DiPyMe in SDS Micelles: Artifacts and Their Implications in the Interpretation of Micellar Properties
Bibliographic record
Abstract
This study provides experimental evidence that di(1-pyrenylmethyl) ether or DiPyMe, a well-known fluorescent probe employed to determine the microviscosity of surfactant or polymeric micelles, is being hydrolyzed in the presence of water upon UV irradiation. This effect was established from a careful analysis of the fluorescence spectra and decays acquired with aqueous solutions of DiPyMe dissolved in micelles of sodium dodecyl sulfate (SDS). The size of the SDS micelles could be adjusted from an aggregation number (N(agg)) of 70 to 172 by increasing the ionic strength of the aqueous solution from 0.0 to 0.5 M NaCl. The hydrolysis of DiPyMe was much reduced in the larger SDS micelles. While the degradation of DiPyMe in aqueous solutions of SDS micelles affected the analysis of the fluorescence spectra, model-free analysis (MFA) of the fluorescence decays of DiPyMe could reliably retrieve the rate constant ⟨k⟩ of excimer formation for DiPyMe. After calibration with mixtures of organic solvents of known macroscopic viscosity, the ⟨k⟩ values obtained for DiPyMe yielded the microviscosity (μη) of the SDS micelles as a function of salt concentration. The μη was found to increase from 4.0 to 8.8 mPa·s as the salt concentration increased from 0.0 to 0.5 M. This study demonstrated that, regardless of the problem of its hydrolysis that jeopardizes its use in steady-state fluorescence experiments, DiPyMe remains an extremely valuable probe for describing the microviscosity of hydrophobic domains in aqueous solution as long as its decays are analyzed with a model that accounts for the presence of degradation products as the MFA does.
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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 | 0.000 |
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".