# Functionalization of collagen fiber with nano-islands of silver via atomic layer deposition to promote bone healing

## TL;DR

Researchers used atomic layer deposition to coat collagen with silver nano-islands, which improved bone healing without harming cells.

## Contribution

First use of atomic layer deposition to coat collagen with silver nano-islands for enhanced bone healing.

## Key findings

- Silver nano-islands of ∼16 nm were successfully deposited on collagen fibrils using ALD.
- Silver-coated collagen showed no cytotoxicity in in vitro and in vivo tests.
- In vivo experiments showed a significant increase in new bone formation with silver-coated collagen.

## Abstract

Modern techniques of thin film deposition (e.g., atomic layer deposition [ALD]) have paved the way for the modification of the surface of target substrates with thin films, nanoparticles, or other types of nanomaterials. This novel way can improve the base material's properties and enhance specific properties through adding functionalized groups to the surface. In this study, ALD of silver was conducted on commercially available Type I collagen membrane to improve its bioactivity and promote bone healing. Two different sample groups were studied: pristine collagen and silver-coated collagen via ALD (Ag/Collagen). Chemical and morphological changes of the collagen membrane were investigated with X-ray photoelectron spectroscopy and scanning electron microscopy and the bioactivity of functionalized collagen with silver was studied in vitro and in vivo. Nano-islands of silver were obtained on collagen fibrils with an average diameter of ∼16 nm. Comparison of gingival cells cultured on pristine collagen, and silver-coated collagen, demonstrated that the attained silver nanoparticle size and concentration are below the toxicity level of silver. In vivo assessment in rat model showed the biocompatibility of the Ag/Collagen, and greater new bone formation compared to control. This novel solvent-free method can be used to functionalize sensitive materials used in surgeries as bone grafting agents to enhance osteopromotive properties without any adverse effects to the cellular environment.

•For the first time, collagen (COL) was coated with silver nano-islands, ∼16 nm in size, using atomic layer deposition.•Coated collagen (COL-1300Ag) did not affect cytotoxicity, confirmed by in-vitro and in-vivo analysis of animal experiments.•In-vivo experiments revealed adding silver to collagen increased newly formed bone by an order of magnitude compared to COL.•In-vivo experiments revealed that adding silver to collagen increased the amount of newly formed bone in large defects.

For the first time, collagen (COL) was coated with silver nano-islands, ∼16 nm in size, using atomic layer deposition.

Coated collagen (COL-1300Ag) did not affect cytotoxicity, confirmed by in-vitro and in-vivo analysis of animal experiments.

In-vivo experiments revealed adding silver to collagen increased newly formed bone by an order of magnitude compared to COL.

In-vivo experiments revealed that adding silver to collagen increased the amount of newly formed bone in large defects.