Synthesis of [18F]FAZA using micro-fluidic technology
Bibliographic record
Abstract
1449 Objectives [18F]FAZA is a frequently used radiotracer for PET imaging of hypoxia. Current automated synthesis of [18F]FAZA involves a 5 min [18F]fluoride incorporation on 1-(2,3-di-O-acetyl-5-O-tosyl-a-D-arabinofuranosyl)-2-nitroimidazole followed by a 2 min hydrolysis step. However, the overall radiochemical yield (RCY) is reported to be low. Microfluidic technology is a rapidly evolving novel technique enabling micro-scale chemical reactions. This technology allows fast reactions in a simple experimental set-up, while using only very low amounts of starting material. The present study describes radiosynthesis of [18F]FAZA by means of micro-fluidic technology. Methods Radiosynthesis in a microfluidic apparatus was optimized through varying various reaction parameters like temperature (80°C to 140°C), flow rate (8 uL x min-1 to 40 uL x min-1), reaction time (using different length of reactor), solvent (DMSO or CH3CN), and precursor concentration (2.5 mg x mL-1 to 5 mg x mL-1). Results Optimal reaction conditions for [18F]fluoride incorporation were developed for small scale (0.1 MBq to 100 MBq) and large scale preparations (400 Mq to 2 GBq). Best reaction conditions at small scale include a reaction temperature of 120°C, a flow rate of 18 uL x min-1 for 5 min 20 sec, DMSO as solvent, and a precursor concentration of 2.5 mg x mL-1. These conditions afforded purified [18F]FAZA in 72% RCY. Large scale synthesis of [18F]FAZA employed a reaction temperature of 120°C, a flow rate of 28 uL x min-1 for 4 min 10 sec, DMSO as the solvent, and a precursor concentration of 5 mg x mL-1. These conditions gave HPLC-purified [18F]FAZA in 29 % RCY. Subsequent radiopharmacological evaluation of [18F]FAZA involved dynamic small animal PET studies in EMT-6 tumor bearing mice. Conclusions Application of microfluidic technology significantly improved radiochemical yields of [18F]FAZA. Microfluidic technology represents an interesting alternative for the synthesis of clinically relevant PET radiotracers like [18F]FAZA. Future work is focused on the use of larger starting activities of [18F]fluoride (>5 GBq)
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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 | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".