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There are numerous studies on the application of soybean whey protein in three-dimensional (3D) printing. In this study, the effects of soybean meal particles (5%, 6%, 7%, 8%, 9%, and 10%) and oil-phase concentrations (70%, 72%, 74%, 76%, and 78%) on the stability and 3D-printing performance of a soybean-meal-based high-internal-phase emulsion were investigated. The results showed that the particle size of the emulsion decreased with increasing soybean meal particle concentration, and that increasing the concentration of the oil phase improved the viscoelasticity of the emulsion. Rheological tests further showed that the higher storage modulus of the emulsion indicated better support and stability. The emulsion with 8% soybean meal-particles and 76% oil-phase concentration exhibited the best printing effect. This study provides an effective solution for the preparation of stabilized high-internal-phase emulsions of soybean meal particles suitable for 3D printing., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The influence of ferulic acid (FA) on rice starch was investigated by incorporating it at various concentrations (0, 2.5, 5, 7.5, and 10 %, w/w, on dry starch basis) and subjecting the resulting composites to hot-extrusion 3D printing (HE-3DP) process. This study examined the effects of FA addition and HE-3DP on the structural, rheological, and physicochemical properties as well as the printability and digestibility of rice starch. The results indicated that adding 0-5 % FA had no significant effect; however, as the amount of FA increased, the printed product edges became less defined, the product's overall stability decreased, and it collapsed. The addition of FA reduced the elasticity and viscosity, making it easier to extrude the composite gel from the nozzle. Moreover, the crystallinity and short-range ordered structure of the HE-3D printed rice starch gel decreased with the addition of FA, resulting in a decrease in the yield stress and an increase in fluidity. Furthermore, the addition of FA reduced the digestibility of the HE-3D-printed rice starch. The findings of this study may be useful for the development of healthier modified starch products by adding bioactive substances and employing the 3D printing technology., Competing Interests: Declaration of competing interest All authors of this manuscript declare that they do not have any conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The aim of this study was to investigate the changes of the microstructural, rheological and printing properties of rice starch-stearic acid (SA) paste during the hot-extrusion 3D printing (HE-3DP). The results showed that starch chains could complex with SA to form V-type crystalline structure and its molecular kinematic behaviors were changed under shear force, and crystalline structure were then embedded and rearranged to constitute an ordered sea-island structure, thus improving the rigidity and dynamic storage modulus of network structure, leading to the increased layer number. Interestingly, with the increase of SA addition, the network structure became weakened and the viscosity decreased which might due to the destroyed continuity and the breaking of entanglement and hydrogen bonding between starch chains, and finally impairing the printing accuracy of objects. Overall, this study provided important information for the application of lipid in the preparation of starch-based food by HE-3DP., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Three-dimensional (3D) bioprinting using biocompatible materials is widely used in the field of tissue engineering and regenerative medicine. However, precise printing of 3D structures is challenging due to weak and uncontrollable mechanical properties of various hydrogels, thus limiting their potential in preclinical and clinical applications. In this study, our goal is to demonstrate the feasibility of precise fabrication of alginate/carrageenan composite scaffolds using extrusion-based 3D bioprinting. At first, the proper concentration of crosslinking agents was determined by the assessment of shear modulus of alginate-based hydrogels. Moreover, alginate/carrageenan composite hydrogels were prepared with different concentrations of carrageenan and used to measure their rheological properties. Based on the assessed viscosities and shear moduli of alginate and alginate/carrageenan hydrogels, printing resolutions in different printing parameters were simulated and presented in the printability maps. In addition, alginate and alginate/carrageenan scaffolds were bioprinted with various printing parameters and used to compare their printability with the simulated results. Also, 3D deposition of both alginate and alginate/carrageenan hydrogels were assessed and compared with each other by continuous monitoring of shape fidelity in 3D structures in ten layers and similar printing resolution. Finally, the cell viability of the 3D alginate/carrageenan composite scaffolds, printed using optimized printing parameters, was evaluated using live/dead staining and confocal fluorescence imaging. Thus, the results in the study show the potential uses of carrageenan for a prospective bioink with remarkable mechanical properties suitable for precise fabrication of 3D hydrogel scaffolds using bioprinting techniques., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In food ink systems in which the particles are dispersed in a hydrocolloid matrix, the source of the particles and the particle content are the main factors affecting the printability and rheological properties of the system. In this study, different contents (10% and 30% w/w) of vegetable (broccoli, spinach, or carrot) powders were added to hydrocolloid matrices with different hydration properties, and their influence on the printability and rheological properties was investigated. At low powder contents (10%), slight differences in the printability and rheological values were observed between the different vegetable sources in all hydrocolloids. When the powder content was increased to 30%, the hydrocolloid with the lowest water hydration capacity, hydroxypropyl methylcellulose, showed the greatest differences in rheology and printability when different vegetable sources were used. Xanthan gum, with its higher water hydration capacity, inhibited the swelling of the particles, thus minimizing the increase in the rheological values at high volume fractions of powder and reducing the differences in printability between different vegetable sources. Confocal laser scanning microscopy analysis of the vegetable inks showed that xanthan gum inhibited swelling of the particles regardless of the vegetable powder source. The mixtures using xanthan gum could be smoothly extruded from the nozzle due to their low extruded hardness (2.96 ± 0.23 to 3.46 ± 0.16 kg), and the resulting objects showed high resolution without collapse over time. PRACTICAL APPLICATION: The powder-based texturization technology introduced in this study provides a standardized method of preparing food ink that can be universally applied to all food materials that can be powdered. In addition, the present invention can be applied to a 3D printing technique in which a powder and a hydrocolloid matrix are independently stored and mixed immediately before printing. This technique can minimize the inherent rheological differences between formulations with different food sources and compositions., (© 2018 Institute of Food Technologists®.)

