RESUMEN
Current equipment and methods for preparation of radiopharmaceuticals for positron emission tomography (PET) are expensive and best suited for large-scale multi-doses batches. Microfluidic radiosynthesizers have been shown to provide an economic approach to synthesize these compounds in smaller quantities, but can also be scaled to clinically-relevant levels. Batch microfluidic approaches, in particular, offer significant reduction in system size and reagent consumption. Here we show a simple and rapid technique to concentrate the radioisotope, prior to synthesis in a droplet-based radiosynthesizer, enabling production of clinically-relevant batches of [18F]FET and [18F]FBB. The synthesis was carried out with an automated synthesizer platform based on a disposable Teflon-silicon surface-tension trap chip. Up to 0.1 mL (4 GBq) of radioactivity was used per synthesis by drying cyclotron-produced aqueous [18F]fluoride in small increments directly inside the reaction site. Precursor solution (10 µL) was added to the dried [18F]fluoride, the reaction chip was heated for 5 min to perform radiofluorination, and then a deprotection step was performed with addition of acid solution and heating. The product was recovered in 80 µL volume and transferred to analytical HPLC for purification. Purified product was formulated via evaporation and resuspension or a micro-SPE formulation system. Quality control testing was performed on 3 sequential batches of each tracer. The method afforded production of up to 0.8 GBq of [18F]FET and [18F]FBB. Each production was completed within an hour. All batches passed quality control testing, confirming suitability for human use. In summary, we present a simple and efficient synthesis of clinically-relevant batches of [18F]FET and [18F]FBB using a microfluidic radiosynthesizer. This work demonstrates that the droplet-based micro-radiosynthesizer has a potential for batch-on-demand synthesis of 18F-labeled radiopharmaceuticals for human use.
Asunto(s)
Radioisótopos de Flúor/química , Microfluídica/métodos , Radiofármacos/síntesis química , Cromatografía Líquida de Alta Presión , Fluoruros , Radioisótopos de Flúor/farmacología , Humanos , Tomografía de Emisión de Positrones/métodos , Radioquímica/métodos , Radioisótopos/química , Tomografía Computarizada por Rayos XRESUMEN
Aggregates of hyperphosphorylated tau (PHF-tau), such as neurofibrillary tangles, are linked to the degree of cognitive impairment in Alzheimer's disease. We have recently reported early clinical results of a novel PHF-tau targeting PET imaging agent, [F18]-T807. Since then, we have investigated a second novel PHF-tau targeting PET imaging agent, [F18]-T808, with different pharmacokinetic characteristics, which may be favorable for imaging Alzheimer's disease and other tauopathies. Here, we describe the first human brain images with [F18]-T808.
Asunto(s)
Enfermedad de Alzheimer/diagnóstico por imagen , Bencimidazoles , Encéfalo/diagnóstico por imagen , Encéfalo/metabolismo , Fluorodesoxiglucosa F18 , Pirimidinas , Proteínas tau/metabolismo , Anciano , Anciano de 80 o más Años , Bencimidazoles/farmacocinética , Encéfalo/efectos de los fármacos , Mapeo Encefálico , Femenino , Humanos , Masculino , Escala del Estado Mental , Persona de Mediana Edad , Tomografía de Emisión de Positrones , Pirimidinas/farmacocinética , Factores de TiempoRESUMEN
Aggregates of hyperphosphorylated tau (PHF-tau), such as neurofibrillary tangles, are linked to the degree of cognitive impairment in Alzheimer's disease. We have developed a novel PHF-tau targeting positron emission tomography imaging agent, [F-18]-T807, which may be useful for imaging Alzheimer's disease and other tauopathies. Here in, we describe the first human brain images with [F-18]-T807.
