is an allotrope of carbon that has indeed unique mechanical, electrical and surface properties and has been functionalized to interact with a wide range of synthetic and natural polymers resembling native musculoskeletal tissue. More importantly, graphene can stimulate stem cell differentiation and has been studied for cardiac, neuronal, bone, skin, adipose, and cartilage tissue regeneration. Here we recapitulate recent findings on 3D scaffolds for skeletal muscle repairing and give some hints for future research in multifunctional graphene implants.

Development of a 3D-printed Medication Label for the Blind and Visually Impaired

This study explored the potential of three-dimensional printing (3DP) technology in producing a three-dimensional (3D) medication label for blind and visually impaired (BVI) patients to ease their drug administration. Different variations of label wordings, dosing instructions, and medication identifiers were designed with reference to guidelines by the American Foundation for the Blind. Shapes and symbols were used as dosing instructions and medication identifiers to the patient's medical conditions. Prototype designs were created with common graphics computer-assisted drafting software and 3D-printed using acrylonitrile butadiene styrene as the polymer filament. Feedback was then obtained from five people with normal vision and four BVI persons. The initial prototype comprised four components, namely, medication name and strength, patient's name, dosing instruction, and medication identifier. A revised label comprising the latter two components was developed after feedback by BVI persons. Words were in all uppercase and regular font type, with a 5-mm center-to-center letter spacing. Elevation heights of the letters alternated between 1 mm and 1.5 mm. A half sphere represented the medication dose unit, while vertical lines and a horizontal center line with alternating elevation of arrowheads represented the frequency of administration and the medication's consumption in relation to food, respectively. Symbols based on target organs were used as medication identifiers. With rapid advancements in 3DP technologies, there is tremendous potential for producing 3D labels in patients' medication management.

Customizable live-cell imaging chambers for multimodal and multiplex fluorescence microscopy

Using multiple imaging modalities while performing independent experiments in parallel can greatly enhance the throughput of microscopy-based research, but requires the provision of appropriate experimental conditions in a format that meets the optical requirements of the microscope. Although customized imaging chambers can meet these challenges, the difficulty of manufacturing custom chambers and the relatively high cost and design inflexibility of commercial chambers has limited the adoption of this approach. Herein, we demonstrate the use of 3D printing to produce inexpensive, customized, live-cell imaging chambers that are compatible with a range of imaging modalities, including super-resolution microscopy. In this approach, biocompatible plastics are used to print imaging chambers designed to meet the specific needs of an experiment, followed by adhesion of the printed chamber to a glass coverslip, producing a chamber that is impermeant to liquids and that supports the growth and imaging of cells over multiple days. This approach can also be used to produce moulds for casting microfluidic devices made of polydimethylsiloxane. The utility of these chambers is demonstrated using designs for multiplex microscopy, imaging under shear, chemotaxis, and general cellular imaging. Together, this approach represents an inexpensive yet highly customizable approach for producing imaging chambers that are compatible with modern microscopy techniques.

Three-Dimensional Printed Devices in Droplet Microfluidics

Droplet microfluidics has become the most promising subcategory of microfluidics since it contributes numerous applications to diverse fields. However, fabrication of microfluidic devices for droplet formation, manipulation and applications is usually complicated and expensive. Three-dimensional printing (3DP) provides an exciting alternative to conventional techniques by simplifying the process and reducing the cost of fabrication. Complex and novel structures can be achieved via 3DP in a simple and rapid manner, enabling droplet microfluidics accessible to more extensive users. In this article, we review and discuss current development, opportunities and challenges of applications of 3DP to droplet microfluidics.

