Fast preparing bioelectrode with conductive bioink for nitrite detection in high sensitivity and stability.

Electrochemically active biofilms (EABs) for nitrite detection have high specificity, rapid response, operational simplicity, and extended lifespan advantages. However, their scale production remains challenging due to time-consuming and uniform preparation. In this study, a novel approach was proposed to fast fabricate an EAB biosensor with a synthetic biofilm electrode for nitrite detection. The biofilm electrode was prepared by coating bioinks with varying conductive materials onto the surface of the graphite sheets, showing short incubation time and good reproducibility. Incorporating conductive materials into the bioinks remarkably enhanced the maximum voltage of the first cycle of bioelectrode incubation, with an increase of up to 633% for carbon nanofiber. The nitrite reduction current was amplified by a factor of 2.97, due to the enhancement of extracellular electron transfer (EET). The developed nitrite biosensor exhibited a detection range of 0.1 to 15 mg NO-2-N L-1, with a high sensitivity of 610.8 µA mM-1 cm-2, and a stabilization operation time of at least 280 cycles. This study not only provided valuable insights into conductive materials for synthetic biofilms but also presented a practical approach for the rapid preparation, scale production, and optimization of highly sensitive and stable EAB sensors.

A Visual, In-Expensive, and Wireless Capillary Rheometer for Characterizing Wholly-Cellular Bioinks.

Rheological measurements with in situ visualization can elucidate the microstructural origin of complex flow behaviors of an ink. However, existing commercial rheometers suffer from high costs, the need for dedicated facilities for microfabrication, a lack of design flexibility, and cabling that complicates operation in sterile or enclosed environments. To address these limitations, a low-cost ($300) visual, in-expensive and wireless rheometer (VIEWR) using 3D-printed and off-the-shelf components is presented. VIEWR measurements are validated by steady-state and transient flow responses for different complex fluids, and microstructural flow profiles and evolution of yield-planes are revealed via particle image velocimetry. Using the VIEWR, a wholly-cellular bioink system comprised of compacted cell aggregates is characterized, and complex yield-stress and viscoelastic responses are captured via concomitantly visualizing the spatiotemporal evolution of aggregate morphology. A symmetric hyperbolic extensional-flow geometry is further constructed inside a capillary tube using digital light processing. Such geometries allow for measuring the extensional viscosity at varying deformation rates and further visualizing the alignment and stretching of aggregates under external flow. Synchronized but asymmetric evolution of aggregate orientation and strain through the neck is visualized. Using varying geometries, the jamming and viscoelastic deformation of aggregates are shown to contribute to the extensional viscosity of the wholly-cellular bioinks.

Thermo-Responsive Nanocomposite Bioink with Growth-Factor Holding and its Application to Bone Regeneration.

Three-dimensional (3D) bioprinting, which is being increasingly used in tissue engineering, requires bioinks with tunable mechanical properties, biological activities, and mechanical strength for in vivo implantation. Herein, a growth-factor-holding poly(organophosphazene)-based thermo-responsive nanocomposite (TNC) bioink system is developed. The mechanical properties of the TNC bioink are easily controlled within a moderate temperature range (5-37 °C). During printing, the mechanical properties of the TNC bioink, which determine the 3D printing resolution, can be tuned by varying the temperature (15-30 °C). After printing, TNC bioink scaffolds exhibit maximum stiffness at 37 °C. Additionally, because of its shear-thinning and self-healing properties, TNC bioinks can be extruded smoothly, demonstrating good printing outcomes. TNC bioink loaded with bone morphogenetic protein-2 (BMP-2) and transforming growth factor-beta1 (TGF-ß1), key growth factors for osteogenesis, is used to print a scaffold that can stimulate biological activity. A biological scaffold printed using TNC bioink loaded with both growth factors and implanted on a rat calvarial defect model reveals significantly improved bone regenerative effects. The TNC bioink system is a promising next-generation bioink platform because its mechanical properties can be tuned easily for high-resolution 3D bioprinting with long-term stability and its growth-factor holding capability has strong clinical applicability.

Additive manufacturing of bioactive glass biomaterials.

Tissue engineering (TE) and regenerative medicine have held great promises for the repair and regeneration of damaged tissues and organs. Additive manufacturing has recently appeared as a versatile technology in TE strategies that enables the production of objects through layered printing. By applying 3D printing and bioprinting, it is now possible to make tissue-engineered constructs according to desired thickness, shape, and size that resemble the native structure of lost tissues. Up to now, several organic and inorganic materials were used as raw materials for 3D printing; bioactive glasses (BGs) are among the most hopeful substances regarding their excellent properties (e.g., bioactivity and biocompatibility). In addition, the reported studies have confirmed that BG-reinforced constructs can improve osteogenic, angiogenic, and antibacterial activities. This review aims to provide an up-to-date report on the development of BG-containing raw biomaterials that are currently being employed for the fabrication of 3D printed scaffolds used in tissue regeneration applications with a focus on their advantages and remaining challenges.

