64CuCl2 PET Imaging of 4T1-Related Allograft of Triple-Negative Breast Cancer in Mice.

64CuCl2 is an economic radiotracer for oncologic PET investigations. In the present study, we characterized the uptake of 64CuCl2 in vivo by µPET/CT in an allograft 4T1-related mouse model (BALB/c) of advanced breast cancer. 18F-FDG was used as a comparator. Twenty-two animals were imaged 7-9 days following 4T1-cell implantation inside mammary glands. Dynamic 64CuCl2 µPET/CT acquisition or iterative static images up to 8 h p.i. were performed. Animal biodistribution and tumor uptake were first evaluated in vivo by µPET analysis and then assessed on tissue specimens. Concerning 18F-FDG µPET, a static acquisition was performed at 15 min and 60 min p.i. Tumor 64CuCl2 accumulation increased from 5 min to 4 h p.i., reaching a maximum value of 5.0 ± 0.20 %ID/g. Liver, brain, and muscle 64CuCl2 accumulation was stable over time. The tumor-to-muscle ratio remained stable from 1 to 8 h p.i., ranging from 3.0 to 3.7. Ex vivo data were consistent with in vivo estimations. The 18F-FDG tumor accumulation was 8.82 ± 1.03 %ID/g, and the tumor-to-muscle ratio was 4.54 ± 1.11. 64CuCl2 PET/CT provides good characterization of the 4T1-related breast cancer model and allows for exploration of non-glycolytic cellular pathways potentially of interest for theragnostic strategies.

Heptadentate chelates for 89Zr-radiolabelling of monoclonal antibodies.

Herein, we report the synthesis of three new bifunctional heptadentate metal ion binding chelates derived from desferrioxamine B (DFO) linked to a tripeptide unit that comprises of a glutamic acid and two glycine residues. The three DFO derivatives were also functionalised with a photoactivatable aryl azide unit for light-triggered labelling of proteins. The chelates were obtained in 3 synthetic steps in good overall yields by using solid phase peptide synthesis (SPPS). Density Functional Theory (DFT) calculations were used to estimate thermodynamic formation constants (log ß) of the corresponding Zr4+ complexes. Quantitative zirconium-89 radiolabelling (>95%) was obtained in <5 min at room temperature, and the stability of the radioconjugates toward different competitors (human serum, EDTA and Fe3+) was assessed in vitro. One-pot 89Zr-photoradiosynthesis produced [89Zr]Zr-2-onartuzumab directly from the formulated, clinical-grade sample MetMAb™, without pre-purifying the monoclonal antibody (mAb) component, with an isolated decay-corrected radiochemical yield of 36.4 ± 2.4%. PET imaging and biodistribution studies were performed in female athymic nude mice bearing subcutaneous xenografts derived from the MKN-45 human gastric cancer cell line to assess the pharmacokinetic profile and tumour binding of [89Zr]Zr-2-onartuzumab. Specific tumour uptake of [89Zr]Zr-2-onartuzumab was confirmed by using competitive inhibition (blocking) studies and bone uptake was significantly reduced compared to the parent DFO analogue.

Comparison of the [18F]-FDG and [18F]-FLT PET Tracers in the Evaluation of the Preclinical Proton Therapy Response in Hepatocellular Carcinoma.

