Abstract

In this paper an attempt is made to examine on magnesium alloys has made them even more interesting because of their potential in biodegradable implants owing to the wonderful properties of biocompatibility, very low mechanical properties compared to natural bone, and biodegradability in physiological environments. However, the rapid corrosion rates and problems associated with it, such as hydrogen evolution and mechanical integrity loss, have focused attention on magnesium alloy composites. This mini-review hence presents a short summary of progress made over recent years towards the development of magnesium-based composites suitable for biodegradable implant applications. The introduction is meant to give the significance of biodegradable implants and the role that magnesium is going to play there. The article spells alloying strategies, reinforcement materials, and surface modification used to improve corrosion resistance, biocompatibility, and mechanical performance. It shows the most promising future for magnesium-based composites through clear definitions of problems and opportunities for future work.

Keywords: Magnesium-based biomaterials; Bioactivity; Temporary implants; Bone fixture materials; Surface modifications; Bio-corrosion

Magnesium-Based Alloys, Various Reinforcements, and Surface Modification Strategies

Magnesium alloys for biodegradable implants

Possible Mg alloys being explored for biomedical applications include AZ31, WE43, and ZE21. Theoretically, they offer superior mechanical properties and corrosion resistance compared with pure Mg. However, further improvements are still needed to meet strict implant application requirements mandates the development of composites.

Reinforcements in magnesium-based composites

The incorporation of reinforcements in magnesium alloys has recently been considered an effective method for reducing their rapid degradation and enhancing performance. Common reinforcements include:

a) Ceramic particles: This includes hydroxyapatite (HA), bioactive glass, and zirconia as the reinforcement elements by which biocompatibility is improved and the corrosion rates reduced. However, HA has been the one that is found to promote osseointegration as well as bioactivity [8,9].

b) Metallic particles: Zinc, silver, and titanium are some of the metals known to increase the corrosion resistance coupled with an antibacterial effect, such as silver, which endows both mechanical strength and antimicrobial activity.

c) Carbon-based nanomaterials: An example of which would include graphene oxide and carbon nanotubes, which are used essentially for their high strength as well as corrosion resistance. Another benefit is that these materials provide functional sites for drug delivery.

Surface modification techniques

Using several surface treatments and coatings, corrosion behavior of magnesium composite can be well controlled. Some of the techniques include:

a) Chemical conversion coating: The protective layer formed is phosphate or fluoride, which attenuate the degradation.

b) Polymer coatings: Agents such as polylactic acid (PLA) and polycaprolactone (PCL) control the degradation through a barrier that allows imparting time for corrosion to occur while generating a platform for controlled drug releases [10].

c) Micro-Arc Oxidation (MAO): This is the process in which an oxide coat is created, and it is thick enough to ensure corrosion resistance and yet maintain its biocompatibility.

Challenges and Opportunities

However, there are still numerous challenges in optimizing Mg composites for clinical applications. Degradation rates of materials need to be balanced with mechanical stability. Scalability and reproducibility of the procedures are also very important to translate successes from the laboratory to the clinic. Hybrid reinforcements and advanced manufacturing techniques, such as additive manufacturing, are fascinating topics for future studies.

Conclusion

a) The composites of magnesium alloy have a great deal to offer in the area of application for biodegradable implants, because of fulfilling the requirements for biodegradability, mechanical properties, and biocompatibility at one go.

b) Several works were undertaken in the direction of alloying, reinforcement strategies, and surface modifications, and have taken this subject much forward. But one of the most important areas to investigate is the compromise between corrosion resistance and mechanical integrity, which must be settled with biocompatibility.

c) Each future research must pay attention to the development of specific composites and coatings; advanced fabrication techniques; and a complete in vivo evaluation, as this would help in realizing the clinical applications of magnesium-based biodegradable implants.

References

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