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Bioactive compounds (BCs) provide numerous health benefits by interacting with one or more components of living tissues and systems. However, despite their potential health benefits, most of the BCs have low bioaccessibility and bioavailability, hindering their potential health-promoting activities. The conventional encapsulation techniques are time-consuming and have major limitations in their food applications, including the use of non-food grade chemicals, undesired sensory attributes, and storage stability issues. A cutting-edge, new technique based on 3D printing can assist in resolving the problems associated with conventional encapsulation technologies. 3D food printing can help protect BCs by incorporating them precisely into three-dimensional matrices, which can provide (i) protection during storage, (ii) enhanced bioavailability, and (iii) effective delivery and controlled release of BCs. Recently, various 3D printing techniques and inks have been investigated in order to create delivery systems with different compositions and geometries, as well as diverse release patterns. This review emphasizes the advances in 3D printing-based encapsulation approaches, leading to enhanced delivery systems and customized food formulations. HIGHLIGHTS: Conventional techniques for encapsulating bioactive compounds (BCs) are summarized. Potential applications of 3D food printing for encapsulating BCs are discussed. Extrusion-based 3D food printing can enhance the stability/bioavailability of BCs. Hydrogels are promising materials for 3D food printing-based encapsulation. Future prospects for integrating 3D printing with encapsulation are highlighted. [ABSTRACT FROM AUTHOR]

For porous dressing production through 3D printing, it is challenging to adjust the printability of ink while balancing its bioactivity. The present study introduces an example of a modular construction method for heterogeneous granular ink. Gelatin microspheres (gelatin‐MSs) are assembled by poly (gallic acid)‐coated zinc‐containing nano‐hydroxyapatite (ZnHA‐NP/p(GA)), and further cooperate with Ag+ to form a kind of granular inks. The three modules including gelatin‐MS, ZnHA‐NP/p(GA), and Ag have their own functions: The viscoelastic gelatin‐MS module is the essential component that realizes ink extrusion. The ZnHA‐NP/p(GA) module not only forms reversible interactions with gelatin‐MS that realize the assembly but also takes the responsibility of reactive oxygen species‐scavenging and anti‐inflammatory. The Ag module not only interacts with ZnHA‐NP/p(GA) module to promote the stability but also exhibits strong antibacterial property. The gelatin‐MS size, p(GA)‐coating duration, ZnHA‐NP/p(GA) content, and Ag content are optimized to yield a nano‐micro granular ink for bioactive porous dressing preparation that is used to significantly promote the healing of refractory wounds. Therefore, this method allows particles with different structures and bio‐functions that serve as modules to assemble into inks, realizing the balance of printability and biological functions for dressing manufacturing. [ABSTRACT FROM AUTHOR]

Chiral carbon dots (CDs) with circularly polarized luminescence (CPL) are one of the most dynamic areas of modern science. However, the design, preparation, and ambiguity mechanism of solid‐state CPL‐active CDs remains a formidable challenge. Herein, for the first time, CDs with customized chiroptical activities in the solid state, especially CPL, are transcribed from chiral metal–organic framework (CMOFs) via a bottle‐around‐ship strategy. Within these CMOFs⊃CDs assemblies, CDs inherited the chirality of the host CMOFs through host–guest interactions, which is revealed by density functional theory (DFT) simulations and experimental results, and amplified the luminescence dissymmetry factor (glum) by effective artificial chiral light‐harvesting systems. Impressively, CMOFs⊃CDs in pairs generated color‐tunable CPL and white CPL with chromaticity coordinates of (0.32, 0.32). Furthermore, benefiting from excellent processability, as luminescent coatings and 3D printing inks, a white circularly polarized light‐emitting diode, and an extended 3D model "light bulb" featuring white CPL are successfully fabricated, respectively. This strategy paves a new avenue for the synthesis and advanced application of solid‐state CPL‐active CDs‐based materials. [ABSTRACT FROM AUTHOR]

3D printing, as an advanced and promising strategy for processing electrode for energy storage devices, such as supercapacitors and batteries, has garnered considerable interest in recent decades. The interest in 3D printed electrodes stems from its exceptional performance and manufacturing features, including customized sizes and shapes and the layer‐by‐layer processing principle, etc., especially integrating with MXene which allows the manufacturing of electrodes from different raw materials and possessing desired electrochemical properties. Herculean challenges, such as material compatibility of the printing inks, nondurable interfacial or bulk mechanical strength of the printed electrodes, and sometimes the low capacitance, lead to inferior electrochemical performance and hinder the practical applications of this promising technology. In this review, we firstly summarize the representative 3D printing methods, then, review the MXene‐based 3D printing electrodes made from different materials, and last, provide electrochemical performance of 3D printing MXene‐based electrodes for supercapacitors. Furthermore, based on a summary on the recent progress, an outlook on these promising electrodes for sustainable energy devices is provided. We anticipate that this review could provide some insights into overcoming the challenges and achieving more remarkable electrochemical performance of 3D printing supercapacitor electrodes and offer perspectives in the future for emerging energy devices. [ABSTRACT FROM AUTHOR]

Inkjet printing offers significant benefits for additive manufacturing (AM) and printed electronics, such as cost-effectiveness, scalability, non-contact printing, and the flexibility for ad-hoc customization. However, some challenges such as stable jetting states and defined printing zone still needs attention. Data driven modeling such as machine/deep learning (ML/DL) as a predictive methodology has proven to reduce the experimental cost and workload in AM for low-viscosity inks. However, there is an oversight in ML extension to high-viscosity inks due to some inherit challenges such as irregular shape formation, and adhesiveness. Therefore, this study is focused on the prediction of jetting states and defining the printing zone for three-dimensional (3D) inkjet printing of high-viscosity ink. The experimental data is comprised of equipment parameter settings, material properties, and camera-captured features. The jetting behavior is recorded with a high-speed camera and carefully categorized into five classes: no jetting, orifice adhesion, droplet jetting, orifice tail , and beads hanging. A robust and efficient high-viscosity 3D printing U-Net (HV3DP-UNet) model is proposed, that achieved the jetting state and printing zone prediction accuracy of 97.98% and 100% respectively. For the fair comparison, three traditional ML and two more DL models are tested and analyzed in detail. The robustness and efficacy of the proposed model is supplemented with four performance metrics, i.e., accuracy, precision, recall and f1-score. The models' efficacy has been proved by achieving improved results on the public dataset, the proposed model has achieved overall prediction accuracy of 92.95%. The presented data-driven approach serves as a systematic framework for enhancing quality of inkjet-based 3D printing utilizing high-viscosity ink. • Extensive experimentation conducted on 3D printing of high-viscosity ink. • Data-driven framework HV3DP-UNet for inkjet-based 3D printing. • Method to accurately predict jetting states and printability zone for high-viscosity inks. [ABSTRACT FROM AUTHOR]