PURPOSE: The main objective of the present study was to compare the 2-deoxy-2-[18F]fluoro-D-glucose ([18F]-FDG) and 3'-[18F]fluoro-3'-deoxythymidine ([18F]-FLT) PET imaging biomarkers for the longitudinal follow-up of small animal proton therapy studies in the context of hepatocellular carcinoma (HCC). PROCEDURES: SK-HEP-1 cells were injected into NMRI nude mice to mimic human HCC. The behavior of [18F]-FDG and [18F]-FLT tumor uptake was evaluated after proton therapy procedures. The proton single-fraction doses were 5, 10, and 20 Gy, with a dose rate of 10 Gy/min. The experimental protocol consisted of 8 groups of 10 mice, each group experiencing a particular dose/radiotracer condition. A reference PET exam was performed on each mouse the day before the irradiation procedure, followed by PET exams every 3 days up to 16 days after irradiation. RESULTS: [18F]-FDG uptake showed a linear dose-dependent increase in the first days after treatment (37%, p < 0.05), while [18F]-FLT uptake decreased in a dose-dependent manner (e.g., 21% for 5 Gy compared to 10 Gy, p = 1.1e-2). At the later time point, [18F]-FDG normalized activity showed an 85% decrease (p < 0.01) for both 10 and 20 Gy doses and no variation for 5 Gy. Conversely, a significant 61% (p = 0.002) increase was observed for [18F]-FLT normalized activity at 5 Gy and no variation for higher doses. CONCLUSION: We showed that the use of the [18F]-FDG and [18F]-FLT radiolabeled molecules can provide useful and complementary information for longitudinal follow-up of small animal proton therapy studies in the context of HCC. [18F]-FDG PET imaging enables a treatment monitoring several days/weeks postirradiation. On the other hand, [18F]-FLT could represent a good candidate to monitor the treatment few days postirradiation, in the context of hypo-fractioned and close irradiation planning. This opens new perspectives in terms of treatment efficacy verification depending on the irradiation scheme.

Imaging thrombosis with 99mTc-labeled RAM.1-antibody in vivo.

INTRODUCTION: Platelets play a major role in thrombo-embolic diseases, notably by forming a thrombus that can ultimately occlude a vessel. This may provoke ischemic pathologies such as myocardial infarction, stroke or peripheral artery diseases, which represent the major causes of death worldwide. The aim of this study was to evaluate the specificity of radiolabeled Rat-Anti-Mouse antibody (RAM.1). METHODS: We describe a method to detect platelets by using a RAM.1 coupled with the chelating agent hydrazinonicotinic acid (HYNIC) conjugated to 99mTc, for Single Photon Emission Computed Tomography (SPECT). To induce platelet accumulation at a site of interest, we used a mouse model of FeCl3 induced injury of the carotid artery. 90 min after i.v. injection of [99mTc][Tc(HYNIC)-RAM.1], biodistribution of the radiolabeled RAM.1 was assessed, SPECT imaging and histological analysis were performed on the mice that underwent FeCl3-induced vessel damage. RESULTS: We demonstrated a quick and strong affinity of the radiolabeled RAM.1 for the platelet thrombus. Results clearly demonstrated the ability of this radioimmunoconjugate for detecting thrombi from 10 min post injection with an exceptional thrombi uptake. Using FeCl3, the median ratio between the thrombus and the background was 12.4 (range 9.3-42.3) as compared to 1.0 (range: 0.86-2.7) p < 0.05 when using 0.9% NaCl. CONCLUSION: Thanks to the high sensitivity of SPECT, we provided evidence that [99mTc][Tc(HYNIC)-RAM.1] represents a powerful tool to detect localized platelet thrombi which could potentially be used in humans. Because of the relative low cost and high sensitivity, these results encourage further study like the detection of non-induced thrombus and further developments toward clinical application. This is further supported by the fact that RAM.1 recognizes human platelets.

Physicochemical regulation of TGF and VEGF delivery from mesoporous calcium phosphate bone substitutes.

AIM: Determination of the physicochemical parameters governing growth factors (GFs) adsorption and release from mesoporous calcium phosphate ceramics. MATERIALS & METHODS: Six mesoporous calcium phosphate ceramics prepared by soft and hard templating were loaded with two different physiological concentrations of TGF-ß1 or VEGF165 and their in vitro kinetics of adsorption/release were studied. RESULTS: This low GF loading promotes adsorption on the highest binding sites. The usually encountered detrimental burst release is thus considerably reduced for samples prepared by hard-templating method. CONCLUSION: Our findings highlight that the strong affinity of GFs with the ceramic surfaces, demonstrated by a slow GFs release, is enhanced by the large surface area, confinement into mesopores of ceramics and high difference of surface charge between ceramic surfaces and GFs.