Differentiation of Bioengineered Skeletal Muscle within a 3D Printed Perfusion Bioreactor Reduces Atrophic and Inflammatory Gene Expression

Bioengineered skeletal muscle tissues benefit from dynamic culture environments which facilitate the appropriate provision of nutrients and removal of cellular waste products. Biologically compatible perfusion systems hold the potential to enhance the physiological biomimicry of in vitro tissues via dynamic culture, in addition to providing technological advances in analytical testing and live cellular imaging for analysis of cellular development. To meet such diverse requirements, perfusion systems require the capacity and adaptability to incorporate multiple cell laden constructs of both monolayer and bioengineered tissues. This work reports perfusion systems produced using additive manufacturing technology for the in situ phenotypic development of myogenic precursor cells in monolayer and bioengineered tissue. Biocompatibility of systems 3D printed using stereolithography (SL), laser sintering (LS), and PolyJet outlined preferential morphological development within both SL and LS devices. When exposed to intermittent perfusion in the monolayer, delayed yet physiologically representative cellular proliferation, MyoD and myogenin transcription of C₂C₁₂ cells was evident. Long-term (8 days) intermittent perfusion of monolayer cultures outlined viable morphological and genetic in situ differentiation for the live cellular imaging of myogenic development. Continuous perfusion cultures (13 days) of bioengineered skeletal muscle tissues outlined in situ myogenic differentiation, forming mature multinucleated myotubes. Here, reductions in IL-1β and TNF-α inflammatory cytokines, myostatin, and MuRF-1 atrophic mRNA expression were observed. Comparable myosin heavy chain (MyHC) isoform transcription profiles were evident between conditions; however, total mRNA expression was reduced in perfusion conditions. Decreased transcription of MuRF1 and subsequent reduced ubiquitination of the MyHC protein allude to a decreased requirement for transcription of MyHC isoform transcripts. Together, these data appear to indicate that 3D printed perfusion systems elicit enhanced stability of the culture environment, resulting in a reduced basal requirement for MyHC gene expression within bioengineered skeletal muscle tissue.

Functional regeneration of tissue engineered skeletal muscle in vitro is dependent on the inclusion of basement membrane proteins

Skeletal muscle has a high regenerative capacity, injuries trigger a regenerative program which restores tissue function to a level indistinguishable to the pre-injury state. However, in some cases where significant trauma occurs, such as injuries seen in military populations, the regenerative process is overwhelmed and cannot restore full function. Limited clinical interventions exist which can be used to promote regeneration and prevent the formation of non-regenerative defects following severe skeletal muscle trauma. Robust and reproducible techniques for modelling complex tissue responses are essential to promote the discovery of effective clinical interventions. Tissue engineering has been highlighted as an alternative method, allowing the generation of three-dimensional in vivo like tissues without laboratory animals. Reducing the requirement for animal models promotes rapid screening of potential clinical interventions, as these models are more easily manipulated, genetically and pharmacologically, and reduce the associated cost and complexity, whilst increasing access to models for laboratories without animal facilities. In this study, an in vitro chemical injury using barium chloride is validated using the C2C12 myoblast cell line, and is shown to selectively remove multinucleated myotubes, whilst retaining a regenerative mononuclear cell population. Monolayer cultures showed limited regenerative capacity, with basement membrane supplementation or extended regenerative time incapable of improving the regenerative response. Conversely tissue engineered skeletal muscles, supplemented with basement membrane proteins, showed full functional regeneration, and a broader in vivo like inflammatory response. This work outlines a freely available and open access methodology to produce a cell line-based tissue engineered model of skeletal muscle regeneration.

4D anisotropic skeletal muscle tissue constructs fabricated by staircase effect strategy

Like the morphology of native tissue fiber arrangement (such as skeletal muscle), unidirectional anisotropic scaffolds are highly desired as a means to guide cell behavior in anisotropic tissue engineering. In contrast, contour-like staircases exhibit directional topographical cues and are judged as an inevitable defect of fused deposition modeling (FDM). In this study, we will translate this staircase defect into an effective bioengineering strategy by integrating FDM with surface coating technique (FCT) to investigate the effect of topographical cues on regulating behaviors of human mesenchymal stem cells (hMSCs) toward skeletal muscle tissues. This integrated approach serves to fabricate shape-specific, multiple dimensional, anisotropic scaffolds using different biomaterials. 2D anisotropic scaffolds, first demonstrated with different polycaprolactone concentrations herein, efficiently direct hMSC alignment, especially when the scaffold is immobilized on a support ring. By surface coating the polymer solution inside FDM-printed sacrificial structures, 3D anisotropic scaffolds with thin wall features are developed and used to regulate seeded hMSCs through a self-established rotating bioreactor. Using layer-by-layer coating, along with a shape memory polymer, smart constructs exhibiting shape fix and recovery processes are prepared, bringing this study into the realm of 4D printing. Immunofluorescence staining and real-time quantitative polymerase chain reaction analysis confirm that the topographical cues created via FCT significantly enhance the expression of myogenic genes, including myoblast differentiation protein-1, desmin, and myosin heavy chain-2. We conclude that there are broad application potentials for this FCT strategy in tissue engineering as many tissues and organs, including skeletal muscle, possess highly organized and anisotropic extracellular matrix components.

