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

M. J. Kwon, J. Lee, Alastair Wark, Hye Jin Lee

Research output: Contribution to journalArticle

131 Citations (Scopus)

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.
Original languageEnglish
Pages (from-to)1702-1707
Number of pages6
JournalAnalytical Chemistry
Volume84
Issue number3
Early online date6 Jan 2012
DOIs
Publication statusPublished - 2012

Keywords

  • plasmon resonance detection
  • proteins
  • nanoparticle shapes
  • attomolar concentrations

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