Liquid metals (LMs) are opening large spaces for achieving functional 3D printing. However, previous fabrication strategies ever developed so far can only address a specific printing task that has yet to fulfill various needs. Conceiving that all fabrications and their output quality are dominated by the interactions between printing inks and their ambient environment, this review is dedicated to presenting a generalized framework toward the ubiquitous LM 3D printing and summarizing its fabrication category thus integrated. A panoramic view is provided that intentionally administrating the interfacial interactions among different media can guide ink modification and printing optimization. Further, the interactions between LM inks and various media are interpreted, ranging from gases, and liquids to soft matters, biological tissues, and even rigid materials, exploring key mechanisms such as oxidation facilitation, heat dissipation, structural support, modulus matching, strong wettability, and high reactivity. Following that, the LM inks, typical printing technologies, diverse working media, and enabled applications are reviewed. The elucidation of these interactions, particularly physical and chemical effects, can lead to the incubation of future LM 3D printing centers. It is expected that interactional LM 3D printing can mold additive manufacturing into ever‐powerful tools in the coming time. [ABSTRACT FROM AUTHOR]

This work pioneers the application of direct ink writing (DIW) to fabricate elastomeric additively manufactured vision based tactile sensor (VBTS). DIW cuts down the fabrication time by 76%, allowing design precise control and reducing the complexities of the process compared to the state‐of‐the‐art (SOTA) molding techniques. Successful fabrication of DIW sensor is verified in three stages. Firstly, the mechanical characteristics of the DIW sensor are at par with those of SOTA molded Ecoflex in terms of depth of compression, compression rate, and the number of cycles. Secondly, using robotic pose estimation as a demonstration, the force enables deformation in the DIW sensor shows comparable normality estimation performance to that of the SOTA Ecoflex with a mean absolute error of less than 0.6°. Thirdly, finite element analysis (FEA) of DIW and SOTA Ecoflex sensors using Yeoh model shows similar stress and strain distributions as another evidence of DIW deformability and durability signaling sensor's successful fabrication. [ABSTRACT FROM AUTHOR]

Summary: Three‐dimensional (3D) printing technology digitally designs and manufactures objects through computer‐controlled processes. It requires raw materials with specific rheological properties for extrusion and shape retention. Dairy products hold promise for 3D printing due to their ability to form structures and their nutritional value. However, the quality of 3D printing with dairy products relies on the properties of the printing ink and printer parameters, presenting challenges for practical applications. This work provided a summary of the suitability of dairy‐based 3D printed products, discussing physicochemical modifications and additives to enhance their suitability and nutritional properties. The internal structure and composition of printing inks derived from dairy products are closely linked to their printing performance. Physicochemical modifications and additives effectively improve printability and the nutritional aspects of dairy inks. The 3D printing suitability of dairy inks can be enhanced through physical, chemical or enzymatic treatments. The gel properties of dairy products can be improved by mixing them with hydrophilic gels, introducing calcium, and incorporating lipids to enhance the 3D printing performance of dairy products. 3D printing technology enables the customisation of dairy products with personalised control of nutritional content, meeting the increasing consumer and market demand for healthier foods. In the future, 3D printed dairy products are expected to constitute convenient and quick nutritious food and enter home kitchens. [ABSTRACT FROM AUTHOR]

Polymer blends containing up to 70% organosolv lignin content and lyotropic cellulose derivatives have been established as "lignin inks" for direct ink writing of fully biobased 3D parts. However, a fast-crosslinking mechanism is needed to improve throughput and design space. In this paper, UV-photocrosslinkable organosolv lignin/hydroxypropyl cellulose inks are formulated through doping with common photocrosslinkers. The most potent photocrosslinkers for neat hydroxypropyl cellulose, lignin and their blends are determined through a series of DOEs. Hydroxypropyl cellulose is significantly more amenable to photocrosslinking than organosolv lignin. The optimal photocrosslinkable ink formulations are printable and exhibit up to 70% gel content, although thermal post-curing remains essential. Chemical, thermal, and mechanical investigations of the photocrosslinked 3D parts evidence efficient crosslinking of HPC through its hydroxyl groups, while lignin appears internally plasticized and/or degraded during inefficient photocrosslinking. Despite this, photocrosslinkable inks exhibit improved tensile properties, shape flexibility, and fidelity. The heterogeneous crosslinking and residual creep highlight the need to further activate lignin for homogeneous photocrosslinking in order to fully exploit the potential of lignin inks in DIW. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The functional principle behind extrusion‐based printing is the capability of flowing material through a nozzle on demand, which must solidify upon deposition, a behavior exhibited only by some materials. Embedded printing offers a solution to maintain shape fidelity during the deposition of a wider range of materials. However, the use of a moving nozzle in a support bath can lead to bath disturbance and the spreading of the ink. In this study, a novel embedded printing technique that eliminates the need for a nozzle by employing a magnetic sphere as the plotting moiety is introduced. The externally steered sphere creates a path by locally fluidizing the bath, allowing the simultaneously injected ink to flow into the space behind it. The method is benchmarked using water as an ink, achieving free‐form printing without additional stabilization methods. The creation of solid structures is also demonstrated by printing a photocurable ink that is crosslinked and removed from the bath. Moreover, the plotting magnet can be incorporated into the printed part during the crosslinking, thus giving place to a magnetically responsive structure. This advancement paves the way for innovations in fields such as tissue engineering and microrobotics by enabling the fabrication of intricate and functional designs. [ABSTRACT FROM AUTHOR]

Direct ink writing 3D printing, using ink extrusion, promises to transform conventional 2D thin electrodes into 3D thick architectures for high‐performance supercapacitors. However, formulating 3D printing inks and designing 3D architectures for electrodes remain challenges. In this work, a novel MXene/graphene oxide/lignosulfonate (MGL) ink with excellent rheological properties is developed for 3D printing MGL thick electrodes with vertically aligned architectures. The MGL ink exhibited excellent shear‐thinning properties for smooth 3D printing and shape retention after printing. The 3D‐printed MGL thick electrode, with a thickness of up to 4 mm, achieved a breakthrough mass loading of 72.1 mg cm−2, resulting in an extremely high areal capacitance of 8.6 F cm−2 that is 9.6 times greater than the value observed for the bulk MGL electrode (0.9 F cm−2). Additionally, supercapacitors using the 3D MGL electrode achieved an energy density of 505.3 µWh cm−2, significantly surpassing the value for bulk MGL electrode (52.8 µWh cm−2). This enhancement is attributed to the efficient design of the electrodes, where vertically aligned pores in the 3D MGL electrode enhanced ion transfer and reaction kinetics. This study demonstrates an innovative approach for formulating inks and provides guidance for designing 3D thick electrodes with rapid ion transport and excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Semisolid extrusion (SSE) 3D printing (3DP) technology is emerging due to its simplicity and potential for on-site manufacturing of personalized drug products with tailored functionality (dose, release profile), as well as recognizability (size, shape, color). However, even a minor change in the composition of the ink (the feedstock material) and the printing process parameters can largely influence the outcome of printing. This paper summarizes the recent SSE 3DP studies, where the important factors affecting the quality of the printed drug products are discussed. Further challenges are showcased by introducing a case study focusing on the design of oral theophylline immediate-release drug products. The identified crucial factors, such as the printing hardware and connected software, printing parameters, and composition of the ink are discussed. Especially, the rheological properties of the ink during the printing process, together with solidification, mechanical properties, and morphology studies of already printed products are deliberated to gain more understanding of the printability of drug products by SSE. This work aims to provide an overview of design aspects related to SSE-based fabrication of personalized drug products. [Display omitted] [ABSTRACT FROM AUTHOR]

