synthesis of graphene-based nanomaterials with ...€¦ · synthesis of graphene-based...
TRANSCRIPT
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Synthesis of graphene-based nanomaterials with applications in
the electrochemical detection of biomolecules
Stela Pruneanu
INCDTIM-Cluj-Napoca
NANOGENTOOLS Spring School May 2019- Alessandria
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TOPICS 1. Graphene synthesis 2. Electrochemical detection of dopamine 3. Electrochemical detection of cancer biomarker (8-OHdG) 4. Conclusions
NANOGENTOOLS Spring School May 2019- Alessandria
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Single layer of sp2 hybridized carbon atoms High mobility of charge carriers: 200.000 cm2V−1s−1 Surface area of a single graphene sheet is 2630 m2/g Graphene is resistant to attack by powerful acids and alkalis (hydrofluoric acid, ammonia)
1. Graphene synthesis
NANOGENTOOLS Spring School May 2019- Alessandria
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Au(x)/MgO- catalyst, where x = 1, 2 or 3 wt% Ag(x)/MgO-catalyst, where x = 1,2 or 3 wt% Pt(x)/MgO-catalyst, where x = 1,2 or 3 wt%
AuAg(x)/ MgO-catalyst, where x = 1:1 or 1.5:1.5 wt% AuPd (x)/ MgO-catalyst, where x = 1:1 or 1.5:1.5 wt% AuCu (x)/ MgO-catalyst, where x = 1:1 or 1.5:1.5 wt% AuPt (x)/ MgO-catalyst, where x = 1:1 or 1.5:1.5 wt% Methane (CH4)- carbon source 1000 oC- synthesis temperature (60 minutes) Purification in HCl (30 minutes) Drying - 120 oC (overnight)
A.R. Biris et al, Carbon, 50 (2012) 2252
A) Chemical Vapor Deposition (CVD)-bottom up
NANOGENTOOLS Spring School May 2019- Alessandria
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Time-lapsed HRTEM images of the growing graphene layers on Pt recorded in situ under exposure of 1.3 mbar iso-butene at 475 C (a: 10 min; b: 1 s; c: 1.2 min; and d: 3.2 min)
Schematic illustration of graphene layer growth on Pt particles of increasing size: (c and d) envelopment of Pt particles by graphene for particles greater than 6 nm in diameter; (e and f) formation of graphene nanotubes on Pt particles of 2–6 nm; (g and h) formation of graphene sheets and their migration to the support for Pt particles less than 2 nm in diameter.
A.T. Bell et al., Journal of Catalysis 286 (2012) 22–29
iso-butene
NANOGENTOOLS Spring School May 2019- Alessandria
http://www.google.ro/url?sa=i&source=images&cd=&docid=k9m5xcvmx1knoM&tbnid=CVzl4F8T37ttFM:&ved=0CAgQjRwwAA&url=http://commons.wikimedia.org/wiki/File:Isobutene_struttura.PNG&ei=eBVAUonrIKLG0QXan4HABA&psig=AFQjCNGg0ukpFrn1XUo9SFQ5j0GqrAus2Q&ust=1380017912670466
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NANOGENTOOLS Spring School May 2019- Alessandria
EDX analysis
F. Pogacean et al., International Journal of Nanomedicine 2014:9 1111–1125
TEM images of Graphene-AuAg
Au: Ag (1:1 wt.%) Au:Ag (1.5:1.5 wt.%)
AuAg: 5- 50 nm; 13 nm AuAg: 5-100 nm; 20 nm
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Rate of electron transfer at the edge planes >> than that at the basal planes
C. E. Banks et al., RSC Adv., 2011, 1, 978–988.
HR-TEM images of Graphene-AuAg
NANOGENTOOLS Spring School May 2019- Alessandria
Graphene flakes
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Advantages of CVD method:
- Low amount of oxygen-containing groups (due to the lack of oxygen from the reaction chamber)
- The honeycomb structure is preserved
- Metallic nanoparticles are attached during synthesis (no need for additional reaction)
Disadvantages:
- Low quantity of graphene can be obtained after one synthesis (50 mg)
NANOGENTOOLS Spring School May 2019- Alessandria
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B) Chemical synthesis (top-down)
C. Socaci et al., Sensors and Actuators B 213 (2015) 474–483
Thermal reduction (300o Ar) Chemical reduction
NANOGENTOOLS Spring School May 2019- Alessandria
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Graphene-metallic nanoparticles (chemical)
NANOGENTOOLS Spring School May 2019- Alessandria
Graphene/Au (10 – 40 nm)
Graphene/AuPd (10 – 30 nm)
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Advantages of chemical synthesis:
- Large quantity of graphene-oxide (GO) can be obtained after one synthesis (8 g)
- After reduction - RGO (4 g)
Disadvantages:
- Chemical/Thermal treatment is needed, in order to reduce graphene-oxide
- Large amount of oxygen-containing groups (the honeycomb structure is not well preserved)
NANOGENTOOLS Spring School May 2019- Alessandria
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Dopamine- is a neurotransmitter and a hormone Concentration in body fluid : 1-10 µM Low levels of dopamine - Parkinson's disease Higher dopamine concentrations: schizophrenia, attention deficit hyperactivity disorder (ADHD), and restless legs syndrome (RLS).
