New Physico-Chemical Analysis of Magnesium-Doped Hydroxyapatite in Dextran Matrix Nanocomposites

Abstract

The new magnesium-doped hydroxyapatite in dextran matrix (10MgHApD) nanocomposites were synthesized using coprecipitation technique. A spherical morphology was observed by scanning electron microscopy (SEM). The X-ray diffraction (XRD) characterization results show hydroxyapatite hexagonal phase formation. The element map scanning during the EDS analysis revealed homogenous distribution of constituent elements of calcium, phosphor, oxygen and magnesium. The presence of dextran in the sample was revealed by Fourier transform infrared (FTIR) spectroscopy. The antimicrobial activity of the 10MgHAPD nanocomposites was assessed by in vitro assays using Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Streptococcus mutans ATCC 25175, Porphyromonas gingivalis ATCC 33277 and Candida albicans ATCC 10231 microbial strains. The results of the antimicrobial assays highlighted that the 10MgHApD nanocomposites presented excellent antimicrobial activity against all the tested microorganisms and for all the tested time intervals. Furthermore, the biocompatibility assays determined that the 10MgHApD nanocomposites did not exhibit any toxicity towards Human gingival fibroblast (HGF-1) cells.

Keywords: biomedical applications; dextran; fractal features; hydroxyapatite; magnesium.

Figure 1

XRD spectrum of dextran (a), 10MgHApD nanocomposites (b) and 10MgHAp (c). The lines of the ICDD-PDF#9-432 reference file of hexagonal hydroxyapatite (d) and the ICDD-PDF#063-1501 reference file of dextran (e).

Figure 2

SEM micrograph at low (a) and high (b) resolution of 10MgHApD nanocomposites, EDS spectrum of 10MgHApD nanocomposites (c) and average particle size (d).

Figure 3

The EDS mapping of Ca, P, O and Mg in 10MgHApD nanocomposites.

Figure 4

2D AFM images of 10MgHApD pellet’s topography recorded on an area of 10 × 10 µm² (a), 5 × 5 µm² (b), 3 × 3 µm² (c) and their corresponding 3D representations (d–f).

Figure 5

(a) 2D and (b) 3D representation of the atomic force microscopy (AFM) surface topography image of the 10MgHApD sample, with 10 × 10 μm scanned area.

Figure 6

(a) 2D and (b) 3D AFM micrographs of 10MgHApD nanocomposites. (c) Height histogram and Abbot–Firestone curves from the respective image.

Figure 7

The MFs functionals of the surface of 10MgHApD obtained from AFM image for (a) Minkowski volume, (b) Minkowski boundary, and (c) Minkowski connectivity.

Figure 8

Representative fractal dimension determined using a cube counting method of 10MgHApD nanocomposites, obtained from AFM images shown in Figure 2.

Figure 9

(a) Multifractal spectra (f(α) versus α), (b) generalized dimensions D_q, and (c) mass exponent τ(q), as a function of the order of moments computed for 10MgHApD nanocomposites obtained using their 3D AFM topographical map.

Figure 10

Comparative FTIR-ATR spectra of the dextran powder (a–c), 10MgHApD nanocomposites (d–f) and 10MgHAp (g–i).

Figure 11

Antimicrobial assay of 10MgHApD nanocomposites, HAp and 10MgHAp nanoparticles against S. aureus, P. aeruginosa, S. mutans, P. gingivalis and C. albicans microbial strains. The results were considered statistically significant at * p < 0.05.

Figure 12

The graphical representation of the cell viability of HGF-1 cells exposed to 10MgHApD nanocomposites for 24, 48 and 72 h. The data are presented as mean ± standard deviation (SD) and are quantified as percentages of control (100% viability). The statistical analysis was performed using the ANOVA single-factor test and p ≤ 0.05 was accepted as statistically significant.