Biosensors
and
Bioelectronics
26 (2011) 4596–
4600
Contents
lists
available
at
ScienceDirect
Biosensors
and
Bioelectronics
jou
rn
al
h
om
epa
ge:
www.elsevier.com/locate/bios
Short
communication
A
novel
homogenous
detection
method
based
on
the
self-assembled
DNAzyme
labeled
DNA
probes
with
SWNT
conjugates
and
its
application
in
detecting
pathogen
Xinghua
Ding
1
,
Hua
Li
1
,
Le
Deng
∗
,
Zhihui
Peng,
Hui
Chen,
Dan
Wang
The
Co-construction
Laboratory
of
Microbial
Molecular
Biology
of
Province
Department
and
Ministry
of
Science
and
Technology,
College
of
Life
Sciences,
Hunan
Normal
University,
Changsha,
Hunan
410081,
People’s
Republic
of
China
a
r
t
i
c
l
e
i
n
f
o
Article
history:
Received
28
January
2011
Received
in
revised
form
16
April
2011
Accepted
21
April
2011
Available online 28 April 2011
Keywords:
Homogeneous
detection
method
DNAzyme
Self-assembly
SWNTs
Protection
Pathogen
detection
a
b
s
t
r
a
c
t
In
this
paper,
a
novel
and
cost-effective
homogeneous
detection
method
was
constructed
for
the
detection
of
genomic
DNA
and
Staphylococcus
aureus
(S.
aureus),
based
on
the
noncovalent
assembly
of
DNAzyme-
labeled
detection
probe
and
single-walled
carbon
nanotubes
(SWNTs).
When
the
target
genomic
DNA
and
hemin
was
existed
in
the
detection
solution,
the
detection
probe
wrapped
on
the
SWNTs
by
-stacking
interactions
would
keep
away
from
SWNTs
and
form
a
DNAzyme-self-assembly
construction.
This
DNAzyme
construction
could
catalyze
2,2
-azino-bis(3-ethylbenzothiazoline-6-sulfonic
acid)
(ABTS
2−
)
and
generate
a
colored
product
which
could
lead
to
the
absorbance
changes.
Hence,
according
to
its
catalyzed
capacity,
the
DNAzyme
construction
could
amplify
the
detection
signal.
The
concentration
of
target
DNA
could
be
quantified
by
exploiting
their
optical
absorption
changes
at
414
nm
and
the
con-
centration
limit
of
detection
of
the
method
was
30
nM.
And
this
detection
method
detected
S.
aureus
quantitatively.
In
addition,
this
work
proved
that
the
method
obtain
higher
detection
sensitivity
com-
pared
with
the
method
without
SWNTs
because
of
the
protection
profile
of
SWNTs
towards
the
detection
probe.
Crown Copyright ©
2011 Published by Elsevier B.V. All rights reserved.
1.
Introduction
Recently,
the
applications
of
many
analyte-dependent
DNAzymes
as
catalysts
that
amplify
sensing
events
are
espe-
cially
attractive
as
a
platform
to
design
biosensors.
It
reveals
several
advantages
as
catalytic
labels
for
amplifying
detection
signal.
First,
they
have
higher
stability
and
can
be
denatured
and
renatured
many
times
without
losing
their
catalytic
or
binding
abilities.
Second,
they
are
relatively
less
expensive
to
produce
and
do
not
need
sophisticated
probe
design
and
costly
fluorescence
labeling
and
fussy
modification
as
label
(Wang
et
al.,
2010).
Its
application
in
the
detection
of
pathogen
is
worthwhile.
As
we
all
know,
the
traditional
bacterial
detection
method
involving
plate
incubation
often
has
limitations
of
time-consuming
and
lacking
precision.
To
overcome
these
shortages,
the
molecular
era
of
pathogens
detection
emerged
in
the
1980s
which
is
based
on
the
sequence
molecular
methods
(Morteza,
2004).
During
this
era,
the
∗
Corresponding
author
at:
Department
of
Microbiology,
College
of
Life
Science,
Hunan
Normal
University,
Changsha,
Hunan
410081,
People’s
Republic
of
China.
Tel.:
+86
0731
88872927;
fax:
+86
0731
88883310.
E-mail
address:
dengle@hunnu.edu.cn
(L.
Deng).
1
These
authors
contributed
equally
to
this
work.
distinguished
detection
approach
is
the
detection
method
based
on
the
PCR
techniques,
but
its
quantification
is
still
lacking
in
precision
and
it
necessitates
extensive
laboratory
work.
While,
the
electrochemistry-based
methods
and
the
homogeneous
optical
methods
(Basu
et
al.,
2004;
Campbell
et
al.,
2002;
Drummond
et
al.,
2003;
Palecek
and
Jelen.,
2002),
because
the
initial
step
of
these
approaches
in
the
detection
strategies
is
nucleic
acid
hybridization
rather
than
enzyme-based
target
amplification,
have
the
capability
to
directly
detect
target
nucleic
acids
in
clinical
specimens,
which
is
an
advantage
over
nucleic
acid
amplification
techniques,
such
as
PCR
(Joseph
et
al.,
2006).
However,
the
electrochemistry-based
methods
have
drawbacks
of
fussy
modification
and
washing
steps.
Homogeneous
optical
methods
require
costly
fluorescence
labeling,
and
involve
sophisticated
probe
design
and
synthesis,
dye–quencher
pair
optimization,
complicated
preparation
and
operation
procedures
(Li
et
al.,
2008).
Their
preparation
and
oper-
ation
were
not
only
complicated,
but
also
costly.
A
fluorescence
label-free
method
with
simple
probe
design,
synthesis,
preparation
and
operation
is
well-appreciated
and
worthwhile.
The
DNAzyme
would
be
a
good
option.
In
molecular
era,
the
bare
DNA
detection
probes
are
easily
degraded
by
cellular
enzymes
or
digested
by
cellular
nucleases
(Wu
et
al.,
2008).
The
carbon
nanotubes
have
been
most
extensively
studied
due
to
their
unique
chemical,
electrical,
and
mechanical
0956-5663/$
–
see
front
matter.
Crown Copyright ©
2011 Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.bios.2011.04.041