[11C]Carboxylated tetrazines for facile labeling of trans-cyclooctene-functionalized PeptoBrushes

Functionalization of macromolecules (antibodies, polymers, nanoparticles) with click-reactive groups greatly enhances the versatility of their potential applications. Click chemistry based on tetrazine - trans-cyclooctene (TCO) ligation is especially promising and is already widely applied for pretargeted imaging and therapy. Indirect radiolabeling of TCO-functionalized macromolecules with substoichiometric amounts of radioactive tetrazines is a convenient way to monitor the fate of those macromolecules by means of positron emission tomography (PET) imaging after their administration into the test subject. In this work, the preparation is reported of TCO-containing graft copolymers, namely PeptoBrushes (polyglutamic acid-graft-polysarcosine), novel [11C]carboxylated tetrazines, and their combined use in radiolabeling the polymer by inverse electron demand Diels Alder reaction, to investigate it is potential for an application in pretarget imaging or injectable brachytherapy. The procedure for [11C]tetrazine production is easy and scalable, while indirect TCO-PeptoBrushes labeling with these [11C]tetrazines is mild, fast, and quantitative. This strategy allows facile 11C-labeling of diverse TCO-functionalized macromolecules, so that their localization and distribution shortly after injection can be assessed by PET.Drug Delivery Technolog

Radiolabeling of a polypeptide polymer for intratumoral delivery of alpha-particle emitter, 225Ac, and beta-particle emitter, 177Lu

INTRODUCTION\nMETHODS\nRESULTS\nCONCLUSION\nRadiotherapy of cancer requires both alpha- and beta-particle emitting radionuclides, as these radionuclide types are efficient at destroying different types of tumors. Both classes of radionuclides require a vehicle, such as an antibody or a polymer, to be delivered and retained within the tumor. Polyglutamic acid (pGlu) is a polymer that has proven itself effective as a basis of drug-polymer conjugates in the clinic, while its derivatives have been used for pretargeted tumor imaging in a research setup. trans-Cyclooctene (TCO) modified pGlu is suitable for pretargeted imaging or therapy, as well as for intratumoral radionuclide therapy. In all cases, it becomes indirectly radiolabeled via the bioorthogonal click reaction with the tetrazine (Tz) molecule carrying the radionuclide. In this study, we report the radiolabeling of TCO-modified pGlu with either lutetium-177 (177Lu), a beta-particle emitter, or actinium-225 (225Ac), an alpha-particle emitter, using the click reaction between TCO and Tz.\nA panel of Tz derivatives containing a metal ion binding chelator (DOTA or macropa) connected to the Tz moiety directly or through a polyethylene glycol (PEG) linker was synthesized and tested for their ability to chelate 177Lu and 225Ac, and click to pGlu-TCO. Radiolabeled 177Lu-pGlu and 225Ac-pGlu were isolated by size exclusion chromatography. The retention of 177Lu or 225Ac by the obtained conjugates was investigated in vitro in human serum.\nAll DOTA-modified Tzs efficiently chelated 177Lu resulting in average radiochemical conversions (RCC) of >75%. Isolated radiochemical yields (RCY) for 177Lu-pGlu prepared from 177Lu-Tzs ranged from 31% to 55%. TLC analyses detected 177Lu for all 177Lu-pGlu preparations over six days in human serum. For 225Ac chelation, optimized RCCs ranged from 61 ± 34% to quantitative for DOTA-Tzs and were quantitative for the macropa-modified Tz (>98%). Isolated radiochemical yields (RCY) for 225Ac-pGlu prepared from 225Ac-Tzs ranged from 28% to 51%. For 3 out of 5 225Ac-pGlu conjugates prepared from DOTA-Tzs, the amount of unchelated 225Ac stayed below 10% over six days in human serum, while 225Ac-pGlu prepared from macropa-Tz showed a steady release of up to 37% 225Ac.\nWe labeled TCO-modified pGlu polymers with alpha- and beta-emitting radionuclides in acceptable RCYs. All 177Lu-pGlu preparations and some 225Ac-pGlu preparations showed excellent stability in human plasma. Our work shows the potential of pGlu as a vehicle for alpha- and beta-radiotherapy of tumors and demonstrated the usefulness of Tz ligation for indirect radiolabeling.Drug Delivery Technolog

Исследование поверхностного натяжения и углов смачивания для создания эффективных полимерных связующих на основе эпоксидных олигомеров с активными разбавителями

