Physico-Chemical Properties and In Vitro Antifungal Evaluation of Samarium Doped Hydroxyapatite Coatings

Abstract

Hydroxyapatite (HAp) and samarium doped hydroxyapatite, Ca10−xSmx(PO4)6(OH)2, xSm = 0.05, (5SmHAp), coatings were prepared by sol-gel process using the dip coating method. The stability of 5SmHAp suspension was evaluated by ultrasound measurements. Fourier transform infrared spectroscopy (FTIR) was used to examine the optical characteristics of HAp and 5SmHAp nanoparticles in suspension and coatings. The FTIR analysis revealed the presence of the functional groups specific to the structure of hydroxyapatite in the 5SmHAp suspensions and coatings. The morphology of 5SmHAp nanoparticles in suspension was evaluated by transmission electron microscopy (TEM). Moreover, scanning electron microscope (SEM) was used to evaluate the morphology of nanoparticle in suspension and the morphology of the surface on the coating. The SEM and TEM studies on 5SmHAp nanoparticles in suspension showed that our samples consist of nanometric particles with elongated morphology. The SEM micrographs of HAp and 5SmHAp coatings pointed out that the coatings are continuous and homogeneous. The surface morphology of the 5SmHAp coatings was also assessed by Atomic Force Microscopy (AFM) studies. The AFM results emphasized that the coatings presented the morphology of a uniformly deposited layer with no cracks and fissures. The crystal structure of 5SmHAp coating was characterized by X-ray diffraction (XRD). The surface composition of 5SmHAp coating was analyzed by X-ray photoelectron spectroscopy (XPS). The XRD and XPS analysis shown that the Sm3+ ions have been incorporated into the 5SmHAp synthesized material. The antifungal properties of the 5SmHAp suspensions and coatings were studied using Candida albicans ATCC 10231 (C. albicans) fungal strains. The quantitative results of the antifungal assay showed that colony forming unity development was inhibited from the early phase of adherence in the case of both suspensions and coatings. Furthermore, the adhesion, cell proliferation and biofilm formation of the C. albicans were also investigated by AFM, SEM and Confocal Laser Scanning Microscopy (CLSM) techniques. The results highlighted that the C. albicans adhesion and cell development was inhibited by the 5SmHAp coatings. Moreover, the data also revealed that the 5SmHAp coatings were effective in stopping the biofilm formation on their surface. The toxicity of the 5SmHap was also investigated in vitro using HeLa cell line.

Investigation of Spin Coating Cerium-Doped Hydroxyapatite Thin Films with Antifungal Properties

“…More than that, the CLSM investigation showed that the few adhered C. albicans cells did not undergo transformation into their filamentous form, hence demonstrating that C. albicans were unable to evolve into their biofilm phenotype on the 10Ce-HAp surfaces [59]. These results are in good agreement with SEM visualization as well as the results of the quantitative antifungal assay and with previously reported studies regarding the antifungal properties of composite layers [60,61].…”

Antimicrobial Properties of Samarium Doped Hydroxyapatite Suspensions and Coatings

“…These results are in good agreement with other similar studies regarding the potential antimicrobial activity of samarium ions or samarium based composites [27,29,[53][54][55][56][57][58]. Moreover, the quantitative assays were in good agreement with the results obtained in the qualitative studies performed on 5Sm-HAp suspension, target and coatings.…”

Ce/Sm/Sr-Incorporating Ceramic Scaffolds Obtained via Sol-Gel Route

“…Even for these two cases, it is possible to attain a better evolution at longer testing intervals. Overall, the LIVE/DEAD assay confirms the beneficial influence of Sm on the cells development in simulating conditions, as it was also reported by other researchers [ 30 , 31 , 32 , 33 , 34 , 35 ].…”

“…Ershad et al [ 33 ] studied melt-derived bioactive glasses with up to 4 wt.% Sm 2 O 3 ; they found that nucleation and crystal growth temperature decrease, while bioactivity and mechanical properties improve with Sm 2 O 3 concentration increasing. Sm-doped thin films were prepared from the desire to ensure two key features contributing to a better outcome following bone graft implantation: rapid osseointegration and infection avoidance; the tests evidenced antifungal properties, simultaneously with lack of toxicity against regular cell lines for Sm contents below 1 mol% [ 34 , 35 ]. Moreover, 153 Sm isotope was demonstrated to be an efficient radiotracer [ 36 ] and helpful agent for nuclear therapy through beta emission [ 37 , 38 ].…”