96-well capped gold nanoslits for backside-reflection plasmonic biosensing

摘要

A nanostructure-based plasmonic biochip with the same size as standard 96-well plates for backside reflection-typebiosensing was proposed and validated through analyses of biological interactions. The capped gold nanoslit arrays werefabricated on a polycarbonate plastic film using a rapid hot embossing nanoimprint lithography process. The opticalproperties of capped gold nanoslits with different structure parameters in backside reflection geometry were studied;their refractive index (bulk) and surface (thickness) sensitivities were verified. By changing the cavity length, thecoupling between a broadband cavity resonance and a narrowband surface plasmon resonance mode results in anasymmetric Fano resonance in the reflection spectra. The coupling mode is able to enhance the thickness sensitivity by afactor of 2.4 with wavelength interrogation. The bulk and thickness sensitivities were 454 nm/RIU and 1.14 nm/nm,respectively. The protein-protein interaction experiments verified the sensing capabilities and high sensitivity of thecapped nanostructures; a limit of detection (LOD) of 2 ng/mL IgA was achieved. Such a multi-well plate with backsidereflection-type geometry, decoupling the optical paths, allows for sensing with opaque, bubbly or highly scatteringliquids and benefits multiple sensing applications in the biotechnology and agricultural products.