3D Bioprinting of Induced Pluripotent Stem Cells and Disease Modeling.

Patient-derived induced pluripotent stem cells (iPSCs), carrying the genetic information of the disease and capable of differentiating into multilineages in vitro, are valuable for disease modeling. 3D bioprinting enables the assembly of the cell-laden hydrogel into hierarchically three-dimensional architectures that recapitulate the natural tissues and organs. Investigation of iPSC-derived physiological and pathological models constructed by 3D bioprinting is a fast-growing field still in its infancy. Distinctly from cell lines and adult stem cells, iPSCs and iPSC-derived cells are more susceptible to external stimuli which can disturb the differentiation, maturation, and organization of iPSCs and their progeny. Here we discuss the fitness of iPSCs and 3D bioprinting from the perspective of bioinks and printing technologies. We provide a timely review of the progress of 3D bioprinting iPSC-derived physiological and pathological models by exemplifying the relatively prosperous cardiac and neurological fields. We also discuss scientific rigors and highlight the remaining issues to offer a guiding framework for bioprinting-assisted personalized medicine.

Advances in Cartilage Tissue Engineering Using Bioinks with Decellularized Cartilage and Three-Dimensional Printing.

Osteoarthritis, a chronic, debilitating, and painful disease, is one of the leading causes of disability and socioeconomic burden, with an estimated 250 million people affected worldwide. Currently, there is no cure for osteoarthritis and treatments for joint disease require improvements. To address the challenge of improving cartilage repair and regeneration, three-dimensional (3D) printing for tissue engineering purposes has been developed. In this review, emerging technologies are presented with an overview of bioprinting, cartilage structure, current treatment options, decellularization, bioinks, and recent progress in the field of decellularized extracellular matrix (dECM)-bioink composites is discussed. The optimization of tissue engineering approaches using 3D-bioprinted biological scaffolds with dECM incorporated to create novel bioinks is an innovative strategy to promote cartilage repair and regeneration. Challenges and future directions that may lead to innovative improvements to currently available treatments for cartilage regeneration are presented.

New Insights into the Applications of 3D-Printed Biomaterial in Wound Healing and Prosthesis.

Recently three-dimensional bioprinting (3D-bioP) has emerged as a revolutionary technique for numerous biomedical applications. 3D-bioP has facilitated the printing of advanced and complex human organs resulting in satisfactory therapeutic practice. One of the important biomedical applications of 3D-bioP is in tissue engineering, wound healing, and prosthetics. 3D-bioP is basically aimed to restore the natural extracellular matrix of human's damage due to wounds. The relevant search was explored using various scientific database, viz., PubMed, Web of Science, Scopus, and ScienceDirect. The objective of this review is to emphasize interpretations from the pre-executed studies and to assess the worth of employing 3D-bioP in wound healing as well as prosthetics in terms of patient compliance, clinical outcomes, and economic viability. Furthermore, the benefits of applying 3D-bioP in wound healing over traditional methods have been covered along with the biocompatible biomaterials employed as bioinks has been discussion. Additionally, the review expands about the clinical trials in 3D-bioP field, showing promise of biomedical applicability of this technique with growing advancement in recent years.

3D Printed Biocatalytic Living Materials with Dual-Network Reinforced Bioinks.

The field of living materials seeks to harness living cells as microfactories that can construct a material itself or enhance the performance of material in some manner. While recent advances in 3D printing allow microbe manipulation to create bespoke living materials, the effective coupling of these living components in reinforced bioink designs remains a major challenge due to the difficulty in building a robust and cell-friendly microenvironment. Here, a type of dual-network bioink is reported for the 3D printing of living materials with enhanced biocatalysis capabilities, where bioinks are readily printable and provide a biocompatible environment along with desirable mechanical performance. It is demonstrated that integrating microbes into these bioinks enables the direct printing of catalytically living materials with high cell viability and maintains metabolic activity, which those living materials can be preserved and reused. Further, a bacteria-algae coculture system is fabricated for the bioremediation of chemicals, giving rise to its potential field applications.

Nanoengineered Granular Hydrogel Bioinks with Preserved Interconnected Microporosity for Extrusion Bioprinting.

