3D Macrostructures Research Articles

From Spheroids to Bioprinting: A Literature Review on Biomanufacturing Strategies of 3D In Vitro Osteosarcoma Models

AbstractOsteosarcoma (OS) is a rare primary malignant bone cancer affecting mainly young individuals. Treatment typically consists of chemotherapy and surgical tumor resection, which has undergone few improvements since the 1970s. This therapeutic approach encounters several limitations attributed to the tumor's inherent chemoresistance, marked heterogeneity and metastatic potential. Therefore, the development of in vitro platforms that closely mimic the OS pathophysiology is crucial to understand tumor progression and discover effective anticancer therapeutics. Contrary to 2D monolayer cultures and animal models, 3D in vitro platforms show promise in replicating the 3D tumor macrostructure, cell‐cell and cell‐extracellular matrix interactions. This review provides an overview of the biomanufacturing strategies employed in developing 3D in vitro OS models, highlighting their role in replicating different aspects of OS and improving OS anticancer research and drug screening. A variety of 3D in vitro models are explored, including both scaffold‐free and scaffold‐based models, encompassing cell spheroids, hydrogels, and innovative approaches like electrospun nanofibers, microfluidic devices and bioprinted constructs. By examining the distinctive features of each model type, this review offers insights into their potential transformative impact on the landscape of OS research and therapeutic innovation, addressing the challenges and future directions of 3D in vitro OS modeling.

Dimensional crossover of microscopic magnetic metasurfaces for magnetic field amplification

Transformation optics applied to low frequency magnetic systems have been recently implemented to design magnetic field concentrators and cloaks with superior performance. Although this achievement has been amply demonstrated theoretically and experimentally in bulk 3D macrostructures, the performance of these devices at low dimensions remains an open question. In this work, we numerically investigate the non-monotonic evolution of the gain of a magnetic metamaterial field concentrator as the axial dimension is progressively shrunk. In particular, we show that in planar structures, the role played by the diamagnetic components becomes negligible, whereas the paramagnetic elements increase their magnetic field channeling efficiency. This is further demonstrated experimentally by tracking the gain of superconductor-ferromagnet concentrators through the superconducting transition. Interestingly, for thicknesses where the diamagnetic petals play an important role in the concentration gain, they also help to reduce the stray field of the concentrator, thus limiting the perturbation of the external field (invisibility). Our findings establish a roadmap and set clear geometrical limits for designing low dimensional magnetic field concentrators.

Deep learning of antibody epitopes using positional permutation vectors

BackgroundThe accurate computational prediction of B cell epitopes can vastly reduce the cost and time required for identifying potential epitope candidates for the design of vaccines and immunodiagnostics. However, current computational tools for B cell epitope prediction perform poorly and are not fit-for-purpose, and there remains enormous room for improvement and the need for superior prediction strategies. ResultsHere we propose a novel approach that improves B cell epitope prediction by encoding epitopes as binary positional permutation vectors that represent the position and structural properties of the amino acids within a protein antigen sequence that interact with an antibody. This approach supersedes the traditional method of defining epitopes as scores per amino acid on a protein sequence, where each score reflects each amino acids predicted probability of partaking in a B cell epitope antibody interaction. In addition to defining epitopes as binary positional permutation vectors, the approach also uses the 3D macrostructure features of the unbound protein structures, and in turn uses these features to train another deep learning model on the corresponding antibody-bound protein 3D structures. This enables the algorithm to learn the key structural and physiochemical features of the unbound protein and embedded epitope that initiate the antibody binding process helping to eliminate “induced fit” biases in the training data. We demonstrate that the strategy predicts B cell epitopes with improved accuracy compared to the existing tools. Additionally, we show that this approach reliably identifies the majority of experimentally verified epitopes on the spike protein of SARS-CoV-2 not seen by the model during training and generalizes in a very robust manner on dissimilar data not seen by the model during training. ConclusionsWith the approach described herein, a primary protein sequence and a query positional permutation vector encoding a putative epitope is sufficient to predict B cell epitopes in a reliable manner, potentially advancing the use of computational prediction of B cell epitopes in biomedical research applications.

Fabrication of 3D Polycaprolactone Macrostructures by 3D Electrospinning.

