Surface plasmon resonance scattering and absorption sensing of Concanavalin A using glycoconjugated gold nanoparticles

Abstract

Glycoconjugated gold nanoparticles (AuNPs) are of great interest as probes for detecting carbohydrate–protein interactions. Three sensing methods – absorption, light scattering and wavelength-ratiometric scattering – were used to detect polyvalent interactions between mannose-conjugated AuNPs and Concanavalin A (Con A). Nanoparticle aggregation was induced by protein–carbohydrate interaction, which shifted the plasmon absorption to longer wavelengths and increased the intensity of plasmon light scattering. The plasmon absorption wavelength shift and scattering light intensity enhancement were proportional to the concentration of Con A in the range 5.7–20.2 nM and 3.8–36.7 nM, respectively, and the corresponding limits of detection were 3.4 and 2.3 nM, respectively. The wavelength-ratiometric scattering method showed the lowest detection limits (1.9 nM) for Con A, at 5–40 times lower than those obtained using existing glycoconjugated AuNPs.