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A nanocomposite made from hydroxyapatite (HAP) and silver nanoparticles (AgNPs), namely HAP-4.5 wt% AgNPs, is reported. HAP was prepared using a wet precipitation technique, and AgNPs were made by reducing silver nitrate with glucose in basic medium. HAP, AgNPs and HAP-4.5 wt% AgNPs composite were characterized by X-ray diffraction (XRD), SEM - energy dispersive X-ray spectroscopy (EDS) and different imagistic methods: TEM and AFM. The antibacterial effect of the HAP-4.5 wt% AgNPs nanocomposite was tested using diffusion technique in nutritive agar on two pathogenic species, one Gram-negative (Salmonella typhimurium) and one Gram-positive (Bacillus cereus) and promising results were obtained. This hydroxyapatite-silver nanocomposite can be employed as a potential antimicrobial coating for dental and orthopedic implants, or they can be utilized such as bone cements in clinical procedures. [ABSTRACT FROM AUTHOR]

The use of toothpastes is the best way to combat enamel loss and degradation. When they also contain hydroxyapatite nanoparticles, HAP NPs, the tooth enamel can be restored by remineralization. In this study, we developed two types of toothpastes, one with nano sized HAP, noted P1, and the other with nano multi-substituted hydroxyapatite (ms-HAP, HAP-Mg-Zn-Si), noted P2, which were used to treat the artificially demineralized teeth enamel surface. The remineralization efficacy of the two toothpastes was determined on artificially created enamel lesions by suspending healthy enamel slices in demineralizing solution, made of orthophosphoric acid of 37.5% for 90 s. For this purpose, six extracted third molars were collected and twenty-four enamel slices were cut and arbitrarily allocated to the four groups, namely n = 6 enamel slices for each group. One group served as untreated (natural) enamel control, and another group comprised demineralized enamel and two test groups, firstly demineralized, and then, they were treated with toothpastes P1 and P2, respectively, each of them for ten days, and finally were noted P1 and P2 enamel surfaces. The surface morphology and roughness of all enamel specimens were studied by atomic force microscopy (AFM) before and after applying the treatment with the toothpastes. The toothpastes effect was evidenced by the average diameter of ceramic nanoparticles deposited within the superficial smooth layer on enamel surface having, at the completion of 10 days treatment, a low surface roughness close to that of natural enamel. This in vitro comparative study demonstrated that both toothpastes P1 and P2 can promote surface enamel repair by remineralization and the formation of a protective hydroxyapatite coating layer on the enamel surface treated with these toothpastes. [ABSTRACT FROM AUTHOR]

Due to the ions in its structure, that have a variety of important roles in bone metabolism, forsterite (FS, Mg2SiO4) is a promising candidate for orthopedic and dental applications. This paper studies forsterite synthesized through two methods, namely sol-gel (FSsg) and precipitation (FSpp), based on a thermodynamic approach. Therefore, the precursor gel and precipitate were analyzed through thermal gravimetric (TG), differential thermal gravimetric (DTG) and differential scanning calorimetric (DSC) analysis. The FSsg and FSpp powders were characterized by X-ray powder diffraction (XRD) and atomic force microscopy (AFM). XRD reveals that the synthesized forsterite is of high crystallinity. As is evidenced by AFM, the average size of the nanoparticles is around 40 nm for FSsg and 30 nm for FSpp. The potential reaction mechanisms for the two synthesis routes were also established. [ABSTRACT FROM AUTHOR]

The stability and solubility of curcumin, CCM, can be enhanced by complexation with whey protein concentrate (WPC). The CCM-WPC of 1:1 and 1:0.5 molar ratio complexes were encapsulated by two methods, namely spray drying (SD) and freeze drying (FD). The major objective of this work is to determine the stability and solubility of the CCM-WPC complexes encapsulated by SD and FD method. The X-ray diffraction and thermogravimetric analysis were performed on raw CCM and WPC, and on their complexes. The changes in thermal degradation and in crystallinity suggest the formation of these CCMWPC complexes. Scanning electron microscopy images showed that the used methods influenced the morphology and the properties of the formed complexes. The stability and solubility of curcumin are enhanced by complexation in both encapsulation methods. However, comparing the used molar ratio and drying methods, the results are various. The solubility of samples obtained by FD method was higher than in the case of the SD method, which can explain the difference of their morphology (FD samples are more amorphous than SD samples). The antioxidant property of curcumin and its protein-complexes compared to vitamin C showed that CCM and its complexes have a lower IC50 value than vitamin C, i.e., the antioxidant effect of CCM is higher. The addition of WPC improved the antioxidant activity of CCM, probably due to its encapsulation in the protein. Our results suggest that the 1CCM-1WPC_SD complex is the best antioxidant from these studied CCM-WPC complexes. [ABSTRACT FROM AUTHOR]