Building 3D electrospun macrostructures and monitoring the biological activities inside them are challenging. In this study, 3D fibrous polycaprolactone (PCL) macrostructures were successfully fabricated using in-house 3D electrospinning. The main factors supporting the 3D self-assembled nanofiber fabrication are the H3PO4 additives, flow rate, and initial distance. The effects of solution concentration, solvent, H3PO4 concentration, flow rate, initial distance, voltage, and nozzle speed on the 3D macrostructures were examined. The optimal conditions of 4 mL/h flow rate, 4 cm initial nozzle-collector distance, 14 kV voltage, and 1 mm/s nozzle speed provided a rapid buildup of cylinder macrostructures with 6 cm of diameter, reaching a final height of 16.18 ± 2.58 mm and a wall thickness of 3.98 ± 1.01 mm on one perimeter with uniform diameter across different sections (1.40 ± 1.10 μm average). Oxygen plasma treatment with 30-50 W for 5 min significantly improved the hydrophilicity of the PCL macrostructures, proving a suitable scaffold for in vitro cell cultures. Additionally, 3D images obtained by synchrotron radiation X-ray tomographic microscopy (SRXTM) presented cell penetration and cell growth within the scaffolds. This breakthrough in 3D electrospinning surpasses current scaffold fabrication limitations, opening new possibilities in various fields.

γ-AlOOH decorated 3D-reduce graphene oxide: An effective adsorbent for removal of methylene blue and ciprofloxacin

Engineering and synthesis of high-efficiency adsorbent is imperative for water purification. Herein, γ-AlOOH nanoflakes were in-situ decorated onto 3D-reduced graphene oxide (3D-rGO) with the intention of augmenting the specific surface area and ameliorating the adsorption capacity of 3D-rGO in virtue of a facile one-step hydrothermal method. The detailed morphological and structural information of γ-AlOOH/3D-rGO nanocomposite were captured via various instruments. γ-AlOOH/3D-rGO exhibited outstanding removal efficiency towards methylene blue (MB) and ciprofloxacin (CIP) due to its abundant mesopores, increased specific surface area and 3D macro structure. The MB model could well describe the MB adsorption behavior and CIP adsorption process can be fitted by the Elovich model. Isotherm fitting results proclaim that MB adsorption and CIP adsorption followed the Langmuir model; and γ-AlOOH/3D-rGO possessed outstanding adsorption for MB and CIP with the maximum adsorption capacity of 930.0889 mg/g at 288 K and 353.9148 mg/g at 318 K, respectively. The MB and CIP adsorption onto γ-AlOOH/3D-rGO should be the results of the joint action of hydrogen bonds, π-π interaction and complexation. γ-AlOOH/3D-rGO also exhibited excellent reusability after five cycles owing to its 3D macro structure.

Flexible, Biodegradable, and Wireless Magnetoelectric Paper for Simple In Situ Personalization of Bioelectric Implants.

Bioelectronic implants delivering electrical stimulation offer an attractive alternative to traditional pharmaceuticals in electrotherapy. However, achieving simple, rapid, and cost-effective personalization of these implants for customized treatment in unique clinical and physical scenarios presents a substantial challenge. This challenge is further compounded by the need to ensure safety and minimal invasiveness, requiring essential attributes such as flexibility, biocompatibility, lightness, biodegradability, and wireless stimulation capability. Here, a flexible, biodegradable bioelectronic paper with homogeneously distributed wireless stimulation functionality for simple personalization of bioelectronic implants is introduced. The bioelectronic paper synergistically combines i) lead-free magnetoelectric nanoparticles (MENs) that facilitate electrical stimulation in response to external magnetic field and ii) flexible and biodegradable nanofibers (NFs) that enable localization of MENs for high-selectivity stimulation, oxygen/nutrient permeation, cell orientation modulation, and biodegradation rate control. The effectiveness of wireless electrical stimulation in vitro through enhanced neuronal differentiation of neuron-like PC12 cells and the controllability of their microstructural orientation are shown. Also, scalability, design flexibility, and rapid customizability of the bioelectronic paper are shown by creating various 3D macrostructures using simple paper crafting techniques such as cutting and folding. This platform holds promise for simple and rapid personalization of temporary bioelectronic implants for minimally invasive wireless stimulation therapies.