Asunto(s)
Enfermedad de Alzheimer/diagnóstico por imagen , Carbolinas , Radioisótopos de Flúor , Tomografía de Emisión de Positrones/métodos , Proteínas tau , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/metabolismo , Carbolinas/metabolismo , Diagnóstico Precoz , Femenino , Radioisótopos de Flúor/metabolismo , Lóbulo Frontal/diagnóstico por imagen , Lóbulo Frontal/metabolismo , Humanos , Masculino , Persona de Mediana Edad , Fosforilación/fisiología , Proteínas tau/metabolismoRESUMEN
The very first microfluidic device used for the production of (18)F-labeled tracers for clinical research is reported along with the first human Positron Emission Tomography scan obtained with a microfluidically produced radiotracer. The system integrates all operations necessary for the transformation of [(18)F]fluoride in irradiated cyclotron target water to a dose of radiopharmaceutical suitable for use in clinical research. The key microfluidic technologies developed for the device are a fluoride concentration system and a microfluidic batch reactor assembly. Concentration of fluoride was achieved by means of absorption of the fluoride anion on a micro ion-exchange column (5 µL of resin) followed by release of the radioactivity with 45 µL of the release solution (95 ± 3% overall efficiency). The reactor assembly includes an injection-molded reactor chip and a transparent machined lid press-fitted together. The resulting 50 µL cavity has a unique shape designed to minimize losses of liquid during reactor filling and liquid evaporation. The cavity has 8 ports for gases and liquids, each equipped with a 2-way on-chip mechanical valve rated for pressure up to 20.68 bar (300 psi). The temperature is controlled by a thermoelectric heater capable of heating the reactor up to 180 °C from RT in 150 s. A camera captures live video of the processes in the reactor. HPLC-based purification and reformulation units are also integrated in the device. The system is based on "split-box architecture", with reagents loaded from outside of the radiation shielding. It can be installed either in a standard hot cell, or as a self-shielded unit. Along with a high level of integration and automation, split-box architecture allowed for multiple production runs without the user being exposed to radiation fields. The system was used to support clinical trials of [(18)F]fallypride, a neuroimaging radiopharmaceutical under IND Application #109,880.
Asunto(s)
Radioisótopos de Flúor/química , Técnicas Analíticas Microfluídicas/instrumentación , Técnicas Analíticas Microfluídicas/métodos , Tomografía de Emisión de Positrones/métodos , Radiofármacos/química , Benzamidas/química , Benzamidas/aislamiento & purificación , Benzamidas/farmacocinética , Encéfalo/diagnóstico por imagen , Encéfalo/metabolismo , Química Encefálica , Cromatografía Líquida de Alta Presión , Diseño de Equipo , Radioisótopos de Flúor/aislamiento & purificación , Radioisótopos de Flúor/farmacocinética , Humanos , Tomografía de Emisión de Positrones/instrumentación , Trazadores Radiactivos , Radiofármacos/aislamiento & purificación , Radiofármacos/farmacocinética , Programas Informáticos , Distribución TisularRESUMEN
We report an automated synthesis of [(18)F]-FMISO utilizing a prototype microfluidic radiochemistry module. The instrument allows for production of the tracer with 58%±2% (11 runs) decay corrected yield. Total time of production, including synthesis and purification averages 60 min. Use of the microfluidic platform results in a specific activity of 138.6 GBq/µ mol, which is higher than previously reported for conventional reactors.
Asunto(s)
Radioisótopos de Flúor/química , Microfluídica , Misonidazol/análogos & derivados , Oxígeno/química , Misonidazol/químicaRESUMEN
We present numerical modeling and experimental studies of flow optimization inside a batch microfluidic micro-reactor used for synthesis of human-scale doses of Positron Emission Tomography (PET) tracers. Novel techniques are used for mixing within, and eluting liquid out of, the coin-shaped reaction chamber. Numerical solutions of the general incompressible Navier Stokes equations along with time-dependent elution scalar field equation for the three dimensional coin-shaped geometry were obtained and validated using fluorescence imaging analysis techniques. Utilizing the approach presented in this work, we were able to identify optimized geometrical and operational conditions for the micro-reactor in the absence of radioactive material commonly used in PET related tracer production platforms as well as evaluate the designed and fabricated micro-reactor using numerical and experimental validations.
