Highly selective detection of epidermal growth factor receptor by multifunctional gold-nanoparticle-based resonance Rayleigh scattering method

Gold nanoparticles (AuNPs) were modified by anti-epidermal growth factor receptor (EGFR) antibody (Ab) and EGFR aptamer (Apt) to obtain multifunctional Apt-AuNP-Ab nanoconjugate immunoprobe. The probe is specifically combined with EGFR to form large volume binding products that exhibited a remarkable enhancement of the resonance Rayleigh scattering (RRS) intensity, and to appear characteristic RRS peak at 312 nm. The scattering enhancement (ΔI) is linear to the EGFR concentration in the range of 20∼100 ng mL−1 with limit of detection of 0.1 ng mL−1. The immunoassay was successfully tested and validated by using esophageal squamous cell carcinoma (ESCC) cell Eca109 cell lysates, as well as human serum samples. The mechanism of selectivity and the reasons for RRS enhancement have been discussed. The experimental results reported in this article opened a new possibility of simple, rapid, selective and reliable determination of EGFR by measuring RRS intensity from multifuncition gold nanosystems.