In Vitro Corrosion Resistance of a Layer-by-Layer Engineered Hybrid Coating on ZK60 Magnesium Alloy

Mostafizur Rahman,Namita Roy Choudhury,Naba Kumar Dutta,Rajkamal Balu

doi:10.3390/su14042459

Mostafizur Rahman, Namita Roy Choudhury + Show 2 more

Open Access

https://doi.org/10.3390/su14042459

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Abstract

Magnesium alloys are next generation biodegradable implants for clinical applications. However, their medical applications are currently hampered by their rapid corrosion rate in the physiological environment. To overcome such limitations, we have applied a novel layer-by-layer engineering approach of introducing anodization-induced microrough oxidized surface on ZK60 magnesium alloy, followed by surface mineralization with natural calcium apatite (hydroxyapatite, HA), and surface coating with natural protein (silk fibroin, SF); which, effectively reduces corrosion and degradation rate of ZK60 in simulated body fluid. Anodization of ZK60 improved the surface adhesion strength of HA layer; HA layer increased the surface roughness, hydrophilicity and micro-hardness, whereas decreased ionic release; SF layer decreased surface microroughness and hydrophilicity, whereas improved the stability of HA layer. The SF + HA coating on anodized ZK60 effectively decreased the in vitro weight loss (degradation) by almost six times, whereas corrosion rate by more than two orders in magnitude. Such interfacial coatings, with biocompatible SF on the outer surface, could potentially expand the application of ZK60 in the field of biomedical engineering.

Highlights

Metallic constructs made of stainless steel, titanium, cobalt-chrome and nickel-titanium alloys have been conventionally used as bone implants
Magnesium (Mg) and its alloys have emerged as a new generation biomaterial, and as an alternative to the above conventional metallic implant materials owing to their superior biocompatibility, biodegradability, density and mechanical properties close to that of human bone [2]
The HA coating on the anodized ZK60 sample was observed to exhibit plate-like structures, which mimic the structure of natural bone tissue, and is considered to be advantageous for improving osseointegration [24]

Summary

Introduction

Metallic constructs made of stainless steel, titanium, cobalt-chrome and nickel-titanium alloys have been conventionally used as bone implants. In the long run, they cause distress to the host body due to release of toxic metal ions, mechanical property mismatch, and non-biodegradability leading to secondary surgical procedures [1]. Magnesium (Mg) and its alloys have emerged as a new generation biomaterial, and as an alternative to the above conventional metallic implant materials owing to their superior biocompatibility, biodegradability, density and mechanical properties close to that of human bone [2]. Mg exists in the human body as an abundant element skeletal muscles and soft tissues (30–40%), distributed in bones (60%), and take part in the physiological activities [3]. The main problem associated with the use of Mg as implant material is their rapid corrosion rate in the biological environments.

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