Biomedical Engineering Reference
In-Depth Information
2mm
type I
800 m
2mm
type II
800 m
2mm
type III
800 m
Fig. 4.9.
Three types of printing tips
compound is concentrated at the electrode surface through association with
formed hybrid, and is irreversibly oxidized on the bare gold electrodes at
about 550 mV. Ishimori has reported sequence-specific gene detection using
a gold electrode modified with probe DNA and Hoechst dye.
Each probe DNA was spotted on the microelectrodes using a microar-
rayer. The printing tips can be moved two-dimensionally and used for loading
of probe DNA onto each electrode. We prepared three types of printing tip,
asshowninFig.4.9.Eachtiphadadifferentsizeofgrooveandthendifferent
spotted areas were obtained. In this study, the type III tip was used because
the spotted area was sucient to cover the whole electrode.
We targeted HIV-1 and Hepatitis C virus DNA. Target sequences were
selected from sequence-conserved regions. The target DNA or control DNA
was hybridized at 37
◦
C for 1 h and allowed to react with 100 nM inter-
calator dye for 10 min. After washing, the electrode electrochemical signals
derived from the dye were measured by linear sweep voltammetry or diffe-
rential pulse voltammetry. Four kinds of probe DNA were immobilized onto
each electrode. The anodic currents were compared between the four types
