Preparation and Characterization of Polyelectrolyte-Coated Gold Nanoparticles
Bibliographic record
Abstract
Gold nanoparticles of 5 nm diameter, stabilized by 4-(dimethylamino)pyridine (DMAP), were coated with poly(sodium 4-styrene sulfonate) (PSS) via electrostatic self-assembly. The suspension stability, monitored by the gold surface plasmon band (SPB), was studied by varying the pH, the PSS chain length, and PSS concentration. Enhanced stability is obtained at pH 10 (above the pKa of DMAP) when the polymer chain length matches or exceeds the particle circumference. Solid state 13C NMR was used to determine the presence of DMAP and polymers after subsequent deposition of weak and strong polycations: poly(allylamine hydrochloride) (PAH) and poly(diallyldimethylammonium chloride) (PDADMAC). At pH 10, DMAP remains associated with the nanoparticle after the first PSS layer has been formed. When PAH or PDADMAC are subsequently added at pH 4.5, DMAP is expelled, the suspensions remain stable, and zeta potential values indicate complete charge reversal. In the case of PDADMAC, however, the first layer of PSS is not fully retained. When PDADMAC is added at pH 10, DMAP and the first PSS layer are retained but lower zeta potentials and a higher SPB shift indicate a degraded stability. For PAH addition at pH 9.5, both DMAP and PSS are expelled and the suspension becomes unstable. These differences in stability of the multilayer components and the nanoparticle suspension are rationalized in terms of chain flexibility, polymer charge density, and the ability of the polymer functional groups to directly interact with the gold surface.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".