The SiO 2 -Al 2 O 3 refractories and corresponding inks for 3D printing were prepared from silica glass binder suspensions and fused alumina with grain sizes of 75 and 240 μm. Phase analysis (XRD) and morphological studies (SEM) were conducted to investigate the influence of sintering temperature and Al 2 O 3 content on the strength, porosity, and density of the refractories. Rheological studies (rotational viscometry) were carried out determine the effect of polyethylene glycol (PEG) and hydroxypropyl methylcellulose (HPMC) content on the flow behavior of the inks. It was established that firing refractories based on fused silica and fused alumina at 1500 and 1600 °C led to the formation of mullite and aluminosilicate melt on the surface of Al 2 O 3 grains, enhancing the strength of the synthesized materials. Addition of PEG and HPMC to the ink composition was found to improve their rheological properties by increasing yield strength and promoting plastic flow. The ink demonstrated high printability and they are suitable for producing refractories using the Direct Ink Writing method. [ABSTRACT FROM AUTHOR]

Direct ink writing (DIW), or robocasting, is emerging as a key additive manufacturing technique for ceramic materials. Nevertheless, controlling ink rheology, finding optimal ink properties for printability, and optimising final mechanical performance have consistently posed major challenges. This review addresses these critical aspects of ceramic DIW through a meta-analysis. It encompasses rheological data from various ceramic inks and reviews methods for tuning ink properties to improve printability. The collected rheological properties are integrated into various printability criteria and models, leading to the proposal of an empirical criterion based on two key rheological parameters. Furthermore, the mechanical properties of both dense and porous ceramic components are discussed, revealing their correlations with rheology and processing defects. The objective of this comprehensive work is to serve as a valuable toolkit and guideline, providing researchers with the necessary insights to develop superior ink formulations and enhance the mechanical performance of robocasted ceramic components. [ABSTRACT FROM AUTHOR]

Direct ink writing (DIW) is a promising additive manufacturing technique for fabricating structural ceramics, including alumina-toughened zirconia (ATZ), heavily reliant on the rheological properties of the paste. The rheological properties of aqueous ATZ pastes with 25 wt% Pluronic® F127 hydrogel and solid loadings of 28–44 vol% were investigated, complemented by characterization of the parts, including relative density and shrinkage measurements, to assess the printability. The 42 vol% paste was identified as most suitable for producing high-density parts with minimal shrinkage. A controlled drying process gradually decreased humidity from 90% to 30% while raising temperature from 25 to 60°C over 4 days to prevent drying defects. Mechanical testing showed DIW-printed high-density (97.2±2.2%) parts with a mean flexural strength of 670±270 MPa, Vickers hardness of 13.6±2.8 GPa, and fracture resistance of 4.4±0.2 MPa, highlighting the potential for DIW to create high-density ATZ ceramic parts with favorable mechanical properties. [ABSTRACT FROM AUTHOR]

Thermoplastic polyurethane (TPU) has emerged as extremely benign materials for next-generation manufacturing using additive manufacturing processes due to its favorable mechanical properties, durability, and as well as biocompatibility. However, the lack of stiffness of TPU affects its buckling strength and performance efficiency. Therefore, an efficient method of optimization of a 3D-printable composition of TPU-based blends is necessary. In this work, attempts were made to explore material extrusion additive manufacturing technique of acrylonitrile–butadiene–styrene (ABS)/TPU blends with particular reference to mechanical and damping behaviour. Design of experiment (DoE) was used to determine the optimum printing parameters. Rheological studies were exploited to understand the printability, and optimum 3D-printable blend composition. The damping behaviour of each blend composition was calculated and a damping ratio (ξ) between 1 ≤ ξ ≤ 2 was observed for 40 wt% ABS loading, which raised to 1 ≤ ξ ≤ 4 for 80 wt% ABS loaded blend specimen. Furthermore, for ABS incorporated TPU, a significant enhancement of stiffness over neat TPU was achieved, thereby reasonably addressing the filament stiffness issue. This work introduces an efficient method of improving TPU filament printability while parallelly identifying the printable blend composition which can be beneficial for several potential applications. [ABSTRACT FROM AUTHOR]

Printability and interlayer adhesion are the most critical issues in 3D printing of immiscible polymer blends. It can affect structural integrity and mechanical performance of the printed parts. In this work, an effective strategy to improve the printability and interlayer adhesion of immiscible acrylonitrile‐butadiene‐styrene/polypropylene (ABS/PP) blends was implemented by introducing styrene–ethylene/butylene–styrene copolymer grafted with maleic anhydride (SEBS‐g‐MA) as a compatibilizer. The printability of the developed blends was investigated using rheological properties such as absolute value of complex viscosity, loss tangent and die‐swell ratio. Interestingly, it was found that the additive manufactured blends with 20 wt% SEBS‐g‐MA loading showed improved interlaminar shear strength, impact strength, Young's modulus and toughness as compared with the pure blend. Fractography analysis revealed that two different possible failure mechanisms, interface and matrix failure were apparent in the 3D printed samples with and without SEBS‐g‐MA content. This work provides a promising pathway to fabricate the complex structures from polymer blends with improved mechanical properties and surface finish. Highlights: This study demonstrated improved interlayer adhesion at the printed interface of immiscible ABS/PP blends in presence of SEBS‐g‐MA.The printability of the developed blends was predicted from rheological properties.Additive manufactured blends with SEBS‐g‐MA loading showed improved mechanical performance. [ABSTRACT FROM AUTHOR]

Sustainability and limitations in embedded reinforcement are the main obstacles in digital fabrication with concrete. This study proposed a 3D printable fiber-reinforced calcined clay-limestone-based cementitious material (FR-LC3). The binder systems incorporating calcined clay (CC) and limestone filler (LF) were optimized by determining the flow characteristics and water retention ability of the paste. The effect of fiber volume on the key fresh and mechanical properties of the fiber-reinforced mortars made with the optimized binder was evaluated. A combination of offline assessments and inline printing were employed to investigate the printability of the FR-LC3 with various binder systems and viscosity-modifying admixture (VMA) dosages. The results revealed that the binary system with 20% CC and the ternary system containing 30% CC and 15% LF were highly advantageous, with enhanced packing density, robustness, and water retention ability. Incorporating 2% 6-mm steel fiber contributed to the highest 28-day compressive and flexural strengths and toughness without significantly compromising the fluidity. Finally, the developed FR-LC3 mixtures were successfully printed using an extrusion-based 3D printer. The LF addition in the ternary system decreased the maximum buildable height of a single-wall printed object while reducing the SP/VMA ratio significantly increased the height due to enhanced yield stress and thixotropy. [ABSTRACT FROM AUTHOR]

Three-dimensional extrusion bioprinting technology aims to become a fundamental tool for tissue regeneration using cell-loaded hydrogels. These biomaterials must have highly specific mechanical and biological properties that allow them to generate biosimilar structures by successive layering of material while maintaining cell viability. The rheological properties of hydrogels used as bioinks are critical to their printability. Correct printability of hydrogels allows the replication of biomimetic structures, which are of great use in medicine, tissue engineering and other fields of study that require the three-dimensional replication of different tissues. When bioprinting cell-loaded hydrogels, a small amount of culture medium can be added to ensure adequate survival, which can modify the rheological properties of the hydrogels. GelMA is a hydrogel used in bioprinting, with very interesting properties and rheological parameters that have been studied and defined for its basic formulation. However, the changes that occur in its rheological parameters and therefore in its printability, when it is mixed with the culture medium necessary to house the cells inside, are unknown. Therefore, in this work, a comparative study of GelMA 100% and GelMA in the proportions 3:1 (GelMA 75%) and 1:1 (GelMA 50%) with culture medium was carried out to determine the printability of the gel (using a device of our own invention), its main rheological parameters and its toxicity after the addition of the medium and to observe whether significant differences in cell viability occur. This raises the possibility of its use in regenerative medicine using a 3D extrusion bioprinter. [ABSTRACT FROM AUTHOR]

