337Graphene-Based Electrochemical Biosensors
Au NPs and subsequently horseradish peroxidase (HRP)–anti-α-fetoprotein. The remain-
ing electrode surface was passivated with bovine serum albumin. In the presence of H
2
O
2
but not the antigen α-fetoprotein, HRP catalyzed the reduction of H
2
O
2
and a cathodic cur-
rent peak corresponding to the regeneration of PTH at the electrode was produced. When
α-fetoprotein was present along with H
2
O
2
, the binding of α-fetoprotein to the HRP–anti-
α-fetoprotein caused a decrease in cathodic current, possibly because the active site of the
HRP was blocked or H
2
O
2
could no longer reach the enzyme.
For graphene-based label-free electrochemical immunosensors no matter the use of
binding-induced changes in current respon ...