Open AccessExtraordinary sensitivity enhancement of Ag-Au alloy nanohole arrays for label-free detection of Escherichia Coli
Author(s) -
Charles Soon Hong Hwang,
MyeongSu Ahn,
KiHun Jeong
Publication year - 2021
Publication title -
biomedical optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.362
H-Index - 86
ISSN - 2156-7085
DOI - 10.1364/boe.420828
Subject(s) - materials science , plasmon , nanoimprint lithography , alloy , detection limit , biosensor , surface plasmon resonance , nanotechnology , refractive index , dielectric , optoelectronics , nanoparticle , composite material , fabrication , chemistry , medicine , alternative medicine , pathology , chromatography
Alloy nanostructures unveil extraordinary plasmonic phenomena that supersede the mono-metallic counterparts. Here we report silver-gold (Ag-Au) alloy nanohole arrays (α-NHA) for ultra-sensitive plasmonic label-free detection of Escherichia Coli ( E. coli ). Large-area α-NHA were fabricated by using nanoimprint lithography and concurrent thermal evaporation of Ag and Au. The completely miscible Ag-Au alloy exhibits an entirely different dielectric function in the near infra-red wavelength range compared to mono-metallic Ag or Au. The α-NHA demonstrate substantially enhanced refractive index sensitivity of 387 nm/RIU, surpassing those of Ag or Au mono-metallic nanohole arrays by approximately 40%. Moreover, the α-NHA provide highly durable material stability to corrosion and oxidation during over one-month observation. The ultra-sensitive α-NHA allow the label-free detection of E. coli in various concentration levels ranging from 10 3 to 10 8 cfu/ ml with a calculated limit of detection of 59 cfu/ ml . This novel alloy plasmonic material provides a new outlook for widely applicable biosensing and bio-medical applications.