Abstract:This study aimed to establish a surface modification technology for ZK60 magnesium alloy implants that can degrade uniformly over time and promote bone healing. It proposes a special micro-arc oxidation (MAO) treatment on ZK60 alloy that enables the composite electrolytes to create a coating with better corrosion resistance and solve the problems of uneven and excessive degradation. A magnesium alloy bone screw made in this way was able to promote the bone healing reaction after implantation in rabbits. Additi… Show more
“…41 There are several mechanisms of Mg implant degradation in vivo. 42,43 These include electrochemical corrosion, hydroxide and hydrogen formation, and chloride attack. The hydrogen that evolved can accumulate as gas bubbles within the defect area, causing serious clinical problems.…”
Section: Biodegradation Of Mgca Implants Within Bone Defects Are Fine...mentioning
Mg-based biodegradable metallic implants are gaining increased attraction for applications in orthopedics and dentistry. However, their current applications are hampered by their high rate of corrosion, degradation, and rapid release of ions and gas bubbles into the physiological medium. The aim of the present study is to investigate the osteogenic and angiogenic potential of coated Mg-based implants in a sheep cranial defect model. Although their osteogenic potential was studied to some extent, their potential to regenerate vascularized bone formation was not studied in detail. We have studied the potential of magnesium−calcium (MgCa)-based alloys modified with zinc (Zn)-or gallium (Ga)-doped calcium phosphate (CaP) coatings as a strategy to control their degradation rate while enhancing bone regeneration capacity. MgCa and its implants with CaP coatings (MgCa/CaP) as undoped or as doped with Zn or Ga (MgCa/CaP + Zn and MgCa/CaP + Ga, respectively) were implanted in bone defects created in the sheep cranium. MgCa implants degraded faster than the others at 4 weeks postop and the weight loss was ca. 50%, while it was ca. 15% for MgCa/CaP and <10% in the presence of Zn and Ga with CaP coating. Scanning electron microscopy (SEM) analysis of the implant surfaces also revealed that the MgCa implants had the largest degree of structural breakdown of all the groups. Radiological evaluation revealed that surface modification with CaP to the MgCa implants induced better bone regeneration within the defects as well as the enhancement of bone−implant surface integration. Bone volume (%) within the defect was ca. 25% in the case of MgCa/CaP + Ga, while it was around 15% for undoped MgCa group upon micro-CT evaluation. This >1.5-fold increase in bone regeneration for MgCa/CaP + Ga implant was also observed in the histopathological examination of the H&E-and Masson's trichrome-stained sections. Immunohistochemical analysis of the bone regeneration (antiosteopontin) and neovascularization (anti-CD31) at the defect sites revealed >2-fold increase in the expression of the markers in both Ga-and Zn-doped, CaP-coated implants. Zn-doped implants further presented low inflammatory reaction, notable bone regeneration, and neovascularization among all the implant groups. These findings indicated that Ga-and Zn-doped CaP coating is an important strategy to control the degradation rate as well as to achieve enhanced bone regeneration capacity of the implants made of Mg-based alloys.
