A comparative study on the uptake of lanthanides from acidic feeds using extraction chromatography resins containing N,N,N',N'-tetra-n-alkyl diglycolamides with varying alkyl chain lengths in an ionic liquid.

A comparative study on the uptake of several rare earth element (REE) ions viz. La(III), Ce(III), Pr(III), Nd(III), Sm(III), Gd(III) and Dy(III) was carried out from nitric acid feeds using four extraction chromatography resins which contained the diglycolamide (DGA) ligands, N,N,N',N'-tetra-n-alkyldiglycolamide with n-pentyl (TPDGA), n-hexyl (THDGA), n-octyl (TODGA) and n-decyl (TDDGA) groups taken in a room temperature ionic liquid (C4mim·NTf2). The uptake of the lanthanides followed the trend: La(III) < Ce(III) < Pr(III) < Nd(III) < Sm(III) < Gd(III) < Dy(III), which is similar to their ionic potential values and the uptake trend of the resins was TPDGA > THDGA > TODGA > TDDGA. The uptake of the metal ions was very high (>104 g/mL) for all the lanthanide ions and was found to increase with increasing nitric acid concentrations. Based on the encouraging batch data, column studies were carried out with all the four extraction chromatography resins with the lanthanide ions used in this work. The column studies were carried out with both individual lanthanide ions and their mixtures. While the loading studies were carried out with 80 mg/L solutions of the metal ions (with respect to each of those) in the mixture of REEs, the elution studies were carried out using a solution of 0.05 M EDTA in 1 M guanidine carbonate. For the column studies involving individual REEs, 550 mg/L solutions were used. The elution profiles appeared to be sharp as >95% elution of the metal ions was accomplished in only 3 mL of the eluent which amounted to only 1.6 bed volumes which is highly impressive. When the studies were carried out with the mixture of the lanthanide ions, the breakthrough of Dy(III) was last while that of La(III) was seen at much lower volumes which was dependent on the nature of the extractant in the resins.

Radiation stability of two extraction chromatography resin materials containing substituted diglycolamide ligands in an ionic liquid.

The radiation stability of two extraction chromatography resins containing diglycolamide ligands viz. TPDGA (N,N,N',N'-tetra-n-pentyl diglycolamide) and TODGA (N,N,N',N'-tetra-n-octyl diglycolamide) in a room temperature ionic liquid (C4mim.NTf2) was studied by exposing to gamma rays from a 60Co source. The resins were irradiated to varying gamma ray dose up to 1000 kGy where both the dry resins and wet resins (containing a fixed amount nitric acid in contact) were used. The performance assessment of the resins was done by physicochemical characterization as well as uptake studies; both by batch as well as column methods. The physicochemical characterization of the resins was done using FTIR analysis while the surface morphology of the resins was carried out by scanning electron microscopy. The uptake of the metal ions, typically that of Am(III) and Eu(III), representing the trivalent actinides and lanthanides was studied by batch method. The dry resins and those in contact with nitric acid yielded nearly identical results suggesting minimal effect of the radiolytic products of nitric acid on the resin performance. There was negligible change in the Kd values up to an absorbed dose of 300 kGy beyond which there was sharp decrease. However, the Kd values were still quite large even after an absorbed dose of 1000 kGy. The column performance of the irradiated resins was also assessed by the uptake and elution of Eu(III) ion and though loading was affected, the elution behavior was found to have insignificant effect.

A brand new two-phase wet oxidation absorption system for the simultaneous removal of SO2 and NOX from simulated marine exhaust gas.

