Fabrication of Silver- and Zinc-Doped Hydroxyapatite Coatings for Enhancing Antimicrobial Effect

Daniela Predoi,Mihai Valentin Predoi,Simona Liliana Iconaru

doi:10.3390/coatings10090905

Daniela Predoi, Mihai Valentin Predoi + Show 1 more

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https://doi.org/10.3390/coatings10090905

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Abstract

This study develops, for the first time, composite coatings based on silver and zinc doped hydroxyapatite in chitosan matrix (AgZnHApCs). The AgZnHApCs composite coatings were prepared by dip coating method. The hydroxyapatite (HAp), biocompatible material for regenerating and strengthening damaged bones were doped with silver and zinc ions and coated with chitosan in order to produce a uniform and homogenous coating with biocompatibility and antimicrobial properties. The stability of AgZnHApCs suspensions was evaluated by ultrasound measurements. The value of stability parameters of AgZnHApCs suspension is in good agreement with the value of bidistilled water used as reference fluid. Homogeneously dispersed solutions of AgZnHApCs were synthesized to endeavor to optimize the physico-chemical and biological characteristics of the coatings obtained at room temperature. The AgZnHApCs composite suspension and coatings were analyzed using various investigation techniques, such as X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenylte-2H-tetrazolium bromide) assay and antimicrobial studies. The optical spectroscopy, atomic force microscopy (AFM), metallographic examination and X-ray photoelectron spectroscopy (XPS) on AgZnHApCs composite coatings were also conducted. Cell culture and MTT assays demonstrate that AgZnHApCs composite suspension and coatings have no negative effect on the cell viability and proliferation. The cell morphology was not affected in presence of AgZnHApCs composite suspension and coatings. The antimicrobial assays conducted against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Candida albicans ATCC 90029 microbial strains revealed that both the AgZnHApCs composite suspension and coatings exhibited great antimicrobial properties.

Highlights

The development of new materials with enhanced antimicrobial properties is one of the priority research areas in the last years
This study develops, for the first time, composite coatings based on silver and zinc doped hydroxyapatite in chitosan matrix (AgZnHApCs)
The reagents used in the synthesis of the materials such as chitosan (Cs) powder, calcium nitrate tetrahydrate, zinc nitrate hexahydrate, silver nitrate, ammonium hydrogen phosphate, ethanol absolute and acetic acid were purchased from Sigma Aldrich, St

Summary

Introduction

The development of new materials with enhanced antimicrobial properties is one of the priority research areas in the last years. Once a substitution occurs, there is a significant change in the physicochemical and biological properties of hydroxyapatite [4] This behavior allows one to improve the properties of HAp, including antibacterial ones, through substitutions [4,5,6,7,8]. Due to the fact that hydroxyapatite does not have antimicrobial properties, and yet it is used in various biomedical applications, one way to improve these properties is to dope HAp with antimicrobial agents. To make it suitable to fight with antibiotic resistant bacteria, we chose to dope HAp with Ag+ and Zn2+ ions. Materials based on HAp doped with Ag and/or zinc ions can be obtained by several methods, among which we mention: hydrothermal method [2], microwave [9] wet-chemical method [1], sol-gel process [10,11], co-precipitation [12,13,14], chemical solution deposition [5], etc

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