Hydroxyapatite Functionalized Calcium Carbonate Composites with Ag Nanoparticles: An Integrated Characterization Study

Abstract

In the present work, composite materials very promising for biomedical and pharma-ceutical applications were investigated. They are composed of silver nanoparticles (Ag NPs) in a matrix constituted of calcium carbonate functionalized with hydroxyapatite (HA-FCC). The composites were obtained by different synthesis methods, starting from a mixture of the silver acetate with HA-FCC (using adsorption or mixing in wet conditions methods) and then treating them by exposure to visible light or calcination to promote the silver reduction; a synthetic procedure based on ultrasound-assisted reduction with NaBH4 or citrate was also carried out. The characterization by X-ray photoelectron spectroscopy and reflected electron energy loss spectroscopy analysis also involved the reference sample of HA-FCC matrix. Then the morphology of the Ag NPs and the crystalline structure of HA-FCC were studied by transmission electron microscopy and X-ray diffraction, respectively. To assess the effectiveness of the different methods on silver reduction, the Auger parameters α’ were calculated and compared. The use of this methodology based on the Auger parameter is neither trivial nor ordinary. We demonstrate its validity since the different values of this parameter allow to identify the oxidation state of silver and consequently to evaluate the formation yield of metallic Ag NPs in the HA-FCC matrix and the effectiveness of the different reduction methods used.

Ag/Ag3PO4 Nanoparticle-Decorated Hydroxyapatite Functionalized Calcium Carbonate: Ultrasound-Assisted Sustainable Synthesis, Characterization, and Antimicrobial Activity

“…Figure 6 presents the spectra of the main photoemission peaks Ag 3d and P 2p acquired for the OMP@silver composites and the Ag 3 PO 4 reference sample. In all composites, the doublet of Ag 3d overlaps with the first shake-up satellite of the Ca 2p line [ 57 ], which was included in the peak fitting ( Figure 6 a). As we can see, the binding energy (BE) values of both elements are constant in all samples.…”

“…The Avantage v.5 software (Thermo Fisher Scientific Ltd., East Grinstead, UK) was applied for the experimental data acquisition and processing [ 57 ].…”

“…The main methods proposed to obtain HA and silver biomaterials were reviewed by Guo et al [ 49 ]. They consist of doping HA with silver during its preparation [ 50 , 51 , 52 , 53 ], the adsorption or deposition of silver nanoparticles that have been previously obtained by reduction on HA [ 41 , 44 , 45 , 54 , 55 , 56 ], and contact between HA and silver salt without chemical reducing agents [ 46 , 57 ]. In this late method, Ag/Ag 3 PO 4 nanoparticles were formed.…”

“…Previously, a hydroxyapatite functionalized calcium carbonate, named OMP, which is characterized by a highly developed surface area and porous structures, was used for obtaining silver@composites. The nature of the silver in the prepared composites was deeply investigated by XPS [ 57 ], showing that the oxidation state of the silver depends on the synthetic procedures used. The composites obtained without reducing agents were composed mainly of Ag 3 PO 4 nanoparticles and showed good antimicrobial activity [ 58 ].…”

Citric Acid-Mediated Microwave-Hydrothermal Synthesis of Mesoporous F-Doped HAp Nanorods from Bio-Waste for Biocidal Implant Applications

“…In the HAp structure, different cations such as Ag + , Tb 3+ , Si 4+ , Fe 3+ , and Mg 2+ can be replaced with Ca 2+ ions, and anions like CO 3 2− , SO 4 4− , and fluorine can be replaced with hydroxyl bonds [ 13 , 14 , 15 , 16 , 17 , 18 ]. Among the anions, F − reveals better physical and biological activities [ 19 ].…”