*Article*

## **Electrospun Sca** ff**olds Containing Silver-Doped Hydroxyapatite with Antimicrobial Properties for Applications in Orthopedic and Dental Bone Surgery**

**Thomas E. Paterson 1,**†**, Rui Shi 2,**†**, Jingjing Tian 3,4,**†**, Caroline J. Harrison 1, Mailys De Sousa Mendes 5, Paul V. Hatton 1,\*, Zhou Li 3,\* and Ilida Ortega 1**


Received: 21 May 2020; Accepted: 28 July 2020; Published: 14 August 2020

**Abstract:** Preventing the development of osteomyelitis while enhancing bone regeneration is challenging, with relatively little progress to date in translating promising technologies to the clinic. Nanoscale hydroxyapatite (nHA) has been employed as a bone graft substitute, and recent work has shown that it may be modified with silver to introduce antimicrobial activity against known pathogens. The aim of this study was to incorporate silver-doped nHA into electrospun sca ffolds for applications in bone repair. Silver-doped nHA was produced using a modified, rapid mixing, wet precipitation method at 2, 5, 10 mol.% silver. The silver-doped nHA was added at 20 wt.% to a polycaprolactone solution for electrospinning. Bacteria studies demonstrated reduced bacterial presence, with *Escherichia coli* and *Staphylococcus aureus* undetectable after 96 h of exposure. Mesenchymal stem cells (MSCs) were used to study both toxicity and osteogenicity of the sca ffolds using PrestoBlue ® and alkaline phosphatase (ALP) assays. Innovative silver nHA sca ffolds significantly reduced *E*. *coli* and *S. aureus* bacterial populations while maintaining cytocompatibility with mammalian cells and enhancing the di fferentiation of MSCs into osteoblasts. It was concluded that silver-doped nHA containing sca ffolds have the potential to act as an antimicrobial device while supporting bone tissue healing for applications in orthopedic and dental bone surgery.

**Keywords:** electrospinning; antimicrobial; nano-hydroxyapatite; silver; toxicity; bone regeneration
