Antibacterial efficacy and cytotoxicity studies of copper (II) and titanium (IV) substituted hydroxyapatite nanoparticles

Cu²⁺ and Ti⁴⁺ substituted hydroxyapatite (CuHA; TiHA) in different molar ratios (M_added/Ca_added = 0.01, 0.05, 0.10 and 0.15) were synthesized using wet chemical method coupled with ion exchange reaction. All characterization results confirmed the samples were hydroxyapatite (HA). XRD data showed that all samples were single phased. Both intensity and width of XRD peaks did not change significantly as substitution concentration increased. The FTIR spectra revealed the occurrence of CO₃^2? ions (B-type carbonated HA). ICP data indicated that the content of Cu and Ti in CuHA and TiHA increased with initial metal salt concentration. Visual examination by FESEM showed all samples possessed elongated spheroid morphology with crystal size of around 70 nm. The CuHA nanoparticles possessed high antibacterial property against Escherichia coli. This was probably due to the leaching of Cu²⁺ ions which subsequently led to the lysis of bacteria. TiHA had slight antibacterial effect compared to pure HA at high Ti content (Ti_added/Ca_added = 0.1). Agar diffusion and extraction cytotoxicity assay revealed that the presence of Cu²⁺ was cytotoxic while Ti⁴⁺ was only slightly toxic to osteoblasts.     

Substitution of manganese and iron into hydroxyapatite: Core/shell nanoparticles

The bioceramics, hydroxyapatite (HAP), is a material which is biocompatible to the human body and is well suited to be used in hyperthermia applications for the treatment of bone cancer. We investigate the substitution of iron and manganese into the hydroxyapatite to yield ceramics having the empirical formula Ca_9.4Fe_0.4Mn_0.2(PO₄)₆(OH)₂. The samples were prepared by the co-precipitation method. The formation of the nanocrystallites in the HAP structure as the heating temperatures were raised to obtain a glass–ceramic system are confirmed by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and electron spin resonance (ESR). TEM images show the core/shell structure of the nanoparticles, with the core being formed by the ferrites and the shell by the hydroxyapatite. The ED patterns indicate the nanoparticles formed at 500 °C have an amorphous structure while the nanoparticles formed at 1000 °C are crystalline. ESR spectroscopy indicated that the Fe³⁺ ions have a g-factor of 4.23 and the Mn²⁺ ions have a g-factor of 2.01. The values of the parameters in the spin Hamiltonian which describes the interaction between the transition metal ions and the Ca²⁺ ions, indicate that the Mn²⁺ ion substitute into the Ca²⁺ sites which are ninefold coordinated, i.e., the Ca(1) sites.     

Synthesis and identification of zeolite-encapsulated iron (II), iron (III)-hydrazone complexes

Complexes of Fe(II) and Fe(III) with N₂O₃ hydrazone ligand (SBSH) derived from salicyaldehyde and benzenesulphonylhydrazide have been encapsulated in zeolite Y-supercages by a diffusion method. The synthesized new materials have been characterized by combination of elemental analysis, FT-IR, UV–Vis., magnetic measurements, XRD, thermal analysis (TG, DTG and DTA) as well as surface area measurements and nitrogen adsorption studies. Additionally, the state of iron was evaluated by the use of Mössbauer spectroscopy at room temperature. Investigation of the stereochemistry of these incorporated chelates pointed out that, Fe(II) and Fe(III) ions in zeolite Y are coordinated with the SBSH ligand through the (CN), (SO₂) and (OH) groups forming mononuclear structure in case of Fe(II) complex and binuclear structure in case of Fe(III) complex. The contribution of the water molecules in all cases was supposed to complete the coordination sphere. The intrazeolitic ferrous and ferric hydrazone complexes have distorted octahedral configuration and are thermally stable up to 543 and 900 °C, respectively.     

Synthesis and characterization of hydroxyapatite nanobelts and nanoparticles

In the present paper, the nanobelts and sphere nanoparticles of hydroxyapatite (HA) had been synthesized using normal (oil in water) surfactant. The experimental results showed that the nanobelts consisted of uniform one-dimensional nanofibers with a width of 1.37 nm. The particle size of the sphere nanoparticles was about 55–60 nm. The presence of these resonance of phosphorus was in at least two types of phosphorus environments. The spectra of the nanobelts and sphere nanoparticles contained two typical bands of hexahedra Ca²⁺ at 200 and 210 nm. The Eg values for the HA of microcrystalline, sphere nanoparticles, and nanobelts samples were 1.60, 1.69 and 1.70 eV, respectively.     

