Biology Reference
In-Depth Information
hybridization of the target DNA via chronocoulometry using the
method of Tarlov [46]. The authors reported that the large surface
areaoftheelectroderesultedinlargemeasuredcurrents(hundreds
of
μ
A to nearly a mA) and large IR drops requiring the use of
resistance compensation to perform effective DNA quantification
measurements.
Theuseofconductingpolyanilinenanowire-modifiedelectrodes
forelectrochemical DNAdetection has also beenreported. Zhu
et al.
[47] directly deposited polyaniline nanowires onto a glassy carbon
electrode from an aniline containing electrolyte solution yielding
nanowires with diameters ranging from 80 to 100 nm. Probe DNA
with a free carboxyl group was covalently linked to free primary
amines on the polyaniline nanowires via carbodiimide chemistry.
Hybridization of target DNA was monitored using differential pulse
voltammetryandmethyleneblue(MB)astheelectroactivereporter.
MBbindstoguaninebasesofssDNAwithhighera
nitythandsDNA
in which the guanine residues are less accessible. This resulted in
a decrease of current, or a “signal off” detection mechanism, with
a detection limit of 1 pM. In a similar work, Chang and coworkers
[48] electrochemically deposited ordered polyaniline nanowires
onto a graphite electrode using a porous aluminum layer template.
The porous aluminum template was prepared by deposition of
aluminum onto the electrode via magnetron sputtering followed by
anodization. Carbodiimide was also used to link carboxyl-modified
DNA probes to the nanowires (40 nm diameter). In this work,
daunorubicin, which binds with higher a
nity to dsDNA, served
as the electroactive reporter. This “signal on” approach yielded a
significantly improved detection limit of 1 fM which the authors
attribute to enhanced conductivity and faster hybridization kinetics
at the oriented nanowires.
Thefirstuseofverticallyalignedconductingdiamondnanowires
for electrochemical DNA detection was also recently reported
[49]. Boron-doped diamond posseses many advantages over other
materials used for producing nanowires including high chemical
stability, low background current, wide potential window, and high
biocompatibility. In this work metal-like diamond nanowires were
fabricated from boron-doped single crystalline diamond produced
by chemical vapor deposition and subsequently exposed to reactive