Superstretchable and Processable Silicone Elastomers by Digital Light Processing 3D Printing

A series of photosensitive resins suitable for the production of silicone elastomers through digital light processing 3D printing are reported. Based on thiol-ene click reaction between a branched mercaptan-functionalized polysiloxane and different-molecular-weight vinyl-terminated poly(dimethylsiloxane), silicone elastomers with tunable hardness and mechanical properties are obtained. Printed elastomeric objects show high printing resolution and excellent mechanical properties. The break elongation of the silicone elastomers can get up to 1400%, which is much higher than the reported UV-cured elastomers and is even higher than the most stretchable thermocuring silicone elastomers. The superstretchable silicone elastomers are then applied to fabricate stretchable electronics with carbon nanotubes-doped hydrogel. The printable and processable silicone elastomers have great potential applications in various fields, including soft robotics, flexible actuators, and medical implants.

Simple and low-cost production of hybrid 3D-printed microfluidic devices

The use of three-dimensional (3D) printing for the fabrication of microfluidic chips has attracted considerable attention among researchers. This low-cost fabrication method allows for rapid prototyping and the creation of complex structures; however, these devices lack optical transparency, which greatly hinders the characterization and quantification of experiment results. To address this problem, integrating a transparent substrate with a 3D-printed chip is an effective approach. In this study, we present a solvent bonding method of poly(methyl methacrylate) (PMMA) and acrylonitrile butadiene styrene (ABS) thermoplastic materials for the creation of optically detectable 3D-printed microfluidic devices. To achieve an excellent bonding between PMMA and ABS substrates, we used spray coating as a method for the distribution of ethanol solution followed by UV exposure and post-annealing step to improve the bonding strength. We fabricated a microfluidic chip with S-microchannel to characterize the bonding protocol, and other two application-oriented microfluidic chips, including a 3D split-and-recombine-based passive micromixer, and an integrated microchip for the mixing of two streams of liquid prior to the formation of double-emulsion droplets, to evaluate the efficacy of the proposed scheme. As a result, at least eight bars of the bonding strength between PMMA/ABS substrates was achieved, and the ability of producing optically detectable 3D-printed microfluidic devices based on this bonding method was confirmed.

Scalable 3D Printed Molds for Human Tissue Engineered Skeletal Muscle

Tissue engineered skeletal muscle allows investigation of the cellular and molecular mechanisms that regulate skeletal muscle pathology. The fabricated model must resemble characteristics of in vivo tissue and incorporate cost-effective and high content primary human tissue. Current models are limited by low throughput due to the complexities associated with recruiting tissue donors, donor specific variations, as well as cellular senescence associated with passaging. This research presents a method using fused deposition modeling (FDM) and laser sintering (LS) 3D printing to generate reproducible and scalable tissue engineered primary human muscle, possessing aligned mature myotubes reminiscent of in vivo tissue. Many existing models are bespoke causing variability when translated between laboratories. To this end, a scalable model has been developed (25–500 μL construct volumes) allowing fabrication of mature primary human skeletal muscle. This research provides a strategy to overcome limited biopsy cell numbers, enabling high throughput screening of functional human tissue.

