Fluorine-18 Radiochemistry: A Novel Thiol-Reactive Prosthetic Group, [18F]FBAMPy

A novel thiol-reactive bifunctional agent, an analogue of fluorobenzaldehyde-O-[6-(2,5-dioxo-2,5- dihydro-pyrrol-1-yl)-hexyl]oxime, (FBAM) has been synthesized. The new prosthetic group, [18F]- FBAMPy, replaces the 4-fluorophenyl moiety with a 2-fluoropyridinyl moiety leading to increased polarity (FBAM analytical HPLC Rf = 6.4 min;FBAMPy Rf = 4.8 min) while retaining the sulfur-reactive pendant. By altering the polarity of the molecule, this new prosthetic group should have significant impact in coupling it with small peptides and other biomolecules.

Strategies for PET imaging of the receptor for advanced glycation endproducts(RAGE)

The implication of the receptor for advanced glycation end-products(RAGE)in numerous diseases and neurodegenerative disorders makes it interesting both as a therapeutic target and as an inflammatory biomarker.In the context of investigating RAGE as a biomarker,there is interest in developing radiotracers that will enable quantification of RAGE using positron emission tomography(PET)imaging.We have synthesized potential small molecule radiotracers for both the intracellular([18F]InRAGER)and extracellular([18F]RAGER)domains of RAGE.Herein we report preclinical evaluation of both using in vitro(lead panel screens)and in vivo(rodent and nonhuman primate PET imaging)methods.Both radiotracers have high affinity for RAGE and show good brain uptake,but suffer from off-target binding.The source of the off-target PET signal is not attributable to binding to melatonin receptors,but remains unexplained.We have also investigated use of lipopolysaccharide(LPS)-treated mice as a possible animal model with upregulated RAGE for evaluation of new imaging agents.Immunoreactivity of the mouse brain sections revealed increases in RAGE in the male cohorts,but no difference in the female groups.However,it proves challenging to quantify the changes in RAGE due to off-target binding of the radiotracers.Nevertheless,they are appropriate lead scaffolds for future development of 2nd generation RAGE PET radiotracers because of their high affinity for the receptor and good CNS penetration.

Absorptive process of ~3H-5-hydroxytryptamine in the intestinal lumen

Absorptive process of ~3H-5-hydroxytryptamine(~3H-5-HT)in the intestinal lumenwas studied by radiochemical method and autoradiography.The results indicated that ~3H-5-HTinjected into the intestinal lumen was rapidly absorbed.The absorptive peak appeared at 1 h af-ter ~3H-5-HT injection.Part of the absorbed ~3H-5-HT might enter the blood circulation,andthe other part was located specifically in the submucous plexus,myenteric plexus and some ep-ithelial cells.Whether these neurones and epithelial cells are 5-HT containing cells or are cellswith specific binding sites awaits further studies.

What Is Exactly the Scope of Nuclear Chemistry and Its Educational Position between Other Chemistry Branches

The undergraduate chemistry programs of different universities across the world show clearly that nuclear chemistry education doesn’t have a permanent status in chemistry curricula like classical sub-branches of chemistry which means like organic, inorganic, analytical, physical, and biochemistry. Before starting the evaluation of the status of nuclear chemistry education, first of all, nuclear chemistry should correctly be defined and its position in chemistry education programs should correctly be determined. In addition, a confusion of terminology or at least, a terminological turbulence exists in this branch of chemistry about the use of terms such as nuclear chemistry, radiochemistry, nuclear and radiochemistry. Also, the scopes of the expressions used in this field such as radiochemistry, radiation chemistry, radiopharmaceutical chemistry, etc. should be exactly defined and the realtions between them should be clearly understood. Breifly, nuclear chemistry may be difined as a large umbrella which covers all chemical studies related to radioactive materials and nuclear radiation including the fine sub-branches such as radiochemistry, radiation chemistry, radioanalytical chemistry, radiopharmaceutical chemistry, environmental radiochemistry. If these are not done, the educational problems in nuclear chemistry could not be correctly investigated and the remedies could not be correctly determined.

