H<sub>2</sub><i>CHX</i>hox: Rigid Cyclohexane-Reinforced Nonmacrocyclic Chelating Ligand for [<sup>nat/67/68</sup>Ga]Ga<sup>3+</sup>
Bibliographic record
Abstract
A rigid chiral acyclic chelator H2CHXhox was synthesized and evaluated for Ga3+-based radiopharmaceutical applications; it was compared to the previously reported hexadentate H2hox to determine the effect of a backbone reinforced from adding a chiral 1S,2S-trans-cyclohexane on metal complex stability, kinetic inertness, and in vivo pharmacokinetics. NMR spectroscopy and theoretical calculation revealed that [Ga(CHXhox)]+ showed a very similar coordination geometry to that of [Ga(hox)]+, and only one isomer in solution was observed by NMR spectroscopy. Solution studies showed that the modification results in a significant improvement in the exceptionally high thermodynamic stability of [Ga(hox)]+ with a 1.56 log unit increase in stability constant (logKML = 35.91(1)). More importantly, H2CHXhox showed very fast Ga3+ complexation at physiological pH 7.4, and acid-assisted Ga3+ complex dissociation kinetic studies (pH 1) in comparison with H2hox revealed a 50-fold increase of the dissociation half-life time from 73 min to 58 h. Fluorescence microscopy imaging study confirmed its cellular uptake and accumulation in endoplasmic reticulum and mitochondria. MTT studies indicated a quite low cytotoxicity of [Ga(CHXhox)]+ over a large concentration range. Dynamic PET imaging studies showed no accumulation in muscle, lungs, bone, and brain, suggesting no release of free Ga3+ ions. [68Ga][Ga(CHXhox)]+ is cleared from the mouse via hepatobiliary and renal pathways. Compared to [68Ga][Ga(hox)]+, the increased lipophilicity of [68Ga][Ga(CHXhox)]+ enhanced heart and liver uptake and decreased kidney clearance. [67Ga][Ga(CHXhox)]+ SPECT/CT imaging and biodistribution study revealed good clearance from liver to gallbladder after 90 min and finally into feces after 5 h. No decomposition or transchelation was observed over the 5 h study. These results confirmed H2CHXhox to be an obvious improvement over H2hox and an excellent candidate in this new “ox” family for the development of radiopharmaceutical compounds.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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 teacher head, 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".