Copper-free click chemistry with the short-lived positron emitter fluorine-18
Bibliographic record
Abstract
The copper-free strain-promoted click chemistry between (18)F-labeled aza-dibenzocyclooctyne [(18)F]FB-DBCO and various azides is described. [(18)F]FB-DBCO was prepared in 85% isolated radiochemical yield (decay-corrected) through acylation of amino aza-dibenzocyclooctyne 1 with N-succinimidyl 4-[(18)F]fluorobenzoate ([(18)F]SFB). [(18)F]FB-DBCO showed promising radiopharmacological profil with fast blood clearance as assessed with dynamic small animal PET studies. Metabolic stability of [(18)F]FB-DBCO was 60% of intact compound after 60 min post injection in normal Balb/C mice and blood clearance half-life was determined to be 53 s based on the time-activity-curve (TAC). Copper-free click chemistry was performed with various azides at low concentrations (1-2 μM) which differed in their structural complexity in different solvents (methanol, water, phosphate buffer and in bovine serum albumin (BSA) solution). Reaction proceeded best in methanol (>95% yield after 15 min at room temperature), whereas reaction in BSA required longer reaction times of 60 min and 40 °C upon completion.
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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 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".