Interaction between calf thymus DNA and cationic bottle-brush copolymers: equilibrium and stopped-flow kinetic studies
Bibliographic record
Abstract
Interaction studies between a set of poly(ethylene glycol) (PEG) based cationic bottle-brush block copolymers (BBCPs) and calf thymus DNA (ctDNA) were carried out using steady state fluorescence spectroscopy, UV melting experiments and dynamic light scattering measurements. Results suggested that these cationic block copolymers could effectively bind with negatively charged DNA. Although electrostatic interaction is believed to be the predominant contributing factor in the overall binding process, hydrophobic interactions between the PEG chains and the DNA base pairs affected the binding process to some extent. Cationic block copolymers with higher PEG content were found to bind more efficiently with DNA. DLS studies revealed the details of the compaction process of elongated DNA chains into a globular structure in the presence of cationic block copolymers. Further, the kinetics of the DNA-cationic BBCP binding process was monitored via the stopped-flow fluorescence technique. In general, a two-step mechanistic pathway was observed in the case of all the cationic BBCP-DNA binding processes and the relative rate constants (k1'and k2') were found to increase with the copolymer concentration. The first step corresponded to a fast electrostatic binding between the cationic BBCP and the anionic ctDNA, while the slow second step indicated a conformational change of the DNA polyplex that led to DNA compaction. In addition to the polymer-DNA charge ratios, the PEG content in the cationic BBCPs was found to have a significant effect on the kinetics of the ctDNA-BBCP polyplex formation.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".