Immobilization of graphene oxide into microbead for fluidized-bed adsorption of methylene blue

Graphene Oxide has shown outstanding performance in the application of adsorption, but these adsorbents are still limited due to some factors. Assembling 2-dimensional (2D) nanomaterials into 3-dimensional (3D) macrostructure (microbead, hydrogel, aerogel, sponge) is a promising alternative to solve the limitation. This paper embedded GO into the two natural polysaccharide polymers (agarose and sodium alginate) to form a 3D-adsorbent. GO-Alg and GO-Agar microbeads were synthesized using the crosslinking method. Analysis techniques such as FT-IR, FESEM-EDX, XRD, and zeta potential were used to characterize the GO-containing microbeads. Adsorption parameters such as adsorbent dosage, pH, contact time, initial ion concentration, and temperature were optimized. Langmuir isotherm and pseudo-first-order kinetic model well fit into the experiment data. The maximum adsorption capacity (qmax) obtained was 120.37 mg.g−1 for removing methylene blue solution. Thermodynamic parameters such as ∆G˚, ∆H˚, and ∆S˚ were determined, and the process was considered endothermic and spontaneous. Reusability results showed good regeneration of GO-Alg microbead up to eight consecutive adsorption-desorption cycles without a significant drop in removal efficiency (> 96%). The application of GO-Alg microbead for MB removal on a packed-bed reactor was investigated in different experimental conditions, and 1 mL.min−1 flow rate with 15 cm bed height revealed a better result. The application of fluidized-bed adsorption was performed to solve the limitation of packed-bed adsorption, and the result showed better adsorption performance than packed-bed using the same operating condition.

Optimal design of 3D macro-structures for multi-layer foams achieving ultra-broadband microwave absorption properties and high retention after immersion in brine

A novel flexible microwave absorbing material (C–MCM–FAS) with a cone-shaped sandwich structure is proposed, which is constructed by carbonyl iron-carbon nanotubes/PDMS foams and SiC–morchella biochar/PDMS film. To enhance broadband absorption properties, a three-level scale design has been creatively introduced into C–MCM–FAS, encompassing millimeter, micron and nano scales. The rational structural parameters of C–MCM–FAS are determined by CST simulation, leading to the preparation of C–MCM–FAS with an impressive minimum reflection loss (RLmin) of −43.26 dB and an effective absorption band (EB) covering the entire C2, X, and Ku bands at 11.79 GHz. Encouragingly, the measured results are basically consistent with the simulation results (an RLmin of −35.78 dB and an EB of 14.68 GHz), which verifies the accuracy of the theoretical simulation and the feasibility of the method. It holds great significance that the investigation of the adsorption retention rate of C–MCM–FAS after immersing it in 3.5 wt% NaCl solution for 21 days. The measured RLmin reaches −48.41 dB with a retention rate of 111.9 %, and the EB reaches 8.56 GHz with a retention rate of 72.6 %. This work presents a groundbreaking concept for designing structural absorbers, expecting the C–MCM–FAS to become a strong contender for application in special environments like microwave detection in the nautical field.

Structure–property relations in graphitic pebbles for nuclear applications

This work presents an analytical approach for holistically characterizing graphitic matrix pebbles for nuclear applications whereby the macrostructure, microstructure, and thermophysical properties of pebbles are determined. A systematic sectioning method was applied to several pebbles to describe the regional properties of the samples. Intact matrix-only spheres and sections of spheres fabricated by Kairos Power were characterized via optical imaging, x-ray computed tomography, x-ray diffraction, and ellipsometry to determine 2D and 3D macrostructure and anisotropy. The thermophysical properties of these materials were determined via measurements of density, specific heat, thermal expansion, and thermal diffusivity. The results of this study indicate that the pebble fabrication methods and their resultant effect on microstructure have a nontrivial effect on thermophysical properties, confirming the importance of robust characterization of these components. A discussion of the characterization approach and its applicability to nuclear fuel development activities is also included.