This research aims to use energy harvested from conductive materials to power microelectronic components. The proposed method involves using vibration-based energy harvesting to increase the natural vibration frequency, reduce the need for battery replacement, and minimise chemical waste. Piezoelectric transduction, known for its high-power density and ease of application, has garnered significant attention. Additionally, graphene, a non-piezoelectric material, exhibits good piezoelectric properties. The research explores a novel method of printing graphene material using 3D printing, specifically Direct Ink Writing (DIW) and fused deposition modelling (FDM). Both simulation and experimental techniques were used to analyse energy harvesting. The experimental technique involved using the cantilever beam-based vibration energy harvesting method. The results showed that the DIW-derived 3D-printed prototype achieved a peak power output of 12.2 µW, surpassing the 6.4 µW output of the FDM-derived 3D-printed prototype. Furthermore, the simulation using COMSOL Multiphysics yielded a harvested output of 0.69 µV. [ABSTRACT FROM AUTHOR]

This paper describes a method for fabricating microfluidic electronics with 3D interconnected networks by direct ink writing (DIW)‐based 3D printing. Existing 3D printing technologies have yet to simultaneously realize 1) direct printing of interconnected multilayered microchannels without supporting materials or post‐processing and 2) integration of electronic elements with microchannels during the process of printing. This research aims to develop a method to fabricate support‐free microchannels consisting of silicone sealant without the collapse of the extruded structure while integrating electronic elements during the fabrication by DIW. The injection of liquid metal into 3D‐printed microchannels allows the formation of electrical connections between 3D conductive networks and the embedded electronic elements, enabling the fabrication of flexible and stretchable liquid metal antenna coils. To demonstrate a practical application, 1) a skin‐attachable radio‐frequency identification (RFID) tag using a commercial skin‐adhesive plaster as a substrate and 2) free‐standing flexible wireless light‐emitting devices with a small footprint (21.4 mm × 15 mm) for potential implantable applications are produced. This technology will offer a new capability to realize the automated fabrication of stretchable printed circuits with 3D configuration of electrical circuits consisting of liquid metals. [ABSTRACT FROM AUTHOR]

An energy supply crisis is impacting all the branches, including the agriculture and food industry. The wise and responsible utilization of plant raw materials already cultivated is becoming a must in the country's economy. Not only the waste of the resources included but also the environmental challenge are concerns behind the not exploited food production by-streams and leftovers' valorization. Fruits and vegetables' out of the market quality "beauty" standards are still valuable sources of nutritious compounds. The conversion of raw materials into edible products can be provided by many techniques, with three-dimensional printing being the most individualized one. The main objective of this review was to summarize the existing efforts for the valorization of fruits and vegetable residuals into edible 3D inks and then 3D printed products. The clustering analysis was used for the separation of certain research approaches in fruit and vegetable wastes exploitation for 3D printing inks' formulation. As the multilayer deposit technique is strongly dependent on the printing conditions and 3D ink formulation, therefore the tabularized description was included presenting the nozzle diameter, printing speed and other conditions specified. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS), commonly used in organ‐on‐a‐chip (OoC) systems, faces limitations in replicating complex geometries, hindering its effectiveness in creating 3D OoC models. In contrast, poly(ethylene glycol)diacrylate (PEGDA‐250), favored for its fabrication ease and resistance to small molecule absorption, is increasingly used for 3D printing microfluidic devices. However, applications in cell culture have been limited due to poor cell adhesion. Here, a nanoporous PEGDA ink (P‐PEGDA) is introduced to enhance cell adhesion. P‐PEGDA is formulated with a porogen, photopolymerized, followed by the porogen removal. Utilizing P‐PEGDA, complex microstructures, and membranes as thin as 27 µm are 3D‐printed. Porogen concentrations from 10 to 30% are tested yielding constructs with increasing porosity and oxygen permeability surpassing PDMS, without compromising printing resolution. Tests across four cell lines show >80% cell viability, with a notable 77‐fold increase in MDA‐MB‐231 cell coverage on the porous scaffolds. Finally, an OoC model comprising a gyroid scaffold with a central opening filled with a cancer spheroid is introduced. This setup, after a 14 days co‐culture, demonstrates significant endothelial sprouting and integration within the spheroid. The P‐PEGDA formulation is suitable for high‐resolution 3D printing of constructs for 3D cell culture and OoC owing to its printability, gas permeability, biocompatibility, and cell adhesion. [ABSTRACT FROM AUTHOR]

Extrusion‐based three‐dimensional (3D) printing has been extensively studied in the food manufacturing industry. This technology places particular emphasis on the rheological properties of the printing ink. Gel system is the most suitable ink system and benefits from the composition of plant raw materials and gel properties of multiple components; green, healthy aspects of the advantages of the development of plant‐based gel system has achieved a great deal of attention. However, the relevant treatment technologies are still only at the laboratory stage. With a view toward encouraging further optimization of ink printing performance and advances in this field, in this review, we present a comprehensive overview of the application of diverse plant‐based gel systems in 3D food printing and emphasize the utilization of different treatment methods to enhance the printability of these gel systems. The treatment technologies described in this review are categorized into three distinct groups, physical, chemical, and physicochemical synergistic treatments. We comprehensively assess the specific application of these technologies in various plant‐based gel 3D printing systems and present valuable insights regarding the challenges and opportunities for further advances in this field. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3D printing inks into liquid bath anti-solvent forms fibers in designated locations. • Structural and electronic properties are tunable by the anti-solvent. • Coiled carbon nanotube yarns stretch up to 50 % with under 1 % change in resistance. • Printed nanotube yarns have specific conductivity on par with metals. Inspired by methods of wet fiber spinning, we introduce a process using a 3D printer to create dense carbon nanotube (CNT) fibers and extensible coils with metal-like DC specific conductivity. An extrusion-based printer with an immersed nozzle extrudes a homogeneous shear-thinning ink (with initially < 1 % CNT concentration in water) into a liquid bath of antisolvent, inducing immediate precipitation-driven solidification slightly beyond the nozzle tip. This process forms continuous fibers of CNTs with conductivity up to 3 × 105 S/m, exceeding that of dense graphite and approaching that of CNTs spun from similar inks in a continuous fiber spinning process (6 × 105 S/m). The specific conductivity is up to 1 × 103 S m2/kg, comparable with gold (2.3 × 103 S m2/kg). The printing regimes are analyzed, with consideration of the draw ratio imposed during printing. Particular focus is placed on adjusting the speed of counter-diffusion of the ink solvent and the bath liquid, which allows for tuning of fiber diameter, conductivity, and specific conductivity respectively over ranges of one, four, and five orders of magnitude. The conductivity of resulting fibers is maximized when the speed of solvent counter-diffusion is high and the radius reduction is largest. When extrusion speed is also high relative to speed of the nozzle motion, a fluid mechanical coiling instability emerges which creates filaments with periodic coils, allowing for intricate designs to be formed along a linear extrusion path. Once dried, these densely coiled structures initially maintain their shape and can subsequently undergo up to 50 % strain with under 1 % change in resistance and 170 % linear extension with 20 % increase in resistance as the coils unwind. The resulting complex coil structures have applications in lightweight circuitry and as flexible interconnects. [ABSTRACT FROM AUTHOR]

