Nanoparticle-enhanced surface plasmon resonance detection of proteins at attomolar concentrations : comparing different nanoparticle shapes and sizes

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Kwon, M. J. and Lee, J. and Wark, Alastair and Lee, Hye Jin (2012) Nanoparticle-enhanced surface plasmon resonance detection of proteins at attomolar concentrations : comparing different nanoparticle shapes and sizes. Analytical Chemistry, 84 (3). pp. 1702-1707. ISSN 0003-2700 (https://doi.org/10.1021/ac202957h)

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Abstract

The application of biofunctionalized nanoparticles possessing various shapes and sizes for the enhanced surface plasmon resonance (SPR) detection of a protein biomarker at attomolar concentrations is described. Three different gold nanoparticle shapes (cubic cages, nanorods and quasi-spherical) with each possessing at least one dimension in the 40-50 nm range were systematically compared. Each nanoparticle (NP) was covalently functionalized with an antibody (anti-thrombin) and used as part of a sandwich assay in conjunction with a Au SPR chip modified with a DNA-aptamer probe specific to thrombin. The concentration of each NP-antibody conjugate solution was first optimized prior to establishing that the quasi-spherical nanoparticles resulted in the greatest enhancement in sensitivity with the detection of thrombin at concentrations as low as 1 aM. When nanorod and nanocage antibody conjugates were instead used, the minimum target concentrations detected were 10 aM (rods) and 1 fM (cages). This is a significant improvement (>103) on previous NP-enhanced SPR studies utilizing smaller (~15 nm) gold NP conjugates and is attributed to the functionalization of both the NP and chip surfaces resulting in low nonspecific adsorption as well as a combination of density increases and plasmonic coupling inducing large shifts in the local refractive index at the chip surface upon nanoparticle adsorption.

ORCID iDs

Kwon, M. J., Lee, J., Wark, Alastair ORCID logoORCID: https://orcid.org/0000-0001-8736-7566 and Lee, Hye Jin;
CORE (COnnecting REpositories)