Phase Separation in Supported Phospholipid Bilayers Visualized by Near-Field Scanning Optical Microscopy in Aqueous Solution
Bibliographic record
Abstract
An experimental approach for near-field scanning optical microscopy (NSOM) of biological samples in an aqueous environment with a resolution of <100 nm has been developed. This was accomplished by using high-throughput bent optical fiber probes prepared by a two-step chemical etching method followed by focused ion beam milling to fabricate a reproducible aperture. The utility of the method for high-resolution fluorescence imaging of biological samples in liquid was demonstrated using phase separated, supported phospholipid bilayers as models for natural membranes. Bilayers with a phase separated dipalmitoyl−phosphatidylcholine/dilauroyl−phosphatidylcholine (DPPC/DLPC) mixture in one or both leaflets were imaged by both atomic force microscopy and NSOM. The addition of dihexadecanoyl- sn -glycero-3-phosphoethanolamine−Texas Red (DHPE−TR) was used to visualize fluid and gel phases for the NSOM fluorescence measurements. Hybrid bilayers with 7:3 DLPC/DPPC in the bottom leaflet and DPPC on top showed phase separation to give striped DPPC domains similar to those observed for the corresponding monolayer. By contrast, the DLPC/DPPC mixture in the upper leaflet gave primarily large condensed DPPC domains. A bilayer with 7:3 DLPC/DPPC in both leaflets showed clear evidence for superposition of DPPC domains in the two layers. The resolution and image quality obtained for bilayers in aqueous solution clearly demonstrate the potential of NSOM for applications to biological imaging under physiological conditions.
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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 | 0.000 |
| 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".