Summary: Aqueous solutions of Konjac glucomannan (KGM)/κ‐Carrageenan (κ‐C) of different ratios (1:2, 1:5, 1:8 and 1:10) and a fixed κ‐C content of 1.5%, were proposed as a new 3D food printing ink. Their thermo‐responsive behaviour was evaluated by temperature ramp rheological tests. This characterisation allowed for the evaluation of the synergistic effect between KGM and κ‐C and gave indications useful to the printing performance. Both elastic (G′) and loss (G″) moduli were found to increase by increasing the KGM concentration. Samples were printed by controlling the thermally reversible sol/gel transition occurring during the process. Direct pressure and flow rate measurements in the 3D printer were used to obtain the viscosity versus shear rate curves under processing conditions, useful to validate a scaling law relating the printing filament diameter to the relevant process and material properties (inks viscosity and printing pressure). The 3D printing performance of inks was evaluated by means of a novel, integrated score system. The results obtained indicate that aqueous mixtures of KGM/κ‐C can be successfully employed as a base for 3D printing food hydrogels. The use of the score system above outlined proved to be an easy yet efficient tool for the optimisation of the gel composition. [ABSTRACT FROM AUTHOR]

Adhesives and sealants show fine rheology with good physical and mechanical properties as viscous pastes, a possible starting point for developing direct ink writing (DIW) 3D printing ink. However, many commercial adhesives and sealants take days or weeks to cure fully. DIW 3D‐printed parts made directly from these sealants are not designed for a scalable manufacturing process and high‐volume production. Moreover, most of these adhesives and sealants have volume shrinkage during cure. A systematic understanding of formulation methods and design principles for an elastomeric silicone DIW ink can overcome these issues. This study presents the cogent formulation development of a 3D printable thermoset elastomer silicone that gels and cures isotropically in minutes, reducing cycle time for rapid ink development with no shrinkage during cure. More specifically, we outline the principles of raw material selection of a formulation to achieve excellent rheology, printability, synchronized working, and gel time fitting requirements closer to scalable manufacturing. The reaction kinetics and their corresponding 3D‐printed structural properties are also described. Interest in future work is toward a rational DIW 3D printing ink material development protocol and use of machine learning (ML). Highlights: Formulation method flexibility and design principle of DIW ink.Raw material selection principle to achieve optimal rheology for DIW printing.Ink gel kinetics for large‐scale DIW manufacturing.Hydrosilylation conversion over time at different ambient temperatures.Structural properties of DIW 3D printed parts. [ABSTRACT FROM AUTHOR]

Due to the difficulty of simultaneously ensuring printability and controlling their mechanical properties, 3D printed hydrogels thus far have low modulus, far less than that of many biological tissues and organs. Therefore, their feasibility toward various biomimetic applications is currently limited. Herein, Direct‐Ink‐Writing (DIW) based 3D printable hydrogel ink with broadly adjustable mechanical properties is introduced. The salting‐out effect is utilized to effectively lower the gelation temperature of hydrogel inks with a wide range of modulus (0.193–1.072 MPa), making them all 3D printable. As a proof of concept, multi‐layered synthetic blood vessels that mimic the mechanical properties of biological blood vessels are printed, and their practicability toward surgical training is demonstrated. The versatility and simplicity of this technique make it highly promising for use in various 3D‐printed hydrogel biomaterials applications. [ABSTRACT FROM AUTHOR]

Gradient matters with hierarchical structures endow the natural world with excellent integrity and diversity. Currently, direct ink writing 3D printing is attracting tremendous interest, and has been used to explore the fabrication of 1D and 2D hierarchical structures by adjusting the diameter, spacing, and angle between filaments. However, it is difficult to generate complex 3D gradient matters owing to the inherent limitations of existing methods in terms of available gradient dimension, gradient resolution, and shape fidelity. Here, we report a filament diameter-adjustable 3D printing strategy that enables conventional extrusion 3D printers to produce 1D, 2D, and 3D gradient matters with tunable heterogeneous structures by continuously varying the volume of deposited ink on the printing trajectory. In detail, we develop diameter-programmable filaments by customizing the printing velocity and height. To achieve high shape fidelity, we specially add supporting layers at needed locations. Finally, we showcase multi-disciplinary applications of our strategy in creating horizontal, radial, and axial gradient structures, letter-embedded structures, metastructures, tissue-mimicking scaffolds, flexible electronics, and time-driven devices. By showing the potential of this strategy, we anticipate that it could be easily extended to a variety of filament-based additive manufacturing technologies and facilitate the development of functionally graded structures. Direct ink writing of complex 3D gradient structures can be challenging due to inherent method limitations. Here, the authors report continuous diameter-adjustable filament by varying printing speed and height and enable extrusion 3D printers to produce complex gradient porous matters. [ABSTRACT FROM AUTHOR]

Microneedle patches are emerging multifunctional platforms for transdermal diagnostics and drug delivery. However, it still remains challenging to develop smart microneedles integrated with customization, sensing, detection and drug delivery by 3D printing strategy. Here, we present an innovative but facile strategy to rationally design and fabricate multifunctional eutectogel microneedle (EMN) patches via multi-material 3D printing. Polymerizable deep eutectic solvents (PDES) were selected as printing inks for rapid one-step fabrication of 3D printing functional EMN patches due to fast photopolymerization rate and ultrahigh drug solubility. Moreover, stretchable EMN patches incorporating rigid needles and flexible backing layers were easily realized by changing PDES compositions of multi-material 3D printing. Meanwhile, we developed multifunctional smart multi-material EMN patches capable of performing wireless monitoring of body movements, painless colorimetric glucose detection, and controlled transdermal drug delivery. Thus, such multi-material EMN system could provide an effective platform for the painless diagnosis, detection, and therapy of a variety of diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