3D printing is an additive manufacturing technology that locates constructed models with computer-controlled printing equipment. To achieve high-quality printing, the requirements on rheological properties of raw materials are extremely restrictive. Given the special structure and high modifiability under external physicochemical factors, the rheological properties of proteins can be easily adjusted to suitable properties for 3D printing. Although protein has great potential as a printing material, there are many challenges in the actual printing process. This review summarizes the technical considerations for protein-based ink 3Dprinting. The physicochemical factors used to enhance the printing adaptability of protein inks are discussed. The post-processing methods for improving the quality of 3D structures are described, and the application and problems of fourth dimension (4D) printing are illustrated. The prospects of 3D printing in protein manufacturing are presented to support its application in food and cultured meat. The native structure and physicochemical factors of proteins are closely related to their rheological properties, which directly link with their adaptability for 3D printing. Printing parameters include extrusion pressure, printing speed, printing temperature, nozzle diameter, filling mode, and density, which significantly affect the precision and stability of the 3D structure. Post-processing can improve the stability and quality of 3D structures. 4D design can enrich the sensory quality of the structure. 3D-printed protein products can meet consumer needs for nutritional or cultured meat alternatives. [ABSTRACT FROM AUTHOR]

Purpose: In pursuit of affordable and nutrient-rich food alternatives, the symbiotic culture of bacteria and yeast (SCOBY) emerged as a selected food ink for 3D printing. The purpose of this paper is to harness SCOBY's potential to create cost-effective and nourishing food options using the innovative technique of 3D printing. Design/methodology/approach: This work presents a comparative analysis of the printability of SCOBY with blends of wheat flour, with a focus on the optimization of process variables such as printing composition, nozzle height, nozzle diameter, printing speed, extrusion motor speed and extrusion rate. Extensive research was carried out to explore the diverse physical, mechanical and rheological properties of food ink. Findings: Among the ratios tested, SCOBY, with SCOBY:wheat flour ratio at 1:0.33 exhibited the highest precision and layer definition when 3D printed at 50 and 60 mm/s printing speeds, 180 rpm motor speed and 0.8 mm nozzle with a 0.005 cm3/s extrusion rate, with minimum alteration in colour. Originality/value: Food layered manufacturing (FLM) is a novel concept that uses a specialized printer to fabricate edible objects by layering edible materials, such as chocolate, confectionaries and pureed fruits and vegetables. FLM is a disruptive technology that enables the creation of personalized and texture-tailored foods, incorporating desired nutritional values and food quality, using a variety of ingredients and additions. This research highlights the potential of SCOBY as a viable material for 3D food printing applications. [ABSTRACT FROM AUTHOR]

Robocasting stands as a pertinent additive manufacturing technique for producing intricate ceramic parts. Amidst stricter environmental regulations, the adoption of natural additives becomes imperative. This study investigates the influence of plant-based additives on the rheology and printability of eco-friendly pastes.Various 50 vol%-alumina pastes were formulated using natural binders, plasticizers and dispersants (e.g., lignosulfonate, polysaccharides, glycerol) and then assessed through oscillation and flow rheological analyses. Paste viscosity and rigidity often deviated from printability maps reported in the literature, showing the complexity of defining universal printability criteria. A comprehensive investigation was conducted on the water retention capabilities of additives, liquid phase migration and paste drying kinetics.This paper highlights the critical importance of constraining liquid phase migration within eco-friendly ceramic pastes and the crucial role of polymer chain reorientation under shear. Consequently, this research lays diversifying formulations, offering sustainable solutions for industrial ceramic applications.

This study aimed to analyze the printability of corn-based dough during screw-based three-dimensional (3D) food printing (3DFP) by relating its rheological and mechanical properties to its screw-based 3DFP performance, with the objective of providing insights into the utilization of corn-based dough to produce 3D-printed foods. Screw-based 3DFP was performed using seven corn-based doughs with different nixtamalized corn flour (NCF) and water contents. Afterward, their rheological and mechanical properties were analyzed and associated with their screw-based 3DFP performance. The results showed that stable printability was obtained within a specific range of NCF content in the dough (30–32.5 wt%). Below this range, the 3D-printed foods flattened, while above it, the extrudability of the dough was affected. The printability of the dough was influenced by different rheological and mechanical properties, depending on the stage of the screw-based 3DFP process. During the extrusion stage, the loss tangent at nozzle strain, yield stress, apparent viscosity, and adhesiveness mainly affected the extrudability of the dough. In contrast, the loss tangent at minimum strain, elastic modulus, Young's modulus, and hardness influenced the self-supporting stage. Therefore, it is important to find a balance between all of these properties, where stable extrudability and self-supporting of the 3D structure are achieved. [ABSTRACT FROM AUTHOR]

This paper examines how extrusion-based 3D-printing technology is evolving, utilising geopolymers (GPs) as sustainable inorganic aluminosilicate materials. Particularly, the current state of 3D-printing geopolymers is critically examined in this study from the perspectives of the production process, printability need, mix design, early-age material features, and sustainability, with an emphasis on the effects of various elements including the examination of the fresh and hardened properties of 3D-printed geopolymers, depending on the matrix composition, reinforcement type, curing process, and printing configuration. The differences and potential of two-part and one-part geopolymers are also analysed. The applications of advanced printable geopolymer materials and products are highlighted, along with some specific examples. The primary issues, outlooks, and paths for future efforts necessary to advance this technology are identified. [ABSTRACT FROM AUTHOR]

Sustainability and limitations in embedded reinforcement are the main obstacles in digital fabrication with concrete. This study proposed a 3D printable fiber-reinforced calcined clay-limestone-based cementitious material (FR-LC3). The binder systems incorporating calcined clay (CC) and limestone filler (LF) were optimized by determining the flow characteristics and water retention ability of the paste. The effect of fiber volume on the key fresh and mechanical properties of the fiber-reinforced mortars made with the optimized binder was evaluated. A combination of offline assessments and inline printing were employed to investigate the printability of the FR-LC3 with various binder systems and viscosity-modifying admixture (VMA) dosages. The results revealed that the binary system with 20% CC and the ternary system containing 30% CC and 15% LF were highly advantageous, with enhanced packing density, robustness, and water retention ability. Incorporating 2% 6-mm steel fiber contributed to the highest 28-day compressive and flexural strengths and toughness without significantly compromising the fluidity. Finally, the developed FR-LC3 mixtures were successfully printed using an extrusion-based 3D printer. The LF addition in the ternary system decreased the maximum buildable height of a single-wall printed object while reducing the SP/VMA ratio significantly increased the height due to enhanced yield stress and thixotropy.

