Synthesis and Stability of Fluorescent Gold Nanoparticles by Sodium Borohydride in the Presence of Mono-6-deoxy-6-pyridinium-β-cyclodextrin Chloride
Bibliographic record
Abstract
Gold nanoparticles in the range of 5−6 nm were synthesized by the reduction of gold(III) chloride trihydrate by sodium borohydride (SBH) in the presence of newly synthesized mono-6-deoxy-6-pyridinium-β-cyclodextrin chloride (p-βCD). NMR, mass spectroscopy, and UV−vis spectroscopy illustrated that SBH would simultaneously reduce both p-βCD and gold salt even though the reduction of the latter occurs more rapidly. Resulting gold nanoparticles were capable of oxidizing the reduced p-βCD, leading to the formation of the p-βCD−gold complex via hydrogen bonding and ionic interaction. Gold nanoparticles were synthesized from a much higher concentration (1.0 mM vs 0.25 mM in the absence of p-βCD) of gold salt and were not susceptible to aggregation by NaCl, phosphate (pH 4−10), acetate, citrate, and borate. The p-βCD−gold nanoparticle assembly displayed intensified fluorescence with emission at 498 nm when excited at 470 nm, a phenomenon known as metal-enhanced fluorescence. The gold nanoparticles acted as electron acceptors and controlled the pathways of the excited-state deactivation. Surface binding of the pyridinium moiety of p-βCD to gold nanoparticles suppressed the intramolecular photoinduced electron transfer from the lone pair of the nitrogen atom to the aromatic ring and thereby increased the efficiency of radiative deactivation, leading to a fluorescence enhancement. The p-βCD−gold nanoparticle system could be exploited for various fluorescence chemosensing and biosensing schemes, especially for applications demanding long observation times without photobleaching.
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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 | 0.002 | 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 | 0.001 | 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".