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Due to the uncertainty of trauma or infection, customized bone substitutes are often required in clinic. Meanwhile, excessive use of antibiotics may lead to drug resistance. Therefore, the design of anti-infection bone tissue engineering scaffold is of very important. In this study, porous titanium alloy bone tissue engineering scaffolds were designed and fabricated by 3D printing. TiO2 nanotubes were further constructed on the scaffolds through electrochemical anodic oxidation, achieving the drug loading and anti-infection functions. The micron-level bionic pores were fabricated by the 3D printing process, and the secondary nanoscale-level nanotubes were achieved through the anodic oxidation process. Thereafter, the micro–nano structured porous bone tissue engineering scaffolds are presented. This structure features that the drug release rate can be regulated by loading the anti-infection drug minocycline and coating them with poly(lactic-co-glycolic acid) (PLGA) in the nanotubes. According to the results, the micro–nano composite porous scaffold showed uniform and controllable micro–nano pores, it may load anti-infection drugs and shown anti-infection ability. In addition, the PLGA coating may delay the drug release and maintain a sustained anti-infection function for the scaffold in a week. This study provides new ideas for designing antibacterial bone tissue engineering scaffold.

The emergence of tissue engineering provides an alternative therapeutic strategy for various regeneration. It is the crucial step for choosing an ideal scaffold to support the cellular behaviors of various functional cells. Various biomaterials have been found or synthesized and applied to tissue repair. Among these biomaterials, as a natural-derived material, decellularized extracellular matrix (dECM) derived from cells, tissues, and organs is attracting more and more interest due to its good biocompatibility, biodegradability, and the ability to mimic a microenvironment similar to extracellular matrix. More and more researchers utilized dECM derived from cells, tissues, and organs to fabricate tissue-engineered scaffolds to repair musculoskeletal tissues, since the bioactive molecules of dECM, such as fibrous proteins, proteoglycans, and adhesive glycoproteins, could provide various bioactive cues for tissue regeneration and remodeling. The physiochemical properties of dECM can be enhanced by changing decellularization and modification techniques. In addition, dECM can act as carriers of drugs, factors, or exosomes, delivering agents to injured tissues and promoting tissue repair and regeneration. Therefore, we conduct this review to discuss the current status and challenges of dECM in repairing the musculoskeletal system. Furthermore, the fabrication and modification of dECM were also discussed in our study.

Porous structures and surface morphology of bone tissue scaffolds play an important role in improving the biocompatibility and antibacterial properties for bone repair. In this study, we investigated the effect of different anodic oxidation parameters on the nanotubes morphology in 3D printed porous titanium scaffolds. Micron-scale pores were fabricated by 3D printing first, and then the nano-scale tubes were obtained via anodizing treatments. The results demonstrated that the morphology of the nanotubes depended on the anodic oxidation time and voltage, respectively. Longer anodic oxidation led to the formation of circle-like nanotubes, and the diameter of the nanotubes increased with the voltage. The scaffolds anodized at 30 V showed the best cell proliferation potential. The presence of nanotubes on the surface of scaffold altered the adhesion of bacteria so that it improved the antibacterial properties of scaffold. The formation of nanotubes improved the drug-loading ability of the scaffold, which are used for loading of minocycline antibacterial drugs. The proposed 3D printed porous Ti6Al4V scaffold with nanotubes surface modification showed obvious antibacterial effect, which is expected to have a promising application in antibacterial bone prosthesis.

The bed structure of high-grade large-scale CNC machine tools is crucial for maintaining their long-term service accuracy. This study focused on the key casting process of large nodular cast iron beds. AnyCasting software was employed to simulate and analyze the casting scheme, and then the mold filling and solidification processes were proposed based on the simulation results. The proposed casting scheme indicates that the designed gating system exhibited excellent filling capability. The dual sprue ceramic pipe bottom pouring technique, in conjunction with the chills, not only improved casting efficiency but also met the requirements of sequential solidification design. The castings possessed a dense microstructure characterized by uniform and stable phase composition, primarily comprising lamellar pearlite, with ≤0.5% of phosphorus eutectic and cementite. Furthermore, the microstructure of these materials displayed favorable graphite morphology with a spheroidization rate exceeding 85% and spheroidization grade of 2–3. This study has important academic and application value for the casting process of producing low-stress, high-grade CNC machine tool bed cast iron materials.

