In-vivo bone remodeling potential of Sr-d-Ca-P /PLLA-HAp coated biodegradable ZK60 alloy bone plate

Mg alloys with antitumor and anticorrosion properties for orthopedic oncology: A review from mechanisms to application strategies

As a primary malignant bone cancer, osteosarcoma (OS) poses a great threat to human health and is still a huge challenge for clinicians. At present, surgical resection is the main treatment strategy for OS. However, surgical intervention will result in a large bone defect, and some tumor cells remaining around the excised bone tissue often lead to the recurrence and metastasis of OS. Biomedical Mg-based materials have been widely employed as orthopedic implants in bone defect reconstruction, and, especially, they can eradicate the residual OS cells due to the antitumor activities of their degradation products. Nevertheless, the fast corrosion rate of Mg alloys has greatly limited their application scope in the biomedical field, and the improvement of the corrosion resistance will impair the antitumor effects, which mainly arise from their rapid corrosion. Hence, it is vital to balance the corrosion resistance and the antitumor activities of Mg alloys. The presented review systematically discussed the potential antitumor mechanisms of three corrosion products of Mg alloys. Moreover, several strategies to simultaneously enhance the anticorrosion properties and antitumor effects of Mg alloys were also proposed.

Evaluation of Gelatin/Hyaluronic Acid-Generated Bridging in a 3D-Printed Titanium Cage for Bone Regeneration

3D-printed titanium (Ti) cages present an attractive alternative for addressing issues related to osteoporosis-induced fractures, accidental fractures, and spinal fusion surgery due to disc herniation. These Ti-based bone implants possess superior strength compared to other metals, allowing for versatile applications in orthopedic scenarios. However, when used as standalone solutions, certain considerations may arise, such as interaction with soft tissues. Therefore, to overcome these issues, the combination with hydrogel has been considered. In this study, to impart Ti with regenerative abilities a 3D-printed Ti cage was loaded with gelatin and hyaluronic acid (G-H) to improve the cell attachment ability of the Ti-based bone implants. The void spaces within the mesh structure of the 3D Ti cage were filled with G-H, creating a network of micro-sized pores. The filled G-H acted as the bridge for the cells to migrate toward the large inner pores of the 3D Ti cage. Due to the microporous surface and slow release of gelatin and hyaluronic acid, the biocompatibility of the coated Ti cage was increased with an elevation in osteoconduction as depicted by the up-regulation of bone-related gene expressions. The in vivo implantation in the rabbit femur model showed enhanced bone regeneration due to the coated G-H on the Ti cage compared to the pristine hollow Ti cage. The G-H filled the large holes of the 3D Ti cage that acted as a bridge for the cells to travel inside the implant and aided in the fast regeneration of bone.

Poly(l-lactide)/polycaprolactone based multifunctional coating to deliver paclitaxel/VEGF and control the degradation rate of magnesium alloy stent

Despite significant advancements made in cardiovascular stents, restenosis, thrombosis, biocompatibility, and clinical complications remain a matter of concern. Herein, we report a biodegradable Mg alloy stent with a dual effect of the drug (Paclitaxel) and growth factor (VEGF) release. To mitigate the fast degradation of Mg alloy, inorganic and organic coatings were formed on the alloy surface. The optimized hierarchal sequence of the coating was the first layer consisting of magnesium fluoride, followed by poly(l-lactide) and hydroxyapatite coating, and finally sealed by a polycaprolactone layer (MgC). PLLA and HAp were used to increase the adhesion strength and biocompatibility of the coating. Paclitaxel and VEGF were loaded in the final PCL layer (Mg-C/PTX-VEGF). As compared to bare Mg alloy (28 % weight loss), our MgC system showed (3.1 % weight loss) successful decrease in the degradation rate. Further, the in vitro biocompatibility illustrated the highly biocompatible nature of our drug and growth factor-loaded system. The in vivo results displayed that the drug loading decreased the inflammation and neointimal hyperplasia as indicated by the α-SMA and CD-68 antibody staining. The growth factor helped in the endothelialization which was established by the FLKI and ICAM antibody staining of the tissue.

Plasma-Enabled Graphene Quantum Dot Hydrogel-Magnesium Composites as Bioactive Scaffolds for In Vivo Bone Defect Repair

Bioactive and mechanically stable metal-based scaffolds are commonly used for bone defect repair. However, conventional metal-based scaffolds induce nonuniform cell growth, limiting damaged tissue restoration. Here, we develop a plasma nanotechnology-enhanced graphene quantum dot (GQD) hydrogel-magnesium (Mg) composite scaffold for functional bone defect repair by integrating a bioresource-derived nitrogen-doped GQD (NGQD) hydrogel into the Mg ZK60 alloy. Each scaffold component brings major synergistic advantages over the current alloy-based state of the art, including (1) mechanical support of the cortical bone and calcium deposition by the released Mg2+ during degradation; (2) enhanced uptake, migration, and distribution of osteoblasts by the porous hydrogel; and (3) improved osteoblast adhesion and proliferation, osteogenesis, and mineralization by the NGQDs in the hydrogel. Through an in vivo study, the hybrid scaffold with the much enhanced osteogenic ability induced by the above synergy promotes a more rapid, uniform, and directional bone growth across the hydrogel channel, compared with the control Mg-based scaffold. This work provides insights into the design of multifunctional hybrid scaffolds, which can be applied in other areas well beyond the demonstrated bone defect repair.

Novel Phosphate Conversion Coating with Superior Corrosion Resistance on the Mg-Al-RE Alloy Based on the Introduction of Silane

A novel chemical conversion method based on an aqueous electrolyte solution containing hydrolyzed silane as a crucial film-forming agent has been developed successfully. An organic/inorganic composite coating with superior corrosion protection was fabricated on the Mg-Al-RE alloy. The micro-morphology and chemical composition of the coating were examined using scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The prepared conversion coating possesses a double-layer structure, with a dense bottom layer and a loose outer layer containing microcracks. In addition, the anti-corrosion capacity of various samples was evaluated using salt spray, hydrogen evolution, and electrochemical tests. The analysis revealed that the samples converted by 3-aminopropyl triethoxysilane (APTES)-phosphate solution possessed a higher corrosion resistance. Compared to the blank sample, a 2 orders of magnitude reduction in icorr (6.678 × 10-7 A/cm2) and a 1.360 V improvement in Ecorr were observed. The MPCC-Si sample exhibited the lowest hydrogen evolution rate, indicating the best corrosion protection. Also, the rust grade could still reach 7 after 72 h of the neutral salt spray test.