3D Printed HA/β-TCP Scaffold: A Macroscopic Microscopic Analysis and Biological Validation Study of the Effect of the Component Ratio on Performance.

3D printed biomaterials have been extensively investigated and developed in the field of bone regeneration related to clinical issues. However, specific applications of 3D printed biomaterials in different dental areas have seldom been reported. In this study, we aimed to and successfully fabricated 3D poly (lactic-co-glycolic acid)/β-tricalcium phosphate (3D-PLGA/TCP) and 3D β-tricalcium phosphate (3D-TCP) scaffolds using two relatively distinct 3D printing (3DP) technologies. Conjunctively, we compared and investigated mechanical and biological responses on human dental pulp stem cells (hDPSCs). Physicochemical properties of the scaffolds, including pore structure, chemical elements, and compression modulus, were characterized. hDPSCs were cultured on scaffolds for subsequent investigations of biocompatibility and osteoconductivity. Our findings indicate that 3D printed PLGA/TCP and β-tricalcium phosphate (β-TCP) scaffolds possessed a highly interconnected and porous structure. 3D-TCP scaffolds exhibited better compressive strength than 3D-PLGA/TCP scaffolds, while the 3D-PLGA/TCP scaffolds revealed a flexible mechanical performance. The introduction of 3D structure and β-TCP components increased the adhesion and proliferation of hDPSCs and promoted osteogenic differentiation. In conclusion, 3D-PLGA/TCP and 3D-TCP scaffolds, with the incorporation of hDPSCs as a personalized restoration approach, has a prospective potential to repair minor and critical bone defects in oral and maxillofacial surgery, respectively.

3D printed polycaprolactone/β-tricalcium phosphate/carbon nanotube composite – Physical properties and biocompatibility

Microcapsules encapsulated within epoxy as a curing agent have been successfully applied in self-healing materials, in which the healing performance significantly depends on the binding behaviour of the epoxy curing agent with the cement matrix. In this paper, the binding energy was investigated by molecular dynamics simulation, which could overcome the shortcomings of traditional microscopic experimental methods. In addition to the construction of different molecular models of epoxy, curing agents, and dilutants, seven models were established to investigate the effects of chain length, curing agent, and epoxy resin chain direction on the interfacial binding energy. The results showed that an increase of chain length exhibited had limited effect on the binding energy, while the curing agent and the direction of the epoxy significantly affected the interfacial binding energy. Among different factors, the curing agent tetrethylenepentamine exhibited the highest value of interfacial binding energy by an increment of 31.03 kcal/mol, indicating a better binding ability of the microcapsule core and the cement matrix. This study provides a microscopic insight into the interface behaviour between the microcapsule core and the cement matrix.

Spine surgery entails a wide spectrum of complicated pathologies. Over the years, numerous assistive tools have been introduced to the modern neurosurgeon's armamentarium including neuronavigation and visualization technologies. In this review, we aimed to summarize the available data on 3D printing applications in spine surgery as well as an assessment of the future implications of 3D printing. We performed a comprehensive review of the literature on 3D printing applications in spine surgery. Over the past decade, 3D printing and additive manufacturing applications, which allow for increased precision and customizability, have gained significant traction, particularly spine surgery. 3D printing applications in spine surgery were initially limited to preoperative visualization, as 3D printing had been primarily used to produce preoperative models of patient-specific deformities or spinal tumors. More recently, 3D printing has been used intraoperatively in the form of 3D customizable implants and personalized screw guides. Despite promising preliminary results, the applications of 3D printing are so recent that the available data regarding these new technologies in spine surgery remains scarce, especially data related to long-term outcomes.

Application of three-dimensional (3D) printing is widely being applied from various fields of studies from mechanical manufacturing to civil constructions. Food is considered an essential factor for human survival. Modern day’s humans are considering food not only for survival but for other qualitative attributes and characteristic properties as well. With the development of 3D printing technologies, it is now possible to print with almost any kind of materials, including organics. This technological development had empowered the new generation food technologists/engineers to print almost all types of foods from chocolate to pizza, of desired characters, shape, size, color, texture, and other properties of interest. Foods with customized nutritional characteristics, lowered production price and processing time are various interesting applications of 3D printing for future foods. Decorated cakes and cookies and customized mobile-based 3D food printing applications, including the real-time printed picture of customers placing the food orders, make the future of food processing quite astonishing. 3D printing provides a wider platform for the food innovators to work more intensely on the new food product developments 52with much complex geometry that manually would be near to impossible. This chapter targets to provide information to the readers about various aspects of 3D printing in food processing, technological development for 3D food printing, and about different printable food component mixtures and recipes. Last part of the chapter discusses briefly the limitations and future scope of 3D food printing keeping in mind the future human needs and requirements.

