Supplementary Material
Nanostructured magnesium oxide biosensing platform for cholera
detection
Manoj K. Patel1, 2, Md. Azahar Ali2, Ved Varun Agrawal2*, Z. A. Ansari1, S. G. Ansari2*,
and B. D. Malhotra3*
1
Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi,
110 025, India.
2
Department of Science and Technology Centre on Biomolecular Electronics, Biomedical
Instrumentation Section, National Physical Laboratory (CSIR), New Delhi, 110 012, India
3
Department of Biotechnology, Delhi Technological University, Main Bawana Road, Delhi,
110 042, India.
Keywords: Genosensor, Electrophoretic deposition, Nanostructured MgO, Vibrio cholerae
*Corresponding Authors: [email protected] (S.G. Ansari, Tel: +911132084481, Fax: +911143851575),
[email protected]
(B.D.
Malhotra,
Tel:
+911127294668,
Fax:
+911127871023),
E-mail: [email protected] (Ved Varun Agrawal, Tel: +911145609489).
FIG. S1. Shows the AFM images of (i) NanoMgO/ITO film and (ii) dsDNA/NanoMgO/ITO
film.
(i)
(ii)
2D
0.0
3D
1.1μm 0.0
10μm
FIG. S2. Zeta potential studies of (a) MgO nanoparticles and (b) ssDNA molecules in water.
140000
140000
(a)
(b)
120000
Total Counts
Total Counts
120000
100000
80000
60000
40000
20000
100000
80000
60000
40000
20000
0
0
-100
0
100
Zeta Potential (mV)
200
-100
0
100
Zeta Potential (mV)
200
FIG. S3. UV-Vis studies of (i) MgO nanoparticles, (ii) immobilization with ssDNA probe
and (iii) after hybridization with ftDNA in water.
Absorbance (a.u.)
250
256
280
(i) NanoMgO
(ii) Probe immobilization
(iii) After ftDNA hybridization
250
275
300
Wavelength (nm)
325
350
FIG. S4. FT-IR spectra of (i) NanoMgO/ITO (ii) ssDNA/NanoMgO/ITO and
(iii) dsDNA/NanoMgO/ITO film.
FIG. S5. Cyclic voltammogram of ssDNA/NanoMgO/ITO bioelectrode on increasing scan
rate from 10-100 mVs-1 in PBS (50 mM, pH 7 containing 0.9 % NaCl) in 40 µM MB
6.0
2.0
6.0
4.0
2.0
100 mV
90 mV
80 mV
70 mV
60 mV
50 mV
40 mV
30 mV
20 mV
10 mV
Anodic current (Ia)
Cathodic current (Ic)
0.0
-2.0
-4.0
-6.0
0
20
40
60
80
100
Scane rate (mV/s)
0.0
-0.15
Peak potential (V)
Current (A)
4.0
Peak Current (A)
solution.
-2.0
-4.0
-0.20
Anodic potential (Ip)
Cathodic potential (Ip)
-0.25
-0.30
-0.35
0
-6.0
-0.5
20
40
60
80
100
Scane rate (mV/s)
-0.4
-0.3
-0.2
Potential (V)
-0.1
0.0
FIG. S6. Chronoamperometric response of dsDNA/NanoMgO/ITO (200 ng/µL) electrode at
-0.25 V potential.
Current (A)
-0.90
-1.20
3s
-1.50
0
5
40
Time (s)
50
60
FIG. S7. Interferent studies of dsDNA/NanoMgO/ITO bioelectrode (200 ng/µL) in presence
of organic (GL, CHL), inorganic molecules (NaCl) and their mixture (MX) concentration.
3.75
Cholesterol
(5.0 mM)
Sodium Chloride
(150 mM)
Mixture of All
1.50
Glucose
(5.54 mM)
2.25
Fragmented Target DNA
(200 ng/L)
Current (A)
3.00
GL
CHL
NaCl
MX
0.75
DNA
Potential (mV)
FIG. S8. Shows the reproducibility studies of dsDNA/NanoMgO/ITO (100 ng/µL) electrode.
Current (A)
3.0
Total number: 05
Mean value: 2.63 A
Sample standard deviation:
Relative standard deviation:
0.08
3.14%
2.5
2.0
1.5
Electrode 1 Electrode 2 Electrode 3 Electrode 4 Electrode 5
Different Electrodes
FIG. S9. Shows the stability curve of dsDNA/NanoMgO/ITO (200 ng/µL) electrode for
0-120 days.
Current (A)
2.90
2.88
2.85
2.83
2.80
0
20
40
60
80
Number of days
100
120
Table SI. Shows the sensing characteristics of dsDNA/NanoMgO/ITO bioelectrode for
Vibrio cholerae detection along with those reported in the literature.
Surface/matrix
Transducer
Optical waveguide
Optical
biosensor
Immunosensor/
Electrochemical
Immunosensor
Copolymer film
Microcapilary based
Gold transducer
CH-NanoMgO/ITO
NanoMgO/ITO
DNA biosensor/
Electrochemical
Electrochemical
DNA sensor
Electrochemical
DNA sensor
Detection
limit (ng/µL)
0.20
Detection range
( ng/µL)
-----
Response
time (s)
300
Sensitivity
nA/ng/cm2
-----
References
0.05
0.05 -500
30
-----
25
6.6 × 10-11
1.0×107-1.6×107
2400
-----
26
100
100-500
60
27.0
27
35.20
100-500
3
36.72
11
59.12
0-500
3
16.80
Present work
24