Electrochemical and PM-IRRAS studies of potential controlled transformations of phospholipid layers on Au(111) electrodes
Bibliographic record
Abstract
Chronocoulometry and photon polarisation modulation infrared reflection absorption spectroscopy (PM-IRRAS) have been employed to study the fusion of dimyristoylphosphatidylcholine (DMPC) vesicles onto a Au(111) electrode surface. The results show that fusion of the vesicles is controlled by the electrode potential or charge at the electrode surface (sigmaM). At charge densities of -15 microC cm(-2) < sigmaM < 0 microC cm(-2), DMPC vesicles fuse to form a condensed film. When sigmaM < -15 microC cm(-2), de-wetting of the film from the electrode surface occurs. The film is detached from the electrode surface; however, phospholipid molecules remain in its close proximity in an ad-vesicle state. The state of the film can be conveniently changed by adjustment of the potential applied to the gold electrode. PM-IRRAS experiments demonstrated that the potential-controlled transitions between various DMPC states proceed without conformational changes and changes in the packing of the acyl chains of DMPC molecules. However, a remarkable change in the tilt angle of the acyl chains with respect to the surface normal occurs when ad-vesicles spread to form a film at the gold surface. When the bilayer is formed at the gold surface, the acyl chains of DMPC molecules are significantly tilted. The IR spectra have also demonstrated a pronounced change in the hydration of the polar head region that accompanies the spreading of ad-vesicles into the film. For the film deposited at the electrode surface, the infrared results showed that the temperature-controlled phase transition from the gel state to the liquid crystalline state occurs within the same temperature range as that observed for aqueous solutions of vesicles. The results presented in this work show that PM-FTIR spectroscopy, in combination with electrochemical techniques, is an extremely powerful tool for the study of the structure of model membrane systems at electrode surfaces.
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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 | 0.000 |
| 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 | 0.000 |
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".