The three-dimensional (3D) printing of hydrogel is an issue of interest in various applications to build optimized 3D structured devices beyond 2D-shaped conventional structures such as film or mesh. The materials design for the hydrogel, as well as the resulting rheological properties, largely affect its applicability in extrusion-based 3D printing. Here, we prepared a new poly(acrylic acid)-based self-healing hydrogel by controlling the hydrogel design factors based on a defined material design window in terms of rheological properties for application in extrusion-based 3D printing. The hydrogel is designed with a poly(acrylic acid) main chain with a 1.0 mol% covalent crosslinker and 2.0 mol% dynamic crosslinker, and is successfully prepared based on radical polymerization utilizing ammonium persulfate as a thermal initiator. With the prepared poly(acrylic acid)-based hydrogel, self-healing characteristics, rheological characteristics, and 3D printing applicability are deeply investigated. The hydrogel spontaneously heals mechanical damage within 30 min and exhibits appropriate rheological characteristics, including G′~1075 Pa and tan δ~0.12, for extrusion-based 3D printing. Upon application in 3D printing, various 3D structures of hydrogel were successfully fabricated without showing structural deformation during the 3D printing process. Furthermore, the 3D-printed hydrogel structures exhibited excellent dimensional accuracy of the printed shape compared to the designed 3D structure.

Polycrystalline diamond (PCD) prepared by the high temperature and pressure method often uses Co as a binder, which had a detrimental effect on the cutting performance of PCD, thus Co needed to be removed. However, the removal of Co would cause residual holes and also make the cutting performance of PCD poorer. To address this issue, hot filament chemical vapor deposition (HFCVD) was used. During deposition, the residual holes cannot be filled fully, and Co would diffuse to the interface between CVD diamond coatings and the PCD substrate, which influenced the adhesive strength of the diamond coating with the PCD substrate. In order to investigate the influencing mechanism, both experiments and the density functional theory (DFT) calculations have been employed. The experimental results demonstrate that Co and the holes in the interface would reduce the interfacial binding strength. Further, we built interfacial structures consisting of diamond (100), (110), (111) surfaces and PCD to calculate the corresponding interfacial binding energy, charge density and charge density difference. After contrast, for Co and the holes located on the (110) surface, the corresponding interfacial binding energy was bigger than the others. This means that the corresponding C-C covalent bond was stronger, and the interfacial binding strength was higher. Based on this, conducting cobalt removal pretreatment, optimizing the PCD synthetic process and designing the site of Co can improve the performance of the PCD substrate CVD diamond coating tools.

The concentration of the binder is a key factor affecting the quality of 3D-printed bone scaffolds. This study analyzed the influence of polyvinyl alcohol (PVA) aqueous solution concentration on the properties of hydroxyapatite (HA)/β-tricalcium phosphate (β-TCP) bone scaffolds from both microscopic and macroscopic perspectives using molecular dynamics (MD) simulations and experimental research. In the MD simulations, the changes in chain length corresponding to different concentrations were used to analyze the microscopic interactions between PVA and the powder material system. In the experiments, the solid content, zeta potential, and extrusion rheological properties of the slurry were analyzed under PVA concentrations ranging from 5% to 15% by mass. Bone scaffolds were then fabricated using 3D printing and freeze-drying processes, and the changes in porosity, mechanical properties, dimensional shrinkage, and swelling effect of the scaffolds were examined. Finally, the biological properties of the scaffolds were verified through in vitro experiments. The results showed that the hydrogen bonds and ionic bonds formed between PVA and the powder materials are the main forces for adhesion, and the increase in chain length, which leads to an increase in Cauchy pressure, enhances the basic mechanical properties of the material. Slurries with higher PVA concentrations have higher solid content and shear-thinning capabilities, ensuring better printability, and the resulting bone scaffolds exhibit higher mechanical properties and drying shrinkage characteristics. However, this also leads to lower porosity and swelling rates. In vitro experiments revealed that an increase in PVA aqueous solution concentration results in decreased porosity and ion concentration of the bone scaffolds, thereby reducing their bioactivity. The conclusions drawn from this study can be used to predict the performance of slurries and bone scaffolds at different binder concentrations, providing a theoretical basis for the selection of binder concentration in 3D-printed bone scaffolds.

