Structural Properties and Antifungal Activity against Candida albicans Biofilm of Different Composite Layers Based on Ag/Zn Doped Hydroxyapatite-Polydimethylsiloxanes

Abstract

Modern medicine is still struggling to find new and more effective methods for fighting off viruses, bacteria and fungi. Among the most dangerous and at times life-threatening fungi is Candida albicans. Our work is focused on surface and structural characterization of hydroxyapatite, silver doped hydroxyapatite and zinc doped hydroxyapatite deposited on a titanium substrate previously coated with polydimethylsiloxane (HAp-PDMS, Ag:HAp-PDMS, Zn:HAp-PDMS) by different techniques: Scanning Electron Microscopy (SEM), Glow Discharge Optical Emission Spectroscopy (GDOES) and Fourier Transform Infrared Spectroscopy (FTIR). The morphological studies revealed that the use of the PDMS polymer as an interlayer improves the quality of the coatings. The structural characterizations of the thin films revealed the basic constituents of both apatitic and PDMS structure. In addition, the GD depth profiles indicated the formation of a composite material as well as the successful embedding of the HAp, Zn:HAp and Ag:HAp into the polymer. On the other hand, in vitro evaluation of the antifungal properties of Ag:HAp-PDMS and Zn:HAp-PDMS demonstrated the fungicidal effects of Ag:HAp-PDMS and the potential antifungal effect of Zn:HAp-PDMS composite layers against C. albicans biofilm. The results acquired in this research complete previous research on the potential use of new complex materials produced by nanotechnology in biomedicine.

Physicochemical and antimicrobial properties of silver‐doped hydroxyapatite collagen biocomposite

“…The anterior results showed that the Ag + and Zn 2+ affect the development of microorganisms . In contrast, in the precedent studies conducted on bacterial resistance to silver in wound care revealed that the Ag + show oligodynamic effect with minimum development of resistant microorganisms. Thus, finding new materials with antibacterial capacity is a crucial step in lowering the number of infections and prevention of invasive infections.…”

The Effect of the Ionizing Radiation on Hydroxyapatite–Polydimethylsiloxane Layers

“…The influence of the ionizing radiation on the surface morphology of the HAp:PDMS layers was analyzed by SEM. In our previous papers , we showed that the use of a polymer interlayer for the HAp coating/rugged Ti substrate could contribute to achieving more uniform layers and prevent cracks in the deposited layer. More than this, it has been shown that HAp is incorporated into the polymer matrix.…”

“…After irradiation with ionizing radiation the HAp:PDMS layers present cracks and tend to exfoliate in the most deep areas (Fig. b) of the substrates even if previously it was showed that the polymers successfully covered all the rugged surfaces. Before the irradiation, the sample surfaces were not cracked or delaminated (Fig.…”

“…In this context, various studies have been conducted regarding the obtaining of a homogenous HAp‐based coating, with antimicrobial properties, good mechanical strength, and exceptional adherence. In our previous papers , we have reported the development and physicochemical characterization of composite layers of HAp‐doped with silver and zinc ions deposited on metallic substrates, which were previously coated with polydimethylsiloxane (PDMS). The use of PDMS as an interlayer has been proven to possess an important role in the improvement of the adherence of the biomaterials to the substrate even when the substrate is rugged and nonuniform.…”

“…The use of PDMS as an interlayer has been proven to possess an important role in the improvement of the adherence of the biomaterials to the substrate even when the substrate is rugged and nonuniform. These studies have indicated that the use of a polymer as an intermediate layer between the metallic substrate and HAp layer lead to the realization of surfaces with homogeneous and uniform morphology and with better adhesion. The structural analysis of these kind of HAp:PDMS layers indicated the incorporation of the HAp into the polymer and that some substitutions between PO 4 3− and SiO 4 4− groups take place.…”