3D bioprinting of granular hydrogels comprising discrete hydrogel microparticles (microgels) may overcome the intrinsic structural limitations of bulk (nanoporous) hydrogel bioinks, enabling the fabrication of modular thick tissue constructs. The additive manufacturing of granular scaffolds has predominantly relied on highly jammed microgels to render the particulate suspensions shear yielding and extrudable. This inevitably compromises void spaces between microgels (microporosity), defeating rapid cell penetration, facile metabolite and oxygen transfer, and cell viability. Here, this persistent bottleneck is overcome by programming microgels with reversible interfacial nanoparticle self-assembly, enabling the fabrication of nanoengineered granular bioinks (NGB) with well-preserved microporosity, enhanced printability, and shape fidelity. The microporous architecture of bioprinted NGB constructs permits immediate post-printing 3D cell seeding, which may expand the library of bioinks via circumventing the necessity of bioorthogonality for cell-laden scaffold formation. This work opens new opportunities for the 3D bioprinting of tissue engineering microporous scaffolds beyond the traditional biofabrication window.

3D Printable Dynamic Hydrogel: As Simple as it Gets!

3D printing technology offers a vast range of applications for tissue engineering applications. Over the past decade a vast range of new equipment has been developed; while, 3D printable biomaterials, especially hydrogels, are investigated to fit the printability requirements. The current candidates for bioprinting often require post-printing cross-linking to maintain their shape. On the other hand, dynamic hydrogels are considered as the most promising candidate for this application with their extrudability and self-healing properties. However, it proves to be very difficult to match the required rheological in a simple material. Here, this study presents for the first time the simplest formulation of a dynamic hydrogel based on thiol-functionalized hyaluronic acid formulated with gold ions that fulfill all the requirements to be printed without the use of external stimuli, as judged by the rheological studies. The printability is also demonstrated with a 3D printer allowing for the printing of the dynamic hydrogel as it is, achieving 3D construct with a relatively good precision and up to 24 layers, corresponding to 10 mm high. This material is the simplest 3D printable hydrogel and its mixture with cells and biological compounds is expected to open a new era in 3D bioprinting.

Ultrashort Peptide Bioinks Support Automated Printing of Large-Scale Constructs Assuring Long-Term Survival of Printed Tissue Constructs.

We report about rationally designed ultrashort peptide bioinks, overcoming severe limitations in current bioprinting procedures. Bioprinting is increasingly relevant in tissue engineering, regenerative and personalized medicine due to its ability to fabricate complex tissue scaffolds through an automated deposition process. Printing stable large-scale constructs with high shape fidelity and enabling long-term cell survival are major challenges that most existing bioinks are unable to solve. Additionally, they require chemical or UV-cross-linking for the structure-solidifying process which compromises the encapsulated cells, resulting in restricted structure complexity and low cell viability. Using ultrashort peptide bioinks as ideal bodylike but synthetic material, we demonstrate an instant solidifying cell-embedding printing process via a sophisticated extrusion procedure under true physiological conditions and at cost-effective low bioink concentrations. Our printed large-scale cell constructs and the chondrogenic differentiation of printed mesenchymal stem cells point to the strong potential of the peptide bioinks for automated complex tissue fabrication.

A Guide to Polysaccharide-Based Hydrogel Bioinks for 3D Bioprinting Applications.

Three-dimensional (3D) bioprinting is an innovative technology in the biomedical field, allowing the fabrication of living constructs through an approach of layer-by-layer deposition of cell-laden inks, the so-called bioinks. An ideal bioink should possess proper mechanical, rheological, chemical, and biological characteristics to ensure high cell viability and the production of tissue constructs with dimensional stability and shape fidelity. Among the several types of bioinks, hydrogels are extremely appealing as they have many similarities with the extracellular matrix, providing a highly hydrated environment for cell proliferation and tunability in terms of mechanical and rheological properties. Hydrogels derived from natural polymers, and polysaccharides, in particular, are an excellent platform to mimic the extracellular matrix, given their low cytotoxicity, high hydrophilicity, and diversity of structures. In fact, polysaccharide-based hydrogels are trendy materials for 3D bioprinting since they are abundant and combine adequate physicochemical and biomimetic features for the development of novel bioinks. Thus, this review portrays the most relevant advances in polysaccharide-based hydrogel bioinks for 3D bioprinting, focusing on the last five years, with emphasis on their properties, advantages, and limitations, considering polysaccharide families classified according to their source, namely from seaweed, higher plants, microbial, and animal (particularly crustaceans) origin.

Cellular Interaction of Human Skin Cells towards Natural Bioink via 3D-Bioprinting Technologies for Chronic Wound: A Comprehensive Review.