This work investigated interactions between calcium cations (Ca2+) and three common types of oxygen-based functional groups of concrete superplasticizers using density functional theory (DFT) calculations and all-atom molecular dynamics (MD) simulations. The three common types of oxygen-based functional groups were modeled as three hypothetical, low-molecular-weight organic molecules, each containing a methyl-terminated oxyethylene dimer and an adsorbing head of two oxygen-based functional groups, and are referred to as carboxylate, sulfonate, and phosphate groups, respectively, following the usual terminology in the field of concrete admixtures. Our DFT results show that the binding strength of the three groups with calcium cations follows (from high to low) phosphate>carboxylate>sulfonate, and both the electrophilic attack and the chemical reactivity of the three groups contribute significantly to the binding strength. The MD simulation results indicate that the adsorption of the three small molecules on the calcite (1 0 4) surface in aqueous solution shares a similar pattern in the sense that just two oxygen atoms of two adjacent anchor groups adsorb on the calcium atoms on the top layer of the crystal. The adsorption strength among the three types of functional groups follows the same order as the binding strength obtained from DFT calculations; both results corroborate a similar rule-of-thumb established by experiments. Furthermore, interactions of the three types of groups with water molecules suggest that strong hydrogen-bonding interactions exist in those systems. Graphical abstract Binding of calcium cations with three different types of oxygen-based functional groups of superplasticizersᅟ.

Recent advancements in science and technology have resulted in important changes in the medical field. Three-dimensional (3D) printing is a good example of such developments and has already achieved a considerable level of technical development in many industrial fields. Use of this innovative manufacturing technique is gradually expanding in the medical field. In clinics, application of 3D printing can be largely divided into diagnostic or treatment purposes. Meanwhile, research in the basic sciences is also advancing, allowing 3D printing of tissue or organs via cell bioprintings. This technology could potentially change the paradigm of the medical community1. Because of its usefulness, various applications of 3D printing should be considered in the area of oral and maxillofacial surgery. In fact, the field of oral and maxillofacial surgery has sought to apply a simple rudimentary form of 3D printing technique for a long time. Use of 3D-printed rapid prototyped models before oral cancer surgery or orthognathic surgery for treatment planning and simulation has been established to assure more precise and safe surgeries2. Moreover, surgical stents are fabricated using computed tomography (CT) images in the field of dental implantology3. It is necessary to move forward and adopt this technology in the fabrication of complex forms of molds in order to provide individualized medical services. For example, easier production of customized and reconstruction plates and morphologic reconstruction of bony defect areas are possible uses of 3D printing in fracture surgery or reconstructive surgery. The 3D printing technique can also be utilized in other areas of oral and maxillofacial surgery. For example, it would be very helpful to be able to design and fabricate a customized non-absorbable barrier of titanium mesh. In addition, 3D printing could be used in other fields of dentistry. For example, individual occlusion could be accurately determined and treated with a unique splint fabricated using 3D printing. It would be beneficial for patients if splints could be fabricated without the need for cast impressions. Orthodontic appliances also could be manufactured with 3D printing. Considering a wide variety of morphologies of the tooth surfaces, appliances with customized surfaces would be helpful4. Of course, there are still problems with 3D printing that need to be solved, such as the high cost; that this technology is not yet cost-effective. However, though it is difficult to justify the use of 3D printing on general surgery patients, the use of 3D printing might be much more appropriate for patients with special needs. For example, it is possible to greatly reduce the operation time if highly customized devices are prepared in advance, since it would exempt the time-consuming process of bending or modifying the appliance during the surgery. This would ultimately benefit the patient. Increased precision of the technique will also result in a wider range of applications for 3D printing. In addition, increased resolution in medical imaging such as CT will allow greater use of 3D printing5. Material science and engineering are also important areas in which 3D printing will be useful. Materials that are relatively easy to modify, such as polymers or plastics, are already at a high level of technological development, though materials such as metals, alloys, or other composites are still under development6. Many countries are increasing their national policies that support the developing 3D technology. In order to respond to the demands and remain competitive, oral and maxillofacial surgeons should have an interest in 3D printing and understand its various applications. Though it is important to have the source technology, its utilization in a variety of fields should not be overlooked. In target business models such as jewelry/accessory and interior, customized device/healthcare structure, early participation of the potential customer is also being encouraged. Moreover, since complex mold forms can be more readily manufactured using 3D printing, mass production is a future goal in applicable fields. In conclusion, the role of 3D printing in oral and maxillofacial surgery should be a focus of interest since the technique could offer endless developmental possibilities.

