Micro/Nano‐Structured Metal–Organic/Inorganic Hybrid Coatings on Biodegradable Zn for Osteogenic and Biocompatible Improvement

Abstract

Biodegradable Zn‐based metals have recently gained great attention for orthopedic implant applications, due to their attractive attributes in biodegradability, mechanics, and bio‐functionalities. However, Zn‐based metals suffer from excessive Zn2+ release leading to bio‐incompatibility and insufficient osteogenic properties. Herein, bioactive molecules incorporated zinc phosphate (ZnP) of metal–organic/inorganic hybrid coatings are constructed on Zn surfaces by dip‐coating, targeting a decrease in Zn2+ release rate and an improvement in biocompatible and osteogenic properties. The bioactive molecules, cysteine, phenylalanine, and bovine serum albumin, are incorporated into inorganic ZnP using a metal–organic/inorganic coordination strategy. As a result, these hybrid coatings are compact, and present different micro/nanostructured surface morphology. The electrochemical and long‐term static immersion results show that the hybrid coatings decrease the corrosion rate of Zn, reduce the Zn2+ ion release rate, and promote hydroxyapatite deposition. In addition, they promote the proliferation and adhesion of preosteoblast MC3T3‐E1 and rat bone marrow mesenchymal stem cells, and up‐regulate the expression of osteogenesis‐related genes. Such appealing properties can be attributed to the characteristic micro/nanostructured surface morphologies and the presence of the bioactive components. These metal–organic/inorganic hybrid coatings provide a novel avenue to modify the surface of Zn‐based metals for orthopedic implant applications.

Effect of Substrates Performance on the Microstructure and Properties of Phosphate Chemical Conversion Coatings on Metal Surfaces

“…Figure 5 d displays the Bode magnitude and phase-angle plots, indicating that the bare-TA and coated-TA samples exhibit different relaxation features. The bare-TA substrate only contains one time constant, but the coated-TA has two capacitive loops, which represent the presence of two interfaces (solution/coating and coating/substrate) in the coated samples [ 35 , 36 ]. In particular, the capacitive loop at high frequency corresponds to the ZnP coating, but the capacitive loop at low frequency is related to the double layer at the interface between the substrate and solution.…”

Crystalline Biomimetic Calcium Phosphate Coating on Mini-Pin Implants to Accelerate Osseointegration and Extend Drug Release Duration for an Orthodontic Application

“…Such an accelerating effect may be attributed to the following three mechanisms: (1) The polar functional groups, such as the hydroxyl ions and phosphate groups in the crystalline coating, make it more hydrophilic than the uncoated SLA Ti surface [ 26 , 66 ]. This hydrophilic surface can support the interaction between cells and the surface, benefit cell adhesion and spreading, and mediate more natural biological cell responses/behaviors [ 67 , 68 , 69 , 70 , 71 ]. (2) The crystalline coating consists of large crystals oriented vertically to the substrate surface.…”

Zinc-based biomaterials for bone repair and regeneration: mechanism and applications

“…The ultimate concentration of zinc ions after 21 days was the highest when the release rate was the fastest. 89 And inhibited cell proliferation by Zn decorated HA could be attributed to the existence of ZnO. ZnO led to DNA damage and cell apoptosis, causing decreased cell proliferation.…”

“…Zinc phosphate containing metal-organic/ inorganic composite coatings was established to retard degradation and zinc ion release. 89 The organic constituents of the composite coatings such as cysteine, phenylalanine, and bovine serum albumin optimized the growth orientation and grain size of the ZnP coating. Slower Zn 2+ release and pH increase accompanying enhanced corrosion resistance further proved the effect of composite coatings.…”

“…Slower Zn 2+ release and pH increase accompanying enhanced corrosion resistance further proved the effect of composite coatings. 89 Collagen embedding calcium/zinc phosphates coatings was also reported to improve corrosion resistance of Zn. 150 In addition, a MAO-PLA modified Zn–Mg–Mn alloy exhibited greater corrosion resistance.…”