Interactions between DNA and a Pyrene-Labeled Surfactant Probed by Pyrene Excimer Formation, Transmission Electron Microscopy, and Dynamic Light Scattering
Bibliographic record
Abstract
The interactions between calf thymus DNA and a pyrene-labeled gemini surfactant termed PyO-3–12 were investigated by using dynamic light scattering (DLS), transmission electron microscopy (TEM), and pyrene excimer formation (PEF) between an excited and a ground-state pyrene. PyO-3–12 was prepared with two dimethylammonium bromide headgroups linked with a propyl spacer, with one ammonium bearing a dodecyl tail and the other bearing a 1-pyrenemethoxyhexyl pendent. The size and electrostatic properties of the colloidal species were characterized by DLS, and TEM was used to describe the overall dimensions and morphologies of the aggregates. PEF enabled the study of PyO-3–12 at the molecular level. The association of PyO-3–12 and DNA was studied in detail for two specific PyO-3–12 concentrations of 16 and 56 μM using a (∓) ratio equal to the [DNA]/[PyO-3–12] ratio with [DNA] expressed in terms of DNA base pairs, yielding a (∓) ratio ranging from 0.1 to 10. An increase in PyO-3–12 association upon adding DNA was detected through an increase in PEF. Analysis of the fluorescence decays indicated a progressive binding of PyO-3–12 to DNA until the equicharge point was reached after which all PyO-3–12 surfactants were bound to DNA. The formation of large colloidal aggregates was observed by DLS, which showed a spike in the hydrodynamic diameter ( D h ) as the (∓) ratio approached unity. Analysis of the fluorescence spectra suggested that the excited pyrenyl labels experienced a more hydrophobic environment for the lipoplexes generated by the 56 μM PyO-3–12 solutions, which appeared smaller and more globular in the TEM images than the lipoplexes obtained with the lower 16 μM PyO-3–12 concentration. Together, these experiments suggest that the concentrations of the cationic gemini surfactants and DNA are important parameters for the morphology of lipoplexes with possible implications for their transfection efficiency.
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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 | 0.001 |
| 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 | 0.001 |
| 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 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".