Using an in situ lunar regolith as a construction material in combination with 3D printing not only reduces the weight of materials carried from the Earth but also improves the automation of lunar infrastructure construction. This study aims to improve the printability of a geopolymer based on a BH-1 lunar regolith simulant, including the extrudability, open time, and buildability, by controlling the temperature and adding admixtures. Rheological parameters were used to represent printability with different water-to-binder ratios, printing temperatures, and contents of additives. The mechanical properties of the hardening geopolymer with different filling paths and loading directions were tested. The results show that heating the printed filaments with a water-to-binder ratio of 0.32 at 80 °C can adjust the printability without adding any additive, which can reduce the construction cost of lunar infrastructure. The printability of the BH-1 geopolymer can also be improved by adding 0.3% Attagel-50 and 0.5% polypropylene fiber by mass at a temperature of 20 °C to cope with the changeable environmental conditions on the Moon. After curing under a simulated lunar environment, the 72-h flexural and compressive strengths of the geopolymer specimens reach 4.1 and 48.1 MPa, respectively, which are promising considering that the acceleration of gravity on the Moon is 1/6 of that on the Earth. [ABSTRACT FROM AUTHOR]

The production of scaffolds for bone tissue applications is requiring a combination of physical and biological properties, which are depending on the materials morphology and pro-cessing conditions during the production process. The aim of the paper is the investigation of rheological behaviour of polymer and composite blends regularly used for the production of scaffolds for bone tissue applications with the use of additive manufacturing. Poly-ε-caprolactone (PCL), hydroxyapatite (HA), β-tri-calcium phosphate (TCP) and Bioglass 45S5 blends containing different ceramic concentrations (10 wt%, 15 wt% and 20 wt%) were prepared with the use of melt blending procedure and investigated with the use of oscillation and rotational rheology tests. Results are showing that all blends are presenting viscoelastic behaviour with higher viscous modulus, compared with elastic modulus for low frequencies, with this difference reducing while the frequency is increasing. All blends are presenting shear-thinning behaviour suitable for use with additive manufacturing methods. Viscous and elastic modulus are increasing by adding ceramic particles. Results are presenting that PCL/HA blends of the same material concentration are presenting higher elastic modulus properties compared with the other blends, while PCL/Bioglass blends are presenting lower loss factor, lower relaxation time and lower shear viscosity making them easier to handle during the printing procedure.

Three-dimensional extrusion bioprinting technology aims to become a fundamental tool for tissue regeneration using cell-loaded hydrogels. These biomaterials must have highly specific mechanical and biological properties that allow them to generate biosimilar structures by successive layering of material while maintaining cell viability. The rheological properties of hydrogels used as bioinks are critical to their printability. Correct printability of hydrogels allows the replication of biomimetic structures, which are of great use in medicine, tissue engineering and other fields of study that require the three-dimensional replication of different tissues. When bioprinting cell-loaded hydrogels, a small amount of culture medium can be added to ensure adequate survival, which can modify the rheological properties of the hydrogels. GelMA is a hydrogel used in bioprinting, with very interesting properties and rheological parameters that have been studied and defined for its basic formulation. However, the changes that occur in its rheological parameters and therefore in its printability, when it is mixed with the culture medium necessary to house the cells inside, are unknown. Therefore, in this work, a comparative study of GelMA 100% and GelMA in the proportions 3:1 (GelMA 75%) and 1:1 (GelMA 50%) with culture medium was carried out to determine the printability of the gel (using a device of our own invention), its main rheological parameters and its toxicity after the addition of the medium and to observe whether significant differences in cell viability occur. This raises the possibility of its use in regenerative medicine using a 3D extrusion bioprinter.

Bioinks for cell-based bioprinting face availability limitations. Furthermore, the bioink development process needs comprehensive printability assessment methods and a thorough understanding of rheological factors' influence on printing outcomes. To bridge this gap, our study aimed to investigate the relationship between rheological properties and printing outcomes. We developed a specialized bioink artifact specifically designed to improve the quantification of printability assessment. This bioink artifact adhered to established criteria from extrusion-based bioprinting approaches. Seven hydrogel-based bioinks were selected and tested using the bioink artifact and rheological measurement. Rheological analysis revealed that the high-performing bioinks exhibited notable characteristics such as high storage modulus, low tan(δ), high shear-thinning capabilities, high yield stress, and fast, near-complete recovery abilities. Although rheological data alone cannot fully explain printing outcomes, certain metrics like storage modulus and tan(δ) correlated well (R2 > 0.9) with specific printing outcomes, such as gap-spanning capability and turn accuracy. This study provides a comprehensive examination of bioink shape fidelity across a wide range of bioinks, rheological measures, and printing outcomes. The results highlight the importance of considering the holistic view of bioink's rheological properties and directly measuring printing outcomes. These findings underscore the need to enhance bioink availability and establish standardized methods for assessing printability.

The present study was conducted to manipulate various biomaterials to find potential hydrogel formulations through three-dimensional (3D) bioprinting fabrication for tissue repair, reconstruction, or regeneration. The hydrogels were prepared using sodium alginate and gelatin combined with different concentrations of Pluronic F127 (6% (3 g), 8% (4 g), and 10% (5 g)) and were marked as AGF-6%, AGF-8%, and AGF-10%, respectively. The properties of the hydrogels were investigated using a contact angle goniometer, rheometer, and 3D bioprinter. In addition, the osteoblast-like cell line (MG-63) was used to evaluate the cell viability including hydrogels before and after 3D bioprinting. It was found that the ratio of contact angle was lowest at AGF-6%, and the rheological results were higher for all samples of AGF-6%, AGF-8%, and AGF-10% compared with the control sample. The printability indicated that the AGF-6% hydrogel possessed great potential in creating a cell scaffold with shape integrity. Moreover, the live/dead assay also presented the highest numbers of live cells before printing compared with after printing. However, the number of live cells on day 7 was higher than on day 1 before and after printing (** p < 0.01). Therefore, the combination of AGF-6% could be developed as a biofunctional hydrogel formulation for potential tissue regeneration applications. [ABSTRACT FROM AUTHOR]

