Fig. 13

Electrochemical assay of label-free DNA protocol on an electrode utilizing a 200 μm diameter electrode b NWA with 50 nm diameter (number of 200 × 200). Electrochemical measurement (square-wave voltammograms and cyclic voltamogram were carried out in 10 mM K3Fe(CN)6 solutions at a scan rate of 100 mV/s: before immobilization (dotted line), and after hybridization (solid line) with a complementary target 21-mer oligonucleotide. Electrochemical response change between the redox current after immobilization (Iim) and after hybridization (Ihy) in the 200 μm electrode a, b and NWA electrodes c, d. The concentration of probe DNA and complementary target DNA was 50 μM/100 mL