Immunoassay using dendritic Au-Pt nanoparticles as signal labels for detection of the biomarker of Burkholderia pseudomallei

In this work, the peroxidase-like properties of dendritic Au-Pt nanoparticles (30~60 nm) were investigated and these nanoparticles were applied in the immunoassay as signal labels for the detection of capsular polysaccharides (CPS, ~ 300 kDa, expressed on the cell envelopes of Burkholderia pseudomallei causing melioidosis). The immunoassay adopts monoclonal anti-CPS antibodies. The assay limit of detection (LOD), which is calculated through the 3σ method, is at 0.36 ng/mL for CPS spiked in PBS with 5% milk, and at 0.88 ng/mL for CPS spiked in human serum. The results from this work show that the dendritic Au-Pt nanoparticles can produce similar assay performance in detecting CPS as HRP did. Considering these particles can be easily prepared and stable in environments (thus avoiding cold-chain based storage/transportation), they have potential to be applicable for both in-house and in-field immunoassay development for the pathogen B. pseudomallei detection.