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Using high-volume cement in 3D printed concrete (3DPC) can lead to later crack formation. Accordingly, mineral admixtures can be used as cement replacements to mitigate this disadvantage. In this study, fly ash, slag, and a type of silica fume (with a high water consumption) are selected as in 3DPC under different substitution rates. A method for the printability evaluation of each test group in the orthogonal experiment is proposed based on a comprehensive analysis of the rheological behavior and mechanical performance of the test samples. The results indicate that a cement replacement ratio of 50% can be achieved in 3DPC while retaining its rheological behavior and mechanical performance. According to the actual printing test, the selected silica fume improves the buildability of 3DPC and can serve as an economical and effective cement substitute. The findings in this study also reveal the potential application of poor-quality mineral admixtures in 3DPC, which can increase economy and reduce CO2 emissions. [ABSTRACT FROM AUTHOR]

Aronia melanocarpa polyphenols (AMP) have good nutritional values and functions. This study aimed to explore the printability and storage properties of AM gels in 3D food printing (3DFP). Therefore, 3DFP was performed on a loaded AMP gel system to determine its textural properties, rheological properties, microstructure, swelling degree and storage performance. The results revealed that the best loading AMP gel system to meet the printability requirements of 3DFP processing was AM fruit pulp:methylcellulose:pea albumin: hyaluronic acid = 100:14:1:1. Compared with other ratios and before 3DFP processing, the best loading AMP gel system processed by 3DFP exhibited the lowest deviation of 4.19%, the highest hardness, the highest elasticity, the least adhesion, a compact structure, uniform porosity, difficulty in collapsing, good support, a high degree of crosslinking, and good water retention. Additionally, they could be stored for 14 d at 4 °C. After post-processing, the AMP gel had a favorable AMP release rate and good sustained release effect in gastrointestinal digestion, which conformed to the Ritger–Peppas equation model. The results revealed that the gel system had good printability and applicability for 3D printing; as well, 3DFP products had good storage properties. These conclusions provide a theoretical basis for the application of 3D printing using fruit pulp as a raw material. [ABSTRACT FROM AUTHOR]

The food industry is seriously considering 3D printing technology as demand for personalized and customized food is rising. Printability is one of the critical parameters to judge the success of an extrusion-based 3D printing process. The printability evaluation includes an assessment of extrudability, dimensional accuracy, and stability of 3D printed objects using computational fluid dynamics (CFD) modeling and qualitative or quantitative methods. For better printability, food ink should have appropriate rheological properties. Thus, food ink is either added with food additives or subjected to pre- and post-processing treatments to facilitate easier extrusion and better shape stability. Hence, the present paper aims to provide a comprehensive overview of printability assessment methods in extrusion-based 3D printing. The paper also elaborates on the desirable rheological properties and 3D printing parameters for better printability and methods to improve the printability of food ink. Therefore, this review can guide future research targeting improved printability of 3D printed foods. [ABSTRACT FROM AUTHOR]

Currently, there is a shortage of pediatric medicines on the market, and 3D printing technology can more flexibly produce personalized medicines to meet individual needs. The study developed a child-friendly composite gel ink (carrageenan-gelatin), created 3D models by computer-aided design technology, then produced personalized medicines using 3D printing to improve the safety and accuracy of medication for pediatric patients. An in-depth understanding of the printability of different formulations was obtained by analyzing the rheological and textural properties of different gel inks and observing the microstructure of different gel inks, which guided the formulation optimization. Through formulation optimization, the printability and thermal stability of gel ink were improved, and F6 formulation (carrageenan: 0.65%; gelatin: 12%) was selected as the 3D printing inks. Additionally, a personalized dose linear model was established with the F6 formulation for the production of 3D printed personalized tablets. Moreover, the dissolution tests showed that the 3D printed tablets were able to dissolve more than 85% within 30 min and had similar dissolution profiles to the commercially available tablets. This study demonstrates that 3D printing is an effective manufacturing technique that allows for flexible, rapid, and automated production of personalized formulations. [ABSTRACT FROM AUTHOR]

A 3D printing technology is applied to digitally design and manufacture a 3D object by using a laser or an inkjet device controlled by a computer. 3D printing has extremely high requirements for raw materials with appropriate rheological properties that allow it to be extruded and maintain shapes. Starches are suitable for 3D printing due to their particular structural features, which make the gelatinised starch gel viscoelastic, resulting in shear thinning and rapid response to applied shear strain. Although starches have great potential to be used as a printing material, some obstacles must be overcome to realise the practical application of starch in 3D printing. The technical considerations of a starch-based 3D bioprinting product are summarised in this work. The physiochemical modifications and additives used to enhance the printability and nutritional function properties of starch-based printing products are discussed. Future perspectives of starch-based 3D printing are provided to support the promising spectrum that these materials can be used in biomedical research, including drug delivery and biopolymeric materials. The internal structures and composition of starch are highly related to its printing performance, the printing parameters significantly influence the printing stability and quality including the design of nozzle, printing speed, filling rate and printing temperature. Physiochemical modifications and additives effectively improve the printability and nutritional properties of starch inks. The 3D printing technology can customise starch products for personalised control of digestion and nutrition, satisfying the growing consumer and market demand for healthy food. [Display omitted] • Starch as an excellent printing material receives extensive attention and research. • Starch source and printing parameters affect the quality of printed starch product. • Additives effectively improve printability and quality of printed starch products. • Printed starch products can apply in drug delivery and bone and tissue engineering. [ABSTRACT FROM AUTHOR]

Ceramic On-Demand Extrusion (CODE) is a direct ink writing process which allows for the creation of near theoretically dense ceramic components with large cross-sections due to oil-assisted drying. Yttria-stabilized zirconia (YSZ) colloidal pastes (∼d 50 ≲ 1 µm) were used in CODE to produce dense (multi-road infill and ≳ 98% relative density), large continuous volume (> 1 cm3), and high fidelity (nozzle diameters ≲ 1 mm) structural ceramic components. However, many of these printed components underwent significant particle migration after forming. The reason for this particle migration defect was investigated using the coffee-ring effect for dilute solutions and rheological methods for dense suspensions. Modifications to the colloidal paste, such as changes in solids loading, pH, or surfactant concentration were explored as to their effectiveness to mitigate the defect. Ultimately, paste formulation and printing trade-offs are discussed with respect to the post-printing defect and as to general direct-write patterning. [ABSTRACT FROM AUTHOR]

The process of 3D food printing is a rapidly growing field that involves the use of specialized 3D printers to produce food items with complex shapes and textures. This technology allows the creation of customized, nutritionally balanced meals on demand. The objective of this study was to evaluate the effect of apricot pulp content on printability. Additionally, the degradation of bioactive compounds of gels before and after printing was evaluated to analyze the effect of the process. For this proposal, physicochemical properties, extrudability, rheology, image analysis, Texture Profile Analysis (TPA), and bioactive compounds content were evaluated. The rheological parameters lead to higher mechanical strength and, thus, a decrease in elastic behavior before and after 3D printing as the pulp content increases. An increase in strength was observed when the pulp content increased; thus, sample gels with 70% apricot pulp were more rigid and presented better buildability (were more stable in their dimensions). On the other hand, a significant (p < 0.05) degradation of total carotenoid content after printing was observed in all samples. From the results obtained, it can be said that the gel with 70% apricot pulp food ink was the best sample in terms of printability and stability. [ABSTRACT FROM AUTHOR]

