<Superscript>68</Superscript>Ga-radiolabeled magnetic nanoparticles for PET–MRI imaging

In this study, magnetic multimodal nanoparticles with potential applications in magnetic- and nuclear-medicine imaging, magnetic resonance imaging, hyperthermia, and theranostic (therapeutic and diagnostic), applications were prepared by coating iron oxide nanoparticles with silica (core–shell), functionalizing with aminopropyltriethoxy silane and coupling with diethylenetriamine pentaacetic acid ligand (DTPA). Radiolabeling of core–shell–DTPA particles with ⁶⁸Ga radiometal was carried out through chelation of ⁶⁸Ga(III) ions by DTPA and was used for positron emission tomography. The biodistribution of the ⁶⁸Ga-radiolabeled magnetic nanoparticles compared to free ⁶⁸Ga(III) was checked in normal Balb/c mice up to 2 h.     

<Superscript>13</Superscript>C-labeled bilirubin: synthesis of 3<Superscript>1</Superscript>(3<Superscript>2</Superscript>),17<Superscript>1</Superscript>(17<Superscript>2</Superscript>)-di-[<Superscript>13</Superscript>C]-mesobilirubin-XIIIα

Abstract  The title compound, labeled with ¹³C in the ethyl groups was synthesized from K¹³CN and low-molecular-weight components. The synthetic relay compound was 3¹(3²)[¹³C]-xanthobilirubinic acid methyl ester in a synthetic route that leads to a label in the ethyl β-substituent of a dipyrrinone model for bilirubin. This labeled dipyrrinone was oxidatively coupled to the dimethyl ester of mesobiliverdin-XIIIα, thereby providing a route to a ¹³C-labeled mesobiliverdin and mesobilirubin, with one carbon of each ethyl being 98% ¹³C-enriched. Graphical Abstract        

Facile radiosynthesis of <Superscript>18</Superscript>F-labeled β-glutamic acid as a new PET tracer for imaging lung cancer

In this paper, N-(2-[¹⁸F]fluoropropionyl)-β-glutamic acid 8 ([¹⁸F]FP-β-Glu), a new N-substituted ¹⁸F-labeled amino acid tracer, was synthesized from the precursor 4 (diethyl 3-(2-bromopropanamido)pentanedioate) via a two-step reaction on the modified FDG synthesizer. The radiochemical yield was 20 ± 5% (n = 10, decay-corrected) from [¹⁸F]fluoride within 40 min, the radiochemical purity was 98%. Moreover, microPET studies showed that [¹⁸F]FP-β-Glu 8 exhibited rapid tumor uptake and good tumor-to-lung ratio in SPC-A-1 tumor-bearing mice. A high accumulation of radioactivity was found in the kidneys and bladder, which suggested that the tracer was mainly eliminated through the urinary system.     

Synthesis and preliminary biological evaluation of [<Superscript>99m</Superscript>Tc(CO)<Subscript>3</Subscript>(IDA–PEG<Subscript>3</Subscript>–CB)]<Superscript>−</Superscript> for tumor imaging

This work reports the synthesis, radiolabeling and preliminary biodistribution results in tumor-bearing mice of [^99mTc(CO)₃(IDA–PEG₃–CB)]⁻. The novel chlorambucil derivative was successfully synthesized by conjugation of iminodiacetic acid (IDA) to chlorambucil via a pegylated linker. The ligand could be labeled by [^99mTc(CO)₃]⁺ core in high yield to get [^99mTc(CO)₃(IDA–PEG₃–CB)]⁻, which was very hydrophilic and was stable at room temperature. Biodistribution studies in tumor-bearing mice showed that [^99mTc(CO)₃(IDA–PEG₃–CB)]⁻ accumulated in the tumor with favorable uptake and retention. The good accumulation in tumor tissue with high tumor/muscle ratios warrants further research to improve tumor targeting efficacy and pharmacokinetic profile of radiolabeled chlorambucil derivative by structural modification.     