Synthetic Control of Thorium Metal-Organic Frameworks for Sequencing and Sensing of Radioiodine Species

Exploring the physiochemical properties and expanding the applications of actinide-containing materials is paramount to address the escalating challenge of radioactive waste accumulation.However,unlocking the full potential of these materials is largely crippled by the radiotoxicity of the actinides.We report here two porous and luminescent thorium-based metal-organic frameworks(Th-BITD-1 and Th-BITD-2)that serve as a bifunctional platform for sequencing and sensing of radioiodine,a much more radioactive fission product discharged during the nuclear fuel reprocessing.In particular,Th-BITD-1 displays better iodine uptake performance than Th-BITD-2 via the solution-based process and vapor diffusion with the maximum adsorption capacities of 831 and 1099 mg/g,respectively.Fur thermore,Th-BITD-1 can function as a highly sensitive luminescence sensor for iodate with a quenching constant(Ksv)of 6.6(5)×10^(3) M^(-1)and a detection limit of 2.02μM,respectively,outperforming 2.96(6)×10^(3)M^(-1)and 10.5μM of Th-BITD-2.Moreover,a positive correlation between the sensing efficacy and the iodate adsorption capacity has been revealed.This work highlights the opportunity in designing novel actinide-based MOFs for their potential applications in radiological fields,e.g.,radionuclide separation and detection.

Gadolinium Neutron Capture Reaction-Induced Nucleodynamic Therapy Potentiates Antitumor Immunity

A nuclear reaction-induced dynamic therapy,denoted as nucleodynamic therapy(NDT),has been invented that triggers immunogenic cell death and successfully treats metastatic tumors due to its unexpected abscopal effect.Gadolinium neutron capture therapy(GdNCT)is binary radiotherapy based on a localized nuclear reaction that produces high-energy radiations(e.g.,Auger electrons,γ-rays,etc.)in cancer cells when^(157Gd)is irradiated with thermal neutrons.Yet,its clinical application has been postponed due to the poor ability of Auger electrons andγ-rays to kill cells.Here,we engineered a^(157Gd)-porphyrin framework that synergizes GdNCT and dynamic therapy to efficiently produce both•OH and immunogenic 1O2 in cancer cells,thereby provoking a strong antitumor immune response.This study unveils the fact and mechanism that NDT heats tumor immunity.Another unexpected finding is that the Auger electron can be the most effective energy-transfer medium for radiation-induced activation of nanomedicines because its nanoscale trajectory perfectlymatches the size of nanomaterials.Inmouse tumormodels,NDT causes nearly complete regression of both primary and distant tumor grafts.Thus,this^(157Gd)-porphyrin framework radioenhancer endows GdNCT with the exotic function of triggering dynamic therapy;its applicationmay expand in clinics as a new radiotherapy modality that utilizes GdNCT to provoke whole-body antitumor immune response for treating metastases,which are responsible for 90%of all cancer deaths.

A Trivalent Americium Organic Framework with Decent Structural Stability against Self-Irradiation

We reported the synthesis,single crystal structure,and solid-state UV-Vis-NIR spectroscopy of a new transplutonium metal-organic framework(MOFs),Am(H_(2)O)[PO[(C6H4)COO]_(3)],denoted as AmTPO(TPO=tris(4-carboxylphenyl)-phosphineoxide).AmTPO forms a three-dimensional metal-organic framework structure with americium dimers as the secondary building unit.Clear 5f→5f transi-tions attributed to trivalent americium was observed in the absorption spectrum of AmTPO ranging from 300 to 1200 nm.Notably,AmTPO can maintain the crystallinity with no observable structural degradation within several months after being synthesized,re-vealing a long-term radiation resistance of this structure and the potential application of MOFs as a platform for nuclear waste dis-posal.

Light-Driven Oxidation of Pu(Ⅳ)to Pu(Ⅵ)Enables Green and Efficient Pu Recovery

Plutonium(Pu)is a key actinide in nuclear industry and is the only element in the periodic table known to date that could exist in four different oxidation states simultaneously in aqueous solution.Efficient recovery of Pu in nuclear wastes relies greatly on the precise control of its oxidation states.Herein,we introduce a light-driven oxidation approach that could effectively oxidize Pu(Ⅳ)to Pu(Ⅵ)in acidic solutions without the addition of extra chemical oxidants.The oxidation proceeds via the reaction of Pu(Ⅳ)with the oxidative species induced by UV light irradiation.This approach can help with the separation of Pu from other metals and can be further extended to a biphasic extraction system to achieve green and efficient stripping of Pu from an organic solvent.

Direct search for primordial ^(244)Pu in Bayan Obo bastnaesite

The abundances of heavy elements produced in r-process nucleosynthesis in the early solar system need experimental verification.^(244)Pu could be the heaviest primordial nuclide produced before the formation of the Earth still being detectable today.As recent attempts failed to confirm the discovery of ^(244)Pu signals at a concentration of 1.0×10^(-18)g/g in bastnaesite reported by Hoffman et al.in this study,the total primordial ^(244)Pu in 450 g bastnaesite sample from Bayan Obo ore (China) was measured using ultrasensitive compact accelerator mass spectrometry (AMS).As no ^(244)Pu signal was detected,an upper limit for the ^(244)Pu in our bastnaesite sample was estimated to be 2.1×10^(-20)g/g at 99%confidence level.