Unveiling the effect of bovine serum albumin on the corrosion resistance of high nitrogen stainless steel for cardiac stents

Abstract

Herein, the effect of bovine serum albumin (BSA) on the corrosion resistance of high nitrogen stainless steel (HNS) is systematically investigated based on experimental characterizations and first-principle calculations. Electrochemical measurements firstly prove that the anodic dissolution rate of HNS has significantly increased due to BSA adsorption and the potential deterioration of the passive film. By subsequent morphology and composition characterizations, it is demonstrated that BSA forms a 1.9 μm porous adsorption layer on HNS surface via the peptide bond mostly in -helix and -turn structure. Furthermore, Mott-Schottky tests confirm that the carrier (cation vacancy) density in the passive film has dramatically risen from 6.29×1021 cm-3 to 1.97×1022 cm-3 after BSA adsorption, which could be ascribed to the detachment of Cr atom from its original lattice due to the preference interaction between BSA molecule and Cr atom. Most importantly, such an increased defects will further promote the dissolution process of both the passive film and HNS matrix according to point defect model (PDM), which will definitely undermine the protective ability of the passive film and eventually result in the declined corrosion resistance of HNS in BSA-contained solution.