Objectives. This study focused on the quantification of the surface tension and the static and dynamic contact angles of epoxy oligomers, active diluents, and their mixtures of various compositions at different temperatures. The active diluents were aliphatic compounds based on glycidyl ethers, namely laproxides and a laprolate of different structure, functionality, molecular weight, and viscosity. Moreover, the preparation of effective polymer binders (matrices) for composites was explored.Methods. In this study, the epoxy oligomers ED-20 and DER-330, laproxides 201B, DEG-1, E-181, and 703, laprolate 301, and their mixtures in various compositions were investigated. Their surface tension and the static and dynamic contact angles were determined by the Wilhelmy plate and ring methods on a semiautomatic tensiometer at different temperatures (20–60 °C). The static contact angle was measured on a thin aluminum borosilicate glass plate, and the dynamic contact angles were determined using an installation for measuring surface tension developed by NPO Stekloplastik.Results. The surface tension and static and dynamic contact angles were obtained for all epoxy oligomers and active diluents, as well as for their mixtures at 20–60 °C. For binders based on systems of epoxy oligomers and active diluents, the impregnation rate of fiber reinforcement was also calculated. The introduction of laproxides or laprolates into the epoxy oligomers led to a decrease in surface tension and contact angles, while the increase in temperature increased the impregnation rate by 10–20 times.Conclusions. The temperature increase from 20 to 60 °C resulted in a decrease in the surface tension of mixed systems of epoxy oligomers and active diluents by almost two times. In addition, the contact angles changed by only 4°–7°, while the impregnation was significantly improved and the corresponding rate increased by 10–20 times.Цели. Определение поверхностного натяжения, статического и динамического углов смачивания при разных температурах для эпоксидных олигомеров марок ЭД-20 и DER-330; для активных разбавителей – алифатических соединений на основе глицидиловых эфиров – Лапроксидов и Лапролата разной структуры, функциональности, молекулярной массы, вязкости; а также для систем, состоящих из эпоксидных олигомеров и активных разбавителей разного состава. Также целью являлось создание эффективных полимерных связующих (матриц) для композитов.Методы. В качестве объектов исследования использовали эпоксидные олигомеры марок ЭД-20 и DER-330; активные разбавители – Лапроксиды (201Б, ДЭГ-1, Э-181, 703) и Лапролат 301; а также системы эпоксидный олигомер + Лапроксид (Лапролат) разных составов. Поверхностное натяжение, статический и динамический углы смачивания определяли методом Вильгельми и методом отрыва кольца на полуавтоматическом тензиометре при разных температурах (20–60 ºС). Статический угол смачивания измеряли на тонкой пластине из алюмоборосиликатного стекла. Значения динамического угла смачивания определяли на установке для измерения поверхностного натяжения, разработанной АО «НПО Стеклопластик».Результаты. Определены значения поверхностного натяжения, углов статического и динамического смачивания для эпоксидных олигомеров ЭД-20 и DER-330, Лапроксидов 201Б, ДЭГ-1, Э-181, 703 и Лапролата 301, а также для смешанных систем при температурах от 20 до 60 ºС. Рассчитаны скорости пропитки армирующих волокнистых наполнителей эффективными связующими на основе смешанных систем. Показано, что при введении в эпоксидные олигомеры Лапроксидов (Лапролата), поверхностное натяжение снижается, углы смачивания уменьшаются, температура повышается, в результате чего скорость пропитки возрастает в 10–20 раз.Выводы. Повышение температуры от 20 до 60 ºС приводит к снижению поверхностного натяжения систем, состоящих из эпоксидных олигомеров и активных разбавителей, практически в 2 раза. Углы смачивания изменяются всего на 4°–7°, существенно улучшается качество пропитки, скорость пропитки увеличивается в 10–20 раз

Характеристики полых стеклянных микросфер и проектирование легких полимерных композиционных материалов различного состава и дисперсной структуры

Currently, to obtain light polymer composite materials with high strength characteristics, hollow microspheres of various nature (glass, quartz, polymer, etc.) are used as fillers. Hollow glass microspheres of different grades (manufactured by JSC «SIO Stekloplastik») were studied by various methods, the disperse structure was described using the generalized parameters model, the light dispersion-filled polymer composite materials (DFPCM) were classified according to the structural principle, generalized and reduced parameters were calculated, and the structure, compositions of light CMs on polymer matrices of various nature were designed.В настоящее время для получения легких полимерных композиционных материалов (КМ) с высокими прочностными характеристиками в качестве наполнителей используют полые микросферы различной природы (стекло, кварц, полимер и т. д.). Исследовали упаковки полых стеклянных микросфер разных марок (производства АО «НПО Стеклопластик») различными методами, описана дисперсная структура с помощью модели обобщенных параметров, произведена классификация легких дисперсно-наполненных полимерных композиционных материалов (ДНПКМ) по структурному принципу, рассчитаны обобщенные и приведенные параметры, спроектированы структуры, составы легких КМ на полимерных матрицах различной природы

Investigation of surface tension and contact angles for effective polymer binders based on epoxy oligomers and active diluents

