Two porphyrinic metal-organic frameworks (PCN-222 and PCN-224) were prepared and their potential as molybdenum adsorbents for the ⁹⁹Mo/^99mTc generator was explored. The molybdenum adsorption properties of the two adsorbents, including adsorption kinetics and equilibrium isotherms, were evaluated at different molybdenum concentrations and pH. The maximum adsorption capacity of PCN-222 and PCN-224 was evaluated to be 525 mg g⁻¹ and 455 mg g⁻¹, respectively. The possible adsorption mechanism was investigated by X-ray Photoelectron Spectra and Fourier-Transform Infrared Spectroscopy. The results demonstrated that molybdenum species were adsorbed on the two MOFs through electrostatic attraction and hydrogen bonds. In the case of PCN-222, the Mo-O-Zr coordination interaction also played an important role. Additionally, the elution performance of two ⁹⁹Mo/^99mTc generators developed by using PCN-222 and PCN-224 as adsorbents was measured to assess possible clinical applications. The PCN-222-based ⁹⁹Mo/^99mTc generator exhibited better elution performance and showed that around 56% of ^99mTc could be obtained without zirconium breakthrough when relatively high pH solutions were used (pH = 9.6).

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The cerium-based metal–organic framework UiO-66 (Ce) was examined as a potential adsorbent for the ⁹⁹Mo/^99mTc generator. The results showed that the adsorbent had an outstanding adsorption performance, reaching up to 475 mg/g adsorption capacity at pH 3. An adsorption mechanism was proposed, where the adsorption was governed by hydrogen bonds, Ce-O-Mo coordination, π-anions and electrostatic interaction. Additionally, the adsorbent exhibited excellent radiation stability and good adsorption performance when radioactive ⁹⁹Mo was applied. A ⁹⁹Mo/^99mTc generator was fabricated with UiO-66 (Ce) as adsorbent and its performance was evaluated over two weeks. The elution results showed that 92 ± 3% of ^99mTc elution efficiency could be obtained with negligible cerium breakthrough, showing the great potential of UiO-66 (Ce) as adsorbent for ⁹⁹Mo/^99mTc generators.

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Four different MOFs were exposed to γrays by a cobalt-60 source reaching a maximum dose of 5 MGy. The results showed that the MIL-100 (Cr) and MIL-100 (Fe) did not exhibit obvious structural damage, suggesting their excellent radiation stability. MIL-101 (Cr) showed good radiation stability up to 4 MGy, but its structure started degrading with increasing radiation dose. Furthermore, the results showed that the structure of AlFu MOFs started to decompose at a gamma dose of 1 MGy, exhibiting a much lower tolerance to γradiation. At this radiation energy, the dominant interaction of the gamma-ray with MOFs is the Compton effect and the radiation stability of MOFs can be improved by prolific aromatic linkers, high linker connectivity, and good crystallinity. The results of this study indicate that MIL-100 and MIL-101 MOFs have a good potential to be employed in nuclear applications, where relatively high radiation doses play a role, for example, nuclear waste treatment and radionuclides production.

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The potential of the metal–organic framework UiO-66 and its functionalized derivatives for their utilization in the ⁹⁹Mo/^99mTc generator was assessed. Molybdenum adsorption experiments, structure characterization, molecular simulations and column experiments with molybdenum-99 were carried out. The results showed that the maximum molybdenum adsorption capacity achieved for UiO-66 was 335 mg g⁻¹. Adsorption on the surface of the UiO-66 occurs via electrostatic interaction and DFT calculations verified the enhanced affinity between the adsorbents and the molybdenum ions by Zr-O-Mo coordination, anion-π as well as hydrogen bonds. In addition, the performance of a ⁹⁹Mo/^99mTc generator fabricated with Form-UiO-66 was evaluated. The results showed that adsorption was comparable with the experiments using non-active molybdenum and that the ^99mTc elution efficiency of around 70% could be achieved without zirconium breakthrough.

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A solid phase extraction based ^177mLu-¹⁷⁷Lu separation method has been investigated for its feasibility to be used in the radionuclide generator. The use of 2,2′,2”-(10-(2,6-dioxotetrahydro-2H-pyran-3-yl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid, (DOTAGA-anhydride) allowed grafting of DOTA (1,4,7,10-tetraazacyclododecane N,N′,N″,N‴-tetraacetic acid) complex on the surface of commercially available amino propyl silica. The grafting of DOTA has been confirmed by several characterization techniques. The thermogravimetric analysis reveals that the 0.33 mmol DOTA groups have been grafted per gram of silica. However, during the Lu ion complexation, a 10 times lower Lu adsorption capacity of 0.03 mmol g⁻¹ could be achieved under the studied reaction conditions. The results indicate that the grafting of DOTA on solid affects the Lu coordination and also influences the kinetics of Lu-DOTA complexation. The weak coordination resulted in high ^177mLu leakage, while the unreacted DOTA groups interfer with the ¹⁷⁷Lu release. This is evident from the 0.3% ^177mLu leakage combined with a¹⁷⁷Lu extraction efficiency of 25%. Overall, the results show a^177mLu-¹⁷⁷Lu separation with a maximum ¹⁷⁷Lu/^177mLu activity ratio of 25. But this is still far away from clinically acceptable activity ratio of 10,000 for which future work is recommended.