Marine engine exhaust emissions are increasingly harmful to the natural environment and human health and must be controlled. A self-synthesized amide (BAD, C12H25NO) in the laboratory shows a strong absorption capacity of nitric acid and nitrous acid, which may solve the problem that only using chlorine-based oxidant as an absorbent cannot completely absorb or retain NO2 produced by NO oxidation in previous studies. Based on Multiwfn and VMD (Visual Molecular Dynamics) program calculation, the formation mechanism of hydrogen bonds between BAD with nitric acid and nitrous acid was revealed by electrostatic potential (ESP) analysis and further confirmed by FT-IR (Fourier transform infrared spectroscopy) spectra research. Subsequently, simultaneous removal of SO2 and NOX from simulated flue gas was carried out by using NaClO/BAD as a two-phase composite absorbent, and the maximum removal efficiencies of SO2 and NOX were 98.9% and 86.6%, respectively. The recycling experiments and the engineering experiments showing that NaClO/BAD can solve the problem of absorption of NO2, and it can be a promising composite absorbent in wet desulfurization and denitrification of marine engine exhaust gas in practical applications.

Structure features, selenylation modification, and improved anti-tumor activity of a polysaccharide from Eriobotrya japonica.

A homogeneous polysaccharide, EJP90-1, was isolated from the leaves of E. japonica by hot water extraction in this study. EJP90-1 (7702 Da) was a heteropolysaccharide mainly consisting of →5)-linked-α-L-Araf-(1→, →4)-linked-ß-D-Manp-(1→, →2,4)-linked-α-L-Rhap-(1→, →4)-linked-α-D-Xylp-(1→, →4)-linked-ß-D-Galp-(1→, →2)-linked-ß-D-Galp-(1→, →6)-linked-ß-D-Glcp-(1→, α-D-Glcp-(4→, and t-linked-α-L-Araf. EJP90-1 was found to show moderate anti-tumor activity at the cellular level. In order to improve the anti-tumor activity and the potential applications of EJP90-1, a typical sodium selenite-nitric acid (Na2SeO3-HNO3) modification on EJP90-1 was carried out. X-ray photoelectron spectroscopy (XPS) and energy dispersive spectrometer (EDS) analysis confirmed that Se was successfully introduced into the polymer chain of EJP90-1. The subsequent in vitro cytotoxicity evaluation showed the selenylation modification derivative (EJP90-1-Se) possessed significant antiproliferative activity against cancer cells (HepG2 and A549 cells) through inducing cell apoptosis. The anti-tumor activity of EJP90-1-Se was further confirmed by zebrafish models, which inhibited the proliferation and migration of HepG2 cells and the angiogenesis.

Selective uptake of thorium(IV) from nitric acid medium using two extraction chromatographic resins based on diglycolamide-calix[4]arenes: Application to thorium-uranyl separation in an actual sample.

Two novel extraction chromatography resins (ECRs) containing two diglycolamide (DGA) -functionalized calix[4]arenes with n-propyl and isopentyl substituents at the amide nitrogen atom, termed as ECR-1 and ECR-2, respectively, were evaluated for the uptake of Th(IV) from nitric acid feed solutions. While both the resins were having a quite high Th(IV) uptake ability (Kd >3000 at 3 M HNO3), the uptake was relatively lower with the resin containing the isopentyl DGA, which appeared magnified at lower nitric acid concentrations. Kinetic modeling of the sorption data suggested fitting to the pseudo-second order model pointing to a chemical reaction during the uptake of the metal ion. Sorption isotherm studies were carried out showing a good fitting to the Langmuir and D-R isotherm models, suggesting the uptake conforming to monolayer sorption and a chemisorption model. Glass columns with a bed volume of ca. 2.5 mL containing ca. 0.5 g lots of the ECRs were used for studies to assess the possibility of actual applications of the ECRs. Breakthrough profiles obtained with feed containing 0.7 g/L Th(NO3)3 solution resulted in breakthrough volumes of 8 and 5 mL, respectively, for the ECR-1 and ECR-2 resins. Near quantitative elution of the loaded metal ion was possible using a solution of oxalic acid and nitric acid. A method for the separation of Th-234 from natural uranium was demonstrated for the possible application of ECR-1.