This study explored the development of polyvinylpyrrolidone (PVP)–honey-gel (PHG) through 3D printing, aiming to develop a multifunctional bio-tape with adhesive and degradable properties. Based on the potential of honey to promote wound healing due to its antibacterial and anti-inflammatory properties, a PVP–honey-based 3D printing ink was developed by combining honey and PVP to create PHG through 3D printing technology that can form a film with strong adhesion and flexibility. First, the chemical–physical properties of PHG and its 3D printing performance were characterized. The line width achievable in 3D printing for the PHG line can extend to ∼100 µm. In addition, the adhesive properties of the PHG film were evaluated by using a 180° peeling test on various materials (glass, copper, wood, and pig skin), highlighting its potential for diverse applications. Finally, the application of the PHG film as a bio-tape was demonstrated through a successful animal experiment on a rabbit's skin wound. Due to its adhesive and degradable properties, the bio-tape exhibited 3D conformability and ease of removal without residue. [ABSTRACT FROM AUTHOR]

Three-dimensional printing provides more versatility in the fabrication of scaffold materials for hard and soft tissue replacement, but a critical component is the ink. The ink solution should be biocompatible, stable, and able to maintain scaffold shape, size, and function once printed. This paper describes the development of a collagen ink that remains in a liquid pre-fibrillized state prior to printing. The liquid stability occurs due to the incorporation of ethylenediaminetetraacetic acid (EDTA) during dialysis of the collagen. Collagen inks were 3D-printed using two different printers. The resulting scaffolds were further processed using two different chemical crosslinkers, 1-Ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride)/N-hydroxysuccinimide (EDC/NHS) and genipin; gold nanoparticles were conjugated to the scaffolds. The 3D-printed scaffolds were characterized to determine their extrudability, stability, amount of AuNP conjugated, and overall biocompatibility via cell culture studies using fibroblast cells and stroma cells. The results demonstrated that the liquid collagen ink was amendable to 3D printing and was able to maintain its 3D shape. The scaffolds could be conjugated with gold nanoparticles and demonstrated enhanced biocompatibility. It was concluded that the liquid collagen ink is a good candidate material for the 3D printing of tissue scaffolds. [ABSTRACT FROM AUTHOR]

The application of 3D printing to calcium phosphates has opened unprecedented possibilities for the fabrication of personalized bone grafts. However, their biocompatibility and bioactivity are counterbalanced by their high brittleness. In this work we aim at overcoming this problem by developing a self-hardening ink containing reactive ceramic particles in a polycaprolactone solution instead of the traditional approach that use hydrogels as binders. The presence of polycaprolactone preserved the printability of the ink and was compatible with the hydrolysis-based hardening process, despite the absence of water in the ink and its hydrophobicity. The microstructure evolved from a continuous polymeric phase with loose ceramic particles to a continuous network of hydroxyapatite nanocrystals intertwined with the polymer, in a configuration radically different from the polymer/ceramic composites obtained by fused deposition modelling. This resulted in the evolution from a ductile behavior, dominated by the polymer, to a stiffer behavior as the ceramic phase reacted. The polycaprolactone binder provides two highly relevant benefits compared to hydrogel-based inks. First, the handleability and elasticity of the as-printed scaffolds, together with the proven possibility of eliminating the solvent, opens the door to implanting the scaffolds freshly printed once lyophilized, while in a ductile state, and the hardening process to take place inside the body, as in the case of calcium phosphate cements. Second, even with a hydroxyapatite content of more than 92 wt.%, the flexural strength and toughness of the scaffolds after hardening are twice and five times those of the all-ceramic scaffolds obtained with the hydrogel-based inks, respectively. Overcoming the brittleness of ceramic scaffolds would extend the applicability of synthetic bone grafts to high load-bearing situations. In this work we developed a 3D printing ink by replacing the conventional hydrogel binder with a water-free polycaprolactone solution. The presence of polycaprolactone not only enhanced significantly the strength and toughness of the scaffolds while keeping the proportion of bioactive ceramic phase larger than 90 wt.%, but it also conferred flexibility and manipulability to the as-printed scaffolds. Since they are able to harden upon contact with water under physiological conditions, this opens up the possibility of implanting them immediately after printing, while they are still in a ductile state, with clear advantages for fixation and press-fit in the bone defect. [Display omitted] [ABSTRACT FROM AUTHOR]

Although significant progress has been made in coaxial printing of vascularized tissue models, this technique has not yet been used to fabricate stimulus‐responsive scaffolds capable of shape change over time. Here, a new method of direct ink printing (DIP) is proposed with a coaxial nozzle, coaxial 4D printing, enabling the manufacturing of thermoresponsive constructs embedded with a network of interconnected channels. In this approach, a poly(N‐isopropylacrylamide) (PNIPAAm)‐based thermoink is coaxially extruded into either core/sheath microfibers or microtubes. PNIPAAm renders a hydrogel temperature‐sensitive and endows it with a shape‐morphing property both at the micro‐ and macroscale. Specifically, the lumen diameter of the microtubes can be controlled by temperature by 30%. The macrostructural soft actuators can undergo programmed and reversible temperature‐dependent shape changes due to the structural anisotropy of the hydrogel. The permeability tests demonstrate that the hydrogel can possess enough strength to maintain the hollow channels without breaking. In vitro tests confirm the biocompatibility of the material with EA.hy926 cells, paving the avenue for new perfusable soft robots, or active implants. Finally, microalgae Chlamydomonas reinhardtii is combined with the hydrogels to fabricate materials having functions of both living microorganisms and stimuli‐responsive polymers toward creating engineered living materials (ELMs) with a vein‐like geometry. [ABSTRACT FROM AUTHOR]

Three‐dimensional (3D) printing via vat photopolymerization is transforming the manufacturing paradigms of biomedical devices, offering tremendous advantages for the production of customized advanced drug delivery systems. However, the existing commercial inks often lack the ability to simultaneously provide elasticity, strength, and biodegradability. Herein, photopolymerizable inks based on poly(β‐aminoester) diacrylates and N‐vinyl pyrrolidone are used to address these limitations. These biodegradable polymers enable the digital light processing 3D printing of elastomers with adjustable elongation at break (103–762%), stress at failure (0.2–8.3 MPa), and hydrolysis rates ranging from 25 min to 80 days. The authors are able to synthesize a soft polymer that possess properties akin to natural latex, which can enhance its elastic modulus when subjected to high strains. It can withstand 762% stretch with a maximum strength of 8.3 MPa. In addition, this polymer demonstrates cytocompatibility and unique biodegradation properties under simulated gastrointestinal conditions (within hours at pH 6.8). By utilizing this elastomer, a prototype of an expandable oral drug delivery device that has the ability to degrade within the average transit time in the jejunum is manufactured. This study paves the way to leverage vat photopolymerization 3D printing in the creation of complex prototypes of biomedical devices where strength, elasticity and biodegradability are essential. [ABSTRACT FROM AUTHOR]