Skin substitutes can provide a temporary or permanent treatment option for chronic wounds. The selection of skin substitutes depends on several factors, including the type of wound and its severity. Full-thickness skin grafts (SGs) require a well-vascularised bed and sometimes will lead to contraction and scarring formation. Besides, donor sites for full-thickness skin grafts are very limited if the wound area is big, and it has been proven to have the lowest survival rate compared to thick- and thin-split thickness. Tissue engineering technology has introduced new advanced strategies since the last decades to fabricate the composite scaffold via the 3D-bioprinting approach as a tissue replacement strategy. Considering the current global donor shortage for autologous split-thickness skin graft (ASSG), skin 3D-bioprinting has emerged as a potential alternative to replace the ASSG treatment. The three-dimensional (3D)-bioprinting technique yields scaffold fabrication with the combination of biomaterials and cells to form bioinks. Thus, the essential key factor for success in 3D-bioprinting is selecting and developing suitable bioinks to maintain the mechanisms of cellular activity. This crucial stage is vital to mimic the native extracellular matrix (ECM) for the sustainability of cell viability before tissue regeneration. This comprehensive review outlined the application of the 3D-bioprinting technique to develop skin tissue regeneration. The cell viability of human skin cells, dermal fibroblasts (DFs), and keratinocytes (KCs) during in vitro testing has been further discussed prior to in vivo application. It is essential to ensure the printed tissue/organ constantly allows cellular activities, including cell proliferation rate and migration capacity. Therefore, 3D-bioprinting plays a vital role in developing a complex skin tissue structure for tissue replacement approach in future precision medicine.

3D Bioprinting of Human Hollow Organs.

3D bioprinting is a rapidly evolving technique that has been found to have extensive applications in disease research, tissue engineering, and regenerative medicine. 3D bioprinting might be a solution to global organ shortages and the growing aversion to testing cell patterning for novel tissue fabrication and building superior disease models. It has the unrivaled capability of layer-by-layer deposition using different types of biomaterials, stem cells, and biomolecules with a perfectly regulated spatial distribution. The tissue regeneration of hollow organs has always been a challenge for medical science because of the complexities of their cell structures. In this mini review, we will address the status of the science behind tissue engineering and 3D bioprinting of epithelialized tubular hollow organs. This review will also cover the current challenges and prospects, as well as the application of these complicated 3D-printed organs.

Intra-Operative Bioprinting of Hard, Soft, and Hard/Soft Composite Tissues for Craniomaxillofacial Reconstruction.

Reconstruction of complex craniomaxillofacial (CMF) defects is challenging due to the highly organized layering of multiple tissue types. Such compartmentalization necessitates the precise and effective use of cells and other biologics to recapitulate the native tissue anatomy. In this study, intra-operative bioprinting (IOB) of different CMF tissues, including bone, skin, and composite (hard/soft) tissues, is demonstrated directly on rats in a surgical setting. A novel extrudable osteogenic hard tissue ink is introduced, which induced substantial bone regeneration, with ≈80% bone coverage area of calvarial defects in 6 weeks. Using droplet-based bioprinting, the soft tissue ink accelerated the reconstruction of full-thickness skin defects and facilitated up to 60% wound closure in 6 days. Most importantly, the use of a hybrid IOB approach is unveiled to reconstitute hard/soft composite tissues in a stratified arrangement with controlled spatial bioink deposition conforming the shape of a new composite defect model, which resulted in ≈80% skin wound closure in 10 days and 50% bone coverage area at Week 6. The presented approach will be absolutely unique in the clinical realm of CMF defects and will have a significant impact on translating bioprinting technologies into the clinic in the future.

Biocatalytic CsPbX3 Perovskite Nanocrystals: A Self-Reporting Nanoprobe for Metabolism Analysis.

CsPbX3 perovskite nanocrystals (NCs), with excellent optical properties, have drawn considerable attention in recent years. However, they also suffer from inherent vulnerability and hydrolysis, causing the new understanding or new applications to be difficultly explored. Herein, for the first time, it is discovered that the phospholipid membrane (PM)-coated CsPbX3 NCs have intrinsic biocatalytic activity. Different from other peroxidase-like nanozymes relying on extra chromogenic reagents, the PM-CsPbX3 NCs can be used as a self-reporting nanoprobe, allowing an "add-to-answer" detection model. Notably, the fluorescence of PM-CsPbX3 NCs can be rapidly quenched by adding H2 O2 and then be restored by removing excess H2 O2 . Initiated from this unexpected observation, the PM-CsPbX3 NCs can be explored to prepare multi-color bioinks and metabolite-responsive paper analytical devices, demonstrating the great potential of CsPbX3 NCs in bioanalysis. This is the first report on the discovery of nanozyme-like property of all-inorganic CsPbX3 perovskite NCs, which adds another piece to the nanozyme puzzle and opens new avenues for in vitro disease diagnostics.

