Exonuclease-Catalyzed Methylene Blue Releasing and
Enriching onto a Dodecanethiol Monolayer for an Immobilization-Free
and Highly Sensitive Electrochemical Nucleic Acid Biosensor
posted on 2017-05-07, 00:00authored byShufeng Liu, Yanqun Wang, Shanshan Zhang, Li Wang
Herein, a unique and versatile immobilization-free
electrochemical
nucleic acid biosensor architecture is proposed for the first time
based on the catalyzed release of a methylene blue (MB)-tagged mononucleotide
by exonuclease III (Exo III) and the successive enrichment onto a
dodecanethiol monolayer, which can be attributed to the hydrophobic
force between the alkyl chain of the dodecanethiol monolayer and the
hydrophobic part of the MB-tagged mononucleotide. The fabricated biosensor
demonstrates considerable advantages including assay simplicity, rapidness,
and high sensitivity owing to its immobilization-free and homogenous
operation for the biorecognition and amplification process. A low
detection limit of approximately 1 pM toward the target DNA could
be achieved with an excellent selectivity. The proposed immobilization-free
electrochemical biosensing strategy was also extended for the assay
of Exo I and III activity. Furthermore, it might be easily extended
for the detection of a wide spectrum of targets and thus provide a
promising avenue for the development of immobilization-free and sensitive
electrochemical biosensors.