Asunto(s)
Técnicas Analíticas Microfluídicas/instrumentación , Microtecnología/métodos , Tomografía de Emisión de Positrones , Trazadores Radiactivos , Indicadores y Reactivos/química , Modelos TeóricosRESUMEN
Hypoxia in solid tumours is associated with the promotion of various metabolic mechanisms and induces resistance to radio- and chemotherapy. Non-invasive positron emission tomography (PET) or single photon emission computed tomography by use of selective biomarkers has emerged as valuable tools for the detection of hypoxic areas within tumours so treatment can be modified accordingly. The aim of this investigation was to evaluate [(18)F]3-NTR, a 3-nitro-1,2,4-triazole analogue (N(1) substituted) of [(18)F]FMISO as a potential hypoxia selective tracer. 3-NTR and its (18)F-radiolabelled isotopic isomer were synthesised and compared with FMISO in vitro and in vivo. Their physicochemical properties were measured, the enzymatic reduction was evaluated, and the reactivity of their metabolites was investigated. Biodistribution and PET scans were performed on CBA mice bearing hypoxic CaNT tumour cells, using (18)F-labelled versions of the tracers. [(18)F]3-NTR uptake within hypoxic cells was lower than [(18)F]FMISO and [(18)F]3-NTR did not exhibit any better selectivity than FMISO as a PET tracer in vivo. Both (18)F-radiolabelled compounds are relatively evenly distributed within the whole body and the radioactive uptake within hypoxic tumours reaches a maximum at 30 min post injection and decreases thereafter. Xanthine oxidase exhibited a nitroreductase activity toward 3-NTR under anaerobic conditions, but reduced metabolites did not bind covalently. It is confirmed that 3-NTR is an electron acceptor. It is postulated that radiolabelled metabolites and fragments of [(18)F]3-NTR are freely diffusing due to their poor binding capacities. Thus [(18)F]3-NTR cannot be used as a hypoxia selective tracer for PET. The investigation provides insights into the importance of the propensity to form covalent adducts for such biomarkers.
Asunto(s)
Misonidazol/análogos & derivados , Tomografía de Emisión de Positrones/métodos , Propanoles , Triazoles , Animales , Biomarcadores/metabolismo , Hipoxia de la Célula , Línea Celular Tumoral , Transformación Celular Neoplásica , Fenómenos Químicos , Evaluación Preclínica de Medicamentos , Femenino , Glutatión/química , Cinética , Ratones , Misonidazol/química , Misonidazol/metabolismo , Misonidazol/farmacocinética , Modelos Biológicos , Neoplasias/diagnóstico por imagen , Neoplasias/metabolismo , Neoplasias/patología , Oxidación-Reducción , Trazadores Radiactivos , Xantina Oxidasa/metabolismoRESUMEN
UNLABELLED: An integrated elastomeric microfluidic device, with a footprint the size of a postage stamp, has been designed and optimized for multistep radiosynthesis of PET tracers. METHODS: The unique architecture of the device is centered around a 5-microL coin-shaped reactor, which yields reaction efficiency and speed from a combination of high reagent concentration, pressurized reactions, and rapid heat and mass transfer. Its novel features facilitate mixing, solvent exchange, and product collection. New mixing mechanisms assisted by vacuum, pressure, and chemical reactions are exploited. RESULTS: The architecture of the reported reactor is the first that has allowed batch-mode microfluidic devices to produce radiopharmaceuticals of sufficient quality and quantity to be validated by in vivo imaging. CONCLUSION: The reactor has the potential to produce multiple human doses of (18)F-FDG; the most impact, however, is expected in the synthesis of PET radiopharmaceuticals that can be made only with low yields by currently available equipment.