Curcumin (CCM) has beneficial effects on human health due to its pharmacological activities, which have a protective role against many diseases. Whey protein concentrate (WPC) is a product from the milk industry that is often used to improve and stabilize different foods. It helps curcumin improve its water solubility, poor bioavailability, low stability, and efficacy. Atomic force microscopy (AFM) was employed to highlight the surface topography of adsorbed films of pure curcumin, pure whey protein concentrate, and their CCM-WPC complex. The obtained results show that individual nanoparticles, NPs, were mobilized into the aqueous dispersion and successfully adsorbed onto the glass slides as thin films. Their NPs shape is rounded, and their diameter differs on each sample, namely about 30 nm for CCM, around 55 nm for WPC, and about 40 nm for the CCM-WPC complex. It proves that both CCM and WPC molecules generate a complex that embeds them in a compact structure. The surface roughness was also monitored, and pure CCM produces the smoothest and uniform film, meanwhile, the presence of WPC makes several pores in the film surface which increases the roughness value. The obtained results provide useful evidence for the application of whey protein as an effective carrier of curcumin, a bioactive polyphenol compound. In addition, this work supports the application of the CCM-WPC complex as health supplements. [ABSTRACT FROM AUTHOR]

Titanium implants are highly resistant to external forces and have affordable prices but the contact between Ti metal and surrounding native tissue could provoke an immunological response. The developing of biomimetic coating onto the Ti surface proves to be a smart choice to enhance the osseointegration and ensure an optimal healing process, due to the creation of nanostructured biomaterials like those in native bone. Thus, we designed a composite coating based on multi-substituted hydroxyapatite (noted ms-HAP or HAPc) nanoparticles, NPs, doped with essential elements: Mg, Zn and Si, functionalized with collagen type 1 (COL), embedded into poly lactic acid, PLA, matrix, and finally covered with COL layer to achieve biomimetic structures. Thin layers of biomimetic composite were self-assembled onto Ti surface via dip-coating method. Both, initial and coated Ti implants were investigated by atomic force microscopy (AFM), which allows surface investigation at high resolution of nano-level. COL amount in composite might self-assemble as COL fibers assuring a biomimetic structure, characterized by important features, like suitable porosity to facilitate the delivery of nutrients to osteoblasts and proper nano-topography and surface roughness to promote cell adhesion and proliferation. The outermost layer is of pure collagen which could assure a natural attachment to the bone tissue promoting osseo-integration. [ABSTRACT FROM AUTHOR]

In this study, the ions release of physiological elements from pure stoichiometric hydroxyapatite, HAP, and from multi-substituted hydroxyapatite, ms-HAPs, containing 1.5%Mg, 0.2%Zn, 0.2%Si and 5 %Sr, noted HAPc-5%Sr, and from HAPc-10%Sr, in water and in simulated body fluid, SBF, was studied by inductively coupled plasma optical emission spectrometry, ICP-OES, both in static and simulated dynamic regimes. The HAP and ms-HAP nanoparticles, NPs, were prepared by wet chemical precipitation and lyophilized powders were physicochemical characterized as presented elsewhere. The in vitro cations and anions release mechanism was investigated by applying a modified Higuchi model, which fits well the experimental results, particularly for simulated dynamic conditions. The predominant role of diffusion in the release of ions from the hydroxyapatites was confirmed. The sustained ions release from these nanomaterials recommends the investigated ms-HAPs for therapeutic applications. [ABSTRACT FROM AUTHOR]

The biocompatibility of uncoated titanium, Ti, nails and coated with an innovative biocomposite is assessed in a rat model of femoral fracture. The biocomposite is based on multi-substituted hydroxyapatite, ms-HAP containing Mg, Zn and Si, and is used as a coating material deposited on Ti implants, due to the excellent biocompatibility and osteoconductive property of ms-HAP. Specific focus has been given to biocomposite coating made of ms-HAP functionalized with collagen (ms-HAP/COL, core/shell nanoparticles) NPs embedded into poly lactic acid, PLA, matrix and finally covered by COL layer. This coating on Ti implants is noted as ms-HAP/COL@PLA/COL and named HAPc, and is characterized by SEM images and EDX spectra. Twenty-four Wistar albino rats with left femoral fracture, were used and divided in two equal groups, namely the control group, CG, with uncoated Ti implants and HAPc rat group with Ti implants coated with HAPc biocomposite through layer-by-layer, LBL, dip coating technique. After two- and eight-weeks postsurgery, they were evaluated by bone markers serum concentration, micro-CT and histological study. The alkaline phosphatase (ALP) and osteocalcin (OCN) expression, in the HAPc group showed higher values with an osteoblastic activity more intense and a more advanced callus stage. The micro-CT results showed that biocomposite coating significantly increased the bone volume/tissue volume (BV/TV). The most advanced stage of bone remodelling with osseointegration of the Ti implants was observed in HAPc group, where the new formed trabecular bone is almost completely replaced by compact bone. This study provides a novel strategy for the treatment of bone fracture with a superior osseointegration of biocomposite coated Ti implants and potential orthopaedic applications. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) were synthesized by chemical reduction method, using different reducing systems. The interaction of AgNPs and vancomycin hydrochloride (V) was investigated by UV-Vis spectroscopy, and their tendency to form AgNP@V associations or complexes was identified in colloidal solutions. Moreover their affinity to self-assembly and aggregate is also examined. This behavior is important and decisively influences the antimicrobial effect of AgNP@V complexes. [ABSTRACT FROM AUTHOR]

