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

Abdullah Al Masud, W. Elliott Martin, Faruk H. Moonschi, So Min Park, Bernadeta R. Srijanto, Kenneth R. Graham, C. Patrick Collier, Christopher I. Richards

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


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.

Original languageEnglish
Pages (from-to)1894-1903
Number of pages10
JournalNanoscale Advances
Issue number5
StatePublished - May 2020

Bibliographical note

Funding Information:
C. I. R. acknowledge support from HFSP (RGY0081/2014) and NIH (DA038817). Zero-mode waveguides were fabricated at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

Publisher Copyright:
© The Royal Society of Chemistry 2020.

ASJC Scopus subject areas

  • Bioengineering
  • Atomic and Molecular Physics, and Optics
  • Chemistry (all)
  • Materials Science (all)
  • Engineering (all)


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