This paper examines how extrusion-based 3D-printing technology is evolving, utilising geopolymers (GPs) as sustainable inorganic aluminosilicate materials. Particularly, the current state of 3D-printing geopolymers is critically examined in this study from the perspectives of the production process, printability need, mix design, early-age material features, and sustainability, with an emphasis on the effects of various elements including the examination of the fresh and hardened properties of 3D-printed geopolymers, depending on the matrix composition, reinforcement type, curing process, and printing configuration. The differences and potential of two-part and one-part geopolymers are also analysed. The applications of advanced printable geopolymer materials and products are highlighted, along with some specific examples. The primary issues, outlooks, and paths for future efforts necessary to advance this technology are identified.

Reinforcement of cement-based systems is one of the main unsolved issues for 3D printing technology (3DP). The use of short fibers is a promising way to improve cement-based systems fresh and hardened strength, overcoming this limitation. Among natural fibers, Sisal fibers (SF) can be an excellent option, due to their irregular cross-section morphology, water retention capacity and high Young modulus. In this study, fresh and hardened properties of 3D printable cement-limestone filler mortar reinforced with 1 % volumetric fraction (VF) of 6.5 mm SF and 0.5, 1 and 1.5 % VF of 13 mm SF was assessed. Fresh state mortar rheology was evaluated using flow table test (FT), Self-weight cone-penetration (WCP), Displacement-controlled cone-penetration (DCP) and fresh squeeze tests (SQT). 3DP was evaluated on mortars using a manual extruder and a 3D cartesian robotic printer. Hardened physical and mechanical properties were tested, comparing the effect of 3DP and SF reinforcement on conventional and 3D printed specimens. It was observed that SF slightly modified mortars' rheology and cohesiveness, while SF improved fresh mechanical behavior and enhanced flexural strength and toughness index (I T) on hardened state, due to SF alignment produced by 3DP. Water capillarity and open porosity was also modified by 3DP, due to particle squeezing and fiber´s alignment during extrusion. Higher VF and longer fibers reduced robotic printability and produced discontinuities and pumping blockage, showing limits for SF addition. • Sisal fiber (SF) of 13 and 6.5 mm length were added to 3D printable mortars. • SF increased shear yield stress and mechanical properties in fresh state. • Ram and screw system 3D printing methods were used and in both SF were aligned. • SF and 3D printing process increase apparent density and reduce open porosity. • Aligned SF increased flexural strength and toughness index of 3D printable mortars. [ABSTRACT FROM AUTHOR]

3D-printed concrete technology has recently gained significant attention due to its numerous benefits. The key factors for successful printing and molding include proper printability, which encompasses fluidity, pumpability, and plasticity. An accurate rheological model can offer insights into these changes, playing a critical role in monitoring and predicting concrete behavior and ensuring efficient and orderly construction. This paper presents a novel thixotropic structural dynamics model derived from a detailed analysis of concrete 3D printing flow characteristics. The model describes the elastic deformation of 3D-printed concrete materials using a new elastic strain evolution equation and represents the structural evolution during the flow process with a structural parameter equation. Comparison with experimental results demonstrates that the proposed model accurately captures the flow behavior of 3D-printed concrete materials. Moreover, the associated parameters effectively reflect the evolution of elastic strain and structural changes in line with the physical mechanism. This model not only describes the rheological properties of 3D-printed concrete but also aids in selecting optimal process parameters for 3D printing. • The rheological properties of 3D-printed concrete in the flowing state were studied. • A new rheological model of 3D-printed concrete is proposed. • The rheological results are well described by the model, including stress overshoot. • The obtained in the equations are consistent with the physical mechanism. [ABSTRACT FROM AUTHOR]

Green recycled hybrid powder (RHP) was proved to partly replace cement to prepare 3D printable mortar, which can recycle the demolition waste and reduce carbon emissions. In this study, different contents of RHP and polyethylene fiber (PE fiber) were selected to prepare 3D printable RHP mortar (3DPRM). The initial rheological parameters, including dynamic yield stress, plastic viscosity, static yield stress and thixotropy, as well as the rheological parameters varying with time were investigated. Besides, the early-age hydration of RHP paste was studied to reveal the influence mechanism on rheological properties. The experimental results show that the dynamic yield stress, plastic viscosity and thixotropy as well as their time-varying properties were all increased with RHP replacement. The static yield stress of 3DPRM with 30 % RHP had the most significant enhancement, which was 416.5 % increased after resting for 20 min, showing the great buildability enhancement potential of RHP. The addition of PE fiber (6 mm and 12 mm) increased the rheological parameters of 3DPRM, among which the increase ratio of initial dynamic yield stress was 60 %-195 %. However, the increase ratio with time for dynamic/static yield stress of 3DPRM with PE fiber was lower than that without PE fiber, indicating that PE fiber had great effect on the extrudability but small effect on buildability of 3DPRM. The energy intensity, carbon emission and cost of RHP were 65.27 %, 66.57 % and 12.5 % lower than that of cement, illustrating the sustainable contribution of RHP for construction industry. The results can be used to guide the printability design of 3D printable mortar containing RHP and PE fiber. • Rheology of 3DPRM with various amounts of RHP and PE fiber was investigated. • RHP enhanced the rheological properties and their time varied properties of 3DPRM. • RHP had the greatest enhancement effect on the static yield stress of 3DPRM. • The carbon emission and cost of RHP were 66.6 % and 12.5 % lower than cement. • The initial dynamic yield stress was 60–195 % increased as 6/12 mm PE fibers used. [ABSTRACT FROM AUTHOR]

The printability of concrete mixtures is evaluated for varying aggregate content using binder pastes of different compositions. The inter-relations between the binder paste rheology and the aggregate content are explored for printable concrete mixtures made with pastes of alkali-activated binders and cement. Concrete printability depends on the paste content for coating aggregate and filling spaces between the aggregate. The paste coating thickness around the aggregate under pressurized flow conditions is identified with the boundary layer at the aggregate surface, and it depends on the paste viscosity. Pressurized concrete flow in extrusion-based printing requires excess paste content beyond filling spaces in compacted aggregate with coating layer. There is a linear relationship between the excess paste content in printable concrete mixture and the yield stress of the paste. Printable concrete mixtures made with pastes of higher yield stress require larger excess paste content and accommodate smaller aggregate fractions. [Display omitted] • Pressurized flow of concrete in extrusion requires paste content in excess of the compacted volume of aggregate. • The printability of concrete depends on the excess paste content. • Paste coating of variable thickness is formed around aggregate in the pressurized flow during extrusion. • Excess paste content required for achieving printability depends upon the yield stress of the paste. • Printable concrete mixtures made with FABANS binder pastes accommodate more aggregate than AASF pastes. [ABSTRACT FROM AUTHOR]

