Issue 5, 2020

Mixed metal zero-mode guides (ZMWs) for tunable fluorescence enhancement

Abstract

Zero-mode waveguides (ZMWs) are capable of modifying fluorescence emission through interactions with surface plasmon modes leading to either plasmon-enhanced fluorescence or quenching. Enhancement requires spectral overlap of the plasmon modes with the absorption or emission of the fluorophore. Thus, enhancement is limited to fluorophores in resonance with metals (e.g. Al, Au, Ag) used for ZMWs. The ability to tune interactions to match a wider range of fluorophores across the visible spectra would significantly extend the utility of ZMWs. We fabricated ZMWs composed of aluminum and gold individually and also in mixtures of three different ratios, (Al : Au; 75 : 25, 50 : 50, 25 : 75). We characterized the effect of mixed-metal ZMWs on single-molecule emission for a range fluorophores across the visible spectrum. Mixed metal ZMWs exhibited a shift in the spectral range where they exhibited the maximum fluorescence enhancement allowing us to match the emission of fluorophores that were nonresonant with single metal ZMWs. We also compared the effect of mixed-metal ZMWs on the photophysical properties of fluorescent molecules due to metal–molecule interactions. We quantified changes in fluorescence lifetimes and photostability that were dependent on the ratio of Au and Al. Tuning the enhancement properties of ZMWs by changing the ratio of Au and Al allowed us to match the fluorescence of fluorophores that emit in different regions of the visible spectrum.

Graphical abstract: Mixed metal zero-mode guides (ZMWs) for tunable fluorescence enhancement

Supplementary files

Article information

Article type
Paper
Submitted
09 okt 2019
Accepted
25 mar 2020
First published
25 mar 2020
This article is Open Access
Creative Commons BY license

Nanoscale Adv., 2020,2, 1894-1903

Mixed metal zero-mode guides (ZMWs) for tunable fluorescence enhancement

A. Al Masud, W. E. Martin, F. H. Moonschi, S. M. Park, B. R. Srijanto, K. R. Graham, C. P. Collier and C. I. Richards, Nanoscale Adv., 2020, 2, 1894 DOI: 10.1039/C9NA00641A

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