Advances and prospective applications of 3D food printing for health improvement and personalized nutrition.

Three-dimensional food printing (3DFP) uses additive manufacturing concepts to fabricate customized designed products with food ingredients in powder, liquid, dough, or paste presentations. In some cases, it uses additives, such as hydrocolloids, starch, enzymes, and antibrowning agents. Chocolate, cheese, sugar, and starch-based materials are among the most used ingredients for 3DFP, and there is a broad and growing interest in meat-, fruit-, vegetable-, insect-, and seaweed-based alternative raw materials. Here, we reviewed the most recent published information related to 3DFP for novel uses, including personalized nutrition and health-oriented applications, such as the use of 3D-printed food as a drug vehicle, and four-dimensional food printing (4DFP). We also reviewed the use of this technology in aesthetic food improvement, which is the most popular use of 3DFP recently. Finally, we provided a prospective and perspective view of this technology. We also reflected on its multidisciplinary character and identified aspects in which social and regulatory affairs must be addressed to fulfill the promises of 3DFP in human health improvement.

Crosslinking Strategies for 3D Bioprinting of Polymeric Hydrogels.

Three-dimensional (3D) bioprinting has recently advanced as an important tool to produce viable constructs that can be used for regenerative purposes or as tissue models. To develop biomimetic and sustainable 3D constructs, several important processing aspects need to be considered, among which crosslinking is most important for achieving desirable biomechanical stability of printed structures, which is reflected in subsequent behavior and use of these constructs. In this work, crosslinking methods used in 3D bioprinting studies are reviewed, parameters that affect bioink chemistry are discussed, and the potential toward improving crosslinking outcomes and construct performance is highlighted. Furthermore, current challenges and future prospects are discussed. Due to the direct connection between crosslinking methods and properties of 3D bioprinted structures, this Review can provide a basis for developing necessary modifications to the design and manufacturing process of advanced tissue-like constructs in future.

Antibody Micropatterned Lubricant-Infused Biosensors Enable Sub-Picogram Immunofluorescence Detection of Interleukin 6 in Human Whole Plasma.

Recent studies have shown a correlation between elevated interleukin 6 (IL-6) concentrations and the risk of respiratory failure in COVID-19 patients. Therefore, detection of IL-6 at low concentrations permits early diagnosis of worst-case outcome in viral respiratory infections. Here, a versatile biointerface is presented that eliminates nonspecific adhesion and thus enables immunofluorescence detection of IL-6 in whole human plasma or whole human blood during coagulation, down to a limit of detection of 0.5 pg mL-1 . The sensitivity of the developed lubricant-infused biosensor for immunofluorescence assays in detecting low molecular weight proteins such as IL-6 is facilitated by i) producing a bioink in which the capture antibody is functionalized by an epoxy-based silane for covalent linkage to the fluorosilanized surface and ii) suppressing nonspecific adhesion by patterning the developed bioink into a lubricant-infused coating. The developed biosensor addresses one of the major challenges for biosensing in complex fluids, namely nonspecific adhesion, therefore paving the way for highly sensitive biosensing in complex fluids.

Engineering inkjet bioprinting processes toward translational therapies.

Bioprinting is the assembly of three-dimensional (3D) tissue constructs by layering cell-laden biomaterials using additive manufacturing techniques, offering great potential for tissue engineering and regenerative medicine. Such a process can be performed with high resolution and control by personalized or commercially available inkjet printers. However, bioprinting's clinical translation is significantly limited due to process engineering challenges. Upstream challenges include synthesis, cellular incorporation, and functionalization of "bioinks," and extrusion of print geometries. Downstream challenges address sterilization, culture, implantation, and degradation. In the long run, bioinks must provide a microenvironment to support cell growth, development, and maturation and must interact and integrate with the surrounding tissues after implantation. Additionally, a robust, scaleable manufacturing process must pass regulatory scrutiny from regulatory bodies such as U.S. Food and Drug Administration, European Medicines Agency, or Australian Therapeutic Goods Administration for bioprinting to have a real clinical impact. In this review, recent advances in inkjet-based 3D bioprinting will be presented, emphasizing on biomaterials available, their properties, and the process to generate bioprinted constructs with application in medicine. Current challenges and the future path of bioprinting and bioinks will be addressed, with emphasis in mass production aspects and the regulatory framework bioink-based products must comply to translate this technology from the bench to the clinic.