Novel dynamic light scattering immunosensor for prostate specific antigens based upon dual-tyramine signal amplification strategy

The sensitive detection of biomarkers is crucial for the early diagnosis, treatment, and improvement of the quality of life of patients. A novel dynamic light scattering-dual tyramine signal amplification strategy (DLS-dTSA) was constructed to detect prostate-specific antigen (PSA). The Oligo 1 was first immobilized in a 96-well plate for PSA capture. Afterwards, horseradish peroxidase (HRP) and Oligo 2 functionalized AuNPs (HRP-Au NPs-Oligo 2) bound to Oligo 1 through DNA hybridization. In the presence of hydrogen peroxide (H2O2), tyramine could be converted into a transient radical intermediate by HRP, leading to the aggregation of tyramine and HRP-labeled AuNPs (tyramine-AuNPs-HRP) near HRP-AuNPs-Oligo 2, triggering the first TSA process. Later, the PSA was added into the 96-well plate, to specifically recognize ap-tamer and thus depart the Au-aggregate from the 96-well plate. Then H2O2 was added to the Au-aggregate solution, triggering the free Au-aggregate to gather again, realizing the second TSA amplification. The average diameter of Au NPs increased linearly with the concentration of PSA during the range of 0.0001 – 1000 ng mL-1, and the limit of detection was 0.033 pg mL-1. Moreover, this strategy has been used to analyze PSA in human serum samples successfully, demonstrating the potential application of the proposed method for rapid clinical and early clinical diagnosis of prostate cancer in vitro.