Directly repurposing waste optical discs with prefabricated nanogrooves as a platform for investigation of cell-substrate interactions and guiding neuronal growth

Due to rapid change in information technology, many consumer electronics become electronic waste which is the fastest-growing pollution problems worldwide. In fact, many discarded electronics with prefabricated micro/nanostructures may provide a good basis to fulfill special needs of other fields, such as tissue engineering, biosensors, and energy. Herein, to take waste optical discs as an example, we demonstrate that discarded electronics can be directly repurposed as highly anisotropic platforms for in vitro investigation of cell behaviors, such as cell adhesion, cell alignment, and cell-cell interactions. The PC12 cells cultured on biocompatible DVD polycarbonate layers with flat and grooved morphology show a distinct cell morphology, indicating the topographical cue of nanogrooves plays a key role in guidance of neurites growth. By further monitoring cell morphology and alignment of PC12 cells cultured on the DVD nanogrooves at different differentiation times, we find that cell contact interaction with nanotopographies is dynamically adjustable with differentiation time from initial disorder to final order. This study adds a new dimension to not only solving the problems of supply of materials and fabrication of nanopatterns in neural tissue engineering, but may also offering a new promising way of waste minimization or reuse for environmental protection.

3D-Printed Biosensor Arrays for Medical Diagnostics

While the technology is relatively new, low-cost 3D printing has impacted many aspects of human life. 3D printers are being used as manufacturing tools for a wide variety of devices in a spectrum of applications ranging from diagnosis to implants to external prostheses. The ease of use, availability of 3D-design software and low cost has made 3D printing an accessible manufacturing and fabrication tool in many bioanalytical research laboratories. 3D printers can print materials with varying density, optical character, strength and chemical properties that provide the user with a vast array of strategic options. In this review, we focus on applications in biomedical diagnostics and how this revolutionary technique is facilitating the development of low-cost, sensitive, and often geometrically complex tools. 3D printing in the fabrication of microfluidics, supporting equipment, and optical and electronic components of diagnostic devices is presented. Emerging diagnostics systems using 3D bioprinting as a tool to incorporate living cells or biomaterials into 3D printing is also reviewed.

Biomaterials in Tendon and Skeletal Muscle Tissue Engineering: Current Trends and Challenges

Tissue engineering is a promising approach to repair tendon and muscle when natural healing fails. Biohybrid constructs obtained after cells&rsquo; seeding and culture in dedicated scaffolds have indeed been considered as relevant tools for mimicking native tissue, leading to a better integration in vivo. They can also be employed to perform advanced in vitro studies to model the cell differentiation or regeneration processes. In this review, we report and analyze the different solutions proposed in literature, for the reconstruction of tendon, muscle, and the myotendinous junction. They classically rely on the three pillars of tissue engineering, i.e., cells, biomaterials and environment (both chemical and physical stimuli). We have chosen to present biomimetic or bioinspired strategies based on understanding of the native tissue structure/functions/properties of the tissue of interest. For each tissue, we sorted the relevant publications according to an increasing degree of complexity in the materials&rsquo; shape or manufacture. We present their biological and mechanical performances, observed in vitro and in vivo when available. Although there is no consensus for a gold standard technique to reconstruct these musculo-skeletal tissues, the reader can find different ways to progress in the field and to understand the recent history in the choice of materials, from collagen to polymer-based matrices.

3D-Printed Graphene/Polylactic Acid Electrodes Promise High Sensitivity in Electroanalysis

Additive manufacturing provides a unique tool for prototyping structures toward electrochemical sensing, due to its ability to produce highly versatile, tailored-shaped devices in a low-cost and fast way with minimized waste. Here we present 3D-printed graphene electrodes for electrochemical sensing. Ring- and disc-shaped electrodes were 3D-printed with a Fused Deposition Modeling printer and characterized using cyclic voltammetry and scanning electron microscopy. Different redox probes K₃Fe(CN)₆:K₄Fe(CN)₆, FeCl₃, ascorbic acid, Ru(NH₃)₆Cl₃, and ferrocene monocarboxylic acid) were used to assess the electrochemical performance of these devices. Finally, the electrochemical detection of picric acid and ascorbic acid was carried out as proof-of-concept analytes for sensing applications. Such customizable platforms represent promising alternatives to conventional electrodes for a wide range of sensing applications.