Dramatic Changes in the Solubilities of Ions Induced by Ligand Addition in Biphasic System D2O/DNO3//[C1C4im][Tf2N]: A Phenomenological Study.

The solubilities of C1C4im(+) and Tf2N(-) in nitric aqueous phases have been measured for several ligand types and concentrations (0.04 M tributylphosphine oxide, 0.05 M N,N'-dimethyl-N,N'-dibutylmalonamide, 0.10 M 1-methyl-3-[4-(dibutylphosphinoyl)butyl]-3H-imidazol-1-ium bis(trifluoromethylsulphonyl)imidate, and 1.1 M N,N-dihexyloctanamide). The data evidence a significant difference between the solubilities of the cations and anions of the ionic liquid as a consequence of several ion-exchange and/or ion-pairing mechanisms involving all ions present in the system as well as the protonation/nitric-extraction ability of the ligand.

Automated and efficient radiosynthesis of [(18)F]FLT using a low amount of precursor.

INTRODUCTION: Since 1991 until now, many radiosyntheses of [(18)F]FLT have been published. Most of them suffer from side reactions and/or difficult purification related to the large amount of precursor necessary for the labeling step. A fully automated synthesis using only commercial and unmodified materials with a reduced amount of precursor would be desirable. METHODS: We first explored the possibility to elute efficiently [(18)F]fluorine from commercial and unmodified cartridges with various amount of base. Based on these results, 10mg and 5mg of precursors were used for the fluorination step. The best conditions were transposed in an automated process for a one pot two steps synthesis of labeled FLT. RESULTS: Using commercial and non-treated carbonate form of QMA cartridges, we were able to elute quantitatively the [(18)F]fluorine with a very low amount of base (0.59mg) and, with only 5mg of precursor, to perform an efficient fluorination reaction with up to 94% incorporation of [(18)F]fluorine. The synthesis was fully automated and radiochemical yields of 54% (decay corrected) were obtained within a synthesis time of 52minutes. CONCLUSION: We demonstrate that a fully automated and efficient radiosynthesis of [(18)F]FLT is feasible with only 5mg of precursor. Compare to the present state of the art, our method provides high yields of pure [(18)F]FLT and is broadly adaptable to other synthesis automates.

Insights into the mechanism of extraction of uranium (VI) from nitric acid solution into an ionic liquid by using tri-n-butyl phosphate.

We present new results on the liquid-liquid extraction of uranium (VI) from a nitric acid aqueous phase into a tri-n-butyl phosphate/1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (TBP/[C4 mim][Tf2 N]) phase. The individual solubilities of the ionic-liquid ions in the upper part of the biphasic system are measured over the whole acidic range and as a function of the TBP concentration. New insights into the extraction mechanism are obtained through the in situ characterization of the extracted uranyl complexes by coupling UV/Vis and extended X-ray absorption fine structure (EXAFS) spectroscopy. We propose a chemical model to explain uranium (VI) extraction that describes the data through a fit of the uranyl distribution ratio DU . In this model, at low acid concentrations uranium (VI) is extracted as the cationic complex [UO2 (TBP)2 ](2+) , by an exchange with one proton and one C4 mim(+) . At high acid concentrations, the extraction proceeds through a cationic exchange between [UO2 (NO3 )(HNO3 )(TBP)2 ](+) and one C4 mim(+) . As a consequence of this mechanism, the variation of DU as a function of TBP concentration depends on the C4 mim(+) concentration in the aqueous phase. This explains why noninteger values are often derived by analysis of DU versus [TBP] plots to determine the number of TBP molecules involved in the extraction of uranyl in an ionic-liquid phase.

Phosphonated chelates for nuclear imaging.