Congenital and acquired valvular heart diseases (VHDs) are significant causes of mortality worldwide. With valve replacement being the primary solution for VHD, current options display shortcomings, including calcification, thrombogenicity, and hemodynamic alteration, leading to repetitive surgeries. Tissue engineering, however, has shown great potential for fabricating heart valves (HVs) with fewer complications. Here, a series of inks are developed, combining poly(vinyl alcohol), gelatin, and carrageenan for 3D printing of tissue‐engineered heart valves (TEHVs). The inks/hydrogels are investigated to characterize their physico‐chemical, morphological, mechanical, and rheological characteristics. In vitro and in vivo biocompatibility, immune response, hemolysis, and thrombogenicity of the inks/hydrogels are also evaluated. Moreover, in vitro hydrodynamics of the TEHVs under physiological conditions are reported. Inks demonstrate mechanical characteristics comparable to native leaflets. Subcutaneous implantation reveals that the hydrogels do not induce chronic inflammation and can undergo remodeling. In vitro hemocompatibility assessments of the hydrogels show minimal hemolysis with low thrombogenicity. Different sizes and types of HVs are successfully printed with high fidelity in the air. In vitro hydrodynamic assessment confirms that the TEHVs can withstand aortic conditions. Altogether, the 3D‐printed TEHVs can be a promising alternative for valve replacement to solve the problems associated with the current options. [ABSTRACT FROM AUTHOR]

Viscoelastic properties of 3D printable peanut‐based food ink were investigated using frequency sweep and relaxation test. The incorporation of xanthan gum (XG) improved the shear thinning behavior (n value ranging from 0.139 to 0.261) and lowered the η*, G′, and G′′ values, thus making food ink 3D printable. The addition of XG also caused a downward shift in the relaxation curve. This study evaluates the possibility of an artificial neural network (ANN) approach as a substitute for the Maxwell three‐element and Peleg model for predicting the viscoelastic behavior of food ink. The results revealed that all three models accurately predicted the decay forces. The inclusion of XG decreased the hardness and enhanced the cohesiveness, so enabling the 3D printing of food ink. The hardness was highly positively correlated with Maxwell model parameters Fe, F1, F2, F3, and Peleg constant k2 (0.57) and negatively correlated with k1 (−0.76). [ABSTRACT FROM AUTHOR]

3D printing is particularly important to take adequate advantage of emerging processing technologies and food ingre-dients. This paper introduced the structural characteristics of plant-based nanocellulose and its functional properties com-patible with 3D printing, including high mechanical strength, convenient surface modification, suitability for printing rhe- ological properties, and favorable biosafety, analyzed the properties and uses of both types of two types of plant-based nanocellulose printing inks, hydrogels and emulsions, summarized its application status in food additives, food packaging, food freshness indicators, functional substance carrier, provided an outlook for the future of preparing emerging functional foods and smart food packaging, and made a prospect in order to provide a referential for future development. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) printing has attracted more attention in food industry because of its potential advantages, including the ability to create customized products according to individual's sensory or nutritional requirements. However, the production of high-quality 3D printed foods requires the availability of edible bio-inks with the required physicochemical and sensory attributes. Starch, as one of the important sources of dietary energy, is widely used in food processing and is considered as one kind of versatile polymers. It is not only because starch has low prices and abundant sources, but also because desirable modified starch can be obtained by altering its physicochemical properties through physical, chemical and enzymatic methods. This article focuses on the utilization of starch as materials to create food-grade bio-inks. Initially, several kinds of commonly used 3D printers are discussed. The factors affecting the printing quality of starch-based materials and improvement methods are then reviewed, as well as areas where future researches are required. The applications of 3D printed starch-based materials in food industry are also introduced. Overall, starch appears to be one kind of useful substances for creating edible bio-inks that can be utilized within 3D food printing applications to create a wide variety of food products. [ABSTRACT FROM AUTHOR]

Protein‐stabilized high internal phase emulsions (HIPEs), which are pseudoplastic fluids with shear thinning and high viscoelasticity, are suitable for 3D printing inks. However, owing to the lack of a universal approach to the 3D printing of HIPEs, existing printing materials are unable to meet the developmental, biocompatibility, and safety requirements of various applications. Herein, it is demonstrated that post‐acidification of protein HIPEs enhances 3D printing performance. This method has the advantage of breaking through protein limitations, pH, and other environmental factors. The self‐supporting property required for 3D printing is achieved through the self‐assembly of continuous‐phase proteins into particle aggregates, and interfacial stability is maintained owing to the constant interfacial tension and contact angle. The acid‐induced protein aggregates in the continuous phase do not affect the stability of the modified HIPEs. This work provides a valuable new idea for advancing the application of protein HIPEs in 3D printing through a post‐acidification strategy. [ABSTRACT FROM AUTHOR]

Vegetables are healthy foods with nutritional benefits; however, nearly one‐third of the world's vegetables are lost each year, and some of the losses happen due to the imperfect shape of the vegetables. In this study, imperfect vegetables (i.e., broccoli and carrots) were upcycled into freeze‐dried powders to improve their shelf‐life before they were formed into food inks for 3D printing. The rheology of the food inks, color analysis of the uncooked and cooked designs, and texture analysis of the cooked designs were determined. The inks with 50% and 75% vegetables provided the best printability and shape fidelity. 3D printing at these conditions retained a volume comparable to the digital file (14.4 and 14.3 cm3 vs. 14.6 cm3, respectively). The control, a wheat flour‐based formulation, showed the lowest level of stability after 3D printing. The viscosity results showed that all the food inks displayed shear‐thinning behavior, with broccoli having the greatest effect on viscosity. There was a significant color difference between uncooked and cooked samples, as well as between different formulations. The hardness of the baked 3D‐printed samples was affected by the type and content of vegetable powders, where carrot‐based snacks were notably harder than snacks containing broccoli. Overall, the results show that 3D food printing can be potentially used to reduce the loss and waste of imperfect vegetables. [ABSTRACT FROM AUTHOR]

While the human body has many different examples of perfusable structures with complex geometries, biofabrication methods to replicate this complexity are still lacking. Specifically, the fabrication of self‐supporting, branched networks with multiple channel diameters is particularly challenging. Herein, the Gelation of Uniform Interfacial Diffusant in Embedded 3D Printing (GUIDE‐3DP) approach for constructing perfusable networks of interconnected channels with precise control over branching geometries and vessel sizes is presented. To achieve user‐specified channel dimensions, this technique leverages the predictable diffusion of cross‐linking reaction‐initiators released from sacrificial inks printed within a hydrogel precursor. The versatility of GUIDE‐3DP to be adapted for use with diverse physicochemical cross‐linking mechanisms is demonstrated by designing seven printable material systems. Importantly, GUIDE‐3DP allows for the independent tunability of both the inner and outer diameters of the printed channels and the ability to fabricate seamless junctions at branch points. This 3D bioprinting platform is uniquely suited for fabricating lumenized structures with complex shapes characteristic of multiple hollow vessels throughout the body. As an exemplary application, the fabrication of vasculature‐like networks lined with endothelial cells is demonstrated. GUIDE‐3DP represents an important advance toward the fabrication of self‐supporting, physiologically relevant networks with intricate and perfusable geometries. [ABSTRACT FROM AUTHOR]