Effects of low-molecular-weight organic acids on Cu(II) adsorption onto hydroxyapatite nanoparticles

Adsorption kinetics and adsorption isotherms of Cu(II) onto a nanosized hydroxyapatite (HAP) in the absence and presence of different low-molecular-weight organic acids are studied in batch experiments. The results show that the adsorption kinetics of Cu(II) onto the HAP are best described by pseudo-second-order model, and the adsorption isotherms of Cu(II) onto the HAP fit Dubinin-Radushkevich model very well with high correlation coefficient (R(2)=0.97-0.99). The amount adsorbed of Cu(II) onto the HAP at pH 5.5 was much higher than that at pH 4.5. The presence of organic acids significantly decreased the adsorption quantity of Cu(II), clarifying the lower sorption affinities of Cu(II)-organic acid complexes onto the HAP rather than Cu(II) ion. The decreased maximal adsorption quantity of Cu(II) onto the HAP increased with the increasing logarithm of cumulative formation constants of Cu(II) and organic acids. The stronger coordination of organic acid with Cu(II), the more decreased Cu(II) adsorption quantity onto the HAP.     

Thermal transformations of iron(III)-nickel(II) mixed oxide gels

Iron-nickel mixed oxide gels have been prepared by a hydroxide co-precipitation technique and their thermal transformation has been studied by thermal analyses, X-ray diffraction and infra-red spectroscopy. Differential thermal analysis (DTA) of the hydrated ferric oxide gel indicates the presence of three exothermic peaks along with a broad endotherm. Addition of nickel oxide decreases the intensities of the exotherms and the peaks are completely absent in the samples containing more than 10 mol % of NiO. On the other hand these samples show the presence of three endothermic peaks. Thermal analysis of the sample containing 50 mol % of NiO indicates the formation of a precursor at around 185° C which changes to nickel ferrite at around 275° C. This ferrite slowly crystallizes with a broad exotherm in the range 280 to 550° C.     

Fine structure study on low concentration zinc substituted hydroxyapatite nanoparticles

The fine structure of zinc substituted hydroxyapatite was studied using experimental analysis and first-principles calculations. The synthetic hydroxyapatite nanoparticles containing low Zn concentration show rod-like morphology. The crystallite sizes and unit-cell volumes tended to decrease with the increased Zn concentration according to X-ray diffraction patterns. The Zn K-edge X-ray absorption spectra and fitting results suggest that the hydroxyapatite doped with 0.1 mole% zinc is different in the zinc coordination environments compared with that containing more zinc. The density function theory calculations were performed on zinc substituted hydroxyapatite. Two mechanisms included replacing calcium by zinc and inserting zinc along the hydroxyl column and were investigated, and the related substitution energies were calculated separately. It is found that the substitution energies are negative and lowest for inserting zinc between the two oxygen atoms along the hydroxyl column (c-axis). Combined with the spectral analysis, it is suggested that the inserting mechanism is favored for low concentration zinc substituted hydroxyapatite.     

Synthesis and luminescence properties of lanthanide (III)-doped YF3 nanoparticles

Synthesis process and luminescence properties of trivalent lanthanide ions (Ln3+) doped YF3 nanoparticles have been investigated. To synthesis Ln(3+)-doped YF3 nanoparticles, the mixture of (YCl3 x nH2O + LnCl3 x nH2O), and NH4F was hydrothermal treated at 180 degrees C in a Teflon-liner auto-clave or heated at higher temperatures (400 degrees C - 600 degrees C) in a stove. The XRD patterns showed that the Ln(3+)-doped orthorhombic YF3 nanoparticles with no second phase have been prepared. The solid solution Y(1-x)Eu(x)F3 (x = 0 - 0.4) nanoparticles have been synthesized. The luminescence concentration quenching resulted from resonance energy transfer between neighboring Eu3+ ions occurred at higher Eu3+ concentrations (30 mol%). The upconversion luminescence of Er(3+)-Yb3+ codoped YF3 nanoparticles under 980 nm excitation has also been observed. With increase of heated temperature, the size of the Er(3+)-Yb3+ codoped YF3 nanoparticles increased gradually, and upconversion luminescence intensity increased significantly.     

The preparation of iron (III) oxide nanoparticles using W/O microemulsion

Iron (III) oxide, Fe₂O₃, nanoparticles were prepared using W/O microemulsion as the reactor. W/O microemulsion was formed using n-heptane as oil phase, water and AOT as the surfactant under the specific composition. Iron (III) Chloride was used as a starting material and Ammonium hydroxide was a precipitating agent. Fe₂O₃, nanoparticles were then produced in situ the water core. Size of particles could be adjusted by the water content of the mixtures. The higher the water content, the bigger the particle size. The average size of the nanoparticles obtained was smaller than 100 nm. Moreover, Fe₂O₃ produced by this method was hematite with hexagonal in structure.     