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Cu-based metal-organic framework (MOF) microdevices are applied in sampling and preconcentration of nerve agents (NAs) diluted in gaseous streams. An in situ electrochemical-assisted synthesis of a Cu-benzene-1,3,5-tricarboxylate (BTC) thick film is carried out to functionalize a Cu-modified glass substrate. This simple, rapid, reproducible, and easy-to-integrate MOF synthesis approach enables the microfabrication of functional micro-preconcentrators with a large Brunauer-Emmett-Teller (BET) surface area (above 2000 cm2) and an active pore volume (above 90 nL) for the efficient adsorption of nerve agent molecules along the microfluidic channel 2.5 cm in length. The equilibrium adsorption capacity of the bulk material has been characterized through thermogravimetric analysis after exposure to controlled atmospheres of a sarin gas surrogate, dimethyl methylphosphonate (DMMP), in both dry and humid conditions (30% RH at 293 K). Breakthrough tests at the ppm level (162 mg/m3) reveal equilibrium adsorption capacities up to 691 mg/g. The preconcentration performance of such μ-devices when dealing with highly diluted surrogate atmosphere, i.e., 520 ppbV (2.6 mg/m3) at 298 K, leads to preconcentration coefficients up to 171 for sample volume up to 600 STP cm3. We demonstrate the potentialities of Cu-BTC micro-preconcentrators as smart first responder tools for "on-field" detection of nerve agents in the gas phase at relevant conditions.

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In this work, ^177mLu has been produced by irradiation of natural Lu₂O₃ targets at the BR2 reactor (Mol, Belgium) and the obtained data together with literature values have been used to theoretically investigate the production of ^177mLu at different neutron fluxes, irradiation times and enrichment of ¹⁷⁶Lu. The irradiation time (t_max) needed to reach the maximum ^177mLu production has been found to change from 42, 12, 4 days with the increase in the thermal neutron flux from 2*10¹⁴, 8*10¹⁴, 2.5*10¹⁵ n cm⁻² s⁻¹, respectively while keeping the maximum ^177mLu activity unaffected. The results of our calculations suggest that 0.11 TBq ^177mLu with a specific activity of 0.3 TBq g⁻¹ Lu can be produced in a short irradiation time of 4 days using 1g of 84.44% ¹⁷⁶Lu enriched Lu₂O₃ and a thermal neutron flux of 2.5*10¹⁵ n cm⁻² s⁻¹.

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In order to determine the potential of ^177mLu/¹⁷⁷Lu radionuclide generator in ¹⁷⁷Lu production it is important to establish the technical needs that can lead to a clinically acceptable ¹⁷⁷Lu product quality. In this work, a model that includes all the processes and the parameters affecting the performance of the ^177mLu/¹⁷⁷Lu radionuclide generator has been developed. The model has been based on the use of a ligand to complex ^177mLu ions, followed by the separation of the freed ¹⁷⁷Lu ions. The dissociation kinetics of the Lu-ligand complex has been found to be the most crucial aspect governing the specific activity and ^177mLu content of the produced ¹⁷⁷Lu. The dissociation rate constants lower than 1*10^-11 s^-1 would be required to lead to onsite ¹⁷⁷Lu production with specific activity close to theoretical maximum of 4.1 TBq ¹⁷⁷Lu/mg Lu and with ^177mLu content of less than 0.01%. Lastly, the calculations suggest that more than one patient dose per week can be supplied for a period of up to 7 months on starting with the ^177mLu produced using 3 g Lu₂O₃ target with 60% ¹⁷⁶Lu enrichment. The requirements of the starting ^177mLu activity production needs to be adapted depending on the required patient doses, and the technical specifications of the involved ^177mLu-¹⁷⁷Lu separation process.

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Background In this work, a lutetium-177 (177Lu) production method based on the separation of nuclear isomers, 177mLu & 177Lu, is reported. The 177mLu-177Lu separation is performed by combining the use of DOTA & DOTA-labelled peptide (DOTATATE) and liquid-liquid extraction. Methods The 177mLu cations were complexed with DOTA & DOTATATE and kept at 77 K for periods of time to allow 177Lu production. The freed 177Lu ions produced via internal conversion of 177mLu were then extracted in dihexyl ether using 0.01 M di-(2-ethylhexyl) phosphoric acid (DEHPA) at room temperature. The liquid-liquid extractions were performed periodically for a period up to 35 days. Results A maximum 177Lu/177mLu activity ratio of 3500 ± 500 was achieved with [177mLu]Lu-DOTA complex, in comparison to 177Lu/177mLu activity ratios of 1086 ± 40 realized using [177mLu]Lu-DOTATATE complex. The 177Lu-177mLu separation was found to be affected by the molar ratio of lutetium and DOTA. A 177Lu/177mLu activity ratio up to 3500 ± 500 was achieved with excess DOTA in comparison to 177Lu/177mLu activity ratio 1500 ± 600 obtained when lutetium and DOTA were present in molar ratio of 1:1. Further, the 177Lu ion extraction efficiency, decreases from 95 ± 4% to 58 ± 2% in the presence of excess DOTA. Conclusion The reported method resulted in a 177Lu/ 177mLu activity ratio up to 3500 after the separation. This ratio is close to the lower end of 177Lu/177mLu activity ratios, attained currently during the direct route 177Lu production for clinical applications (i.e. 4000–10,000). This study forms the basis for further extending the liquid-liquid extraction based 177mLu-177Lu separation in order to lead to a commercial 177mLu/177Lu radionuclide generator.@en

