Conformation of Pyrene End-Labeled Polyamidoamine Dendrimers in Catanionic Surfactant Micelles Probed by Pyrene Excimer Formation
Bibliographic record
Abstract
A series of generation-0 polyamidoamine (PAMAM-G0) dendrimers, referred to as the PyC X -PAMAM-G0 samples, were end-labeled with four identical 1-pyrenealkanoyl derivatives with either ( X = 4) butyroyl, ( X = 6) hexanoyl, ( X = 8) octanoyl, ( X = 10) decanoyl, or ( X = 12) dodecanoyl linkers. Their conformation was investigated in mixed micelles composed of sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB). As the molar fraction ( f DTAB ) of DTAB in the SDS:DTAB mixtures was increased from 0.0 to 0.3, the micellar aggregates grew in size and changed their shape from spheres to ellipsoids. Global model free analysis of the fluorescence decays yielded the average rate constant (⟨ k ⟩) for pyrene excimer formation (PEF) between excited and ground-state pyrenyl labels bound to the PyC X -PAMAM-G0 dendrimers. Plots of ⟨ k ⟩ as a function of the local concentration ([ Py ] loc ) of ground-state pyrenyl labels indicated that the conformation of the PyC X -PAMAM-G0 dendrimers bearing shorter X = 4, 6, and 8 alkanoyl linkers was that expected if the internal segments of these dendrimers obeyed Gaussian statistics. The ⟨ k ⟩-vs-[ Py ] loc plots also indicated that the PyC X -PAMAM-G0 samples with the longer linkers underwent a conformational inversion. However, the conformational inversion experienced by the PyC X -PAMAM-G0 samples with longer linkers appeared to become less pronounced with increasing f DTAB . Analysis of the ⟨ k ⟩-vs-[ Py ] loc trends obtained with increasing f DTAB led to the conclusion that the PyC X -PAMAM-G0 dendrimers with longer alkanoyl linkers underwent conformational inversion in the SDS-rich capping ends of the ellipsoidal micelles but not in their more hydrophobic central section and that partitioning of the dendrimers between the two regions of the surfactant aggregates resulted in the decrease in conformational inversion identified by the PEF study. Consequently, these PEF experiments represent an interesting experimental means for probing the conformation of complex hydrophobically modified water-soluble macromolecules as they interact with the microdomains generated by small amphiphilic molecules.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
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".