Fluorescence Anisotropy in Studies of Solute Interactions with Covalently Modified Colloidal Silica Nanoparticles
Bibliographic record
Abstract
Time-resolved anisotropy decays of a fluorescent cationic solute, rhodamine 6G (R6G), in Ludox sols were measured to characterize the extent of the ionic binding of the probe to silica particles after modification of the surface with neutral or cationic silane coupling agents. The anisotropy decays provided direct evidence for distribution of the dye between the aqueous solution (picosecond decay component) and silica particles (nanosecond decay component and residual anisotropy component, which were attributed to the wobbling motion of dye on the silica surface and to the ionically bound probe, respectively). The dye was strongly adsorbed to unmodified silica nanoparticles, to the extent that less than 1% of the dye was present in the surrounding aqueous solution. Significant decreases in the degree of probe adsorption were obtained upon covalent modification of the silica with neutral or cationic silanes, with up to 80% of the probe being present in the aqueous solution in cases where the surface was coated with (3-aminopropyl)triethoxysilane. The addition of such agents also altered the fractional distribution between the nanosecond decay component and the residual anisotropy component in favor of the nanosecond component, indicative of weaker interactions between the dye and the modified surface (i.e., more wobbling motion). The data clearly show the power of time-resolved fluorescence anisotropy decay measurements for probing the modification of silica surfaces and should prove useful in characterization of new chromatographic stationary phases.
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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".