Direct competitive ELISA enhanced by dynamic light scattering for the ultrasensitive detection of aflatoxin B₁ in...

Compared with absorbance, scattering-based dynamic light scattering (DLS) signal has higher sensitivity because its light-scattering intensity is very sensitive to changes in size, thereby enhancing the sensitivity. Herein, we first developed a DLS-enhanced direct competitive enzyme-linked immunosorbent assay (DLS-dcELISA) for ultrasensitive detection of aflatoxin B₁ (AFB₁) in corn. By using hydroxyl radical-induced gold nanoparticle (AuNP) aggregation to amplify AuNP scattering signals, the developed DLS-dcELISA exhibited ultrahigh sensitivity for AFB₁. The detection limit was 0.12 pg mL^-1, which was 153- and 385-fold lower than those obtained using plasmonic and colorimetric dcELISA. In addition, the DLS-dcELISA exhibited excellent selectivity, high accuracy, and strong practicality. Overall, this work presented a simple and universal strategy for improving the sensitivity of traditional ELISA platform only by using the sensitive DLS signals. This technique can replace absorbance-based plasmonic or colored signals as immunoassay signal output for enhanced competitive detection of mycotoxins.