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Title 

Highly sensitive biosensing using arrays of plasmonic Au nanodisks realized by nanoimprint lithography

Authors 

Seung-Woo LeeK S LeeJun Hyoung AhnJ J LeeMin-Gon KimYong Beom Shin

Publisher 

American Chemical Society

Issue Date 

2011

Citation 

ACS Nano, vol. 5, no. 2, pp. 897-904

Keywords 

enzymatic precipitationlocalized surface plasmon resonancenanodisk arraysnanoimprint lithographyprostate-specific antigen

Abstract 

We describe the fabrication of elliptical Au nanodisk arrays as a localized surface plasmon resonance (LSPR) sensing substrate for clinical immunoassay via thermal nanoimprint lithography (NIL) and enhancement in the sensitivity of the detection of the prostate-specific antigen (PSA) using the precipitation of 5-bromo-4-chloro-3-indolyl phosphate p-toluidine/nitro blue tetrazolium (BCIP/NBT), catalyzed by alkaline phosphatase. Au nanodisks were fabricated on glass through an unconventional tilted evaporation, which could preserve the thickness of imprinted resists and create an undercut beneficial to the subsequent lift-off process without any damage to pattern dimension and the glass while removing the residual polymers. To investigate the optically anisotropic property of the LSPR sensors, a probe light with linear polarization parallel to and perpendicular to the long axis of the elliptical nanodisk array was utilized, and their sensitivity to the bulk refractive index (RI) was measured as 327 and 167 nm/RIU, respectively. To our knowledge, this is the first application of enzyme-substrate reaction to sandwich immunoassay-based LSPR biosensors that previously suffered from a low sensitivity due to the short penetration depth of the plasmon field, especially when large-sized antibodies were used as bioreceptors. As a result, a large change in local refractive index because of the precipitation on the Au nanodisks amplified the wavelength shift of the LSPR peak in the vis-NIR spectrum, resulting in femtomolar detection limits, which was ∼105-fold lower than the label-free detection without the enzyme precipitation. This method can be extended easily to the other clinical diagnostics with a high sensitivity.

ISSN 

1936-0851

Link 

http://dx.doi.org/10.1021/nn102041m

Appears in Collections

1. Journal Articles > Journal Articles

Registered Date

2019-05-02


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