The main purpose of this study was to evaluate the inhibitory effect of glycerol- iron oxide thin films on
During the last decade, iron oxide nanoparticles such as magnetite (Fe3O4) and/or maghemite (
The biocompatibility and low toxicity of functionalized iron oxide magnetic nanoparticles [
Two of the phases of iron oxides, Fe3O4 and
In previous studies, the growth of hematite (
The spin coating method used to deposit glycerol-iron oxide thin films is a simple, inexpensive technique and a promising candidate for obtaining biocompatible surfaces for potential applications in the medical field. The specific characteristics of nanoscale iron oxides particles were determined in order to use them in a variety of different applications. On the other hand, glycerol is a natural antimicrobial agent and a common ingredient found in food and cosmetics. According to Projan et al. [
This study also reports the preparation and characterization of glycerol-iron oxide layer. Firstly, we synthesized glycerol stabilized with iron oxide nanoparticles in normal atmospheric conditions by coprecipitation method. Secondly, glycerol-iron oxide thin films were prepared by spin coating deposition. The glycerol-iron oxide nanoparticles and glycerol-iron oxide thin films were characterized by X-Ray diffraction (XRD) and scanning electron microscopy (SEM). The qualitative chemical analysis of the glycerol-iron oxide thin films was evaluated by glow discharge optical emission spectroscopy (GDOES). Finally the inhibitory effect of glycerol-iron oxide layer on methicillin-resistant
Ferrous chloride tetrahydrate (FeCl2·4H2O), ferric chloride hexahydrate (FeCl3·6H2O), chlorhydric acid (HCl), natrium hydroxide (NaOH), and ammonia (NH3) were purchased from Merck Glycerol. C3H8O3, (99.5%) was purchased from Sigma. Deionized water was used in the synthesis of nanoparticles and in the rinsing of clusters. The Ø6′′ Silicon Wafer, Type P/
The glycerol-iron oxide nanoparticles (GIO) were synthetized by coprecipitation method in air at room temperature. The ferric and ferrous chlorides (molar ratio 2 : 1) were prepared by dissolving 0.30 M of FeCl3·6H2O and FeCl2·4H2O in 60 mL of HCl (0.16 M) [
The samples were characterized for phase content by X-ray diffraction (XRD) with a Bruker D8-Advance X-ray diffractometer in the scanning range 25–70° using Cu K
Methicillin-resistant
The XRD investigations of dried GIO nanoparticles are illustrated in Figure
Experimental (blue), calculated (solid line gray), and difference plots (lover line) of the glycerol coated iron oxide nanoparticles (mixture of the spinel phases
SEM analysis was used to observe the morphology of GIO nanoparticles and GIO thin films (GIO-1 and GIO-2). In Figure
SEM image of the glycerol coated iron oxide nanoparticles.
The XRD patterns of GIO-1 and GIO-2 thin films are also similar and conserve the structure of GIO nanoparticles (Figure
X-ray diffraction patterns of GIO-1 and GIO-2 thin films.
The XRD investigations of GIO-1 and GIO-2 thin films demonstrated that the crystal structure of GIO nanoparticles does not change after spin coating deposition.
The morphology and mean nanoparticle diameters of GIO thin films (GIO-1 and GIO-2) are illustrated in Figure
SEM images of GIO-1 (a) and GIO-2 (b) thin films. The mean nanoparticle diameters of GIO-1 (c) and GIO-2 (d) thin films.
Furthermore, the size of the spherical microspheres increases with the increase of glycerol amount (GIO-2).
Glow discharge optical emission spectroscopy (GDOES) is an atomic emission spectrometer system that can be used mainly to analyze elemental composition of solids, liquids, and gases [
The elemental distribution from coating to substrate with glycerol-iron oxide nanoparticles was investigated using GDOES depth profile. GDOES spectra were acquired for thin films of glycerol-iron oxide nanoparticles dispersed in ethanol solution containing 25 mL (GIO-1) and 50 mL (GIO-2) glycerol under vigorous stirring and deposited on a pure Si substrate (Figure
Typical GDOES composition depth profiles of GIO-1 A and GIO-2 A thin films after dispersion of glycerol-iron oxide nanoparticles in ethanol solution containing 25 mL and 50 mL glycerol under vigorous stirring. The GIO-1 B and GIO-2 B show zoomed in time regions 0–20 s.
The results shown in Figure
The objective of our study was to investigate the antibacterial activity of glycerol-iron oxide thin films (GIO-1 and GIO-2) on
The values of antibacterial activity diameter of the three samples utilized for antimicrobial evaluation.
Sample | Diameter of the complete inhibition zones ( |
Diameter of the complete inhibition zones ( |
Diameter of the complete inhibition zones ( |
Mean diameter of the complete inhibition zones ( |
---|---|---|---|---|
GIO-1 | 21.6 mm | 23.4 mm | 21 mm | 22 mm |
GIO-2 | 25.8 mm | 25.9 mm | 29.3 mm | 27 mm |
Antibacterial activity of glycerol-iron oxide thin films on
To highlight the antimicrobial effect of GIO thin films, the GIO thin films deposited on commercially pure Si (100) were exposed to the MRSA. After 2, 4, 6, 12, and 24 h the suspension was collected. After collection, the suspension was incubated on agar medium for 24 h. More than that, the number of colonies forming units per milliliter (CFU/mL) was established. In Figure
The antimicrobial effects depending on the time of contact with the surface of GIO thin films.
After 24 h a drastic decrease of the MRSA CFU for the two samples (GIO-1 and GIO-2 thin films) was noticed. As you can see in Figure
It is well known that in recent years nanotechnology has made major progress. Thus, different types of metals and metal oxides at the nanoscale with antimicrobial properties were obtained [
The results of our studies are in good agreement with previous studies conducted by Saegeman et al. [
According to the results presented in this research, it can be concluded that the glycerol-iron oxide thin films possess antimicrobial properties against MRSA bacterial strain. It can be stated that the glycerol-iron oxide layer could be used in the medical field to prepare a new antimicrobial product.
In this research, the glycerol-iron oxide thin films were obtained simply by spin coating deposition method on a silicon (111) substrate. The XRD patterns of glycerol-iron oxide thin films conserve the structure of glycerol coated iron oxide nanoparticles. The structure of glycerol-iron oxide thin films is homogenous and the size of the spherical microspheres increases with the increase of glycerol amount. The GDOES spectra performed on glycerol-iron oxide thin films reveal the distribution of the main elements Fe, O, C, H, and Si. The thickness of thin films has been affected by the concentration of glycerol in the glycerol-iron oxide nanoparticles solution.
MRSA bacterial strain presented an inhibition zone which increased when the glycerol amount in the samples increased. In addition, the glycerol-iron oxide thin films showed better antibacterial performance when the amount of glycerol increased. In conclusion, we can say that the present research proposes a new antimicrobial product that could be used for various medical applications involving inhibition of antibiotic-resistant bacteria.
The authors declare that they have no competing interests.
This research was financially supported by the Ministry of Education of Romania, Project no. 131/2014. Also thework has been funded by the Sectoral Operational Programme Human Resources Development 2007–2013 of the Ministry of European Funds through the Financial Agreement POSDRU/159/1.5/S/134398.