Influence of the pre-exposure of a Zn-0.8Mg-0.2Sr absorbable alloy in bovine serum albumin containing media on its surface changes and their impact on the cytocompatibility of the material
Abstract
In this study, the ternary alloy ZnMg0.8Sr0.2 (wt%) was pre-exposed in a phosphate buffer solution (PBS) with and without the addition of 1 wt% of bovine serum albumin (BSA) to simulate the early stage of the post-implantation period. We investigated the influence of the presence of BSA in the pre-exposure medium on surface chemistry, roughness topography and cytotoxicity of the pre-exposed materials.
This study revealed that the pre-exposure in PBS with the addition of BSA induces the formation of a relatively thick and compact phosphate layer on the sample surface. In contrast, the majority of the surface of the samples pre-exposed in pure PBS appear almost untouched, and only a few small areas covered by eye-visible corrosion products were observed.
This resulted in lower ion release (66 mu mol/L) and a consequent decrease of the cytotoxicity of the eluates prepared from the samples pre-exposed in the BSA containing media. Together with the knowledge available from the literature, the obtained results indicate that BSA affects the degradation mechanism of the Zn-based alloy, resulting in the formation of zinc-BSA complexes.
These complexes stimulate the precipitation of phosphates and a consequent formation of solid corrosion products with a protective function. This partially mimics the surface changes occurring in the early post-implantation period.
The aforementioned suggests that a suitable pre-exposure of Zn-based absorbable materials in a protein containing media could be used as an approach to obtain reliable data about cytocompatibility by in vitro tests and reduce the discrepancies with the results obtained in vivo.