Determination of antibacterial properties and cytocompatibility of silver-loaded coral hydroxyapatite

In this study, silver-loaded coral hydroxyapatites (SLCHAs) were used as scaffolds for bone tissue engineering. The SLCHAs were prepared by surface adsorption process and ion-exchange reaction between Ca²⁺ of coral hydroxyapatite (CHA) and Ag⁺ of silver nitrate with different concentrations at room temperature. The properties of the composite SLCHAs were investigated by inductively coupled plasma-atomic emission spectrometry (ICP-AES), scanning electron microscropy (SEM) equipped with backscattered electron detector (BSE), and energy-dispersive X-ray spectrometer (EDS). The SEM images showed that the morphology of the SLCHAs depended on the content of Ag⁺, and the silver ions were uniformly distributed on the surface of SLCHAs. The ICP-AES results demonstrated that the silver content of the SLCHAs decreased along with the decrease of the concentration of silver nitrate. The SLCHAs were found effective against Escherichia coli and Staphylococcus aureus by antibacterial test. Mouse embryonic pre-osteoblast cells (MC3T3-E1) were used to test the cytocompatibility of SLCHAs, CHA, and pure coral. Cell morphology and cell proliferation were studied with SEM, laser scanning confocal microscope (LSCM), and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay after 1, 3, and 5 days of culture. The results indicated the cell morphology and proliferation on the scaffolds of Ag⁺ (13.6 μg/ml)/CHA and Ag⁺ (1.7 μg/ml)/CHA were better than that on Ag⁺ (170 μg/ml)/CHA. In addition, adhesion of MC3T3-E1 on the scaffolds showed that the confluent cells showed fusiform shape and arranged tightly on the scaffolds. All the results showed that the antibacterial SLCHAs would have potential clinical application as the scaffolds for bone tissue engineering.     

Synthesis and sintering of biomimetic hydroxyapatite nanoparticles for biomedical applications

Synthesis of monodisperse nanoparticles with uniform morphology and narrow size distribution as achieved by nature is a challenge to materials scientists. Mimicking the process of biomineralization has led to the development of biomolecules mediated synthesis of nanoparticles that overcomes many of the problems associated with nanoparticle synthesis. Termed as biomimetics this paradigm shift in the philosophy of synthesis of materials is very advantageous for the design-based synthesis of nanoparticles. The effect of concentration of a protein named bovine serum albumin on particle size, morphology and degree of crystallinity of biomimetically synthesized hydroxyapatite particles, has been studied. Results establish 0.5% protein as the required concentration to produce 30–40 nm sized hydroxyapatite particles with an optimum degree of crystallinity as required for biomedical applications. These particles synthesized under certain stringent conditions are found to have stoichiometric calcium:phosphorus ratio of 1.67 and exhibit restricted grain growth during sintering.     

Synthesis and characterization of europium(III) nanoparticles for time-resolved fluoroimmunoassay of prostate-specific antigen

Recent advances in the fabrication and bioconjugation of nanometre-sized lanthanide(III) chelate particles have led to robust high specific activity labels. This paper describes the synthesis and characterization of lanthanide(III) nanoparticle labels and the use of a nanoparticle in a bioaffinity assay system. Two europium(III) nanoparticles were prepared using an extremely simple, inexpensive and fast agglomeration strategy. A?silica-stabilized nanoparticle was synthesized from hydrophobic tris(dibenzoylmethane)-mono(phenanthroline) and tris(dibenzoylmethane)-mono(5-aminophenanthroline) europium(III) chelates in aqueous solution. In addition, a naphthoyl trifluoroacetone:tri-n-octylphosphineoxide:sodium dodecyl sulfate europium(III) complex was agglomerated in water. The particle sizes ranged from 62 to 140?nm in diameter. The silica-stabilized particle was further coated with a monoclonal antibody. The analytical performance of the bioconjugated nanoparticle label was evaluated in a model sandwich immunoassay of prostate-specific antigen. The detection limit of human prostate-specific antigen was 28?ng?l(-1), 850?fM, in a microtiter plate format using time-resolved fluorometry. The coefficient of variation ranged from 1 to 9%. The novel nanoparticle label improves the specific activity of existing lanthanide(III) nanoparticle labels and simplifies the preparation route. In addition, prepared high-density nanoparticle labels using lanthanide(III) chelates or other specific fluorochromes have potential applications in a number of other fields.     

Decolorization of orange II by catalytic oxidation using iron (III) phthalocyanine-tetrasulfonic acid

Orange II, C.I. Acid Orange 7 (AO7), is oxidatively decolorized via catalytic oxidation by iron(III) phthalocyanine-tetrasulfonic acid (Fe(III)-PcTS) as a biomimetic catalyst and KHSO(5) as an oxygen donor. The nature of the decolorization of AO7 was investigated in the catalyst concentration range of 10-50 microM, in which the initial concentration of AO7 was 417 mg l(-1). A 99.6% decolorization was observed at [KHSO(5)] = 2.5 mM and [Fe(III)-PcTS] = 20 microM after a 3-h reaction period. However, the fact that only 4.9% of the TOC was removed indicated that the conversion to CO(2) was incomplete. The results of a total organic nitrogen analysis of the reaction mixture showed that the nitrogen in the azo chain was mainly converted to N(2) gas. In addition, 38.6% of the AO7 was converted to 1,2-dihydroxynaphthalene, and 21.4% to p-phenolsulfonic acid. These results indicate that the degradation via this catalytic system involves the conversion of AO7 to phenolic compounds, followed by N(2) production. In addition, a Microtox test showed that toxicity of the solution increased as a result of AO7 oxidation using this catalytic system.     

