(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.