# Pearl‐Like Bioinspired Coating Enables Regulation of Mg Degradation for Osteoporotic Bone Repair

## TL;DR

A bioinspired coating on magnesium implants helps control degradation and improves bone repair in osteoporosis by regulating immune responses and promoting vascularization.

## Contribution

A bionic coating inspired by pearl structure is developed to regulate Mg degradation and enhance bone-vascular-immune integration in osteoporotic conditions.

## Key findings

- The Ca-P layer reduces rapid Mg degradation and prevents hydrogen gas release and local alkalinization.
- Fn-mimetic peptides promote early bone integration, vascularization, and immune regulation.
- The coating improves bone implant stability and regeneration in osteoporotic rat models.

## Abstract

In osteoporotic bones, the stability of orthopedic implants is compromised, and excessive M1 macrophage polarization at the bone‐implant interface disrupts bone‐immune homeostasis, leading to implant loosening or failure. To address this, this study develops a bionic magnesium alloy internal fixation coating inspired by the “brick‐and‐mortar” structure of pearl, aiming to improve bone‐implant integration and vascularization in osteoporotic conditions. The multifunctional coating consists of a calcium phosphate (Ca‐P) “brick” layer, which serves as a mineralization template and corrosion barrier, and fibronectin‐mimetic peptides (Fn‐mimetic peptides) as the “mortar” to promote cell adhesion, regulate immune responses, and stimulate angiogenesis. This bionic multilayer structure not only alleviates oxidative stress in the osteoporotic microenvironment but also fosters immune regulation‐osteogenesis coupling and improves the bone‐vascular‐immune microenvironment. It precisely controls the degradation rate of Mg alloys and enhances tissue repair. The CaP layer reduces rapid degradation and prevents hydrogen gas release and local alkalinization, whereas Fn‐mimetic peptides enhance early bone integration and vascularization. The synergistic effect of the magnesium alloy implant and bionic coating significantly improved bone implant stability, regeneration, and vascularization, as demonstrated in osteoporotic rat models, offering a promising strategy for the design of bone repair materials under pathological conditions.

In this study, inspired by pearl architecture, we developed a layered Ca–P “brick” and Fn‐mimetic peptide “mortar” coating on Mg alloys. The Ca–P layer moderates corrosion and offers mineral cues, while the peptide enhances adhesion and regulates immune‐vascular responses. This design aims to match Mg degradation with tissue repair, enabling faster, more stable osseointegration in osteoporotic bone.