Synthesis of iron nanoparticles from hemoglobin and myoglobin

Stable iron nanoparticles have been synthesized from naturally occurring and abundant Fe-containing bio-precursors, namely hemoglobin and myoglobin. The formation of stable iron nanoparticles was achieved through a one-pot, single-phase chemical reduction approach. The reduction of iron ions present in the bio-precursors was carried out at room temperature and avoids the use of harsh chemical reagents. The size distribution of the product falls into the narrow 2-5?nm range and the particles were found to be crystalline. This method can be a valuable synthetic approach for producing bio-conjugated nanoparticle systems for biological applications.     

Synthesis and characterization of multifunctional iron oxide nanoparticles

In order to get high water solubility, monodisperse, superparamagnetic nanoparticles, poly (acrylic acid) was employed to modify Fe3O4 by a high-temperature solution-phase hydrolysis approach. Then, folic acid (FA) and fluorescein isothiocyanate were successively conjugated with prepared magnetic nanoparticles (MNPs). The functional MNPs were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscope (TEM), inductively coupled plasma-atomic emission spectrometer (ICP-AES), and vibrating sample magnetometer (VSM), respectively. The toxicity of the materials was evaluated by selecting NIH/3T3 fibroblast cells and no toxic effect was observed. The fluorescent imaging and targeting property of the MNPs were also realized in vitro and in vivo experiments by confocal laser scanning microscopy (CLSM) and Kodak In-Vivo FX Professional Imaging System, respectively. The results indicated that the final products exhibited interesting magnetic, optical and targeting properties for further potential applications in biological and biomedical fields.     

Magnetic gamma-Fe(2)O(3) nanoparticles coated with poly-l-cysteine for chelation of As(III), Cu(II), Cd(II), Ni(II), Pb(II) and Zn(II)

An anaerobic attached-growth bioreactor (AAGBR) of 3.52 L was operated for 510 days to treat sulfide-laden organic wastewater where nitrate and nitrite were introduced as electron acceptors. When the influent sulfide was kept at 200mg S(2-)-S/L and organic carbon was increased from 20 to 33.6 mg C/L, and the hydraulic retention time decreased from 41.4 to 2.67 h, the removal rates of sulfide and organic carbon reached 99.9% and 91.8% at the loading rates of 1800 mg S(2-)-S/(Ld) and 302.4 mg C/(Ld), respectively. Simultaneously, the introduced electron acceptors of nitrate and nitrite were, respectively, removed by 99.9% and 99.9% at the loading rates of 472.5 mg NO(3)(-)-N/(Ld) and 180 mg NO(2)(-)-N/(Ld). Inside the AAGBR, both autotrophic and heterotrophic denitrification processes were noted to take place. When the influent organic carbon was increased from 20 to 33.6 mg C/L, the nitrate and nitrite consumed for heterotrophic denitrification accounted for 27.3% and 48.5%, respectively. This simultaneous autotrophic and heterotrophic desulfurization-denitrification process has provided a demonstration of the possibility to eliminate sulfide and organic carbon with the presence of nitrate and nitrite.     

Synthesis and characterization of waterborne polyurethane/Cu(II)-loaded hydroxyapatite nanocomposites with antibacterial activity

A novel kind of environmentally friendly nanocomposites, waterborne polyurethane (WBPU)/Cu(II)-loaded hydroxyapatite (CuHAp), with improved physical properties and antibacterial activity have been prepared via in-situ polymerization from functionalized CuHAp nanoparticles (CuHAp NPs). The interaction of the CuHAp NPs with isophorone diisocyanate to form the functionalized CuHAp NPs containing isocyanate groups (CuHAp-g-NCO) has been studied. The microstructure and particle distribution of the nanocomposites were observed using scanning electron microscopy. The improvements of mechanical properties, thermal stability and water resistance of the nanocomposites have also been evaluated. Finally, the antibacterial activity was tested against G(-) Escherichia coli and G(+) Staphylococcus aureus by the zone of inhibition test and the direct contact test. The long-lasting antibacterial activity was studied by measuring antibacterial ability of the nanocomposites after being immersed in water. The results indicate that WBPU incorporation with CuHAp NPs shows strong antibacterial activity upon contact, and long-lasting antibacterial property.