Biomedical Engineering Reference
In-Depth Information
Thionine
Graphene
Nanopore gold
(1) glutaraldehyde
(2) Anti-CA 153
(3) BSA
CA 153
HRP@Liposome
Graphene
Nanopore gold
Thionine
Anti-CA 153
CA 153
HRP
BSA
Liposome
Figure 11.11
Schematic representation of the assembly process of the immunosensor.
(Reprinted with permission from ref [66])
self-assembled monolayer on NPG. Alkaline phosphatase is a widely used
enzyme label for immunoassays that shows high activity in a range of sub-
strates [69-70]. h e addition of antigen inhibits the enzymatic conversion of
p-aminophenyl phosphate to p-aminophenol as an electroactive enzymatic
product, thus square-wave voltammetric signal of p-aminophenol dimin-
ishes in the presence of target antigen. Sun and Ma [71] prepared NPG on
GCE by alternating the assembly of AuNPs and AgNPs on GCE using 1,4-ben-
zenedimethanethiol as a crosslinker, and then dissolved AgNPs with HNO
3
to obtain NPG. h e dissolution of Ag and formation of GNP were evaluated
with AFM and analysis of surface roughness (Figure 11.12). h en thionine,
electrostatically and through S-Au bonds, was adsorbed into the NPG. At er
that a nanostructure of gold was electrodeposited on top of the modii ed
electrode via reduction of HAuCl
4
solution, which was used to immobilize
anti-CEA (Figure 11.13). h e electrochemical signal of thionine followed
for quantii cation of CEA.
11.4.2.3
Bioconjugation of Other Proteins to NPG
Ta n
et al.
[72] immobilized bovine Serum Albumin (BSA) and
Immunoglobulin G (IgG) on NPG (with a typical pore size ranging from
it y to a few hundreds of nm) using NHS ester functionalized lipoic acid
SAM. Both static and low-through conditions were examined and the
