Immunochromatographic assay for quantitative and sensitive detection of hepatitis B virus surface antigen using highly luminescent quantum dot-beads

Abstract

Hepatitis B virus infection is one of the major causes of hepatitis, liver cirrhosis and liver cancer. In this study, we used highly luminescent quantum dot-beads (QBs) as signal amplification probes in the sandwich immunochromatographic assay (ICA) for ultrasensitive and quantitative detection of hepatitis B virus surface antigen (HBsAg) in human serum. Various parameters that influenced the sensitivity and stability of the QB-based ICA (QB-ICA) sensor were investigated. Two linear independent regression equations for detection of serum HBsAg were expressed with Y=0.3361X−0.0059 (R2=0.9983) for low HBsAg concentrations between 75pgmL−1 and 4.8ngmL−1, and Y=0.8404 X−2.9364 (R2=0.9939) for high HBsAg concentrations in the range from 4.8ngmL−1 to 75ngmL−1. The detection limit of the proposed ICA sensor achieved was 75pgmL−1, which is much higher than that of the routinely-used gold nanoparticle based ICA. The intra- and inter-assays recovery rates for spiked serum samples at HBsAg concentrations of 75pgmL−1, 3.75ngmL−1 and 18.75ngmL−1 ranged from 90.14% to 97.6%, and coefficients of variation were all below 7%, indicating that the QB-ICA sensor has an acceptable accuracy for HBsAg detection. Additionally, the quantitative method developed showed no false positive results in an analysis of 49 real HBsAg-negative serum samples, and exhibited excellent agreement (R2=0.9209) with a commercial chemiluminescence immunoassay kit in identifying 47 HBsAg-positive serum samples. In summary, due to its high fluorescence intensity, the sandwich QB-ICA sensor is a very promising point-of-care test for rapid, simple and ultrasensitive detection of HBsAg, as well as other disease-related protein biomarkers.