In vitro targeting and selective killing of mcf-7 and colo320dm cells by 5-fluorouracil anchored to carboxylated SWCNTs and MWCNTs.

The intention of the present work was to synthesize the f-MWCNT and f-SWCNT terminated with proper functional group, loading of 5-Flurouracil and to perform cytotoxic activity. Functionalization of MWCNTs and SWCNTs was achieved through the acid treatment (H2SO4 + HNO3). 5-flurouracil was loaded into the prepared functionalized CNTs, thereafter; in vitro drug loading capacity and % drug release were calculated. Also the prepared f-CNTs, 5-flurouracil loaded CNTs were distinguished by using SEM, TGA, DSC, X-ray diffraction, Raman and FTIR spectroscopy. MCF-7 and COLO320DM cells were treated with selected concentrations of 5-FU loaded f-MWCNTs and f-SWCNTs to estimate the cytotoxic activity. It was observed that 5-FU loaded f-SWCNTs showed good activity against selected cell lines than others. Moreover, apoptosis percentage was reported to be 84.46 ± 4.3515 and 92.78 ± 2.6549 for 5-FU loaded f-SWCNTs against MCF-7 and COLO320DM cells respectively. It is evident from the results that the prepared drug loaded CNTs have comparable antitumor activity in cancer cell lines.

Multi-element determination in chocolate bars by microwave-induced plasma optical emission spectrometry.

Macro- and microelement determination in chocolate bars by microwave-induced plasma optical emission spectrometry (MIP OES) was evaluated after microwave-assisted sample digestion. Optimization of the sample digestion was carried out, and the recommended conditions were obtained at a temperature of 190 °C, with a digestion time of 40 min and in a mixture constituted by 2.3 mL of nitric acid, 1.0 mL of hydrogen peroxide and 4.7 mL of water. The method was applied in the analysis of chocolate bars, and the concentration ranges of the elements determined were (in mg kg-1): Ca (653-3096); Cr (<0.6-2.8); Cu (<0.16-19.5); Fe (<1.6-227); Mg (147-2775); K (3554-8573); Mn (<0.03-25.2); Na (45.6-1095); Ni (3.2-10.2); P (1111-22594) and Zn (4.8-33.3). The association of the proposed microwave-assisted acid digestion with the MIP OES technique was adequate for multi-element determination in chocolate bars for routine analysis.

Hydrofluoric acid and nitric acid cotreatment for biofunctionalization of polyetheretherketone in M2 macrophage polarization and osteogenesis.

Due to its excellent mechanical and low-friction properties, polyetheretherketone (PEEK) has been widely investigated for use in orthopedic applications over the past decade. However, the bioinertness and poor osteogenic properties of PEEK have hampered its clinical application. In this study, the surface of PEEK was modified by co-treatment with hydrofluoric acid and nitric acid (AFN). The microstructures of the modified PEEK surfaces were investigated using scanning electron microscopy. The water contact angles of the surfaces were also measured. To evaluate their cytocompatibility, PEEK samples were used as substrates to culture rat bone mesenchymal stem cells, and cell adhesion, viability, and expression of specific marker genes were measured. Treatment of PEEK with AFN (PEEK-AFN) was found to enable better osteoblast adhesion, spreading, and proliferation; the activity of alkaline phosphatase (an early osteogenic differentiation marker) was also found to be enhanced post-treatment. Furthermore, PEEK-AFN was able to modulate macrophage polarization and down regulated the expression of proinflammatory factors via inhibiting the NF-κB pathway. Thus, treatment of PEEK with AFN could promote M2 polarization of the macrophages and stimulate the differentiation of osteoblasts. These results provide valuable information that could facilitate the use of PEEK-based composites as bone implant materials.

Synthesis of Se-polysaccharide mediated by selenium oxychloride: Structure features and antiproliferative activity.