The History of Electrospinning: Past, Present, and Future Developments

AbstractElectrospinning has rapidly progressed over the past few decades as an easy and versatile way to fabricate fibers with diameters ranging from micrometers to tens of nanometers that present unique and intricate morphologies. This has led to the conception of new technologies and diverse methods that exploit the basic electrohydrodynamic phenomena of the electrospinning process, which has in turn led to the invention of novel apparatuses that have reshaped the field. Research on revamping conventional electrospinning has principally focused on achieving three key objectives: upscaling the process while retaining consistent morphological traits, developing 3D nanofibrous macrostructures, and formulating novel fiber configurations. This review introduces an extensive group of diverse electrospinning techniques and presents a comperative study based on the apparatus type and output. Then, each process's advantages and limitations are critically assessed to identify the bona fide practicability and relevance of each technological breakthrough. Finally, the outlook on future developments of advanced electrospinning technologies is outlined, with an emphasis on upscaling, translational research, sustainable manufacturing and prospective solutions to current shortcomings.

Unveiling the Mechanism of the in Situ Formation of 3D Fiber Macroassemblies with Controlled Properties.

Electrospinning technique is well-known for the generation of different fibers. While it is a "simple" technique, it lies in the fact that the fibers are typically produced in the form of densely packed two-dimensional (2D) mats with limited thickness, shape, and porosity. The highly demanded three-dimensional (3D) fiber assemblies have been explored by time-consuming postprocessing and/or complex setup modifications. Here, we use a classic electrospinning setup to directly produce 3D fiber macrostructures only by modulating the spinning solution. Increasing solution conductivity modifies electrodynamic jet behavior and fiber assembling process; both are observed in situ using a high-speed camera. More viscous solutions render thicker fibers that own enhanced mechanical stiffness as examined by finite element analysis. We reveal the correlation between the universal solution parameters and the dimensionality of fiber assemblies, thereof, enlightening the design of more "3D spinnable" solutions that are compatible with any commercial electrospinning equipment. After a calcination step, ultralightweight ceramic fiber assemblies are generated. These inexpensive materials can clean up exceptionally large fractions of oil spillages and provide high-performance thermal insulation. This work would drive the development and scale-up production of next-generation 3D fiber materials for engineering, biomedical, and environmental applications.

Characterization of Electrospinning Prepared Nitrocellulose (NC)-Ammonium Dinitramide (ADN)-Based Composite Fibers.

Nanoscale composite energetic materials (CEMs) based on oxidizer and fuel have potential advantages in energy adjustment and regulation through oxygen balance (OB) change. The micro- and nanosized fibers based on nano nitrocellulose (NC)-ammonium dinitramide (ADN) were prepared by the electrospinning technique, and the morphology, thermal stability, combustion behaviors, and mechanical sensitivity of the fibers were characterized by means of scanning electron microscope (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), gas pressure measurement of thermostatic decomposition, laser ignition, and sensitivity tests. The results showed that the prepared fibers with fluffy 3D macrostructure were constructed by the overlap of micro/nanofibers with the energetic particles embedded in the NC matrix. The first exothermic peak temperature (Tp) of the samples containing ADN decreased by 10.1 °C at most compared to that of ADN, and the pressure rise time of all the samples containing ADN moved forward compared to that of the sample containing NC only. Furthermore, ADN can decrease the ignition delay time of NC-based fibers under atmosphere at room temperature from 33 ms to 9 ms and can enhance the burning intensity of NC-based fibers under normal pressure. In addition, compared to the single high explosive CL-20 or RDX, the mechanical sensitivities of the composite materials containing high explosive CL-20 or RDX were much decreased. The positive oxygen balance of ADN and the intensive interactions between ADN and NC can reduce the ignition delay time and promote the burning reaction intensity of NC-based composite fibers, while the mechanical sensitivities of composite fibers could be improved.

Multiscale Optimization of 3D‐Printed Beam‐Based Lattice Structures through Elastically Tailored Unit Cells

Herein, a numerical multiscale tool is developed to design 3D periodic lattice structures. The work is motivated by the high design freedom of additive manufacturing technologies, which enable complex multiscale lattice structures to be printed. A finite‐element‐based free‐material optimization method is used to determine the ideal orthotropic material properties of a 3D macrostructure space. Subsequently, a population‐based algorithm is established to design optimized microscopic lattice unit cells with the desired structural properties. The design variables are the coordinates of lattice skeleton nodes defined within the 3D lattice unit cell space, and the connectivities between them resulting in a truss skeleton. For the calculation of the mechanical properties of the individual lattice cells, an effective Timoshenko beam‐based finite element calculation method is developed. The macroscale structure can be constructed by periodically filling the domain with the customized unit cell representing a metamaterial. The method is demonstrated by 3D beam problems with compliance constraints. These macroscopic demonstrators of the developed lattice structures were also 3D‐printed. The benefit regarding the weight‐specific structural performance is validated through benchmarking with periodic lattice design solutions using well‐known standard lattice cells.