Nano-hydroxyapatite (nano-HA) has been widely studied as a promising biomaterial because of its potential mechanical and biological properties. In this article, different synthesis methods for nano-HA were summarized. Key factors for the synthesis of nano-HA, including reactant concentration, effects of temperature, PH, additives, aging time, and sintering, were separately investigated. The biological performances of the nano-HA depend strongly on its structures, morphology, and crystallite sizes. Nano-HA with different morphologies may cause different biological effects, such as protein adsorption, cell viability and proliferation, angiogenesis, and vascularization. Recent research progress with respect to the biological functions of the nano-HA in some specific biological applications are summarized and the future development of nano-sized hydroxyapatite is prospected.

Three-dimensional (3D) printing technology has the advantages of fast design and fabrication in clinical orthopedics. This study proposed the application of 3D-printed personalized reverse shoulder prosthesis in a reverse total shoulder arthroplasty for a patient with tuberculosis of the shoulder joint. Traditional and personalized shoulder prostheses were compared and studied. The mechanical simulation analysis was conducted on the individualized prosthesis and scapula. A personalized reverse total shoulder prosthesis was fabricated by 3D printing technology. Finite element analyses were conducted for implantation of traditional and personalized prostheses. The numerical results show that the maximum equivalent stress of screws inserted into bone tissue is 43.23 MPa in the personalized prosthesis. But in traditional prostheses, the maximum equivalent stress of screws performing the same function is 246.50 MPa. The structural advantages of the personalized prosthesis effectively reduce the local pressure of the screws to ensure the safety and effectiveness of the material during service. At the same time, the scapula paired with the personalized prosthesis also shown a smaller mean equivalent stress that can reduce patient stress. The postoperative evaluation of implant stability and patient status was good. The results indicated that 3D printing technology has important application value in orthopedic surgery.

Extracellular vesicles (EVs), products released by cells in multiple biological activities, are currently widely accepted as functional particles and intercellular communicators. From the orthodox perspective, EVs derived from apoptotic cells (apoEVs) are responsible for cell debris clearance, while recent studies have demonstrated that apoEVs participate in tissue regeneration. However, the underlying mechanisms and particular functions in tissue regeneration promotion of apoEVs remain ambiguous. Some molecules active during apoptosis also function in tissue regeneration triggered by apoptosis, such as caspases. ApoEVs are generated in the process of apoptosis, carrying cell contents to manifest biological effects and possess biomarkers to target phagocytes. The regenerative effect of apoEVs might be due to their abilities to facilitate cell proliferation and regulate inflammation. Such regenerative effect has been observed in various tissues, including skin, bone, cardiovascular system, and kidneys. Engineered apoEVs are produced to amplify the biological benefits of apoEVs, rendering them optional for drug delivery. Meanwhile, challenges exist in thorough mechanistic exploration and standardization of production. In this review, we discussed the link between apoptosis and regeneration, current comprehension of the origination and investigation strategies of apoEVs, and mechanisms in tissue regeneration of apoEVs and their applications. Challenges and prospects are also addressed here.

Repair of critical bone defects is a challenge in the orthopedic clinic. 3D printing is an advanced personalized manufacturing technology that can accurately shape internal structures and external contours. In this study, the composite scaffolds of polylactic acid (PLA) and nano-hydroxyapatite (n-HA) were manufactured by the fused deposition modeling (FDM) technique. Equal mass PLA and n-HA were uniformly mixed to simulate the organic and inorganic phases of natural bone. The suitability of the composite scaffolds was evaluated by material characterization, mechanical property, and in vitro biocompatibility, and the osteogenesis induction in vitro was further tested. Finally, the printed scaffold was implanted into the rabbit femoral defect model to evaluate the osteogenic ability in vivo. The results showed that the composite scaffold had sufficient mechanical strength, appropriate pore size, and biocompatibility. Most importantly, the osteogenic induction performance of the composite scaffold was significantly better than that of the pure PLA scaffold. In conclusion, the PLA/n-HA scaffold is a promising composite biomaterial for bone defect repair and has excellent clinical transformation potential.

