Modifications of Hydroxyapatite by Gallium and Silver Ions—Physicochemical Characterization, Cytotoxicity and Antibacterial Evaluation

Kamil Pajor,Joanna Kolmas,Urszula Piotrowska,Anna Zgadzaj,Łukasz Pajchel

doi:10.3390/ijms21145006

Abstract

Hydroxyapatite (HA) powders enriched with silver or gallium ions or both were synthesized by two different routes: standard precipitation and the solid-state method. The powders were characterized by using several methods: inductively coupled plasma optical emission spectrometry (ICP-OES), powder X-ray diffractometry (PXRD), transmission electron microscopy (TEM), infrared spectroscopy (FT-IR) and solid-state nuclear magnetic resonance spectroscopy (ssNMR). The effects of enrichment of the HAs in Ag+ or Ga3+ or both on in vitro cytotoxicity and microbiological activity were discussed. PXRD experiments showed that the samples obtained by the wet method consisted of single-phase nanocrystalline HA, while the samples prepared via the solid-state method are microcrystalline with a small amount of calcium oxide. The introduction of higher amounts of silver ions was found to be more effective than enriching HA with small amounts of Ag+. Gallium and silver ions were found not to affect the lattice parameters. Ga3+ affected the crystallinity of the samples as well as the content of structural hydroxyl groups. Among samples synthesized by the wet method, only one (5Ag-HAw) was cytotoxic, whereas all Ga-containing samples obtained by the dry method showed cytotoxicity. In the preliminary antimicrobial test all the materials containing “foreign” ions showed high antibacterial activity.

Highlights

Life span has been steadily increasing for many years
The results showed that samples containing gallium were less crystalline, while the silver content did not affect crystallinity, which may be due to the small concentration of silver ions
New HA materials containing small amounts of gallium and silver ions were successfully obtained via simple precipitation and solid-state reactions

Summary

Introduction

Life span has been steadily increasing for many years. As a consequence, the number of orthopaedic surgeries related to filling bone defects, fracture treatment or joint replacement is continually increasing. According to Weiser et al, approximately 313 million surgeries were performed in 2012 in member states of the World Health Organization (WHO), an increase of 38% over the previous eight years [1]. Along with this upsurge in the number of orthopaedic surgeries, a significant increase in surgical site infection (SSI) has been observed [2,3,4]. In LMICs, the occurrence of SSI ranges from 6.1–7.8%, and for HICs, this occurrence ranges from approximately 1–3% [7] Orthopaedic surgeries, such as hip and knee prosthesis, are among the highest cumulative incidences of SSI [5]. If infection occurs despite prophylaxis, appropriate antibiotic therapy is used, where drugs are administered orally or intravenously [2,3,10,11]

Methods

Results

Conclusion