Laser-Induced Graphene Enabled Additive Manufacturing of Multifunctional 3D Architectures with Freeform Structures.

3D printing has become an important strategy for constructing graphene smart structures with arbitrary shapes and complexities. Compared with graphene oxide ink/gel/resin based manners, laser-induced graphene (LIG) is unique for facile and scalable assembly of 1D and 2D structures but still faces size and shape obstacles for constructing 3D macrostructures. In this work, a brand-new LIG based additive manufacturing (LIG-AM) protocol is developed to form bulk 3D graphene with freeform structures without introducing extra binders, templates, and catalysts. On the basis of selective laser sintering, LIG-AM creatively irradiates polyimide (PI) powder-bed for triggering both particle-sintering and graphene-converting processes layer-by-layer, which is unique for assembling varied types of graphene architectures including identical-section, variable-section, and graphene/PI hybrid structures. In addition to exploring combined graphitizing and fusing discipline, processing efficiency and assembling resolution of LIG-AM are also balanceable through synergistic control of lasing power and powder-feeding thickness. By further studying various process dependent properties, a LIG-AM enabled aircraft-wing section model is finally printed to comprehensively demonstrate its shiftable process, hybridizable structure, and multifunctional performance including force-sensing, anti-icing/deicing, and microwave shielding and absorption.

Experimental and numerical study on fracture behavior of SiC particle reinforced aluminum matrix composites based on Gurson–Tvergaard–Needleman damage model

AbstractIn this paper, the mechanical behavior of 10 and 14 vol.% SiCp/Al composites was studied with both experiments and numerical analysis. A 3D macrostructure model based on modified Gurson–Tvergaard–Needleman (GTN) model was developed to predict the elasto‐plastic response and fracture behavior of particle reinforced aluminum matrix composites (PRAMCs). The particle size effects on the plastic strengthening induced by geometrically necessary dislocations (GNDs) were introduced, and the size distribution of the SiC particles was obtained according to the statistical analysis of the microstructure. The material parameters for GTN model were determined with a parameter identification process, and the validity of the numerical results was validated by the agreement of the experimental stress–strain curve. Results reveal that particle size randomness plays an important role in the fracture morphologies.

Electric-Field-Assisted Ultrasonic Spray Pyrolysis of Solid State Electrolytes

Solid polymer electrolytes (SPEs) hold the potential to revolutionize energy storage by enabling secondary batteries containing lithium metal anodes, which have ultra-high theoretical capacity of 3860 mAh g−1, compared to a typical graphite anode’s theoretical capacity of 372 mAh g−1. The bulk of SPE research focuses on optimizing SPE chemistry, while the manufacturing process receives little attention. In this interdisciplinary study, as shown in Figure 1, an electric-field-assisted ultrasonic spray pyrolysis (EFAUSP) setup is proposed and integrated with a cyclone-separator, which was simulated ANSYS Fluent, then built based on the results. Digital in-line holography is performed to determine the droplet size distribution and investigate the droplet trajectories near the substrate surface. This newly proposed EFAUSP setup is based on a 3D printer controller, promising macrostructure and microstructure control in future work. Future work will build upon these results to investigate the mechanical and electrochemical properties of the deposited SPEs. Figure 1

Real-time Multiple-particle Tracking in Ultrasonic Spray Pyrolysis

Solid polymer electrolytes (SPEs) hold the potential to revolutionize energy storage by enabling secondary batteries containing lithium metal anodes, which have an ultra-high theoretical capacity of 3860 mAh g−1, compared to a typical graphite anode’s theoretical capacity of 372 mAh g−1. The bulk of SPE research focuses on optimizing SPE chemistry, while the manufacturing process receives little attention. In this interdisciplinary study, an electric-field-assisted ultrasonic spray pyrolysis (EFAUSP) setup is proposed and integrated with a cyclone-separator, which was simulated ANSYS Fluent, then built based on the results. Digital in-line holography is performed to determine the droplet size distribution and investigate the droplet trajectories near the substrate surface. This newly proposed EFAUSP setup is based on a 3D printer controller, promising macrostructure and microstructure control in future work. Future work will build upon these results to investigate the mechanical and electrochemical properties of the deposited SPEs.