A series of bis-, tris- and tetra-phosphonated pyridine ligands is presented. In view of their potential use as chelates for radiopharmaceutical applications, the physico-chemical properties of the ligands and of their Co(II), Ni(II), Cu(II), and Zn(II) complexes were studied by means of potentiometry and UV-Vis absorption spectroscopy. The pKa values of the ligands and of the complexes, as well as the stability constants for the formation of the complexes, are presented. The kinetic aspects of the formation of Cu(II) complexes and of their dissociation in acidic media were studied by means of stopped flow experiments, and the stability of the Cu(II) complex toward reduction to Cu(I) was investigated by cyclic voltammetry and by titration with different reducing agents. The different thermodynamic and kinetic aspects of the polyphosphonated ligands were compared with regard to the impact of the number of phosphonic acid functions. Considering the very promising properties for complexation, preliminary SPECT/CT imaging experiments were carried out on mice with (99m)Tc using the bis- and tetra-phosphonated ligands L(2) and L(1). Finally, a bifunctional version of chelate L(1), L*, was used to label MTn12, a rat monoclonal antibody with both specificity and relatively high affinity for murine tenascin-C. The labeling was monitored by MALDI/MS spectrometry and the affinity of the labeled antibody was checked by immunostaining experiments. After chelation with (99m)Tc, the (99m)Tc-L*-MTn12 antibody was injected into a transgenic mouse with breast cancer and the biodistribution of the labeled antibody was followed by SPECT/CT imaging.

Is a universal model to describe liquid-liquid extraction of cations by use of ionic liquids in reach?

A general chemical model describing the extraction mechanism of cations from an acidified aqueous phase toward an ionic liquid phase in which an extracting agent is dissolved is proposed. On this basis, fits are made which recover very satisfactorily the variation of the distribution ratio as a function of [HNO(3)] for several experimental data sets from the literature. This chemical model is discussed and compared to another model.

Potent calcium phosphate nanoparticle surface coating for in vitro and in vivo siRNA delivery: a step toward multifunctional nanovectors.

The present study describes hybrid nanoparticles, built by alternate deposition of siRNA and modified polyethyleneimine (tyrosine-grafted PEI or tyrosine/galactose-grafted PEI) on calcium phosphate nanoparticles. These "easy to produce" nanoparticles (NPs) present an efficient gene silencing effect demonstrated in vitro in a luciferase expressing cell culture model and in vivo in a tumour xenograft mouse model. The luciferase gene silencing percentage reached up to 95% in vitro with biocompatible doses of siRNA. Interestingly, we show by SPECT imaging of radiolabeled particles that without modifying the size, stability and in vitro efficiency, the grafting of a sugar moiety on PEI can modify the in vivo biodistribution of the particles. The proof of concept that galactose-grafting on PEI could change biodistribution without changing the gene silencing efficiency makes them versatile tools for specific delivery of small interfering RNA. As they have been designed so far, biodistribution is mainly located in the liver and thus these innovative nanoparticles open a realistic and feasible strategy for siRNA delivery into the liver in vivo.

Comparison of uranyl extraction mechanisms in an ionic liquid by use of malonamide or malonamide-functionalized ionic liquid.

The extraction of uranyl from acidic (HNO(3)) aqueous solutions toward an ionic liquid phase, C(1)-C(4)-imTf(2)N (1-methyl,3-butylimidazolium Tf(2)N), has been investigated as a function of initial acid concentration and ligand concentration for two different extracting moieties: a classical malonamide, N,N'-dimethyl-N,N'-dibutylmalonamide (DMDBMA) and a functionalized IL composed of the Tf(2)N(-) anion and an imidazolium cation on which a malonamide pattern has been grafted (FIL-MA). The extraction mechanism, as demonstrated through the influence of added C(1)-C(4)-imCl or added LiTf(2)N in the aqueous phase, is slightly different between the DMDBMA and FIL-MA extracting agents. Modeling of the extraction data evidences a double extraction mechanism, with cation exchange of UO(2)(2+)versus 2 H(+) for DMDBMA or versus C(1)-C(4) -im(+) and H(+) for FIL-MA at low acidic values, and through anion exchange of [UO(2)(NO(3))(3)](-)versus Tf(2)N(-) for both ligands at high HNO(3) concentrations. The FIL-MA molecule is more efficient than its classical DMDBMA parent.

