Nanoparticle-enhanced surface plasmon resonance detection of proteins at attomolar concentrations: comparing different nanoparticle shapes and sizes.
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, rods 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 (>10(3)) 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.
Department of Chemistry and Green-Nano Materials Research Center, Kyungpook National University, 1370 Sankyuk-dong, Buk-gu, Daegu-city, 702-701, Republic of Korea.
Min Jeong
MJ
Kwon
Jaeyoung
J
Lee
Alastair W
AW
Wark
Hye Jin
HJ
Lee
D000906:Antibodies / Q000276:immunology; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D020349:Surface Plasmon Resonance; D013917:Thrombin / Q000032:analysis* / Q000276:immunology
D000906:Antibodies; D006046:Gold; D013917:Thrombin