# From Corrosion Control to Cell Adhesion: Parascholzite as a Functional Interface for Biodegradable Zinc Alloys

## TL;DR

A phosphate layer called parascholzite improves the corrosion resistance and cell compatibility of biodegradable zinc alloys for biomedical implants.

## Contribution

A parascholzite layer is developed to control corrosion and enhance cell adhesion on biodegradable zinc alloys.

## Key findings

- The Zn-Ca-P layer significantly improves corrosion resistance and enables controlled degradation.
- The parascholzite layer enhances cell adhesion and cytocompatibility compared to the bare alloy.
- The phosphate-rich surface chemistry and morphology contribute to improved biological response.

## Abstract

Zinc-based alloys are promising candidates for biodegradable implant applications; however, their rapid initial corrosion and limited cytocompatibility remain major challenges. In this study, a Zn-Ca-P layer in a form of parascholzite (CaZn2(PO4)2·2H2O) was prepared on a Zn-0.8Mg-0.2Sr alloy via anodic oxidation followed by short-time biomimetic calcium–phosphate deposition. The formation mechanism, corrosion behaviour, and preliminary biological response of the modified surface were systematically investigated. The Zn-Ca-P layer formed a compact and crystalline phosphate layer that significantly altered the corrosion response of the zinc substrate in Leibovitz L-15 medium containing foetal bovine serum. Electrochemical measurements revealed a pronounced improvement in corrosion resistance and a transition from rapid active dissolution to a controlled, ion-exchange-driven degradation mechanism. The moderate solubility of parascholzite enabled the gradual release of Zn2+ and Ca2+ ions while maintaining surface stability during immersion. Preliminary cell adhesion experiments demonstrated a clear enhancement of cytocompatibility for the Zn-Ca-P-layer-coated samples, where cells readily adhered and spread, in contrast to the bare alloy surface, which showed lower cell attachment. The improved biological response is attributed to the phosphate-rich surface chemistry, favourable surface morphology, and moderated corrosion behaviour. Overall, the parascholzite-like layer provides an effective strategy with which to regulate both corrosion and early cell–material interactions of zinc-based biodegradable alloys, highlighting its potential for temporary biomedical implant applications.