Due to excellent biocompatibility, sufficient raw material, robust mechanical properties and easy cross‐linking, Silk Fibroin (SF) is a promising protein for 3D printing inks and an ideal candidate for 3D scaffolds in fields like regenerative medicine, bioelectronics and bio‐optics. In order to meet the requirements of print accuracy, mechanical properties and form retention capabilities, the first step is to prepare SF 3D printing inks using physical, chemical or other strategies of cross‐linking. The basic chemical groups and physical structure of SF determines its ability to form 3D networks under different conditions using various cross‐linking strategies. In the preparation of SF‐based 3D printing inks, physical, chemical or other strategies of cross‐linking improve the qualities of printing, but each strategy has its advantages and disadvantages. This paper discusses different crosslinking strategies for SF to support the development of exciting potential for SF‐based 3D printing inks to meet more needs in the future. [ABSTRACT FROM AUTHOR]

Mimicking the native properties and architecture of natural bone is a remaining challenge within the field of regenerative medicine. Due to the chemical similarity of calcium phosphate cements (CPCs) to bone mineral, these cements are well studied as potential bone replacement material. Nevertheless, the processing and handling of CPCs into prefabricated pastes with adequate properties for 3D printing has drawbacks due to slow reaction times, limited design freedom, as well as fabrication issues such as filter pressing during ejection through thin nozzles. Herein, an aqueous cement paste containing α‐tricalcium phosphate powder is proposed, which is stabilized by sodium pyrophosphate (Na4P2O7·10H2O) as additive. Since high powder loadings within pastes can result in filter pressing during extrusion, various concentrations and molecular weights of hyaluronic acid (HyAc) are added to the cement paste, resulting in reduced filter pressing during 3D extrusion‐based printing. These cement pastes are investigated regarding their setting reaction after activation with orthophosphate solution by isothermal calorimetry and X‐ray diffraction, as well as their hardening performance using Imeter measurements, while the processability is assessed by extrusion through 1.2 and 0.8 mm cannulas. The 3D‐printed structures with appropriate HyAc molecular weight and concentration demonstrate suitable mechanical properties and resolution for clinical application. [ABSTRACT FROM AUTHOR]

Different statistical approaches were used to analyze the rheological properties of a rice-protein-based product before and after printing. The printing ink was composed of 30% rice protein and 70% water, with the addition of 0.5% xanthan gum. Printing parameters: The layer height (1 and 1.5 mm), printing speed (50 and 35 mm/s), and nozzle diameter (1.2 and 1.7 mm) were evaluated. Rheological properties were determined before and after printing using an oscillatory test from 0.1 to 10 Hz at 1 Pa. The decomposition of the curves into principal components helped us better understand the variations of the rheological properties along the frequency, differentiating the samples before and after printing. [ABSTRACT FROM AUTHOR]

This report presents an additive manufacturing approach, for the first time, to producing high-entropy oxides (HEOs) using a 3D extrusion-based technique with oxide precursors. The precursors were prepared by a wet chemical method from sulfates. Additives were utilized to optimize the rheological properties of the printing inks with these precursors, and the properties of the printed HEOs were improved by increasing the solid content of the inks. When ink with a solid content of 78 wt% was used for printing, the resulting HEO exhibited a relative density of 92% and a high dielectric constant after undergoing pressureless sintering at 800 °C. Compared to traditional methods of manufacturing HEOs, the 3D extrusion technique is a very promising method for producing HEOs with complex geometries. [ABSTRACT FROM AUTHOR]

The current high production of plastics has prompted the exploration of alternative pathways to facilitate recycling, aiming for a progressively sustainable society. This paper presents an alternative and affordable technology for treating waste expanded polystyrene (EPS) mixed with acetone in a 100:1 volume ratio to be used as 3D printing ink for Direct Ink Write technology. In order to optimize the printing parameters, a comprehensive study was conducted, evaluating different needle diameters, printing speeds, and bed temperature values to achieve homogenous pieces and a highly repeatable 3D printing process. Results showed that the main optimum printing parameters were using needles with diameters of 14 to 16 G and printing speeds ranging from 2 to 12 mm/s, which were found to yield the most uniform ribbons. Increasing the bed temperature, despite favoring acetone evaporation, led to the generation of more heterogeneous structures due to void growth inside the printed ribbons. Thus, employing room temperature for the bed proved to be the optimal value. Lastly, a comparative study between the starting material and the EPS after the printing process was conducted using FTIR-ATR and GPC analyses, ensuring the preservation of the original polymer's integrity during physical recycling. [ABSTRACT FROM AUTHOR]

Critical-size bone defects of complex geometries are challenging to repair, making current approaches less satisfactory. Although calcium silicate (CaS) scaffolds prepared using 3D printing can be promising, these scaffolds are commonly treated with harsh conditions to reinforce their strength, significantly affecting the activity of biomolecules in the scaffolds. In this study, we developed a novel CaS biomaterial ink that did not require harsh post-treatments. It is shown that the printability was significantly improved using polyethylene glycol (PEG) and pluronic F-127 (PF), and the scaffolds showed excellent shape fidelity after printing. Moreover, the scaffolds demonstrated compatible mechanical strength with trabecular bone (∼7.07 MPa vs. 0.6 ∼ 16.8 MPa), and adding teriparatide (TP) in scaffolds could further improve the scaffold's potential for bone tissue engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

The nanoparticle (NP) exhibits numerous distinctive and extraordinary properties than micron level and up. The inclusion of NP effects in the rheological and densification behavior of extrusion-based (direct ink writing (DIW)) inks has been extensively investigated. The aqueous-based alumina-silica inks were first designed using waste rice husk ash (RHA) derived nano-silica (NS) (0–10 wt%) and found that the solid-to-liquid ratio reduces continuously with NS addition for printable rheology. For functionalization of NS, dispersant requirement is increased that improve the solids loading of inks. Second, the optimized inks are printed via DIW technique and sintered at a temperature of 1400–1650 °C. The NS has remarkably enhanced the shrinkage, density, and morphology of sintered DIW specimens and 7.5 wt% RHA NS reduces the sintering temperature ∼150 °C. Incorporating NP in the 3D printing ink is a clean approach to filling pores generated by binder-burnout and fabricating a dense ceramic at a low temperature. [Display omitted] • Printable direct ink writing ink is designed using waste derived nanoparticle (NP). • Solids volume fractions need to reduce for develop a printable ink with NP. • Dispersant need increases for functionalization of ink particles with NP. • NP contributes a faster sintering rate and reduces the sintering temperature. • NP enables to develop of a 3D printed dense ceramic at a low temperature. [ABSTRACT FROM AUTHOR]