Selenium oxychloride (SOC) was employed as a highly reactive selenide reagent to synthesize selenized Artemisia sphaerocephala polysaccharides (SeASP). Se content of SeASP was significantly increased (∼22,400 µg/g) as compared to HNO3/H2SeO3 selenylation method (1703 µg/g). Furthermore, selenized ASP was prepared by using microwave-assisted synthesis which obviously enhanced selenylation kinetics. FT-IR, Raman, XPS and NMR results exhibited seleno-group was substituted at C6 position in the form of selenite (Se4+). SEC-MALLS suggested SOC system could effectively avoid the degradation of polysaccharide chain. Meanwhile, MALLS calculation, MB spectrophotometric method and AFM observation showed SeASP appeared spherical and rod-shaped conformation after selenylation. Seleno-groups were more likely to affect the conformational transformation of polysaccharide chains. Moreover, SeASP could significantly enhance antiproliferative activity against three tumor cells, of which the IC50 value of HepG2 was calculated as 24.35 µg/mL. It was found that higher Se content could effectively improve the antitumor activities of Se-polysaccharides in vitro.

Effect of biochar modified with magnetite nanoparticles and HNO3 for efficient removal of Cr(VI) from contaminated water: A batch and column scale study.

Chromium (Cr) poses serious consequences on human and animal health due to its potential carcinogenicity. The present study aims at preparing a novel biochar derived from Chenopodium quinoa crop residues (QBC), its activation with magnetite nanoparticles (QBC/MNPs) and strong acid HNO3 (QBC/Acid) to evaluate their batch and column scale potential to remove Cr (VI) from polluted water. The QBC, QBC/MNPs and QBC/Acid were characterized with SEM, FTIR, EDX, XRD as well as point of zero charge (PZC) to get an insight into their adsorption mechanism. The impact of different process parameters including dose of the adsorbent (1-4 g/L), contact time (0-180 min), initial concentration of Cr (25-200 mg/L) as well as solution pH (2-8) was evaluated on the Cr (VI) removal from contaminated water. The results revealed that QBC/MNPs proved more effective (73.35-93.62-%) for the Cr (VI) removal with 77.35 mg/g adsorption capacity as compared with QBC/Acid (55.85-79.8%) and QBC (48.85-75.28-%) when Cr concentration was changed from 200 to 25 mg/L. The isothermal experimental results follow the Freundlich adsorption model rather than Langmuir, Temkin and Dubinin-Radushkevich adsorption isotherm models. While kinetic adsorption results were well demonstrated by pseudo second order kinetic model. Column scale experiments conducted at steady state exhibited excellent retention of Cr (VI) by QBC, QBC/MNPs and QBC/Acid at 50 and 100 mg Cr/L. The results showed that this novel biochar (QBC) and its modified forms (QBC/Acid and QBC/MNPs) are applicable with excellent reusability and stability under acidic conditions for the practical treatment of Cr (VI) contaminated water.

Microwave-assisted digestion employing diluted nitric acid for mineral determination in rice by ICP OES.

A microwave-assisted digestion method using diluted HNO3 was developed for further determination of Al, Ca, Cr, Cu, Fe, K, Mn, Mo and Ni in rice samples by ICP OES. The following optimized conditions were established after full factorial design: digestion time of 14 min, concentration of 1 mol L-1 HNO3 and 2.5 mL of H2O2. The efficiency in decomposing organic matter with diluted acid was higher than 89%. The methodology was validated using the SRM NIST 1568a Rice Flour and recovery tests, with agreement between the determined and certified/added concentration values, and RSD of up to 12%. The limits of detection of the method were in the range of 0.0087 mg kg-1 (Mn) to 1.6 mg kg-1 (Ca). In addition, a simple and inexpensive spectrophotometric method was proposed for the quantification of organic carbon in varied samples (carbohydrates, proteins, lipids) in the form of digested or solids.

High specificity and efficiency electrochemical detection of poly(ADP-ribose) polymerase-1 activity based on versatile peptide-templated copper nanoparticles and detection array.

