DNA electrochemical sensors are most likely to become the accurate, sensitive,
and rapid detection method for the transgenic plant products. DNA
electrochemical sensors can be specially applied to the research of DNA with
specific sequence. Its sequence selectivity can detect the sequence of DNA
rapidly, and the detection cost is low, providing many advantages in the detection
of the transgenic plants’ transgenes. Human gene research shows that gene
mutations often lead to genetic disease happen. Therefore, it is important to
develop rapid DNA-detection methods for life science research and clinical
diagnosis of pathogenic and genetic diseases [1]. Electrochemistry-based sensors
offer sensitivity, selectivity and low cost for detection of selected DNA sequences
or mutated genes with human disease. In this work, we report on the preparation of
a simple, sensitive DNA nanosensor. A new sensitive DNA electrochemical
biosensor is described based on electrochemical impedance spectroscopic (EIS)
detection of the sequence-specific DNA related to PAT transgene in the transgenic
plants. Firstly gold nanoparticles were electrodeposited on the surface of a gold
electrode, and then the probe ss-DNA was immobilized on the surface of the gold
nanoparticles through a 5’-thiol-linker. Electrochemical impedance spectroscopy
(EIS) was used to investigate the DNA immobilization and hybridization.
Compared to the bare gold electrode, the gold nanoparticles modified electrode
could improve the density of probe DNA attachment and the sensitivity of DNA
sensor greatly. The difference of electron transfer resistance (DRet) was linear
with the logarithm of complementary oligonucleotides sequence concentrations in
the range of 2.0 × 10-13 to 9.0 × 10-8 mol L-1, and the detection limit was 6.7 ×
10-13 mol L-1. The applicability of the sensor was tested using blood samples, with
satisfactory rsults.