A novel AmBF3-succinimide prosthetic group for facile 18F-labeling of biomolecules
Bibliographic record
Abstract
1092 Objectives Radiolabeled biomolecules like peptides and antibodies have widespread diagnostic and therapeutic applications. Due to its suitable half-life, ideal emission energies, and ease of production, fluorine-18 (18F) is often incorporated into the design of PET imaging agents. Different radioprosthetic groups like N-succinimidyl-4-[18F]fluorobenzoate have been used extensively for labeling biomolecules such as antibody fragments that are heat-sensitive and not compatible with organic solvents. However, the preparation of N-succinimidyl-4-[18F]fluorobenzoate require multiple synthesis steps. Leveraging the one step 18F-19F isotope exchange reaction, we synthesized succinimido 4-(N-trifluoroborylmethyl-N,N-dimethylammonio)methylbenzoate (AmBF3-succinimide) and evaluated its ability to radiofluorinate selected biomolecules. Methods The AmBF3-succinimide was synthesized in four steps: coupling of tert-butyl 4-(bromomethyl)benzoate with dimethylamine, formation of quaternary ammonium iodide salt with 2-(iodomethyl)-4,4,5,5-tetramethyl-1,3,4-dioxaborolane, deprotection and simultaneous conversion to trifluoroborate using HCl/KHF2, and the final formation of succinimide with diisopropylcarbodiimide and N-hydroxysuccinimide. For radiolabeling, 100 nmol of 19F-AmBF3-succinimide was re-suspended in a mixture of DMF and pyridazine buffer (1 M, pH 2.0). 18F-fluoride (~1 Ci ) was eluted off from a QMA cartridge with saline to the precursor solution. The solution was incubated at 85°C for 20 min, and purified by solid phase extraction using a C-18 sep-pak cartridge. To test its suitability for labeling biomolecules, 18F-AmBF3-succinimide (~ 5 mCi) was added to a solution of Cetuximab (100 µg) in PBS (pH 8.9, 100 µL), and the reaction mixture was incubated at 37 °C for 30 min and purified by PD-10 column. Results The overall synthesis yield for the non-radioactive 19F-AmBF3-succinimide was 15% for four steps. 18F-AmBF3-succinimide was obtained directly in aqueous solution via 18F-19F isotope exchange with 9-16 % decay-corrected radiochemical yield. 18F-AmBF3-succinimide was successfully conjugated to Cetuximab in mild conditions. After PD-10 column purification, 18F-AmBF3-Cetuximab was obtained in 20-22 % decay-corrected radiochemical yield from 18F-AmBF3-succinimide with >97 % radiochemical purity and 44-48 GBq/µmol specific activity. Conclusions 18F-AmBF3-succinimide was successfully synthesized and characterized as a radioprosthetic group. For proof of concept, we selected Cetuximab as a surrogate biomolecule for conjugation. Our preliminary data suggests that 18F-AmBF3-succinimide may be an attractive option for the radiofluorination of biomolecules for PET imaging.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".