Immunoassay with Single-Walled Carbon Nanotubes as Near-Infrared Fluorescent Labels

Abstract

The intrinsic photoluminescence of single-walled carbon nanotubes (CNTs) in the near-infrared (NIR) above 1000 nm makes them promising candidates for biological probes owing to low interference by bioorganic molecules and deep tissue penetration. We here demonstrate an immunoassay by using a NIR CNT labels conjugated to immunoglobulin G (IgG) antibodies. Most of the CNT-conjugated IgG was successfully immunoprecipitated with protein G-attached magnetic beads and eluted from them, which was confirmed by the NIR emission of the conjugated CNTs at 1000–1200 nm. The photoluminescence intensity of the CNT labels was strong enough to detect antigens at 600 pM by our simple procedures