Hybrid materials bearing organic and inorganic motifs have been extensively discussed as playgrounds for the implementation of atomically resolved inorganic sites within a confined environment, with an exciting similarity to enzymes. Here, we present the successful design of a site-isolated mixed-metal metal organic framework (MOF) that mimics the reactivity of soluble methane monooxygenase enzyme and demonstrates the potential of this strategy to overcome current challenges in selective methane oxidation. We describe the synthesis and characterization of an Fe-containing MOF that comprises the desired antiferromagnetically coupled high-spin species in a coordination environment closely resembling that of the enzyme. An electrochemical synthesis method is used to build the microporous MOF matrix while integrating the atomically dispersed Fe active sites in the crystalline scaffold. The model mimics the catalytic C-H activation behavior of the enzyme to produce methanol and shows that the key to this reactivity is the formation of isolated oxo-bridged Fe units.

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Much attention is currently being paid to imaging prompt gamma (PG) rays for in vivo proton range monitoring in proton therapy. PG imaging using a collimator is affected by neutron-related background. We study the effectiveness of background reduction experimentally, using a scanning parallel-slit PG collimator as a simplified model of a multislat PG camera. The analysis is focused on the falloff region of the PG intensity profile near the Bragg peak, which is the typical region of interest for proton range estimation. Background reduction was studied for different energy windows, with and without a shifting time-of-flight window that takes into account the proton velocity within the phantom. Practical methods are put forward that apply to cyclotron-based pencil beams. The parallel-slit collimator was placed in front of arrays of cerium-doped lutetium yttrium silicate-coupled digital silicon photomultipliers, used to measure energy and time spectra together with intensity profiles of prompt events emitted from a polymethylmethacrylate phantom irradiated with a 160-MeV proton pencil beam. The best signal-to-background ratio of ~1.6 was similar to that obtained previously with a knife-edge-slit collimator. However, the slope-over-noise ratio in the PG-profile falloff region, was ~1.2 higher for the present collimator, given its better resolution.@en

177Lu has sprung as a promising radionuclide for targeted therapy. The low soft tissue penetration of its β− emission results in very efficient energy deposition in small-size tumours. Because of this, 177Lu is used in the treatment of neuroendocrine tumours and is also clinically approved for prostate cancer therapy. In this work, we report a separation method that achieves the challenging separation of the physically and chemically identical nuclear isomers, 177mLu and 177Lu. The separation method combines the nuclear after-effects of the nuclear decay, the use of a very stable chemical complex and a chromatographic separation. Based on this separation concept, a new type of radionuclide generator has been devised, in which the parent and the daughter radionuclides are the same elements. The 177mLu/177Lu radionuclide generator provides a new production route for the therapeutic radionuclide 177Lu and can bring significant growth in the research and development of 177Lu based pharmaceuticals.@en

Photothermal therapy (PTT) and photodynamic therapy (PDT) both utilize light to induce a therapeutic effect. These therapies are rapidly gaining importance due to the noninvasiveness of light and the limited adverse effect associated with these treatments. However, most preclinical studies show that complete elimination of tumors is rarely observed. Combining PDT and PTT with chemotherapy or radiotherapy can improve the therapeutic outcome and simultaneously decrease side effects of these conventional treatments. Nanocarriers can help to facilitate such a combined treatment. Here, the most recent advancements in the field of photochemotherapy and photoradiotherapy, in which nanocarriers are employed, are reviewed.

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Chemical clocks are often used as exciting classroom experiments, where an induction time is followed by rapidly changing colours that expose oscillating concentration patterns. This type of reaction belongs to a class of nonlinear chemical kinetics also linked to chaos, wave propagation and Turing patterns. Despite its vastness in occurrence and applicability, the clock reaction is only well understood for liquid-state processes. Here we report a chemical clock reaction, in which a solidifying entity, metal-organic framework UiO-66, displays oscillations in crystal dimension and number, as shown by X-ray scattering. In rationalizing this result, we introduce a computational approach, the metal-organic molecular orbital methodology, to pinpoint interaction between the tectonic building blocks that construct the metal-organic framework material. In this way, we show that hydrochloric acid plays the role of autocatalyst, bridging separate processes of condensation and crystallization.

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