Objectives. This study focused on the quantification of the surface tension and the static and dynamic contact angles of epoxy oligomers, active diluents, and their mixtures of various compositions at different temperatures. The active diluents were aliphatic compounds based on glycidyl ethers, namely laproxides and a laprolate of different structure, functionality, molecular weight, and viscosity. Moreover, the preparation of effective polymer binders (matrices) for composites was explored.Methods. In this study, the epoxy oligomers ED-20 and DER-330, laproxides 201B, DEG-1, E-181, and 703, laprolate 301, and their mixtures in various compositions were investigated. Their surface tension and the static and dynamic contact angles were determined by the Wilhelmy plate and ring methods on a semiautomatic tensiometer at different temperatures (20–60 °C). The static contact angle was measured on a thin aluminum borosilicate glass plate, and the dynamic contact angles were determined using an installation for measuring surface tension developed by NPO Stekloplastik.Results. The surface tension and static and dynamic contact angles were obtained for all epoxy oligomers and active diluents, as well as for their mixtures at 20–60 °C. For binders based on systems of epoxy oligomers and active diluents, the impregnation rate of fiber reinforcement was also calculated. The introduction of laproxides or laprolates into the epoxy oligomers led to a decrease in surface tension and contact angles, while the increase in temperature increased the impregnation rate by 10–20 times.Conclusions. The temperature increase from 20 to 60 °C resulted in a decrease in the surface tension of mixed systems of epoxy oligomers and active diluents by almost two times. In addition, the contact angles changed by only 4°–7°, while the impregnation was significantly improved and the corresponding rate increased by 10–20 times

HIGH-THROUGHPUT RAT BRAIN PET IMAGING AND AUTOMATIC SPATIAL NORMALIZATION OF THE DOPAMINE D2/3 RECEPTOR LIGAND [18F]FALLYPRIDE

Objectives: Rat Brain Positron Emission Tomography (PET) imaging is often quite labor- and time intensive, as only single animals are scanned at a time and isotopic decay offers a limited window of optimal scan time. To optimize the throughput, we created a 2x2 rat holder into the human head High-Resolution Research Tomography (HRRT) scanner, enabling the scanning of four animals at a time. This higher throughput shifts the bottle-neck towards the analysis of the PET images. There is an unmet need in preclinical brain PET analysis to create reliable automated methods of spatial normalization, because manual alignment and normalization is time-consuming and inevitably operator biased. We present a non-biased standardized method for automatic spatial normalization of multimodal (CT, MR and PET) scans for the radioligand [18F]fallypride. Similar approaches are already done ([18F]FDG) or are planned ([18F]MHMZ). Methods: [18F]Fallypride was synthesized using standard procedures and obtained a molar radioactivity of over 40 GBq/µmol. Rats were anesthetized with isoflurane, placed in a customized 2x2 holder, injected with [18F]fallypride and scanned in the HRRT scanner for 45 min post injection. Up to 12 rats (three times four) were scanned with the same tracer production. Using brain PET, and a standard MR and CT image, an image template in standard space was created. In combination with this template, we created an automatic spatial normalization and VOI extraction algorithm based on MATLAB, FSL and PMOD. The non-displaceable binding potential (BPND) was calculated using a delayed scan logan plot (Tantawy et al. 2009). The automated algorithm was further assessed by transforming the PET template back to the original image, calculating the mean voxel displacement. Lastly, we used the holder and automatic procedure to measure drug induced occupancy at the dopamine D2 receptor. Values are reported ± standard deviation. Results: Nine [18F]fallypride baseline PET Scans were used to generate the PET template, which were the basis for the automatic procedure for spatial normalization. The BPND of 18 [18F]fallypride baseline scans were then compared between manually and automated spatial normalization. By using the same VOI-template the correlation between the automated and manual analyzed BPNDs in the ventral and dorsal striatum as well as mPFC (Medial Prefrontal Cortex) was R2=0.8 (ventral striatum: 2.40±0.44 automatic and 3.33 ± 1.39 manual, dorsal striatum 3.70±0.80 automatic and 5.23±2.41 manual, mPFC: 1.01±0.23 automatic and 0.83±0.64 manual). The back transformation gave a mean voxel displacement of -0.44±0.83 mm, however three out of 18 transformations failed. Conclusions: The automated analysis underestimated the BPND compared with the manual analysis, however the manually analyzed scans have a higher standard deviation, suggesting some degree of operator bias. The voxel-displacement succeeded since it is far lower than the voxel size (1.21875 mm3). In summary, it can be stated that we generated a fast and reliable procedure for reproducible spatial normalization of rat PET images for [18F]fallypride. The method has a high potential for being applicable to images from other radioligands with sufficient spatial information in the future like [18F]MHMZ