Production of Gas-Phase Uranium Fluoroanions Via Solubilization of Uranium Oxides in the [1-Ethyl-3-Methylimidazolium]<Superscript>+</Superscript>[F(HF)<Subscript>2.3</Subscript>]<Superscript>−</Superscript> Ionic Liquid

A new methodology for gas-phase uranium ion formation is described in which UO₂ is dissolved in neat N-ethyl,N′-methylimidazolium fluorohydrogenate ionic liquid [EMIm⁺][F(HF)_2.3^?], yielding a blue-green solution. The solution was diluted with acetonitrile and then analyzed by electrospray ionization mass spectrometry. UF₆^? (a U(V) species) was observed at m/z?=?352, and other than cluster ions derived from the ionic liquid, nothing else was observed. When the sample was analyzed using infusion desorption chemical ionization, UF₆^? was the base peak, and it was accompanied by a less intense UF₅^? that most likely was formed by elimination of a fluorine radical from UF₆^?. Formation of UF₆^? required dissolution of UO₂ followed by or concurrent with oxidation of uranium from the +?4 to the +?5 state and finally formation of the fluorouranate. Dissolution of UO₃ produced a bright yellow solution indicative of a U(VI) species; however, electrospray ionization did not produce abundant U-containing ions. The abundant UF₆^? provides a vehicle for accurate measurement of uranium isotopic abundances free from interference from minor isotopes of other elements and a convenient ion synthesis route that is needed gas-phase structure and reactivity studies like infrared multiphoton dissociation and ion-molecule dissociation and condensation reactions. The reactive fluorohydrogenate ionic liquid may also enable conversion of uranium in oxidic matrices into uranium fluorides that slowly oxidize to uranyl fluoride under ambient conditions, liberating the metal for facile measurement of isotope ratios without extensive chemical separations.

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A new method for the synthesis of metal complexes with <Emphasis Type="Italic">trans</Emphasis>-[B<Subscript>20</Subscript>H<Subscript>18</Subscript>]<Superscript>2–</Superscript> dianion

A new method has been proposed for the synthesis of transition metal complexes with the trans-[B₂₀H₁₈]^2– dianion from complexes with the closo-decaborate anion [B₁₀H₁₀]^2– without changing the cationic part of the complex. A cerium(IV) salt has been used as an oxidizing agent. Complexes [NiL₃][trans-B₂₀H₁₈] (L = Bipy, Phen) have been identified by elemental analysis and IR spectroscopy.     

Fully automated and simplified radiosynthesis of [<Superscript>18</Superscript>F]-3′-deoxy-3′-fluorothymidine using anhydro precursor and single neutral alumina column purification

[¹⁸F]-3′-deoxy-3′-fluorothymidine ([¹⁸F]FLT) is an established positron emission tomograph (PET)—radiopharmaceutical to study cell-proliferation rate in tumors. Very low practical yield, uncertain and time-consuming high performance liquid chromatography (HPLC) purification, are the main obstacles for the routine use of [¹⁸F]FLT in clinical PET. To obviate these difficulties, we have developed a fully automated radiosynthesis procedure for [¹⁸F]FLT using 5′-O-(4,4′-dimethoxytriphenylmethyl)-2,3′-anhydro-thymidine (DMTThy) and simplified single neutral alumina column purification. The [¹⁸F]FLT yield was 8.48 ± 0.93% (n = 5) (without radioactive decay correction) in a synthesis time of 68 ± 3 min. The radiochemical purity was greater than 95% as confirmed by analytical HPLC using reference standard FLT and also free of non-radioactive impurity. Soluble aluminum in the final product was much below the permissible limits. Di-methyl sulfoxide (DMSO), the reaction medium, could be detected in the final product in trace amounts, well below the permissible levels. The synthesized [¹⁸F]FLT was sterile and bacterial endotoxin free by appropriate tests. PET imaging study in normal rabbits showed distinct localization of [¹⁸F]FLT in organs having rapid cell division rate like bone marrow, guts and snout and the excretion was through the renal route. There were no significant uptakes in bone and brain. The former finding confirms the in vivo stability of the [¹⁸F]FLT. This simplified radiosynthesis procedure can easily be adapted in any commercial or indigenous [¹⁸F]FDG synthesis module for routine [¹⁸F]FLT synthesis without the need of additional automation for HPLC purification.     

Solvothermal synthesis,characterization and properties of [ReCl<Subscript>5</Subscript>(py)]<Superscript>−</Superscript> complex with T (Néel) of 5.5 K

The synthesis and properties of a rhenium(IV) complex with pyridine as a ligand are presented. The complex, with the formula (2-methyl-pyH)[ReCl₅(py)] 4,4′-bipyridyl 1 has been characterized by elemental analysis, IR spectroscopy, SQUID and X-ray measurements. The single crystal X-ray structure of 1 shows that the rhenium center is of distorted octahedral environment, consisting of five chloride atoms and one pyridine ligand. The solid-state magnetic measurements show antiferromagnetic interactions with T (Néel) of 5.5 K.     