Poly(ADP-ribose) polymerase-1 (PARP-1) activity is closely related to tumor, which is a promising biomarker for cancer diagnosis. So far, only a few methods have been developed for PARP-1 activity assay because both PARP-1 and its catalytic products lack valuable optical or electrochemical property. Herein, we propose a more specific method to label probes on great deal of phosphate groups of PAR. Firstly, versatile peptides were used to prepare CuNPs. This peptide not only worked as reducing agent to prepare CuNPs but also had guanidine groups to label PAR autonomously and specifically. Unlike most previously reported methods based on unspecific electrostatic interactions, CuNPs probes covered by guanidine groups labelled PAR with phosphate groups via intense covalent-like interactions. On the other hand, PARP-1 catalyzed the formation of PAR in each isolated reaction container of the detection array, realizing the high-throughput detection and enhancing the detection efficiency. Ultimately, CuNPs were oxidized into Cu2+ and precisely detected by stripping voltammetry. Hence, selectivity and efficiency of PARP-1 detection were both improved. Meanwhile, this approach was successfully used to detect the efficiency of PARP-1 inhibitor and the PARP-1 contents in real cells, indicating its great potential for clinical diagnosis and high-throughput PARP-1 inhibitor screen.

Crude Oil Sensing using Carbon Nano Structures Synthetized from Phoenix Dactylifera L. Cellulose.

This study reports on the crude oil-sensing using carbon nano structures (CNSs). A mixture of CNSs was obtained by a simple method of preparation using palm cellulose ash and nitric acid as precursors, the powder was characterized by x-ray diffraction and infrared spectroscopy. The optical density of crude oil from Rhoud El-Baguel area (Southeast of Algeria) studied using UV-Vis spectroscopy, before and after adding an amount of CNSs powder to view the CNSs crude oil sensing and therefore a new method to determine the quality of crude oils and the comparison between them. Results show that CNSs prepared from palm cellulose ash have a good crystallinity and it is formed mainly from carbon nano dots (CNDs) with 4.32 Å in layers spacing and 7.4 Å in crystallite size, indicate that CNSs can be used as an excellent crude oil sensor.

Amino modification of rice straw-derived biochar for enhancing its cadmium (II) ions adsorption from water.

To enhance the adsorption capacity of Cd2+, -NH2 groups were introduced into the rice straw-derived biochar surface by combining nitrification and amination. The batch and continuous Cd2+ adsorption experiments were performed to determine the role of -NH2 groups on the surface of biochar. The physical and chemical characteristics were analyzed for comparison. The results indicated that the adsorption capacity of the modified biochar (BC-NH2) was boosted by 72.1%. The results of continuous adsorption experiments in fixed bed columns showed that the penetration time of BC-NH2 was three times that of original biochar. The adsorption of Cd2+ by BC-NH2 is a spontaneous endothermic chemical reaction, which was obtained by combing sorption kinetics, isotherms and thermodynamic analysis. The Cd2+ adsorption was mainly the complexation between -NH2 group on biochar surface and Cd2+ in solution. Finally, a possible interaction mechanism between Cd2+ and BC-NH2 was proposed.

Dry-bonding to dentin using alternative conditioners based on iron-containing solutions or nitric acid.

