Lithographically-prepared gold nanobowls to detect mesoscale target analytes

Abstract

To detect mesoscale analytes with a size of hundreds of nanometers, we propose a three-dimensional gold nanobowl as a localized surface plasmon resonance (LSPR) sensor. Electromagnetic simulations demonstrated that the structural advantage obtained from the concave shape of the nanobowl enabled to extention of the local plasmon fields and consequently detected mesoscale analytes. Because the gold nanobowl arrays were prepared by nanoimprint lithography and vacuum deposition, uniform gold nanobowls could be perfectly arranged on a wafer-scale substrate, which resulted in reliable and reproducible LSPR signals. In addition, experimental measurements of extinction spectra demonstrated a zeptomole-level detection for 200-nm-sized analytes with the proposed LSPR sensor. Our results highlight the potential of gold nanobowl arrays as a plasmonic sensing platform for mesoscale analytes, such as viruses and exosomes.