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Hydrogel ink formulations based on rheology additives are becoming increasingly popular as they enable 3‐dimensional (3D) printing of non‐printable but biologically relevant materials. Despite the widespread use, a generalized understanding of how these hydrogel formulations become printable is still missing, mainly due to their variety and diversity. Employing an interpretable machine learning approach allows the authors to explain the process of rendering printability through bulk rheological indices, with no bias toward the composition of formulations and the type of rheology additives. Based on an extensive library of rheological data and printability scores for 180 different formulations, 13 critical rheological measures that describe the printability of hydrogel formulations, are identified. Using advanced statistical methods, it is demonstrated that even though unique criteria to predict printability on a global scale are highly unlikely, the accretive and collaborative nature of rheological measures provides a qualitative and physically interpretable guideline for designing new printable materials. [ABSTRACT FROM AUTHOR]

The present study was to investigate the rheological property, printability, and cell viability of alginate–gelatin composed hydrogels as a potential cell-laden bioink for three-dimensional (3D) bioprinting applications. The 2 g of sodium alginate dissolved in 50 mL of phosphate buffered saline solution was mixed with different concentrations (1% (0.5 g), 2% (1 g), 3% (1.5 g), and 4% (2 g)) of gelatin, denoted as GBH-1, GBH-2, GBH-3, and GBH-4, respectively. The properties of the investigated hydrogels were characterized by contact angle goniometer, rheometer, and bioprinter. In addition, the hydrogel with a proper concentration was adopted as a cell-laden bioink to conduct cell viability testing (before and after bioprinting) using Live/Dead assay and immunofluorescence staining with a human corneal fibroblast cell line. The analytical results indicated that the GBH-2 hydrogel exhibited the lowest loss rate of contact angle (28%) and similar rheological performance as compared with other investigated hydrogels and the control group. Printability results also showed that the average wire diameter of the GBH-2 bioink (0.84 ± 0.02 mm (*** p < 0.001)) post-printing was similar to that of the control group (0.79 ± 0.05 mm). Moreover, a cell scaffold could be fabricated from the GBH-2 bioink and retained its shape integrity for 24 h post-printing. For bioprinting evaluation, it demonstrated that the GBH-2 bioink possessed well viability (>70%) of the human corneal fibroblast cell after seven days of printing under an ideal printing parameter combination (0.4 mm of inner diameter needle, 0.8 bar of printing pressure, and 25 °C of printing temperature). Therefore, the present study suggests that the GBH-2 hydrogel could be developed as a potential cell-laden bioink to print a cell scaffold with biocompatibility and structural integrity for soft tissues such as skin, cornea, nerve, and blood vessel regeneration applications. [ABSTRACT FROM AUTHOR]

In this work, the novel bioink composed of alginate and polyethyleneimine were prepared with different concentrations of alginate and polyethyleneimine (PEI) and used to measure printability, rheological behavior, and cellular functions. The results indicated that viscosity tends to increase about 1.3 times with increasing the alginate and PEI content, which gradually affected structural fidelity. The presence of PEI can create a bioink that is partially gelled with higher storage modulus, high shape fidelity, and printability than alginate. Increasing in the mechanical strength and decreasing in the swelling rate for alginate/PEI bioink demonstrated the strong effect of PEI on the enhancing of structure rigidity in the alginate‐based bioinks. Finally, the cell viability and cell proliferation of the 3D alginate/PEI scaffolds were examined using live/dead and 40,6‐diamidino‐2‐phenylindole staining to select the best bioink formulation. Fibroblast‐laden bioink of 6% alginate and 7% PEI indicated the high proliferation of the printed cells via increasing in hydrophilicity of the surface. The in‐vivo evaluations on the wound rat model indicated that the 3D scaffold effectively accelerated the wound healing process and promoted tissue regeneration by activation of vimentin along with cytokeratin as well as collagen synthesis. Hair follicles started to form at Day 7 in alginate/PEI scaffold. [ABSTRACT FROM AUTHOR]

Soy protein isolate (SPI)-based pastes are widely employed for 3D printing of food materials. However, their rheological properties often do not meet the 3D printing requirements. To enhance the 3D printing characteristics of SPI pastes, this study combined SPI with carrageenan and sodium alginate to form composite materials. The effect of polysaccharide type and concentration on the rheological and textural properties of the ink was investigated to elucidate the mechanism of interaction between proteins and polysaccharides. The results demonstrated that the addition of carrageenan (1.5%, wt %) and sodium alginate (1.5%, wt %) effectively improved the mechanical properties of the paste, such as hardness and adhesiveness, enhanced thus the quality of 3D printed products. With the increase of polysaccharide proportion, the apparent viscosity and storage modulus (G′) of the composite paste increased significantly. Fourier-transform infrared spectroscopy (FT-IR), protein solubility measurement, X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were employed and the results revealed notable interactions among SPI and two kinds of polysaccharides, with electrostatic interactions and hydrophobic interactions being the primary driving forces. The addition of polysaccharides induced changes in the paste crystalline state and improved its thermal stability. Scanning electron microscopy (SEM) confirmed a uniform and compact microstructure due to the incorporation of polysaccharides. Consequently, the SPI-polysaccharide paste can be considered as novel material for 3D printing food materials, and the results of this study provides a theoretical foundation for its application in the field of plant-based food products. [Display omitted] • Soy protein isolate-polysaccharides-based inks were prepared with different types and concentrations of polysaccharides for 3D printing. • The storage and loss modulus of composite inks increased by adding sodium alginate and carrageenan. • The addition of carrageenan (1.5%, wt%) and sodium alginate (1.5%, wt%) effectively improved the hardness and adhesiveness of the paste. • Electrostatic and hydrophobic interactions are critical in the SPI-polysaccharide paste. [ABSTRACT FROM AUTHOR]

The process of 3D food printing is a rapidly growing field that involves the use of specialized 3D printers to produce food items with complex shapes and textures. This technology allows the creation of customized, nutritionally balanced meals on demand. The objective of this study was to evaluate the effect of apricot pulp content on printability. Additionally, the degradation of bioactive compounds of gels before and after printing was evaluated to analyze the effect of the process. For this proposal, physicochemical properties, extrudability, rheology, image analysis, Texture Profile Analysis (TPA), and bioactive compounds content were evaluated. The rheological parameters lead to higher mechanical strength and, thus, a decrease in elastic behavior before and after 3D printing as the pulp content increases. An increase in strength was observed when the pulp content increased; thus, sample gels with 70% apricot pulp were more rigid and presented better buildability (were more stable in their dimensions). On the other hand, a significant (p < 0.05) degradation of total carotenoid content after printing was observed in all samples. From the results obtained, it can be said that the gel with 70% apricot pulp food ink was the best sample in terms of printability and stability.

