Development of Biodegradable Zinc, Magnesium and Calcium Phosphate Based Metal Matrix Composites for Potential Pediatric Orthopedic Applications

Abstract

Mostly biodegradable implants are used because it does not need any kind of second surgery. Implant is not necessary to remove outside the body. Revision surgeries are painful, costly and cause infection at the site. In case of biodegradable implants, the implants degrade and absorb in the surrounding tissues and release ions that are mostly consumed by the human body or are excreted from the body. Zn, Mg and CaP based composites implants are biodegradable and have less corrosion rate when these materials are combined to form the alloys. Pure Zn possess low mechanical strength that limits its applications in orthopedics field. So Zn is combined with Magnesium and make a solid metal matrix with CaP as a reinforced phase inside that matrix. In this metal matrix transfer load to reinforcement phase that better the mechanical properties of the composites. Addition of different elements in the Zn can improve the biocompatibility, cell viability and corrosion rate of the implant. As calcium phosphate is main constituent of the bone about 60-70% present in bones so addition of CaP in Zn make it better composite implant used for orthopedic applications. CaP help in regeneration of osteoblast cells in human body so it also improves the cell viability in the human cell. As it is cell friendly so one disadvantage of using CaP is that it does not give good anti-bacterial results. It helps to grow bacteria as calcium is also part of bacterial cell. Bacterial cells contain number of calcium binding proteins. This work mainly focuses on the synthesis of Zn-xMg-xCaP composites through powder metallurgy route. In this procedure all the three powders were ball milled at 300rpm for 3 hrs. then is being compressed at 2500 KGS force and at the end it is being sintered at 350oC. Then different experiments like density difference, micro hardness, degradation, cell viability and anti-bacterial activity were performed. Also different characterizations like SEM, XRD, optical images were taken for the analysis.