Signal-Enhanced Lateral Flow Immunoassay with Dual Gold Nanoparticle Conjugates for the Detection of Hepatitis B Surface Antigen

We developed a signal-enhanced lateral flow immunoassay based on dual gold nanoparticle conjugates for the determination of hepatitis B surface antigen, in which no additional operation step for signal amplification was required. The first conjugates were gold nanoparticles modified with biotin and antibody. The second conjugates were gold nanoparticles modified with streptavidin. They were immobilized on different conjugate pads. When the sample solution flowed along the strip, the first conjugates were captured on the test line via antigen-antibody reaction, while the second conjugates were also immobilized on the test line through biotin-streptavidin. The signals were enhanced due to twice aggregation of gold nanoparticle conjugates. The immunoassay was used to detect hepatitis B surface antigen in the range of 0.1-30 ng/mL. The detection limit is 0.06 ng/mL (based on S/N = 3). The method was simple, rapid, quantitative, and on-site. The application can provide a new platform for detection of hepatitis B surface antigen and even cancer markers.