• Ceramic pastes are used for microextrusion based 3D-printing, including colloidal suspensions and hydrogel or organogel based inks. • Direct ink writing imposes stringent requirements on the ink's rheological behaviour. • As applications become more sophisticated, • inks with excellent extrudability and shape fidelity are required. • Often, the development of ink formulations has been based on trial-and-error, overlooking the rheological characterisation. • A thorough rheological characterisation is crucial fora rational design of ceramic inks with enhanced performance. 3D printing is a competitive manufacturing technology, which has opened up new possibilities for the fabrication of complex ceramic structures and customised parts. Extrusion-based technologies, also known as direct ink writing (DIW) or robocasting, are amongst the most used for ceramic materials. In them, the rheological properties of the ink play a crucial role, determining both the extrudability of the paste and the shape fidelity of the printed parts. However, comprehensive rheological studies of printable ceramic inks are scarce and may be difficult to understand for non-specialists. The aim of this review is to provide an overview of the main types of ceramic ink formulations developed for DIW and a detailed description of the more relevant rheological tests for assessing the printability of ceramic pastes. Moreover, the key rheological parameters are identified and linked to printability aspects, including the values reported in the literature for different ink compositions. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF)-reinforced thermoplastic composites have been widely used in different structural applications due to their superior thermal and mechanical properties. The big area additive manufacturing (BAAM) system, developed at Oak Ridge National Laboratory's Manufacturing Demonstration Facility, has been used to manufacture several composite components, demonstration vehicles, molds, and dies. These components have been designed and fabricated using various CF-reinforced thermoplastics. In this study, the dynamic rheological and mechanical properties of a material commonly used in additive manufacturing, 20 wt% CF-acrylonitrile butadiene styrene (ABS), as well as three CF-reinforced high-temperature polymers, 25 wt% CF-polyphenylsulfone (PPSU), 35 wt% CF-polyethersulfone (PES), and 40 wt% CF-polyphenylene sulfide (PPS), used to print molds were investigated. The viscoelastic properties, namely storage modulus, loss modulus, tan delta, and complex viscosity, of these composites were studied, and the rheological behavior was related to the BAAM extrusion and bead formation process. The results showed 20 wt% CF-ABS and 40 wt% CF-PPS to display a more dominant elastic component at all frequencies tested while 25 wt% CF-PPSU and 35 wt% CF-PES have a more dominant viscous component. This viscoelastic behavior is then used to inform the deposition and bead formation process during extrusion on the BAAM system. [ABSTRACT FROM AUTHOR]

In this paper, the effects of attapulgite (ATP) and nano-silica (NS) on printability such as pumpability, rheology, buildability as well as solidified sample strength of a-hemihydrate gypsum plaster for 3D printing were investigated. Results show that the pumping force of plaster with ATP remains at (0.57 ± 0.02) kN. The shear stress against strain rate curve does not change much with ATP addition. The 0 h and 4 h collapse angles of the printed plaster with 2.8% (mass fraction, the same below) ATP decrease from 24° and 32° to 8° and 11°, respectively. In comparison to ATP, the pumping force increases by the addition of NS. The pumping force of the plaster is nearly doubled with 2.8% NS in comparison with the plaster with ATP of the same additive content. Meanwhile, the initial shear stress of the plaster with the increase of NS addition also increases. Although the addition of NS leads to the increase of the pumping force, the buildability of the plaster with NS is better than the plaster with ATP. 0 h and 4 h printed plasters with 2.8% NS both show little slump. The solidified plaster with ATP or NS addition amount 1% to 2% is printable, and its compressive strength is strengthened, but the interlaminar bonding strength is weakened by 2/3 compared with the control sample. [ABSTRACT FROM AUTHOR]

[Display omitted] The trial-and-error method currently used to create formulations with excellent printability demands considerable time and resources, primarily due to the increasing number of variables involved. Rheology serves as a relatively rapid and highly beneficial method for assessing materials and evaluating their effectiveness as 3D constructs. However, the data obtained can be overwhelming, especially for users lacking experience in this field. This study examined the rheological properties of formulations of agar, hydroxypropyl methylcellulose, and the model drug caffeine, alongside exploring their printability as gummy formulations. The gels' rheological properties were characterized using oscillatory and rotational experiments. The correlation between these gels' rheological properties and their printability was established, and three clusters were formed based on the rheological properties and printability of the samples using principal component analysis. Furthermore, the printability was predicted using the sample's rheological property that correlated most with printability, the phase angle δ , and the regression models resulted in an accuracy of over 80 %. Although these relationships merit confirmation in later studies, this study suggests a quantitative definition of the relationship between printability and one rheological property and can be used for the development of formulations destined for extrusion 3D printing. [ABSTRACT FROM AUTHOR]

Gelatin methacrylate (GelMA) bioink has been widely used in bioprinting because it is a printable and biocompatible biomaterial. However, it is difficult to print GelMA bioink without any temperature control because it has a thermally-sensitive rheological property. Therefore, in this study, we developed a temperature-controlled printing system in real time without affecting the viability of the cells encapsulated in the bioink. In addition, a skin-derived decellularized extracellular matrix (SdECM) was printed with GelMA to better mimic the native tissue environment compared with solely using GelMA bioink with the enhancement of structural stability. The temperature setting accuracy was calculated to be 98.58 ± 1.8 % for the module and 99.48 ± 1.33 % for the plate from 5 °C to 37 °C. The group of the temperature of the module at 10 °C and the plate at 20 °C have 93.84 % cell viability with the printable range in the printability window. In particular, the cell viability and proliferation were increased in the encapsulated fibroblasts in the GelMA/SdECM bioink, relative to the GelMA bioink, with a morphology that significantly spread for seven days. The gene expression and growth factors related to skin tissue regeneration were relatively upregulated with SdECM components. In the bioprinting process, the rheological properties of the GelMA/SdECM bioink were successfully adjusted in real time to increase printability, and the native skin tissue mimicked components providing tissue-specific biofunctions to the encapsulated cells. The developed bioprinting strategies and bioinks could support future studies related to the skin tissue reconstruction, regeneration, and other medical applications using the bioprinting process. [Display omitted] [ABSTRACT FROM AUTHOR]