Biocompatibility of hydroxyapatite scaffolds processed by lithography-based additive manufacturing

The Impact of Particle Size and Surface Treatment of Zirconia Suspension for Photocuring Additive Manufacturing

To prepare a photocurable ceramic suspension for use in commercialized additive manufacturing equipment, the effects of the rheological properties of zirconia particles added to a binder, and the presence or absence of a silane coupling agent on the particles was evaluated. To this end, three experimental groups (ZSs, ZMs, ZLs) and three control groups (ZS, ZM, ZL) were designed depending on the size of the underlying zirconia particles. The test-group zirconia suspensions were prepared through silanization, which was not applied to the control-group suspensions. Depending on the particle size, viscosity differences between the test and control groups were 16,842, 18,623, and 12,303 mPa·s, respectively. Compared to the other groups, the viscosity of the ZLs group suspension decreased by 70.98-88.04%. This confirmed that the viscosity of the suspensions was affected by the particle size and the presence of silane coating. The dispersion stability of the zirconia suspensions was evaluated over 20 days. A sedimentation test confirmed that the sedimentation rate of the ZLs group was slower than those of the other groups. This study aimed to optimize the suspension manufacturing method to effectively be utilized in further commercializing zirconia three-dimensional (3D) printing and could also help to develop various medical applications.

CAD/CAM scaffolds for bone tissue engineering: investigation of biocompatibility of selective laser melted lightweight titanium

The objective of the current in-vitro study was to evaluate the biocompatibility of a new type of CAD/CAM scaffold for bone tissue engineering by using human cells. Porous lightweight titanium scaffolds and Bio-Oss® scaffolds as well as their eluates were used for incubation with human osteoblasts, fibroblasts and osteosarcoma cells. The cell viability was assessed by using fluorescein diazo-acetate propidium iodide staining. Cell proliferation and metabolism was examined by using MTT-, WST-Test and BrdU-ELISA tests. Scanning electron microscope was used for investigation of the cell adhesion behaviour. The number of devitalised cells in all treatment groups did not significantly deviate from the control group. According to MTT and WST results, the number of metabolically active cells was decreased by the eluates of both test groups with a more pronounced impact of the eluate from Bio-Oss®. The proliferation of the cells was inhibited by the addition of the eluates. Both scaffolds showed a partial surface coverage after 1 week and an extensive to complete coverage after 3 weeks. The CAD/CAM titanium scaffolds showed favourable biocompatibility compared to Bio-Oss® scaffolds in vitro. The opportunity of a defect-specific design and rapid prototyping by selective laser melting are relevant advantages in the field of bone tissue engineering and regenerative medicine.

Advances in Antibacterial Functionalized Coatings on Mg and Its Alloys for Medical Use—A Review

As a revolutionary implant material, magnesium and its alloys have many exciting performances, such as biodegradability, mechanical compatibility, and excellent biosecurity. However, the rapid and uncontrollable degradation rate of magnesium greatly hampers its clinical use. Many efforts have been taken to enhance the corrosion resistance of magnesium. However, it must be noted that improving the corrosion resistance of magnesium will lead to the compromise of its antibacterial abilities, which are attribute and proportional to the alkaline pH during its degradation. Providing antibacterial functionalized coating is one of the best methods for balancing the degradation rate and the antibacterial ability of magnesium. Antibacterial functionalized magnesium is especially well-suited for patients with diabetes and infected wounds. Considering the extremely complex biological environment in the human body and the demands of enhancing corrosion resistance, biocompatibility, osteogenesis, and antibacterial ability, composite coatings with combined properties of different materials may be promising. The aim of this review isto collect and compare recent studies on antibacterial functionalized coatings on magnesium and its alloys. The clinical applications of antibacterial functionalized coatings and their material characteristics, antibacterial abilities, in vitro cytocompatibility, and corrosion resistance are also discussed in detail.

Strontium-substituted hydroxyapatite stimulates osteogenesis on poly(propylene fumarate) nanocomposite scaffolds

Incorporation of hydroxyapatite (HA) into polymer networks is a promising strategy to enhance the mechanical properties and osteoinductivity of the composite scaffolds for bone tissue engineering. In this study, we designed a group of nanocomposite scaffolds based on cross-linkable poly(propylene fumarate) (PPF) and 30 wt % strontium-hydroxyapatite (Sr-HA) nanoparticles. Four different Sr contents [Sr:(Sr + Ca), molar ratio] in the Sr-HA particles were studied: 0% (HA), 5% (Sr5-HA), 10% (Sr10-HA), and 20% (Sr20-HA). Two-dimensional (2D) disks were prepared using a thermal crosslinking method. The structure and surface morphology of different Sr-HA and PPF/Sr-HA composites were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). To detect cellular responses in vitro, MC3T3-E1 cells were seeded and cultured on the different PPF/Sr-HA composite disks. Cell morphology after 24 h and 5 days were imaged using Live/Dead live cell staining and SEM, respectively. Cell proliferation was quantified using an MTS assay at 1, 4, and 7 days. Osteogenic differentiation of the cells was examined by alkaline phosphatase (ALP) staining at 10 days and quantified using ALP activity and osteocalcin assays at 7, 14, and 21 days. The sizes of the HA, Sr5-HA, Sr10-HA, and Sr20-HA particles were mainly between 10 × 20 nm and 10 × 250 nm, and these nanoparticles were dispersed or clustered in the composite scaffolds. in vitro cell studies showed that the PPF/Sr10-HA scaffold was significantly better than the other three groups (PPF/HA, PPF/Sr5-HA, and PPF/Sr20-HA) in supporting MC3T3-E1 cell adhesion, proliferation, and differentiation. PPF/Sr10-HA may, therefore, serve as a promising scaffold material for bone tissue engineering. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 631-642, 2019.

Recent advances in the reconstruction of cranio-maxillofacial defects using computer-aided design/computer-aided manufacturing

With the development of computer-aided design/computer-aided manufacturing (CAD/CAM) technology, it has been possible to reconstruct the cranio-maxillofacial defect with more accurate preoperative planning, precise patient-specific implants (PSIs), and shorter operation times. The manufacturing processes include subtractive manufacturing and additive manufacturing and should be selected in consideration of the material type, available technology, post-processing, accuracy, lead time, properties, and surface quality. Materials such as titanium, polyethylene, polyetheretherketone (PEEK), hydroxyapatite (HA), poly-DL-lactic acid (PDLLA), polylactide-co-glycolide acid (PLGA), and calcium phosphate are used. Design methods for the reconstruction of cranio-maxillofacial defects include the use of a pre-operative model printed with pre-operative data, printing a cutting guide or template after virtual surgery, a model after virtual surgery printed with reconstructed data using a mirror image, and manufacturing PSIs by directly obtaining PSI data after reconstruction using a mirror image. By selecting the appropriate design method, manufacturing process, and implant material according to the case, it is possible to obtain a more accurate surgical procedure, reduced operation time, the prevention of various complications that can occur using the traditional method, and predictive results compared to the traditional method.

Study on the corrosion resistance and anti-infection of modified magnesium alloy

In this paper, a low-cost and multifunctional hydroxyapatite (HA)/pefloxacin (PFLX) drug eluting layer is coated on magnesium (Mg) alloy through a simple hydrothermal and dip process. The drug PFLX could provide effective prevention for bone infection and inflammation due to its broad-spectrum antibacterial property. And HA would promote the growth of new bone and further improve the biocompatibility of implants. Besides, both PFLX and HA exhibits excellent corrosion protection for Mg alloy substrate. This coating is of great value for improving the application of Mg alloy as biomaterials.