Asunto(s)
Técnicas Analíticas Microfluídicas/instrumentación , Tomografía de Emisión de Positrones , Radiofármacos/síntesis química , Animales , Cromatografía por Intercambio Iónico/instrumentación , Elastómeros , Diseño de Equipo , Radioisótopos de Flúor , Fluorodesoxiglucosa F18/síntesis química , Humanos , Ratones , Rabdomiosarcoma/diagnóstico por imagenRESUMEN
Multiple advantages of microfluidics have been demonstrated in the area of organic synthesis. However, only a limited number of them have found applications in radiopharmaceutical synthesis, while that is an area where the need for improvements offered by microfluidics is very significant. The need is to create an environment where all reactions involving short-lived radioisotopes such as (18)F (110 min half-life) or (11)C (20 min half-life) are rapid and high-yielding while the devices are controlled remotely. Several groups have identified the potential of microfluidics in this area and have demonstrated that various steps of conventional radiosynthesis can be replaced by microfluidic devices. However, despite promising results that stir up the interest in the scientific community, none of these inventions has found commercial applications with broad use yet. This article will review the technologies reported to date and analyze the unmet needs that will have to be addressed before microfluidic technology has a chance of becoming a viable and truly advantageous method of preparation of commercial radiopharmaceuticals. The latter mostly center around Positron Emission Tomography (PET) biomarkers.
Asunto(s)
Microfluídica , Radiofármacos/síntesis química , Biomarcadores Farmacológicos , Diseño de Equipo , Microfluídica/instrumentación , Microfluídica/métodos , Tomografía de Emisión de Positrones , RadioisótoposRESUMEN
Microreactor technology has shown potential for optimizing synthetic efficiency, particularly in preparing sensitive compounds. We achieved the synthesis of an [(18)F]fluoride-radiolabeled molecular imaging probe, 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG), in an integrated microfluidic device. Five sequential processes-[18F]fluoride concentration, water evaporation, radiofluorination, solvent exchange, and hydrolytic deprotection-proceeded with high radio-chemical yield and purity and with shorter synthesis time relative to conventional automated synthesis. Multiple doses of [18F]FDG for positron emission tomography imaging studies in mice were prepared. These results, which constitute a proof of principle for automated multistep syntheses at the nanogram to microgram scale, could be generalized to a range of radiolabeled substrates.
Asunto(s)
Fluorodesoxiglucosa F18/síntesis química , Microfluídica , Sondas Moleculares/síntesis química , Radiofármacos/síntesis química , Animales , Automatización , Fluoruros , Cromatografía de Gases y Espectrometría de Masas , Ratones , Miniaturización , Tomografía de Emisión de Positrones , Rabdomiosarcoma/diagnóstico por imagen , Solventes , Tomografía Computarizada de EmisiónRESUMEN
We have investigated the electrochemical behavior, and chemical and photosensitized reduction of two dendrimers based on a 1,3,5-trisubstituted benzenoid core, which contain 9 and 21 4,4'-bipyridinium (usually called viologen) units, respectively, in their branches and are terminated with tetraarylmethane groups. For comparison purposes, the behavior of reference compounds that contain a single viologen unit have also been investigated. We have found that only part of the viologen units can be reduced in the dendrimer species. For the larger dendrimer, the number of reducible viologens (out of the 21 present) is 14 in electrochemical experiments (in MeCN), 9 on reduction with bis(benzene)chromium (in MeCN), and 13 by photoinduced electron transfer with 9-methylanthracene as a photosensitizer and triethanolamine as a sacrificial reductant in CH2Cl2. The reduced viologen units undergo partial dimerization. The photochemical experiments have shown that only monomeric, one-electron-reduced viologen units are formed at the beginning of the irradiation, followed by dimer formation, until a photostationary state is reached that contains 40 % nonreduced, 33 % monomeric reduced, and 27 % reduced units associated in the dimeric form. The results suggest that, upon reduction of a fraction of the viologen units, the dendrimer structure shrinks, with the result that the bulky terminal groups protect other viologen units from being reduced.