To highlight the various applications of 3D printing in cardiovascular disease and discuss its limitations and future direction. Use of handheld 3D printed models of cardiovascular structures has emerged as a facile modality in procedural and surgical planning as well as education and communication. Three-dimensional (3D) printing is a novel imaging modality which involves creating patient-specific models of cardiovascular structures. As percutaneous and surgical therapies evolve, spatial recognition of complex cardiovascular anatomic relationships by cardiologists and cardiovascular surgeons is imperative. Handheld 3D printed models of cardiovascular structures provide a facile and intuitive road map for procedural and surgical planning, complementing conventional imaging modalities. Moreover, 3D printed models are efficacious educational and communication tools. This review highlights the various applications of 3D printing in cardiovascular diseases and discusses its limitations and future directions.

Lycium barbarum polysaccharides (LBPs), bioactive macromolecules derived from goji berries, have gained attention for their biocompatibility, water retention, and hydrogel-forming abilities. These properties make LBPs promising candidates for 3D printing applications in the food and pharmaceutical industries. This review comprehensively analyzes LBPs' chemical composition, structural characteristics, and biological functions. The study examines the rheological properties of LBPs, including flow behavior, shear-thinning, and gelation mechanisms, and explores network formation through physical and chemical gelation processes. The potential of LBPs in bio-ink formulations for 3D food printing and biomedical applications is discussed, focusing on cross-linking strategies to enhance printing performance. LBPs exhibit favorable rheological and gelation properties, supporting their use in 3D printing applications. However, challenges, such as thermal sensitivity, mechanical limitations, and scalability, remain significant hurdles. Strategies for optimization are proposed to enhance their application in food and biomedical 3D printing. Future research should focus on refining cross-linking methods, improving mechanical stability, and addressing challenges in large-scale production to fully leverage LBPs in advanced 3D printing technologies.

The two marine inorganic polymers, biosilica (BS), enzymatically synthesized from ortho-silicate, and polyphosphate (polyP), a likewise enzymatically synthesized polymer consisting of 10 to >100 phosphate residues linked by high-energy phosphoanhydride bonds, have previously been shown to display a morphogenetic effect on osteoblasts. In the present study, the effect of these polymers on the differential differentiation of human multipotent stromal cells (hMSC), mesenchymal stem cells, that had been encapsulated into beads of the biocompatible plant polymer alginate, was studied. The differentiation of the hMSCs in the alginate beads was directed either to the osteogenic cell lineage by exposure to an osteogenic medium (mineralization activation cocktail; differentiation into osteoblasts) or to the chondrogenic cell lineage by incubating in chondrocyte differentiation medium (triggering chondrocyte maturation). Both biosilica and polyP, applied as Ca2+ salts, were found to induce an increased mineralization in osteogenic cells; these inorganic polymers display also morphogenetic potential. The effects were substantiated by gene expression studies, which revealed that biosilica and polyP strongly and significantly increase the expression of bone morphogenetic protein 2 (BMP-2) and alkaline phosphatase (ALP) in osteogenic cells, which was significantly more pronounced in osteogenic versus chondrogenic cells. A differential effect of the two polymers was seen on the expression of the two collagen types, I and II. While collagen Type I is highly expressed in osteogenic cells, but not in chondrogenic cells after exposure to biosilica or polyP, the upregulation of the steady-state level of collagen Type II transcripts in chondrogenic cells is comparably stronger than in osteogenic cells. It is concluded that the two polymers, biosilica and polyP, are morphogenetically active additives for the otherwise biologically inert alginate polymer. It is proposed that alginate, supplemented with polyP and/or biosilica, is a suitable biomaterial that promotes the growth and differentiation of hMSCs and might be beneficial for application in 3D tissue printing of hMSCs and for the delivery of hMSCs in fractures, surgically created during distraction osteogenesis.

Is This the Future of Medical Technology?

Molecular dynamics simulations on the interaction between polymers and hydroxyapatite with and without coupling agents