Fluorescent dye nano-assemblies by thiol attachment directed to the tips of gold nanorods for effective emission enhancement

The conjugation of dye-labelled DNA oligonucleotides with gold nanorods has been widely explored for the development of multifunctional fluorescent nanoprobes. Here, we show that the functionalization route is crucial to achieve enhanced emission in dye nano-assemblies based on gold nanorods. By usi...

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Bibliographic Details
Published in:	Nanoscale Vol. 12; no. 11; p. 6334
Main Authors:	Botequim, David, Silva, Inês I R, Serra, Sofia G, Melo, Eduardo P, Prazeres, Duarte M F, Costa, Sílvia M B, Paulo, Pedro M R
Format:	Journal Article
Language:	English
Published:	England 19-03-2020
Subjects:	Fluorescence Fluorescent Dyes - chemistry Gold - chemistry Metal Nanoparticles - chemistry Nanotubes - chemistry Oligonucleotides - chemistry
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Summary:	The conjugation of dye-labelled DNA oligonucleotides with gold nanorods has been widely explored for the development of multifunctional fluorescent nanoprobes. Here, we show that the functionalization route is crucial to achieve enhanced emission in dye nano-assemblies based on gold nanorods. By using a tip-selective approach for thiol attachment of dye molecules onto gold nanorods, it was possible to effectively increase the emission by more than 10-fold relatively to that of a free dye. On the other hand, a non-selective approach revealed that indiscriminate surface functionalization has a detrimental effect on the enhancement. Simulations of discrete dipole approximation gave further insight into the surface distribution of plasmon-enhanced emission by confirming that tip regions afford an effective enhancement, while side regions exhibit a negligible effect or even emission quenching. The contrast between dye nano-assemblies obtained from tip- and non-selective functionalization was further characterized by single-particle fluorescence emission. These studies showed that tip-functionalized gold nanorods with an average of only 30 dye molecules have a comparable to or even stronger emission than non-selectively functionalized particles with approximately 10 times more dye molecules. The results herein reported could significantly improve the performance of dye nano-assemblies for imaging or sensing applications.
ISSN:	2040-3372
DOI:	10.1039/d0nr00267d