Evidence for the formation of UO2(NO3)4(2-) in an ionic liquid by EXAFS.

The complexation between uranium(vi) and nitrate ions in a hydrophobic ionic liquid (IL), namely [BMI][NO(3)] (BMI = 1-butyl-3-methylimidazolium(+)), is investigated by EXAFS spectroscopy. It was performed by dissolution of uranyl nitrate UO(2)(NO(3))(2)·6H(2)O or UO(2)(Tf(2)N)(2) (Tf(2)N = bis(trifluoromethylsulfonyl)imide (CF(3)SO(2))(2)N(-)). The formation of the complex UO(2)(NO(3))(4)(2-) is evidenced.

Perrhenate complexation by uranyl in traditional solvents and in ionic liquids: a joint molecular dynamics/spectroscopic study.

The complexation of perrhenate (ReO(4)(-)) anions by the uranyl (UO(2)(2+)) cation has been investigated by joint molecular dynamics simulations and spectroscopic (UV-vis, TRLFS, and EXAFS) studies in aqueous solution, acetonitrile, and three ionic liquids (ILs), namely, [Bmi][Tf(2)N], [Me(3)BuN][Tf(2)N], and [Bu(3)MeN][Tf(2)N] that are based on the same Tf(2)N(-) anion (bis(trifluoromethylsulfonyl)imide) and either Bmi(+) (1-butyl,3-methylimidazolium), Me(3)BuN(+), or Bu(3)MeN(+) cations. They show that ReO(4)(-) behaves as a weak ligand in aqueous solution and as a strong ligand in acetonitrile and in the ILs. According to MD simulations in aqueous solution, the UO(2)(ReO(4))(2) complex quickly dissociates to form UO(2)(H(2)O)(5)(2+), while in acetonitrile, a stable UO(2)(ReO(4))(5)(3-) species forms from dissociated ions. In the ILs, the UO(2)(ReO(4))(n)(2-n) complexes (n = 1 to 5) remained stable along the dynamics, and to assess their relative stabilities, we computed the free energy profiles for stepwise ReO(4)(-) complexation to uranyl. In the two studied ILs, complexation is favored, leading to the UO(2)(ReO(4))(5)(3-) species in [Bmi][Tf(2)N] and to UO(2)(ReO(4))(4)(2-) in [Bu(3)MeN][Tf(2)N]. Furthermore, in both acetonitrile and [Bmi][Tf(2)N] solutions, MD and PMF simulations support the formation of dimeric uranyl complexes [UO(2)(ReO(4))(4)](2)(4-) with two bridging ReO(4)(-) ligands. The simulation results are qualitatively consistent with spectroscopic observations in the different solvents, without firmly concluding, however, on the precise composition and structure of the complexes in the solutions.

Liquid-liquid extraction of actinides, lanthanides, and fission products by use of ionic liquids: from discovery to understanding.

Liquid-liquid extraction of actinides and lanthanides by use of ionic liquids is reviewed, considering, first, phenomenological aspects, then looking more deeply at the various mechanisms. Future trends in this developing field are presented.

Effect of prior treatment with resveratrol on density and structure of rat long bones under tail-suspension.

