Enhanced Photoluminescence from Micellar Assemblies of Cadmium Sulfide Quantum Dots and Gold Nanoparticles
Bibliographic record
Abstract
We report the preparation and characterization of well-defined hierarchically structured colloidal assemblies, consisting of a block copolymer micelle with a single photoluminescent cadmium sulfide (CdS) quantum dot (QD) in the core and various numbers of gold nanoparticles (GNPs, between 0.001 and 0.077 GNPs per micelle) chemically bonded to thiol groups at the terminus of the micelle coronal chains. These assemblies were prepared from tetrablock copolymer chains, poly(acrylic acid)- b -polystyrene-TTC-polystyrene- b -poly(acrylic acid) (PAA- b -PS-TTC-PS- b -PAA), where TTC represents a single trithiocarbonate group, synthesized using reversible addition–fragmentation chain transfer polymerization. The block copolymer chains were first self-assembled in 1,4-dioxane by adding cadmium acetate to form flower-like micelles, followed by templated synthesis of CdS QDs in the micelle cores. Then, the TTC groups in the micelle coronae were reductively transformed into thiol groups, which bonded to added GNPs. In the final structures, each GNP was anchored at a distance of a single solubilized PS block (∼20 nm) away from a CdS QDs. This precise spacing between QDs and GNPs prevented any quenching of QD photoluminescence (PL) by the colloidal metal and instead led to an apparent enhancement of QD PL emission relative to QD emission from micelles without GNPs. The observed enhancement increased as the number of GNPs per micelle increased, with a maximum observed emission amplification (EA) of ∼8 times the PL intensity in the absence of GNPs. The EA was also found to increase as the excitation wavelength increased toward the spectral region of the surface plasmon resonance of the GNPs. Lifetime measurements revealed no significant difference between QD emission lifetimes in the absence and presence of GNPs. These results suggest a mechanism of PL enhancement via an excitation antenna effect associated with proximal GNP surface plasmons.
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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) | 0.000 | 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 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".