Gold coated Cicada wings: Anti-reflective micro-environment for plasmonic enhancement of fluorescence from upconversion nanoparticles

Akash Gupta, Hao Yu Cheng, Kung Hsuan Lin, Chien Ting Wu, Pradip Kumar Roy, Sandip Ghosh, Surojit Chattopadhyay*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

We demonstrate that the upconversion nanoparticles (UCNPs) fluoresce 50 times more on a gold (Au) coated Cicada wing. UCNPs are attractive bioimaging, and therapeutic materials as it is excited in the infrared, limited only by the low fluorescence quantum yield. Here, a plasmonic effect, coupled with an anti-reflecting (AR) Cicada wing substrate coated with Au is demonstrated to enhance the fluorescence of the UCNPs. Silica (SiO2) coated Erbium doped green emitting core-shell UCNPs (NaYF4: Yb3+, Er3+@SiO2) show conventional metal enhanced fluorescence. The AR property of the Cicada wing (R ~0.2% @ 1000 nm) contributes >6-fold enhancement as compared to flat (silicon, and quartz) substrates (R~10–30% @ 1000 nm). Upon plasmon coupling, with an optimally sputtered Au coating, an unprecedented enhancement of >50-fold for the 520, and 655 nm emission was obtained on the Au coated Cicada wings, vis-à-vis planar uncoated (silicon, and quartz) substrates. The enhancement was also confirmed by direct fluorescence imaging of the photonic substrates used. The fluorescence lifetime of the core, and the core-shell UCNPs (~300 μs) decreased by ~30–40%, and 10–30%, respectively, when placed on Au coated substrates.

Original languageEnglish
Pages (from-to)569-577
Number of pages9
JournalMaterials Science and Engineering C
Volume102
DOIs
StatePublished - Sep 2019

Keywords

  • Anti-reflection
  • Cicada wing
  • Photonic substrate
  • Plasmonic enhancement
  • Upconversion nanoparticle

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