Role of proteins in the degradation of relatively inert alloys in the human body

Abstract

Many biomedical materials used today for applications such as orthopedic, dental, and cardiovascular implants and devices are made of corrosion-resistant, 'inert', metallic materials of the cobalt-chromium, titanium, and stainless steel alloy groups. This perspective focuses on the role of proteins in the degradation of these materials in a human body environment. After adsorption, the proteins interact relatively slowly with the metal and metal surface oxide. A number of factors, including the individual body chemistry (especially the presence of inflammatory cells producing oxidative species), determine whether the proteins can bind to metals in the surface oxide and whether the metal-protein conjugates can detach from the surface. Metals in the forms of proteinbound metal ions or nanosized particles can also increase protein-protein interactions and aggregation, which can cause some health effects and change the material degradation mechanism. While proteins in some short-term studies (<6 h) even decrease material degradation due to shielding effects and better lubrication, they may increase degradation after longer time periods due to relatively slow binding, detachment, and combined corrosion processes. In-vitro material degradation studies of relatively corrosion-resistant alloys for biomedical applications should therefore include long-term studies, complexing agents or proteins, and realistic oxidative environments simulating inflammatory conditions.

Influence of Biocorona Formation on the Transformation and Dissolution of Cobalt Nanoparticles under Physiological Conditions

“…Initially hindered release processes in the presence of adsorbed polypeptides/proteins are in general concordance with the trends often observed for corrosion and metal release. 57 The adsorbed molecules will temporarily block the surface areas for ongoing dissolution/corrosion processes. However, slower corrosion/release processes such as ligand exchange that take place after certain time periods can result in enhanced dissolution, 57 even though some exceptions from this trend have been reported for corrosion.…”

“…57 The adsorbed molecules will temporarily block the surface areas for ongoing dissolution/corrosion processes. However, slower corrosion/release processes such as ligand exchange that take place after certain time periods can result in enhanced dissolution, 57 even though some exceptions from this trend have been reported for corrosion. 58 There is moreover a possibility that the biomolecules may slowly replace the adsorbed phosphate.…”

Materials for Orthopedic Bioimplants: Modulating Degradation and Surface Modification Using Integrated Nanomaterials

“…Biological components are also chemically active, generating various ionic species during their metabolism. These chemical moieties are known to interact with the surface of metal/metal alloy-based bioimplants [99]. After initial phases of adsorption and surface oxidation, the proteins slowly interact with the implant surface in a size-dependent manner, with smaller proteins interacting being the initiator.…”

“…Furthermore, it is also evident that some proteins can bypass the normal route of metal-alloy interaction and directly bind to the metal surface without the formation of an oxide layer as shown in Figure 1b. In addition, initiation of localized corrosion at the load-bearing site contributes towards the metal erosion to a greater extent than the other parts [99].…”

Inhibiting Corrosion of Biomedical-Grade Ti-6Al-4V Alloys with Graphene Nanocoating

“…Nevertheless, implant-related issues such as superficial modification, design, fracture, and overloading also decrease success rate (Appendix). Concern has been increasing about impurities in the alloy, irregularities in the oxide layer, functional stresses, and friction during treatment of diseased implant sites, which can increase fatigue, wear, degradation, and crevice corrosion (Sridhar et al 2016; Hedberg 2018; Sikora et al 2018). Additionally, implants can be exposed to biofilms that reduce the environmental pH through oxygen-coupled metabolic activities (Fukushima et al 2014).…”