Physical inactivity during space flight or prolonged bed rest causes rapid and marked loss of bone mass in humans. Resveratrol, a red wine polyphenol that is currently under study for its therapeutic antioxidant properties, has been shown to significantly modulate biomarkers of bone metabolism, i.e., to promote osteoblast differentiation and to prevent bone loss induced by estrogen deficiency. However, there is no direct evidence supporting its inhibitory effect toward bone loss during physical inactivity. In the present study, effects of resveratrol on bone mineral density (BMD), bone mineral content, and bone structure were examined in the femora and tibiae of tail-suspended and unsuspended rats using X-ray micro-computed tomography (micro-CT). Rats were treated with 400 mg/kg/day of resveratrol for 45 days and half of them were suspended during the last 2 weeks of treatment. Suspension caused a decrease in tibial and femoral BMD and deterioration of trabecular and cortical bone. Bone deterioration during suspension was paralleled by increased bone marrow area, which could be caused by an increase in stromal cells with osteoclastogenic potential or in adipocytes. Resveratrol had a preventive effect against bone loss induced by hindlimb immobilization. In particular, trabecular bone in the proximal tibial metaphysis was totally preserved in rats treated with resveratrol before tail-suspension.

Determination of successive complexation constants in an ionic liquid: complexation of UO(2)(2+) with NO(3)(-) in C(4)-mimTf(2)N studied by UV-Vis spectroscopy.

The complexation of UO(2)(2+) with NO(3)(-) has been investigated in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide by UV-vis spectroscopy at T = 18.5 degrees C. The complexation is evidenced through the appearance of four peaks at 425, 438, 453, and 467 nm. EXAFS data indicate that the trinitrato complex, UO(2)(NO(3))(3)(-), is dominating the speciation for a reagent ratio of [NO(3)(-)]/[UO(2)(2+)] > 3. Assuming three successive complexation steps, the conditional stability constants are calculated, the individual absorption spectra are derived, and a speciation plot is presented.

Task-specific ionic liquids bearing 2-hydroxybenzylamine units: synthesis and americium-extraction studies.

The synthesis of two task-specific ionic liquids (TSILs) bearing 2-hydroxybenzylamine entities is described. These compounds are based on an imidazolium substructure onto which one hydrobenzylamine-complexing moiety is grafted. We have demonstrated that, whether pure or diluted, TSIL is able to extract americium ions. Furthermore, recovery of americium from the IL phase into a receiving phase can be achieved under acidic conditions. A possible mechanism for the metal-ion partitioning is presented, in which the extraction system is driven by an ion-exchange mechanism.

Extraction of lanthanides from aqueous solution by using room-temperature ionic liquid and supercritical carbon dioxide in conjunction.

For the first time, the study of a three-step extraction system of water/ionic liquid/supercritical CO2 has been performed. Extraction of trivalent lanthanum and europium from an aqueous nitric acid solution to a supercritical CO2 phase via an imidazolium-based ionic liquid phase is demonstrated, and extraction efficiencies higher than 87 % were achieved. The quantitative extraction is obtained by using different fluorinated beta-diketones with and without the addition of tri(n-butyl)phosphate. The complexation phenomenon occurring in the room-temperature ionic-liquid (RTIL) phase was evidenced by using luminescence spectroscopy.

Europium(III) and its halides in anhydrous room-temperature imidazolium-based ionic liquids: a combined TRES, EXAFS, and molecular dynamics study.

Combining spectroscopic techniques (TRES and EXAFS) and molecular dynamics simulations, we have investigated the state of trivalent europium dissolved in room-temperature ionic liquids (RTILs), as a function of the RTIL anion and in the presence of added chloride anions. The studied RTILs are based on the 1-butyl-3-methyl-imidazolium (Bumim+) cation and differ by their anionic counterparts: BF4-, PF6-, Tf- (triflate, CF3SO3-), and Tf2N- [(CF3SO2)2N-]. The results show the strong influence of the RTIL nature on the first solvation shell of europium and on its complexation with chloride. Depending on the RTIL, europium(III), which was introduced in solution as a triflate salt, is found to be solvated either by RTIL anions only or as neutral undissociated EuTf3 moieties completed by solvent anions. Kinetic effects, related to the viscosity of the RTIL and the nature of the europium salt, also markedly influence the coordination of added Cl- or F- anions to the metal.