ABSTRACT
Of the detection schemes available for DNA biosensors [1], elec-
trochemistry has drawn increasing interest due to enabling high
sensitivities using equipment of relatively low cost. In addition,
electrochemical detection can be coupled readily with available
minaturization technologies [2]. The direct electro-oxidation of
guanine involves high background signals [3], while the use of
enzyme labels may involve deterioration of enzyme activity over
time. Redox compounds which can intercalate with the probe-target
duplex can provide a more stable signal [4] but do not always
provide adequate sensitivity. This has led to interest in using
metal nanoparticles as labels for electrochemical detection of DNA
hybridization (reviewed in Refs. 5-7).