OBJECTIVES: To evaluate the effect of experimental conditioners (10-3 solution - 10-3, 6.8% ferric oxalate - FOX, and 1.4% nitric acid - NI) on dentin elastic modulus, flexural strength, bond strength, failure mode, and adhesive interface morphology of two etch-and-rinse adhesives (XP Bond, Dentsply or One-Step, Bisco) applied on etched dry dentin. METHODS: Sound human third molars were used for the microtensile bond strength test (n = 8), performed at 24 h and after one year of water storage. Failure modes were evaluated by scanning electron microscopy. Dentin bonding interface was analyzed by confocal laser scanning microscopy (n = 3). Adhesive systems were applied on phosphoric acid-etched, wet (positive control) and dry (negative control) dentin, and on etched and dry dentin previously treated with 10-3 (15s), FOX (60s), or NI (15s). Bovine dentin bars (n = 15) were immersed into the conditioning solutions and subjected to a three-point bending test. RESULTS: XP Bond + 10-3 or NI resulted in lower bond strength than phosphoric acid. One-Step + 10-3 or NI resulted in bond strengths equivalent to the positive control. Experimental conditioners presented no bond strength reduction after one year, regardless of the bonding agent tested. One-Step resulted in more adhesive failures than XP Bond at 24 h, and mixed failures increased after storage. All experimental conditioners promoted hybridization and resin tags formation, except FOX. Dentin elastic modulus was not affected by the conditioners, whereas flexural strength was significantly reduced by FOX. CONCLUSIONS: Adequate and stable dentin bonds were achieved when the bonding agents were applied on 10-3 or NI-treated dentin. None of the experimental conditioners reduced dentin elastic modulus, but dentin flexural strength was significantly reduced by FOX-conditioning.

Development and Collaborative Study of a Diluted Acid Mild Extraction Method for Determination of Cadmium in Grain by Graphite Furnace Atomic Absorption Spectrometry.

The traditional pretreatment methods for the determination of cadmium in grain are time-consuming, cost-consuming, and unfriendly to human health and the environment. To eliminate these disadvantages, we developed an accurate, time-, energy- and cost-efficient method for determination of Cd in grain coupled with graphite furnace atomic absorption spectrometry (GFAAS). The optimization conditions of the extraction were achieved, the accuracy was verified and a collaborative study was organized to evaluate the methods. The detection limit and quantification limit were 0.016 and 0.048 µg L-1, respectively. The whole pretreatment time was reduced to 15 min, and there was no significant difference (P >0.05) between the extraction method and the classic pretreatment method. The method proved to be highly consistent with the results of laboratories in different countries, as determined from two international proficiency tests (| Z | ≤0.3). The repeatability, reproducibility, and HorRat values of the collaborative results were 2.7 - 4.9%, 9.4 - 11.7%, and 0.42 - 0.58, respectively. The method of diluted acid mild extraction coupled with GFAAS is efficient, cost-saving, convenient and friendly.

Nitric acid-anionic surfactant modified activated carbon to enhance cadmium(II) removal from wastewater: preparation conditions and physicochemical properties.

The authors used a nitric acid (HNO3)-sodium dodecyl benzene sulfonate (SDBS) method to modify a lignite-based activated carbon. These modified carbons were appraised for their removal of Cd(II) from aqueous solutions. Response surface methodology was employed to optimize the preparation factors including nitric acid concentration CN, temperature T and SDBS concentration CS. Statistical analysis indicated that the interaction of CN and CS incurred the most effect on the maximum cadmium adsorption capacity (Qm). The optimal Qm appeared at CN = 3.29 mol/L, T = 76 °C and CS=30,700 mg/L. The optimal protocol achieved 44.21 mg/g Qm for Cd(II) which was about 7 times larger than for this pristine lignite activated carbon (LAC) (6.78 mg/g). The physical-chemical properties of the modified activated carbons following each synthesis step were characterized relative to their surface area, oxygen functionality, and external surface charge. It was confirmed that the developed surface area, functional groups and negative charges were mainly responsible for the higher adsorption capacity for the LAC that have been more favorably tailored by this HNO3-SDBS protocol.

Selective biosorption of thorium (IV) from aqueous solutions by ginkgo leaf.