In this work, a strain-based degradation model was implemented and validated to better understand the dynamic interactions between the bioresorbable vascular scaffold (BVS) and the artery during the degradation process. Integrating the strain-modulated degradation equation into commercial finite element codes allows a better control and visualization of local mechanical parameters. Both strut thinning and discontinuity of the stent struts within an artery were captured and visualized. The predicted results in terms of mass loss and fracture locations were validated by the documented experimental observations. In addition, results suggested that the heterogeneous degradation of the stent depends on its strain distribution following deployment. Degradation is faster at the locations with higher strains and resulted in the strut thinning and discontinuity, which contributes to the continuous mass loss, and the reduced contact force between the BVS and artery. A nonlinear relationship between the maximum principal strain of the stent and the fracture time was obtained, which could be transformed to predict the degradation process of the BVS in different mechanical environments. The developed computational model provided more insights into the degradation process, which could complement the discrete experimental data for improving the design and clinical management of the BVS.

Hyaluronic acid (HA) is widely distributed in the human body, and it is heavily involved in many physiological functions such as tissue hydration, wound repair, and cell migration. In recent years, HA and its derivatives have been widely used as advanced bioactive polymers for bone regeneration. Many medical products containing HA have been developed because this natural polymer has been proven to be nontoxic, noninflammatory, biodegradable, and biocompatible. Moreover, HA-based composite scaffolds have shown good potential for promoting osteogenesis and mineralization. Recently, many HA-based biomaterials have been fabricated for bone regeneration by combining with electrospinning and 3D printing technology. In this review, the polymer structures, processing, properties, and applications in bone tissue engineering are summarized. The challenges and prospects of HA polymers are also discussed.

In the past decade, biomimetic calcium phosphate (CaP) ceramics have been considered as practicable grafts and biomaterial substitutes in repairing jaw bone defect after tumor resection or traffic accident. Nowadays, increasing incidence of biomedical material-associated infection has raised a concern when applying these materials. In this work, a new porous CaP scaffold with antibacterial coating was proposed. This biomimetic scaffold was composited with berberine (BBR), Ag nanoparticles (nAg), and silk fibroin (SF). The microstructures and phase composition of the scaffolds were analyzed. The cytocompatibility and osteogenic potential of the prepared samples were evaluated in vitro. The scaffolds held hierarchical structure: the first-level porous CaP ceramic with micron pores ranged from 250 to 600 µm; the second-level spongy-like structure with abundant capillary pores ranged from 500 nm to 10 µm; and the third-level structure was achieved by filling BBR, nAg, and SF gel coatings into the above porous structures. The experimental results showed that the antimicrobial capability of single BBR coating is inconspicuous. However, the introduction of nAg could significantly promote the antibacterial effect of scaffolds. At the same time, such scaffolds showed improved osteoinductivity. This new biomimetic CaP scaffold with antibacterial and osteoinductive properties may be a promising candidate for bone tissue engineering.

Adipose tissue reconstruction is an important technique for soft tissue defects caused by facial plastic surgery and trauma. Adipose tissue reconstruction can be repaired by fat transplantation and biomaterial filling, but there are some problems in fat transplantation, such as second operation and limited resources. The application of advanced artificial biomaterials is a promising strategy. In this paper, injectable biomaterials and three-dimensional (3D) tissue-engineered scaffold materials for adipose tissue reconstruction in plastic surgery are reviewed. Injectable biomaterials include natural biomaterials and artificial biomaterials, which generally have problems such as high absorptivity of fillers, repeated injection, and rejection. In recent years, the technology of new 3D tissue-engineering scaffold materials with adipose-derived stem cells (ADSCs) and porous scaffold as the core has made good progress in fat reconstruction, which is expected to solve the current problem of clinical adipose tissue reconstruction, and various biomaterials preparation technology and transformation research also provide the basis for clinical transformation of fat tissue reconstruction.

