Using Polymers To Photoswitch the Aggregation State of Gold Nanoparticles in Aqueous Solution
Bibliographic record
Abstract
Gold nanoparticles (AuNPs) coated with a water-soluble polymer displaying a photoswitchable lower critical solution temperature (LCST) were synthesized, and the photoinduced change in the aggregation state of AuNPs was investigated. The photoactivity of AuNPs was conferred by tethering on the surface a random copolymer of <i><i>N,N</i></i>-dimethylacrylamide and <i>N</i>-4-phenylazophenyl acrylamide (P(DMA-<i>co</i>-Azo)), whose LCST could be lowered upon the trans−cis photoisomerization of azobenzene groups. It was found that the dispersion of P(DMA-<i>co</i>-Azo)-coated AuNPs in aqueous solution remained stable regardless of temperature and the isomeric form of azobenzene groups. However, with the presence of free P(DMA-<i>co</i>-Azo) chains in the solution, the reversible photoinduced shift of LCST of the polymer could result in a reversible photoswitching between dispersion and aggregation of AuNPs. A stable dispersion could be obtained at <i>T</i> < LCST of the polymer with azobenzene in the trans form (without irradiation), while upon UV irradiation, the lowering of LCST with <i>cis</i>-azobenzene put the solution to above the altered LCST and the insoluble polymer chains led to aggregation of AuNPs; the initial dispersion state could be recovered by visible light irradiation, bringing <i>cis</i>-azobenzene back to the trans form. The use of such a photoresponsive polymer to optically tune the aggregation state of AuNPs allows the surface plasmon resonance (SPR) of AuNPs to be reversibly switched by light at two wavelengths, the extent of which depends on the amount of free polymer chains in the solution.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.006 | 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 teacher head, 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".