# Bioengineered hollow nanoflowers to synergistically modulate inflammation, angiogenesis and osteogenesis for enhancing repair of bone defects

## TL;DR

Scientists created hollow nanoflowers that reduce inflammation, boost blood vessel growth, and promote bone formation to improve bone defect repair.

## Contribution

A novel nanoflower platform is introduced that synergistically modulates inflammation, angiogenesis, and osteogenesis for bone regeneration.

## Key findings

- Au NPs@ZIF-8/Ga reduced pro-inflammatory cytokines via NF-κB pathway suppression in macrophages.
- The nanoflowers enhanced endothelial cell migration and tube formation, and promoted osteogenic differentiation.
- In vivo, the nanoflowers improved inflammation resolution, neovascularization, and bone formation in a rat model.

## Abstract

Inadequate control of inflammation and insufficient vascularization remain major challenges in repair of bone defects. Here, we developed a multifunctional nanoflower, Au NPs@ZIF-8/Ga, by loading gallic acid (Ga) into a nanoflower-like structure consisting of gold nanoparticles (Au NPs) core and zeolitic imidazolate framework-8 (ZIF-8) shell, to synergistically exert anti-inflammatory, pro-angiogenic, and osteogenic effects.

The hollow architectures of the synthesized Au NPs@ZIF-8/Ga nanoflowers were characterized by transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and nitrogen adsorption–desorption analysis. In vitro studies demonstrated that Au NPs@ZIF-8/Ga reduced secretion of pro-inflammatory cytokines in macrophages via suppressing NF-κB pathway activation, while concurrently promoted endothelial cell migration, and tube formation. Yet, Au NPs@ZIF-8/Ga enhanced osteogenic differentiation of MC3T3-E1 cells, as evidenced by the upregulated expression of bone formation related genes runt-related transcription factor 2 (RUNX2) and osteocalcin (OCN), as well as increased alkaline phosphatase (ALP) activity and bone matrix mineralization. In vivo studies showed that Au NPs@ZIF-8/Ga promoted early resolution of inflammation, neovascularization and robust new bone formation in a rat model with critical-sized calvarial defects, as confirmed by Micro-computed tomography (micro-CT) and histological analyses.

Collectively, this work presents a versatile nanoplatform for reducing inflammation in early stage while subsequently promoting angiogenesis and osteogenesis, thereby offering a promising therapeutic strategy for bone regeneration under inflammatory conditions.

The online version contains supplementary material available at 10.1186/s12951-025-03891-0.