Figure 35.

(A) Gold nanoparticle (AuNP)-based immunosensor. The immunosensor involves attached Ab₁, which captures antigen from a sample, followed by incubation with Ab₂-magnetic bead-HRP (Ab₂-MB-HRP), providing multiple enzyme labels for each PSA bound. The detection step involves immersing the immunosensor into a buffer containing a mediator, applying voltage, and injecting H₂O₂. (B) Results for AuNP immunosensor incubated with PSA present in 10 μL of a calf serum (ng/mL labeled on curves, dashed lines), cell lysates (HeLa and LNCap cells), and human patient serum samples (1–3) (solid lines) for 1.25 h, followed by an injection of 10 μL of 4 pmol/mL of Ab₂-MB-HRP. (C) Validation of AuNP sensor results for cell lysate and human serum samples by comparing against results from an ELISA determination (relative standard deviation ∼10%) for the same samples. Adapted with permission from ref (794). Copyright 2009 American Chemical Society.