Synthesis and characterization of metal-ceramic based advanced bio-materials for implant applications

Abstract

The demand for implants is increasing due to the aging population, trauma, injury, and daily lifestyle. An improved and advanced materials and processing technique is needed to reduce the complications caused by implants. Pure metallic biomaterials are widely used for orthopedic and high-load bearing implants as permanent replacements or to support damaged body parts as scaffolds and fixation devices. However, their high mechanical properties (modulus, hardness, etc.) and corrosive nature of metals negatively impact the surrounding bones and tissues, termed as “stress-shielding”. Stress-shielding is a phenomenon that causes damage to existing natural bones and surrounding tissues due to a mismatch in their mechanical characteristics (modulus, hardness, stiffness, etc.) with that of implants/scaffolds. This makes the implant-tissue interface critical, as it damages the existing natural tissue. In this work, metal-ceramic-based composites have been synthesized using mechanical alloying followed by sintering with microwave hybrid heating (MHH) to propose a possible advanced material for implant applications. Microstructural, Chemical, Material-phase, Mechanical, Tribological, Corrosion, and in vitro cytocompatibility tests (MTT Assay) have been conducted to establish their effectiveness. The presence of functional groups of 𝑃𝑂43− and 𝐶𝑂3 2− as well as Ca:P ratio of 1.6 in the synthesized composites makes it suitable for implant applications chemically. Further, the same homogeneously alloyed materials have been stacked to synthesize a functionally graded material (FGM) using the powder metallurgy route. The measured microhardness and frictional characteristics exhibit tailored properties along the gradation direction. These results inferred that the synthesized materials could minimize the stress-shielding effect and improve the implant-tissue interaction behaviour. The synthesis and a thorough characterization results strongly supports the fact that the FGM has the desired properties to mimic the architecture of natural bone (having varying density and mechanical strength in a gradient manner). Furthermore, using better biocompatible constituent materials, metals can appreciably enhance the bioactivity of the resulting material. Thus, the proposed advanced composite materials may be used to design and fabricate high-load-bearing implants with the required structural, mechanical, and biological properties.