Antimicrobial Properties of Samarium Doped Hydroxyapatite Suspensions and Coatings

Abstract

Post-implant infections are a major health problem, and it is well-known that treating them with conventional drugs is accompanied by many disadvantages. The development of new biomaterials with enhanced antimicrobial properties are of major interest for the scientific world. The aim of this study was to synthesize and characterize hydroxyapatite doped with Samarium (Ca10−xSmx(PO4)6(OH)2, xSm = 0.05, 5Sm-HAp) suspensions, pellets and coatings. The 5Sm-HAp coatings on Si substrates were obtained by rf magnetron sputtering technique. The different techniques such as ultrasound measurements, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Glow Discharge Optical Emission Spectroscopy (GDOES), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to examine the obtained coatings. The results showed that the doped Sm ions entered the structure of hydroxyapatite successfully and Sm ions was uniformly doped onto the surface of the support. The depth profile curves of Ca, P, O, H, Ce and Si elements exhibit their presence from a surface to substrate interface as function of sputtering time. XPS analysis indicated as calcium-phosphate structures enriched in Sm3+ ions. Furthermore, the antimicrobial properties of the 5Sm-HAp suspensions, targets and coatings were assessed against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Candida albicans ATCC 10231. The results of the antimicrobial assays highlighted that that the samples presented a strong antimicrobial activity against the tested microbial strains. The results showed that the coatings after 48 h of incubation inhibited the growth of all tested microbial strains under the value of 0.6 Log CFU/mL. This study shows that the 5Sm-HAp samples are good candidates for the development of new antimicrobial agents.

Fabrication and Physico-Chemical Properties of Antifungal Samarium Doped Hydroxyapatite Thin Films

“…After the deconvolution of FTIR spectra, four subbands were obtained for 450-700 cm −1 spectral region and six subbands for 900-1200 cm −1 domain. In the case of 50SmHAp coatings the vibrational subbands specific to ν 4 [PO 4 ] 3− from HAp structure are found at: 538 cm −1 ; 566 cm −1 ; 603 cm −1 (Figure 9a) [11,12,41]. Meanwhile the subbands typical for the ν 3 [PO 4 ] 3− were noticed at: 1030 cm −1 ; 1034 cm −1 ; 1045 cm −1 ; 1066 cm −1 ; 1093 cm −1 and 1100 cm −1 (Figure 9b) [11,12,41].…”

“…In the case of 50SmHAp coatings the vibrational subbands specific to ν 4 [PO 4 ] 3− from HAp structure are found at: 538 cm −1 ; 566 cm −1 ; 603 cm −1 (Figure 9a) [11,12,41]. Meanwhile the subbands typical for the ν 3 [PO 4 ] 3− were noticed at: 1030 cm −1 ; 1034 cm −1 ; 1045 cm −1 ; 1066 cm −1 ; 1093 cm −1 and 1100 cm −1 (Figure 9b) [11,12,41]. The main vibrational band found at 961 cm −1 can be attributed to the ν 1 [PO 4 ] 3− from the HAp structure.…”

“…The results of our previous studies conducted on samarium doped hydroxyapatite (x Sm = 0.05 and 0.1) coatings deposited on Si substrate showed, on the one hand their improved biocompatibility with the gingival, HeLa and osteoblastic cells line and on the other hand a superior antimicrobial activity (against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Candida albicans microbial strain) [11][12][13][14]. Therefore, due to these new improved biological properties, this type of materials could be used in many medical applications.…”

“…It is well known, that Samarium (Sm 3+ ) is a lanthanide that could enhance both antimicrobial [8] and photoluminescent properties [9] of the host materials. Recent studies, have also shown that the biological activity of samarium doped hydroxyapatite (SmHAp) it is strongly influenced by the amount of Sm 3+ that is found in the samples [10][11][12][13][14]. Moreover, has been highlighted that the presence of Sm 3+ in various biomaterials, used in the medical field, increases their anticancer activity [15,16].…”

“…Furthermore, previous studies showed that samarium-based compounds, obtained by various techniques could be used in fields such as: nuclear nanomedicine [19,20], molecular dual-targeted radiotherapy of hepatocellular carcinoma [21], low-temperature solid oxide fuel cell application [22], white light-emitting diodes [23], biosensing applications in biological fluids [24], high-density optical memory devices [25], etc. It is well known, that hydroxyapatite coatings could be obtained by various techniques including: pulsed laser deposition (PLD) [26]; thermal evaporation technique [10], rf magnetron sputtering [12,18], dip coating [18,27], spin coating [18], electrochemical and hydrothermal synthesis [28], etc. One of the widely used deposition technique is spin coating, due to the fact that it is a simple route that allows the obtaining of uniform and homogeneous layers at low temperatures [29,30].…”