A hydrogel system with the ability to control the delivery of multiple drugs has gained increasing interest for localized disease treatment and tissue engineering applications. In this study, a triple-drug-loaded model based on a core/shell fiber system (CFS) was fabricated through the co-axial 3D printing of hydrogel inks. A CFS with drug 1 loaded in the core, drug 2 in the shell part, and drug 3 in the hollow channel of the CFS was printed on a rotating collector using a co-axial nozzle. Doxorubicin (DOX), as the model drug, was selected to load in the core, with the shell and channel part of the CFS represented as drugs 1, 2, and 3, respectively. Drug 2 achieved the fastest release, while drug 3 showed the slowest release, which indicated that the three types of drugs printed on the CFS spatially can achieve sequential triple-drug release. Moreover, the release rate and sustained duration of each drug could be controlled by the unique core/shell helical structure, the concentration of alginate gels, the cross-linking density, the size and number of the open orifices in the fibers, and the CFS. Additionally, a near-infrared (NIR) laser or pH-responsive drug release could also be realized by introducing photo-thermal materials or a pH-sensitive polymer into this system. Finally, the drug-loaded system showed effective localized cancer therapy in vitro and in vivo. Therefore, this prepared CFS showed the potential application for disease treatment and tissue engineering by sequential- or stimulus-responsively releasing multi-drugs. [ABSTRACT FROM AUTHOR]

Three-dimensional food printing is an inchoate industry with enormous potential for raising customized food. It offers many advantages as it allows the formulation of complex geometries and permits personalized nutrition to meet special dietary needs without much altering the taste preferences and widens the use of available food sources. A keen surge in this technology has opened the doors to better value addition by supplementing existing processes with 3D food printing and utilizing non-traditional food source for 3D ink formulations. A good understanding of the different properties of ingredients for formulation of 3D ink is necessary to better understand the behavior and properties of the ink system directly affecting the quality of the final printed product. The research and development in the field of ink formulation utilizing non-traditional food ingredients (plant and algae based) is of paramount relevance. In the present article, we review the recent advancements in plant- and algae-based functional ingredients (non-traditional food sources), either added in small amounts or utilized as base material for application in 3D ink formulations. This review spotlights the new ingredients, their physiological function, and impact upon addition on rheological, structural, and printing characteristics of the product. 3D food printing with its application to deliver customized food and personalized nutrition has proven outstanding. Highlighting the advancements in the area of edible ink ingredients and summarizing the existing studies will build the foundation for future studies. [ABSTRACT FROM AUTHOR]

Efficient heat dissipation is vital for advancing device integration and high-frequency performance. Three-dimensional printing, famous for its convenience and structural controllability, facilitates complex parts with high thermal conductivity. Despite this, few studies have considered the influence of shear rate on the thermal conductivity of printed parts. Herein, polydimethylsiloxane/boron nitride (PDMS/BN) composites were prepared and printed by direct ink writing (DIW). In order to ensure the smooth extrusion of the printing process and the structural stability of the part, a system with 40 wt% BN was selected according to the rheological properties. In addition, the effect of printing speed on the morphology of BN particles during 3D printing was studied by XRD, SEM observation, as well as ANSYS Polyflow simulation. The results demonstrated that increasing the printing speed from 10 mm/s to 120 mm/s altered the orientation angle of BN particles from 78.3° to 35.7°, promoting their alignment along the printing direction due to the high shear rate experienced. The resulting printed parts accordingly exhibited an impressive thermal conductivity of 0.849 W∙m−1∙K−1, higher than the 0.454 W∙m−1∙K−1 of the control sample. This study provides valuable insights and an important reference for future developments in the fabrication of thermal management devices with customizable thermal conductivity. [ABSTRACT FROM AUTHOR]

Conductive hydrogels require tunable mechanical properties, high conductivity and complicated 3D structures for advanced functionality in (bio)applications. Here, we report a straightforward strategy to construct 3D conductive hydrogels by programable printing of aqueous inks rich in poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) inside of oil. In this liquid-in-liquid printing method, assemblies of PEDOT:PSS colloidal particles originating from the aqueous phase and polydimethylsiloxane surfactants from the other form an elastic film at the liquid-liquid interface, allowing trapping of the hydrogel precursor inks in the designed 3D nonequilibrium shapes for subsequent gelation and/or chemical cross-linking. Conductivities up to 301 S m−1 are achieved for a low PEDOT:PSS content of 9 mg mL−1 in two interpenetrating hydrogel networks. The effortless printability enables us to tune the hydrogels' components and mechanical properties, thus facilitating the use of these conductive hydrogels as electromicrofluidic devices and to customize near-field communication (NFC) implantable biochips in the future. Three-dimensional conductive hydrogels have promise in bioelectronics, yet achieving the desired conductivity and mechanical properties in 3D structured hydrogels is challenging. Here, the authors report a liquid-in-liquid 3D printing process for preparation of desirable PEDOT:PSS hydrogels. [ABSTRACT FROM AUTHOR]

3D printing technology can be used to develop individualized medicines in hospitals and pharmacies, allowing a high degree of personalization and the possibility to adjust the dose of the API based on the quantity of material extruded. The main goal of incorporating this technology is to have a stock of API-load print cartridges that could be used at different storage times and for different patients. However, it is necessary to study the extrudability, stability, and buildability of these print cartridges during storage time. A paste-like formulation containing hydrochlorothiazide as a model drug was prepared and distributed in five print cartridges, each of which was studied for different storage times (0 h–72 h) and conditions, for repeated use on different days. For each print cartridge, an extrudability analysis was performed, and subsequently, 100 unit forms of 10 mg hydrochlorothiazide were printed. Finally, various dosage units containing different doses were printed, taking into account the optimized printing parameters based on the results of the extrudability analysis carried out previously. An appropriate methodology for the rapid development of appropriate SSE 3DP inks for pediatrics was established and evaluated. The extrudability analysis and several parameters allowed the detection of changes in the mechanical behavior of the printing inks, the pressure interval of the steady flow, and the selection of the volume of ink to be extruded to obtain each of the required doses. The print cartridges were stable for up to 72 h after processing, and orodispersible printlets containing 6 mg to 24 mg of hydrochlorothiazide can be produced using the same print cartridge and during the same printing process with guaranteed content and chemical stability. The proposed workflow for the development of new printing inks containing APIs will allow the optimization of feedstock material and human resources in pharmacy or hospital pharmacy services, thus speeding up their development and reducing costs. [ABSTRACT FROM AUTHOR]

Light‐driven 3D printing can empower the liberty of creation and concretize the original creation in versatile conditions with plenty of choices in resolution or properties. However, photopolymerization‐based 3D printing inks are facing a trade‐off between requiring processing rate and satisfying performance, and a chemical optimization strategy is proposed to achieve the ink demands of rapid direct ink writing utilizing up‐conversion assisted photopolymerization. Since acylphosphonate can generate two reactive radicals and tertiary amine can reinitiate polymerization in oxygen inhibition, the yielded active species in limited irradiation of 3D printing are maximized to accelerate the polymerization by theoretically and experimentally interpreting the roles of up‐conversion particle, photoinitiators, and co‐initiator played in printing. High print speed in depositing and in situ curing (3.56 × 104 mm3 h−1) are realized, and the manufacturing time is shortened by multi‐resolution printing which is impressive compared to current 3D printing methods. The strategy is simultaneously compatible with rigid and elastomeric materials, and will surely contribute to other light‐driven 3D printing technologies for extensive applications. [ABSTRACT FROM AUTHOR]