A New Era of Integrative Ice Frozen Assembly into Multiscale Architecturing of Energy Materials

AbstractThe ice templating assembly has been investigated to construct macroporous channels of functional nanomaterials with well‐defined homogeneous morphology. Recently, this templating method has been revisited integrating with other materials’ synthesis and processing methodologies (such as, spinning, spraying, filtration, hydrothermal, oxygenation, gelation, and 3D printing) for electrochemical energy conversion and storage applications. Herein, the recent progress on “integrative ice frozen assembly” focusing on the hierarchical structures and chemistries of functional nanomaterials such as, organic, inorganic, carbon, and composite materials for a rational design of energy application‐oriented materials is comprehensively reviewed. This integrative process allows functional nanomaterials to be assembled into various dimensions, such as, 0D, 1D, 2D, and 3D macrostructures, as well as, into larger bulk objects such as, fibers, films, monoliths, and powders. The fundamental understanding of the integrative ice frozen assembly is thermodynamically and kinetically discussed with the help of primitive freeze casting domain knowledge and the energy conversion and storage performances of the as‐designed electrodes with their hierarchical structures and chemistries are further correlated. The applications of the as‐assembled electrodes into batteries, supercapacitors, fuel cells, and electrocatalysis are also addressed. Finally, the perspective on the current impediments and future directions in this field is discussed.

Synthesis of Three‐Dimensional Reduced‐Graphene Oxide from Graphene Oxide

Carbon materials and their allotropes have been involved significantly in our daily lives. Zero‐dimensional (0D) fullerenes, one‐dimensional (1D) carbon materials, and two‐dimensional (2D) graphene materials have distinctive properties and thus received immense attention from the early 2000s. To meet the growing demand for these materials in applications like energy storage, electrochemical catalysis, and environmental remediation, the special category, i.e., three‐dimensional (3D) structures assembled from graphene sheets, has been developed. Graphene oxide is a chemically altered graphene, the desired building block for 3D graphene matter (i.e., 3D graphene macrostructures). A simple synthesis route and pore morphologies make 3D reduced‐graphene oxide (rGO) a major candidate for the 3D graphene group. To obtain target‐specific 3D rGO, its synthesis mechanism plays an important role. Hence, in this article, we will discuss the general mechanism for 3D rGO synthesis, vital procedures for fabricating advanced 3D rGO, and important aspects controlling the growth of 3D rGO.

3D Printed MXene Aerogels with Truly 3D Macrostructure and Highly Engineered Microstructure for Enhanced Electrical and Electrochemical Performance.

Assembling 2D materials such as MXenes into functional 3D aerogels using 3D printing technologies gains attention due to simplicity of fabrication, customized geometry and physical properties, and improved performance. Also, the establishment of straightforward electrode fabrication methods with the aim to hinder the restack and/or aggregation of electrode materials, which limits the performance of the electrode, is of great significant. In this study, unidirectional freeze casting and inkjet-based 3D printing are combined to fabricate macroscopic porous aerogels with vertically aligned Ti3 C2 Tx sheets. The fabrication method is developed to easily control the aerogel microstructure and alignment of the MXene sheets. The aerogels show excellent electromechanical performance so that they can withstand almost 50% compression before recovering to the original shape and maintain their electrical conductivities during continuous compression cycles. To enhance the electrochemical performance, an inkjet-printed MXene current collector layer is added with horizontally aligned MXene sheets. This combines the superior electrical conductivity of the current collector layer with the improved ionic diffusion provided by the porous electrode. The cells fabricated with horizontal MXene sheets alignment as current collector with subsequent vertical MXene sheets alignment layers show the best electrochemical performance with thickness-independent capacitive behavior.