Environmental data achieved with the Air Quality Monitoring Station in Dej city, Romania, reveal a normal state of particulate matter (PM) emissions below the standard limit in April and May 2017. These airborne particles contain a large amount of mineral fractions such as: quartz, calcite, clays (e.g., kaolinite and muscovite), and lepidocrocite. Their size varies in a wide range: from 1 to 200 μm for floating particles (FP) and from 1 to 10 μm for PM10 observed by optical microscopy and SEM. The in vivo testing shows the ability of PM10 to penetrate into the upper respiratory tract. Mineral fractions were found in nasal exudates. At a shorter exposure time (e.g., 1 minute), only PM10 particles were observed. Particles larger than PM10 were found in nasal exudates at prolonged exposure for up to 3 minutes. [ABSTRACT FROM AUTHOR]

The wet chemical synthesis of silver nanoparticles (AgNPs) by reduction of silver nitrate with sodium citrate, tannic acid, and their mixture is reported. The obtained silver nanoparticles were investigated by UV-Vis spectroscopy, scanning transmission electron microscopy (STEM), and atomic force microscopy (AFM) images and their antibacterial effect against Escherichia coli was assessed. [ABSTRACT FROM AUTHOR]

The paper is focused on the micro and nano organization of atmospheric particulate matter in Grigorescu district of Cluj-Napoca in April and May 2017. Floating particles (FP) collected from atmosphere have an increased amount of minerals such as: quartz, calcite, clays (e.g. kaolinite and muscovite), and traces of lepidocrocite. Their size varies from less than 1 to over 120 μm, established by Scherer method on an XRD pattern. PM10 contains mainly quartz and calcite followed by fractions of kaolinite and muscovite. PM2.5 contains clay in large amount and less quartz particles. Certain nanoparticles are found among PM2.5. The obtained values were in good agreement to TEM and AFM microscopy. The diameters are 42 nm for clay and 92 nm for quartz particles. Nanostructural features are organized around fine micro particles such as PM 2.5. PM10 is often found as particles around FP. [ABSTRACT FROM AUTHOR]

Nanostructured hydroxyapatite (HAP) and three multiple substituted HAPs, containing Mg, Zn, Sr and Si were synthesized by a wet precipitation method The presence of the HAP lattice as unique crystalline phase was established by XRD and by FTIR spectroscopy. The chemical composition was confirmed by SEM-EDX. The TEM, SEM and AFM imaging showed the morphology of these biomaterials. The elements release in water and in simulated body fluid (SBF) was monitored in time from 1 to 90 days, by using inductively coupled plasma optical emission spectrometry (ICP-OES). The results are important for the future use of these hydroxyapatite biomaterials, as bone substitutes or coatings on metallic implants, able to release essential physiological elements, both in vitro and in vivo, with great impact in orthopedics and dentistry. [ABSTRACT FROM AUTHOR]

The thermal stability over time of the pure and multisubstituted hydroxyapatite (HAP) pastes, doped with magnesium, silicon, strontium and zinc, synthesized using aqueous precipitation method were investigated by thermal analyses (TG-DTA). Results show high thermal stability of pure and multidoped hydroxyapatite pastes, up to 1000 oC and even after ageing for 1 year, making these pastes promising nano materials for medical applications. [ABSTRACT FROM AUTHOR]

HAP powder of a low crystallinity and rather large specific surface area was synthesized by an environmentally friendly, cost effective precipitation method, and characterized by XRD, FTIR, and BET isotherms. TEM and AFM are used to envisage the surface of HAP nano particles, showing a high porosity of this ceramic powder. It was used for the removal of metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) from mine wastewater. Metal contents in the initial and treated samples were quantified by inductively coupled plasma atomic emission spectrometry and high-resolution continuum source atomic absorption spectrometry. By the use of HAP, an efficient removal of all metals was ensured. The increase of Ca2+ ions content in the treated water suggests an ion exchange mechanism. [ABSTRACT FROM AUTHOR]

Nanostructured hydroxyapatite (HAP) and silicon substituted hydroxyapatites (HAP-Si), with 0.47 and 2.34 wt% Si, were prepared by wet precipitation method. Their structure was investigated by X rays diffraction (XRD), FTIR spectroscopy, energy dispersive X ray (EDX) spectroscopy and their images were obtained by TEM, SEM and AFM. Their behavior in water and SBF was investigated by inductively coupled plasma optical emission spectrometry (ICP-OES) for an immersion time from 1 to 90 days. While Ca and P release from HAP is very low, the presence of Si enhances greatly their release in water, along with a continuous and long lasting Si release. In simulated body fluid, SBF, Ca, P and Mg are removed from the solution, by the formation of a new HAP enriched in Mg, while silicon is released as in water. Thus, Si doped HAP might have advantageous applications as bone and tooth materials. [ABSTRACT FROM AUTHOR]