Fabrication and characterization of biodegradable Zn scaffold by vacuum heating-press sintering for bone repair

In Vitro Degradation and Cytocompatibility Study of Biodegradable Porous Zinc Scaffolds Fabricated by Fused Deposition Modeling Based Rapid Tooling Method

An integrative study is conducted on the static biodegradation behavior and cytocompatibility of organized porous network structured (OPNS) zinc scaffolds fabricated via the Fused Deposition Modeling based Rapid Tooling (FDM-RT) method. The degradation study investigates the corrosion mechanism over immersion time in simulated body fluid (SBF), whereas the cytocompatibility study incorporates MTT assay and direct cell counting tests. The results indicate that the scaffold morphology, including scaffold struts, interconnectivity, or porosity, along with the immersion period, significantly influence the degradation behavior. The static corrosion rates are determined to be 0.27 ± 0.006, 0.79 ± 0.01, and 1.35 ± 0.05 mm y-1 for bulk and porous zinc samples after 28 days. The higher corrosion rate of porous zinc alloys is mainly due to their higher surface area, which enhances exposure to the solution. Over time, protective layers form on both porous and bulk samples, leading to a gradual decrease in corrosion rate. The XRD results reveal that the corrosion protective layer is primarily composed of ZnO, Ca3(PO4)2, Zn (OH)2, and Zn3(PO4)2·4H2O. Moreover, MTT assay and direct cell counting of mouse fibroblast 3T3 cells on bulk and porous zinc samples suggest that the prepared zinc samples have potential for tissue engineering applications.

Corrosion behavior, antibacterial properties and in vitro and in vivo biocompatibility of biodegradable Zn-5Cu-xMg alloy for bone-implant applications

Reasonable optimization of degradation rate, antibacterial performance and biocompatibility is crucial for the development of biodegradable zinc alloy medical implant devices with antibacterial properties. In this study, various amounts of Mg elements were incorporated into Zn5Cu alloy to modulate the degradation rate, antibacterial properties and biocompatibility. The effects of Mg contents on the microstructure, corrosion behavior, antibacterial properties and biocompatibility of Zn-5Cu-xMg alloy were extensively investigated. The results revealed that with an increase of Mg content, the amount of Mg2Zn11 phase increased and its galvanic effect with the Zn matrix was enhanced, which accelerated the corrosion process and led to higher corrosion rate and high degradation rate of the alloy. Additionally, there was an increased release of Mg2+ and Zn2+ ions from the alloy which imparted excellent resistance against Escherichia coli and Staphylococcus aureus bacteria and improved biocompatibility, subcutaneous antibacterial and immune microenvironment regulation properties. Zn-5Cu-2 Mg exhibited superior antibacterial ability, cell compatibility, proliferation effect, subcutaneous antibacterial and immune microenvironment regulation performances, which can work as a promising candidate of biodegradable antibacterial medical implants.

Silk fibroin/chitosan-based anal fistula scaffolds loaded with curcumin and 5-aminosalicylic acid

The present work describes the development of silk fibroin (SF)/chitosan (CS)-based porous composite anal fistula scaffold (SCAFS) with anti-inflammatory and healing functions. The SCAFS comprises an inner layer made from degummed silk fiber using a vertical braiding machine, and an outer layer created by freeze-drying a mixture of short SF fibers and curcumin (CUR)/5-aminosalicylic acid (5-ASA) loaded SF/CS solution. Results revealed that the SCAFS has high porosity of 42.4 %, remarkable water absorption rate of 370.5 %, robust dry/wet compression resistance of 12.28 ± 2.61 N/3.08 ± 0.43 N. The in vitro & in vivo biocompatibility and anti-inflammatory effect of SCAFS were further examined. The expression of pro-inflammatory cytokine TNF-α, anti-inflammatory cytokine IL-10, CD31 and CD68 was determined by immunohistochemistry (IHC) staining, H&E staining, Immunofluorescence (IF) staining and Masson assay. The results showed that the scaffolds possess a sustainable drug release above 400 h, better biocompatibility and anti-inflammatory effect than the control groups (p < 0.05). Thus, the SCAFS has potential application in the treatment of Crohn's disease.

Zeolitic imidazolate framework-8: a versatile nanoplatform for tissue regeneration

Extensive research on zeolitic imidazolate framework (ZIF-8) and its derivatives has highlighted their unique properties in nanomedicine. ZIF-8 exhibits advantages such as pH-responsive dissolution, easy surface functionalization, and efficient drug loading, making it an ideal nanosystem for intelligent drug delivery and phototherapy. These characteristics have sparked significant interest in its potential applications in tissue regeneration, particularly in bone, skin, and nerve regeneration. This review provides a comprehensive assessment of ZIF-8's feasibility in tissue engineering, encompassing material synthesis, performance testing, and the development of multifunctional nanosystems. Furthermore, the latest advancements in the field, as well as potential limitations and future prospects, are discussed. Overall, this review emphasizes the latest developments in ZIF-8 in tissue engineering and highlights the potential of its multifunctional nanoplatforms for effective complex tissue repair.

Metallic Materials for Bone Repair

Repair of large bone defects caused by trauma or disease poses significant clinical challenges. Extensive research has focused on metallic materials for bone repair because of their favorable mechanical properties, biocompatibility, and manufacturing processes. Traditional metallic materials, such as stainless steel and titanium alloys, are widely used in clinics. Biodegradable metallic materials, such as iron, magnesium, and zinc alloys, are promising candidates for bone repair because of their ability to degrade over time. Emerging metallic materials, such as porous tantalum and bismuth alloys, have gained attention as bone implants owing to their bone affinity and multifunctionality. However, these metallic materials encounter many practical difficulties that require urgent improvement. This article systematically reviews and analyzes the metallic materials used for bone repair, providing a comprehensive overview of their morphology, mechanical properties, biocompatibility, and in vivo implantation. Furthermore, the strategies and efforts made to address the short-comings of metallic materials are summarized. Finally, the perspectives for the development of metallic materials to guide future research and advancements in clinical practice are identified.

A drug-loaded composite coating to improve osteogenic and antibacterial properties of Zn-1Mg porous scaffolds as biodegradable bone implants

Zinc (Zn) alloy porous scaffolds produced by additive manufacturing own customizable structures and biodegradable functions, having a great application potential for repairing bone defect. In this work, a hydroxyapatite (HA)/polydopamine (PDA) composite coating was constructed on the surface of Zn-1Mg porous scaffolds fabricated by laser powder bed fusion, and was loaded with a bioactive factor BMP2 and an antibacterial drug vancomycin. The microstructure, degradation behavior, biocompatibility, antibacterial performance and osteogenic activities were systematically investigated. Compared with as-built Zn-1Mg scaffolds, the rapid increase of Zn²⁺, which resulted to the deteriorated cell viability and osteogenic differentiation, was inhibited due to the physical barrier of the composite coating. In vitro cellular and bacterial assay indicated that the loaded BMP2 and vancomycin considerably enhanced the cytocompatibility and antibacterial performance. Significantly improved osteogenic and antibacterial functions were also observed according to in vivo implantation in the lateral femoral condyle of rats. The design, influence and mechanism of the composite coating were discussed accordingly. It was concluded that the additively manufactured Zn-1Mg porous scaffolds together with the composite coating could modulate biodegradable performance and contribute to effective promotion of bone recovery and antibacterial function.