Low-cost biosorbents (ginkgo leaf, osmanthus leaf, banyan leaf, magnolia leaf, holly leaf, walnut shell, and grapefruit peel) were evaluated in the simultaneous removal of La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Yb3+, Lu3+, UO22+, Th4+, Y3+, Co2+, Zn2+, Ni2+, and Sr2+ from aqueous solutions. In single metal systems, all adsorbents exhibited good to excellent adsorption capacities toward lanthanides and actinides. In a simulated multicomponent mixed solution study, higher selectivity and efficiency were observed for Th4+ over other metal cations, with ginkgo leaves providing the highest adsorptivity (81.2%) among the seven biosorbents. Through optimization studies, the selectivity of Th4+ biosorption on ginkgo leaf was found to be highly pH-dependent, with optimum Th4+ removal observed at pH 4. Th4+ adsorption was found to proceed rapidly with an equilibrium time of 120 min and conform to pseudo-second-order kinetics. The Langmuir isotherm model best described Th4+ biosorption, with a maximum monolayer adsorption capacity of 103.8 mg g-1. Thermodynamic calculations indicated that Th4+ biosorption was spontaneous and endothermic. Furthermore, the physical and chemical properties of the adsorbent were determined by scanning electron microscopy, Brunauer-Emmett-Teller, X-ray powder diffraction, and Fourier transform infrared analysis. The biosorption of Th from a real sample (monazite mineral) was studied and an efficiency of 90.4% was achieved from nitric acid at pH 4 using ginkgo leaves.

Cyclotriphosphate associated to fluoride increases hydroxyapatite resistance to acid attack.

This study evaluated the effect of sodium trimetaphosphate (TMP) associated or not with fluoride (F) on the structure and dissolution of carbonated hydroxyapatite (CHA). Synthetic CHA powder (1.0 g) was suspended in solutions containing TMP at 0-10%, associated with 0, 1100, 4500, or 9000 ppm F, and the precipitates were submitted to a pH cycle (n = 6/group). Samples were analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. F, calcium (Ca) and phosphorous (P) concentrations were determined in CHA, while P and F were analyzed in the supernatants. Data were submitted to analysis of variance, Student-Newman-Keuls' test and Pearson's correlation coefficient (α = 0.05). Solutions containing 1100 ppm F with TMP between 2-4% and 4500 and 9000 ppm F with TMP between 4 and 8% led to higher Ca/P ratio (p < 0.05) in CHA. Alkali-soluble F deposition was directly related to TMP concentrations whereas an inverse pattern was observed for acid-soluble F incorporation (p < 0.05). Greater P adsorption in the CHA structure was observed with increasing concentrations of TMP for the 0 and 1100 ppm F solutions (p < 0.05). All diffractograms and FTIR spectra showed a similar pattern to that for pure hydroxyapatite. Thus, when TMP and F are coadministered, TMP interferes with F deposition on CHA, and an ideal TMP:F ratio can enhance the precipitation of CHA with lower solubility. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2553-2564, 2018.

An optimised spectrophotometric assay for convenient and accurate quantitation of intracellular iron from iron oxide nanoparticles.

We report the development and optimisation of an assay for quantitating iron from iron oxide nanoparticles in biological matrices by using ferene-s, a chromogenic compound. The method is accurate, reliable and can be performed with basic equipment common to many laboratories making it convenient and inexpensive. The assay we have developed is suited for quantitation of iron in cell culture studies with iron oxide nanoparticles, which tend to manifest low levels of iron. The assay was validated with standard reference materials and with inductively coupled plasma-mass spectrometry (ICP-MS) to accurately measure iron concentrations ∼1 × 10-6 g in about 1 × 106 cells (∼1 × 10-12 g Fe per cell). The assay requires preparation and use of a working solution to which samples can be directly added without further processing. After overnight incubation, the absorbance can be measured with a standard UV/Vis spectrophotometer to provide iron concentration. Alternatively, for expedited processing, samples can be digested with concentrated nitric acid before addition to the working solution. Optimization studies demonstrated significant deviations accompany variable digestion times, highlighting the importance to ensure complete iron ion liberation from the nanoparticle or sample matrix to avoid underestimating iron concentration. When performed correctly, this method yields reliable iron ion concentration measurements to ∼2 × 10-6 M (1 × 10-7 g/ml sample).