Macromolecular Conformation of Low-Generation PAMAM Dendrimers Probed by Pyrene Excimer Formation
Bibliographic record
Abstract
A series of pyrene-labeled PAMAM dendrimers (PyCX-PAMAM-GY, where X (=4, 8, or 12) and Y (=0, 1, or 2) represent the number of atoms in the pyrenyl linker and the dendrimer generation, respectively) were studied by acquiring their time-resolved fluorescence decays in N, N -dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The fluorescence decays were fitted globally according to the model-free analysis (MFA), which yielded the average rate constant ⟨ k ⟩ for pyrene excimer formation (PEF). ⟨ k ⟩ was compared with the local pyrene concentration [Py] loc inside the dendrimers, which was calculated by assuming that the segments constituting the dendrimer interior obey Gaussian statistics. ⟨ k ⟩ was found to increase linearly with [Py] loc in both solvents, but the straight lines had different slopes due to differences in solvent viscosity and polarity. These differences were accounted for by dividing ⟨ k ⟩ by k diff, which is the bimolecular rate constant for PEF generated by n -hexyl-1-pyrenebutyramide used as a model compound. The ⟨ k ⟩/ k diff ratios obtained for all the PyCX-PAMAM-GY samples in DMF and DMSO collapsed onto a single master line where ⟨ k ⟩/ k diff increased linearly with [Py] loc . The strong correlation found between ⟨ k ⟩ and [Py] loc suggested that the oligomeric segments constituting the interior of the low-generation ( Y = 0, 1, and 2) PAMAM dendrimers obeyed Gaussian statistics. This fact was further supported by using the Gaussian approximation to calculate the radius of gyration ( R g ) of PAMAM dendrimers and compare them to the R g values obtained by molecular dynamics simulations. The excellent agreement obtained between the two sets of R g values validated the assumption. Furthermore, the direct relationship between ⟨ k ⟩ and [Py] loc established in this study demonstrates that ⟨ k ⟩ provides a quantitative measure of the internal density of the dendrimers, an observation with considerable implications for the quantitative conformational characterization of macromolecules with a complex architecture in solution.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 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 | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 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".