“…41 There are several mechanisms of Mg implant degradation in vivo. 42,43 These include electrochemical corrosion, hydroxide and hydrogen formation, and chloride attack. The hydrogen that evolved can accumulate as gas bubbles within the defect area, causing serious clinical problems.…”
Section: Biodegradation Of Mgca Implants Within Bone Defects Are Fine...mentioning
Mg-based biodegradable metallic implants are gaining increased attraction for applications in orthopedics and dentistry. However, their current applications are hampered by their high rate of corrosion, degradation, and rapid release of ions and gas bubbles into the physiological medium. The aim of the present study is to investigate the osteogenic and angiogenic potential of coated Mg-based implants in a sheep cranial defect model. Although their osteogenic potential was studied to some extent, their potential to regenerate vascularized bone formation was not studied in detail. We have studied the potential of magnesium−calcium (MgCa)-based alloys modified with zinc (Zn)-or gallium (Ga)-doped calcium phosphate (CaP) coatings as a strategy to control their degradation rate while enhancing bone regeneration capacity. MgCa and its implants with CaP coatings (MgCa/CaP) as undoped or as doped with Zn or Ga (MgCa/CaP + Zn and MgCa/CaP + Ga, respectively) were implanted in bone defects created in the sheep cranium. MgCa implants degraded faster than the others at 4 weeks postop and the weight loss was ca. 50%, while it was ca. 15% for MgCa/CaP and <10% in the presence of Zn and Ga with CaP coating. Scanning electron microscopy (SEM) analysis of the implant surfaces also revealed that the MgCa implants had the largest degree of structural breakdown of all the groups. Radiological evaluation revealed that surface modification with CaP to the MgCa implants induced better bone regeneration within the defects as well as the enhancement of bone−implant surface integration. Bone volume (%) within the defect was ca. 25% in the case of MgCa/CaP + Ga, while it was around 15% for undoped MgCa group upon micro-CT evaluation. This >1.5-fold increase in bone regeneration for MgCa/CaP + Ga implant was also observed in the histopathological examination of the H&E-and Masson's trichrome-stained sections. Immunohistochemical analysis of the bone regeneration (antiosteopontin) and neovascularization (anti-CD31) at the defect sites revealed >2-fold increase in the expression of the markers in both Ga-and Zn-doped, CaP-coated implants. Zn-doped implants further presented low inflammatory reaction, notable bone regeneration, and neovascularization among all the implant groups. These findings indicated that Ga-and Zn-doped CaP coating is an important strategy to control the degradation rate as well as to achieve enhanced bone regeneration capacity of the implants made of Mg-based alloys.
“…Degradability is the preferred choice for temporary implant support in bone healing, such as plates and screws, thus eliminating unnecessary surgical risks and excessive costs for a second surgery [ 58 ]. Currently, magnesium (Mg), Fe, and zinc (Zn) alloys are the best biodegradable metals for orthopedics because they have good in vivo biocompatibility, controlled degradation profiles, and sufficient mechanical strength to support bone during regeneration [ [59] , [60] , [61] , [62] ]. The mechanical properties of biomedical metal materials and natural human bone are listed in Fig.…”
Section: Metal Materialsmentioning
confidence: 99%
“…3 and Table 2 . Figure 3 Properties of 3D printing metal materials (A) Stainless steel [ 51 ], (B) Titanium alloy [ 52 ], (C) Cobalt-chromium alloy [ 53 ], (D) Tantalum alloy [ 52 ], (E) Shape memory alloy [ 54 ], (F) Zinc alloy [ 60 ], (G) Iron alloy [ 61 ], (H) Magnesium alloy [ 62 ], reproduced with permission. …”
“…Micro arc oxidation (MAO) is a common and mature surface treatment method for forming functionalized coatings with good physical, chemical, and biological properties on metal substrates. , MAO pretreatment of a magnesium substrate can form a high-quality MgO ceramic coating, strengthening the interface bonding between the coatings and metal substrates and improving corrosion resistance of the substrates. , In this study, we combined DCPD self-healing coatings with MAO to form biodegradable magnesium with excellent osteoinduction capabilities and corrosion resistance. Double-passivated treatment of the MAO and DCPD coatings (Mg-MAO/DCPD) exhibited mild preparation conditions and effectively maintained the integrity of the magnesium substrates.…”
Magnesium is a revolutionary biomaterial for orthopedic implants, owing to its eminent mechanical properties and biocompatibility. However, its uncontrolled degradation rate remains a severe challenge for its potential applications. In this study, we developed a self-healing micro arc oxidation (MAO) and dicalcium phosphate dihydrate (DCPD) double-passivated coating on a magnesium membrane (Mg-MAO/DCPD) and investigated its potential for bone-defect healing. The Mg-MAO/DCPD membrane possessed a feasible self-repairing ability and good cytocompatibility. In vitro degradation experiments showed that the Mg contents on the coating surface were 0.3, 3.8, 4.1, 6.1, and 7.9% when the degradation times were 0, 1, 2, 3, and 4 weeks, respectively, exhibiting available corrosion resistance. The slow and sustained release of Mg 2+ during the degradation process activated extracellular matrix proteins for bone regeneration, accelerating osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). The extract solutions of Mg-MAO/DCPD considerably promoted the activation of the Wnt and PI3K/AKT signaling pathways. Furthermore, the evaluation of the rat skull defect model manifested the outstanding bone-healing efficiency of the Mg-MAO/DCPD membrane. Taken together, the Mg-MAO/DCPD membrane demonstrates an optimized degradation rate and excellent bioactivity and is believed to have great application prospects in bone tissue engineering.
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