Zirconium oxide (ZrO2) is the general material in dental area, with natural color, high toughness and strength. Recent years, small blocks of ZrO2 such as micro/nano powders have been studied and developed widely. Nano scale ZrO2, which show simproved mechanical characteristics and superior biocompatibility, are usually incorporated into different applications used in dentistry and tissue engineering. This review provides an overview of nano-ZrO2 materials and its applications in dentistry. The synthesis of nano-ZrO2 powders were mainly prepared by coprecipitation, hydrothermal method and sol-gel method. Then different applications of nano-ZrO2 biomaterials in dental ceramics, implants, radio pacifying agents, basement and tissue engineering fields were briefly introduced.

Melanoma is the most lethal dermal tumor, and a high recurrence rate and skin defects are two main serious problems. An antimelanoma material,which effectively inhibits tumor recurrence and possesses excellent biocompatibility, is urgently needed to treat melanoma. In this study, we developed a novel antitumor Yb3+ [Yb(NO3)3]containing chitosan hydrogel (Yb-CS hydrogel) by dissolving Yb(NO3)3 and chitosan in acetic acid solution and forming composite hydrogels by a freeze-drying process after adding NaOH to the mixed solution. In vitro studies demonstrated that the Yb3+ produces effect of inducing cell death in Yb-CS hydrogel. Moreover, we found that the Yb-CS hydrogel inhibited a focal adhesion kinase (FAK)-dependent signaling pathway and induced B-16 cell anoikis. However, the Yb-CS hydrogel was less effective on L929 normal mouse dermal cells. In vivo studies showed that the Yb-CS hydrogel inhibited the recurrence of melanoma in a mouse bare xenograft tumor model. We concluded that the Yb-CS hydrogel could potentially be used in the antimelanoma field, especially in the inhibition of melanoma recurrence.

Conducting computational stress-strain analysis using finite element methods (FEM) is a common approach when dealing with the complex geometries of atherosclerosis, which is a leading cause of global mortality and complex cardiovascular disease. The considerable expense linked to FEM analysis encourages the substitution of FEM with a considerably faster data-driven machine learning (ML) approach. This study investigated the potential of end-to-end deep learning tools as a more effective substitute for FEM in predicting stress-strain fields within 2D cross sections of arterial walls. We first proposed a U-Net-based fully convolutional neural network (CNN) to predict the von Mises stress and strain distribution based on the spatial arrangement of calcification within arterial wall cross-sections. Further, we developed a conditional generative adversarial network (cGAN) to enhance, particularly from the perceptual perspective, the prediction accuracy of stress and strain field maps for arterial walls with various calcification quantities and spatial configurations. On top of U-Net and cGAN, we also proposed their ensemble approaches to improve the prediction accuracy of field maps further. Our dataset, consisting of input and output images, was generated by implementing boundary conditions and extracting stress-strain field maps. The trained U-Net models can accurately predict von Mises stress and strain fields, with structural similarity index scores (SSIM) of 0.854 and 0.830 and mean squared errors of 0.017 and 0.018 for stress and strain, respectively, on a reserved test set. Meanwhile, the cGAN models in a combination of ensemble and transfer learning techniques demonstrate high accuracy in predicting von Mises stress and strain fields, as evidenced by SSIM scores of 0.890 for stress and 0.803 for strain. Additionally, mean squared errors of 0.008 for stress and 0.017 for strain further support the model's performance on a designated test set. Overall, this study developed a surrogate model for finite element analysis, which can accurately and efficiently predict stress-strain fields of arterial walls regardless of complex geometries and boundary conditions. [ABSTRACT FROM AUTHOR]