RESUMEN
The synthesis of two cluster compounds, one containing six secondary dialkylammonium ion centers and the other possessing six benzo-m-phenylene[25]crown-8 (BMP25C8) macrocycles, both appended to hexakis(thiophenyl)benzene cores, is described. The binding of these clusters with complementary mono- and divalent ligands is investigated with NMR spectroscopy to probe polyvalency in these unnatural recognition systems. The ability of the two different families of clusters to bind complementary monovalent ligands is compared with that of the monovalent receptor pair, namely the dibenzylammonium ion and BMP25C8. This comparison is made possible by determining an average association constant (K(AVE)) for the binding of each recognition site on the cluster with the corresponding monovalent ligand. We have found that the clustering of recognition sites together in one molecule is detrimental to their individual abilities to bind monovalent ligands. In the case of the polyvalent interaction between the hexakisBMP25C8 cluster and divalent dialkylammonium ions, an association constant, K(POLY), was calculated from the value of K(AVE) determined for the complexation of the individual component recognition sites. This polyvalent interaction is significantly stronger than that associated with the averaged monovalent interactions.
RESUMEN
We have prepared and investigated two dendrimers based on a 1,3,5-trisubstituted benzenoid-type core, containing 9 and 21 viologen units in their branches, respectively, and terminated with tetraarylmethane derivatives. We have shown that, in dichloromethane solution, such highly charged cationic species give rise to strong host-guest complexes with the dianionic form of the red dye eosin. Upon complexation, the absorption spectrum of eosin becomes broader and is slightly displaced toward lower energies, whereas the strong fluorescence of eosin is completely quenched. Titration experiments based on fluorescence measurements have shown that each viologen unit in the dendrimers becomes associated with an eosin molecule, so that the number of positions ("seats") available for the guest molecules in the hosting dendrimer is clearly established, e.g., 21 for the larger of the two dendrimers. The host-guest interaction can be destroyed by addition of chloride ions, a procedure which permits eosin to escape from the dendrimer's interior in a controlled way and to regain its intense fluorescence. When chloride anions are precipitated out by addition of silver cations, eosin molecules re-enter the dendrimer's interior and their fluorescence again disappears.
RESUMEN
A chemically addressable, bistable [2]rotaxane, which incorporates a dumbbell-shaped component containing both secondary dialkylammonium and 1,2-bis(pyridinium)ethane recognition sites for its ring component, dibenzo[24]crown-8 (DB24C8), has been assembled. (1)H NMR spectroscopy has demonstrated that deprotonation (and reprotonation) of the secondary dialkylammonium (dialkylamine) recognition site induces the DB24C8 ring to move away from this site to the 1,2-bis(pyridinium)ethane one (and back again) in a discrete manner, particularly when the experiment is performed in CDCl(3) solution.
RESUMEN
[structure: see text] Post-assembly covalent modification using Wittig chemistry of [2]rotaxane ylides, wherein NH(2)(+) centers in the dumbbell-shaped components are recognized by dibenzo[24]crown-8 (DB24C8) rings, has afforded a [3]catenane and a [3]rotaxane with a precise and synthetically prescribed shortage of DB24C8 rings. The nondegenerate pairs of translational isomers present in both of these interlocked molecular compounds provide the fundamental platform on which to construct sensory devices and nanochemomechanical systems.
Asunto(s)
Antracenos , Compuestos Policíclicos/química , Isomerismo , Espectroscopía de Resonancia Magnética , RotaxanosRESUMEN
[reaction: see text] A dendrimer with rotaxane-like characteristics has been assembled under thermodynamic control from complementary wedge-shaped precursors by slippage in CH(2)Cl(2). The driving force for the self-assembly process is the molecular recognition that exists as a result of [N(+)-H.O] and [C-H.O] hydrogen bonds between an NH(2)(+) center in one Fréchet-type benzyl ether wedge and a dibenzo[24]crown-8 unit that links the other two such wedges.
RESUMEN
[reaction: see text] A dendrimer wherein the branching points are mechanical in nature has been synthesized. It contains two identical covalently linked bis-dendrons and a core unit fused to two rings that encircle the two bis-dendrons. A "threading-followed-by-stoppering" approach is used in the template-directed synthesis of a precursor bis[2]rotaxane, which undergoes stopper exchange four times to yield the dendrimer in which the two bis-dendrons act as stoppers within the two [2]rotaxane subunits.