Biology Reference
In-Depth Information
Figure 5.7.
Schematic illustration of the fabrication of Au-DNA probe
modified TiO
2
electrode and the detection of target DNA (A) and the
photo-induced processes of electron-hole generation and charge transfer
processes(B)(adaptedfromRef.40withpermission).SeealsoColorInsert.
Fig. 5.7, the probe immobilization and the following hybridization
induced the photocurrent change of the TiO
2
electrode that was
enhanced with the Au-NP-DNA probe immobilization, and then
gradually decreased with increasing the concentration of the target
DNA. They could effectively discriminate the hybridization from un-
hybridization processes, and potentiate this system as a biosensor
to study a wide variety of biologicalprocesses.
A very recent work from Hu
et al.
[41] proposes a direct
electrochemical detection procedure for DNA hybridization using
the electrochemical signal changes of conductive poly(m-amino-
benzenosulfonic) acid (PABSA)/TiO
2
nanosheet membranes, which
were electropolymerized by pulse potentiostatic method (see
scheme in Fig. 5.8). The polymerization e
ciency is greatly
improved by the use of TiO
2
-NPs, and their combination with
PABSA resulted in a highly conductive composite membrane with
unique and novel nanosheet morphology (80 nm thick ramified
membrane) that provides more activation sites and enhances
the surface electron-transfer rate. Furthermore these nanosheets
presented good redox activity and electroconductivity even in
neutral environment (PBS solution of pH 7.0), and the DNA probes
could be easily covalently immobilized, so that the hybridization