Heterobimetallic compounds [Ru(η<Superscript>5</Superscript>-Cp)(dppf)X] (X = Cl,Br, I and N<Subscript>3</Subscript>): synthesis,electrochemical analysis,and the crystal structure of [Ru(η<Superscript>5</Superscript>-Cp)(dppf)I] [dppf = 1,1′-bis(diphenylphosphino)ferrocene]

A series of new ruthenium-iron based derivatives [Ru(η⁵-Cp)(dppf)Cl] (1), [Ru(η⁵-Cp)(dppf)Br] (2), [Ru(η⁵-Cp)(dppf)I] (3) and [Ru(η⁵-Cp)(dppf)N₃] (4) were obtained by reactions of [Ru(η⁵-Cp)(PPh₃)₂Cl] with 1,1′-bis(diphenylphosphino) ferrocene (dppf) and characterized by IR, NMR (¹H, ¹³C and ³¹P), ⁵⁷Fe Mössbauer spectroscopy and cyclic voltammetry. Additionally, the compound (3) was structurally characterized by X-ray crystallography, and the results were as follows: orthorhombic, Pbca, a = 18.2458(10), b = 20.9192(11), c = 34.4138(19) Å, α = β = γ = 90°, V = 13135.3(12) Å³ and Z = 16.     

Application of multilayered strategy for variable selection in QSAR modeling of PET and SPECT imaging agents as diagnostic agents for Alzheimer’s disease

Structural Chemistry - Non-invasive imaging of amyloid beta (Aβ) and tau fibrils in the brain may support an early and precise diagnosis of Alzheimer’s disease. Molecular imaging...     

Thermodynamics of complex formation in mixed solvents <Emphasis Type="Italic">K</Emphasis> and Δ<Emphasis Type="Italic">H</Emphasis> for the formation reaction of [Gly18C6] at 298.15 K

The influence of H₂O–EtOH and H₂O–Acetone mixed solvents at various compositions on the thermodynamics of complex formation reaction between crown ether 18-crown-6 (18C6) and glycine (Gly) was studied. The standard thermodynamic parameters of the complex [Gly18C6] (log K°, Δ_r H°, Δ_r S°) were calculated from thermochemical data at 298.15 K obtained by titration calorimetry. The complex stability and its formation enthalpy increase with increasing the non aqueous component concentration in both mixed solvents. The thermodynamic data were discussed on the basis of the solvation thermodynamic approach and the solvation contributions of the reagents and of the complex to the complex stability were analyzed.     

Phospho sulfonic acid as efficient heterogeneous Brønsted acidic catalyst for one-pot synthesis of 14<Emphasis Type="Italic">H</Emphasis>-dibenzo[<Emphasis Type="Italic">a,j</Emphasis>]xanthenes and 1,8-dioxo-octahydro-xanthenes

A simple, efficient procedure for the preparation of phospho sulfonic acid PO(OSO₃H)₃ as a Brønsted acidic and recoverable heterogeneous catalyst is described, used for the one-pot synthesis of aryl-14H-dibenzo[a,j]xanthenes and 1,8-dioxo-octahydro-xanthenes. A cost-effective, simple and convenient procedure for the synthesis of aryl-14H-dibenzo[a,j]xanthenes was developed via a one-pot condensation from substituted benzaldehydes and β-naphthol under solvent-free conditions. The one-pot condensation of substituted benzaldehydes and 5,5-dimethyl-1,3-cyclohexanedione (dimedone) under solvent-free conditions leads to 1,8-dioxo-octahydro-xanthenes. These protocols afford a number of advantages, such as: excellent yields, very short reaction times, easy procedure, simple methodology and ease of preparation and regeneration of the catalyst.     

Thermodynamic Properties of Peptide Solutions. Part 18. Partial Molar Isentropic Compressibilities of Gly-X-Gly Tripeptides (X = Tyr,Pro, Gln,Asp and Glu), and the Peptide Salts K[GlyAspGly], Na[GlyGluGly] and GlyLysGly Acetate in Aqueous Solution at 25 <Superscript>∘</Superscript>C

The partial molar isentropic compressibilities at infinite dilution, K∘_S,2, have been determined for several tripeptides of the sequence glycyl-X-glycine, where X is one of the amino acids tyrosine, proline, glutamine, aspartic acid, glutamic acid and lysine in aqueous solution at 25 ^∘C. These results, along with those for triglycine, were used to estimate the contributions of the amino acid side-chains to the partial molar isentropic compressibilities of polypeptides. Values for K∘_S,2 have also been determined for aqueous solutions of the two peptide salts K[glyaspgly] and Na[glyglugly]. The K∘_S,2 results for the peptides and their salts have been combined with literature data for electrolytes to calculate the changes in isentropic compressibility upon ionization of the acidic side-chains. The results are compared with those for other carboxylic acid systems.