NANOGENTOOLS Spring School May 2019- Alessandria
2. Electrochemical detection of dopamine
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Increases the active surface area (20-70 %) Current is proportional with surface
area Improves the transfer of electrons
Graphene modified electrodes for the detection of dopamine
NANOGENTOOLS Spring School May 2019- Alessandria
CE WE RE
Screen-printed electrode GC or Au electrode, modified with graphene (10 microL)
Graphene suspension in DMF (1 mg/mL)
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Identification of the FTIR absorption bands: 1716 cm-1 - C=O stretch of the COOH group 1125 and 1205 cm-1 -C-O stretching vibration of epoxy and alkoxy groups 1464 and 1570 cm-1 - OH deformation vibrations 3434 cm-1 - O-H stretch from the adsorbed H2O molecules
Graphene (CVD) vs Graphene (Chemical)
NANOGENTOOLS Spring School May 2019- Alessandria
TEM images of graphene FTIR spectra of graphene
Graphene- CVD
Graphene- Chemical
Graphene- CVD
Graphene- Chemical
S. Pruneanu et al., Electrochimica Acta 154 (2015) 197–204
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NANOGENTOOLS Spring School May 2019- Alessandria
Electrochemical oxidation of dopamine
In acidic solution: -dopamine is present in the cationic form -pKa1 = 8.9 for aminoethyl group -pKa2 = 10.6 hydroxyl group - oxidation occurs as 2e/2H+ process, forming o-dopaminoquinone (o-DQ)
In neutral and basic solutions: -a cyclization reaction occurs, yielding leucodopaminochrome (LDC) - LDC undergoes a 2e/2H+ process, but at lower potentials
S. Pruneanu et al., Electrochimica Acta 154 (2015) 197–204
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Graphene CVD- excellent electro-catalytic activity: The decrease of the peak potential ̴ 140 mV
Increase of the peak current ̴ 5 times
S. Pruneanu et al., Electrochimica Acta 154 (2015) 197–204
NANOGENTOOLS Spring School May 2019- Alessandria
Graphene (CVD) vs Graphene (Chemical)
Au electrodes modified with graphene
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𝐼𝐶 = 𝑑𝑄
𝑑𝑡= 𝐶
𝑑𝐸
𝑑𝑡; C = Q/V
Graphene-Chemical
Graphene- CVD
Ic = 5 x 10-5 A
Ic = 1 x 10-5 A
Graphene (CVD) vs Graphene (Chemical)
NANOGENTOOLS Spring School May 2019- Alessandria
S. Pruneanu et al., Electrochimica Acta 154 (2015) 197–204
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LOD = 10-7 M (graphene-CVD) Linear range: 3 x 10-7 – 10-4 M Covers well the concentrations in body fluid (10-6– 10-5 M)
LOD = 3 x 10-6 M (graphene –chemical) Linear range: 10-5 – 10-4 M Does not cover the concentrations in body fluid
Graphene (CVD) vs Graphene (Chemical)
NANOGENTOOLS Spring School May 2019- Alessandria
S. Pruneanu et al., Electrochimica Acta 154 (2015) 197–204
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Interfering species: ascorbic and uric acid Graphene-CVD
NANOGENTOOLS Spring School May 2019- Alessandria
S. Pruneanu et al., Electrochimica Acta 154 (2015) 197–204
Ascorbic acid- an organic acid with antioxidant properties In the cells, it protect the biological molecules from oxidative degradation; stimulates the production of collagen, neurotransmitters or steroid hormones. Uric acid – an organic acid which results after degradation of purine bases of DNA (adenine; guanine) or RNA.
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Interfering species: ascorbic and uric acid Graphene-CVD
NANOGENTOOLS Spring School May 2019- Alessandria
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Conclusions
- Graphene – CVD has better electrochemical properties comparing with Graphene-chemical
- The linear range and LOD obtained for graphene-CVD: fit well with the concentrations of dopamine in body fluid
- Ascorbic acid and uric acid influence the detection of dopamine
NANOGENTOOLS Spring School May 2019- Alessandria
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C) Electrochemical synthesis of graphene by exfoliation of graphite rods
Experimental set-up: - DC Power Supply (up to 30 V) - Two graphite rods (high purity; 99.995%) - Reaction vessel -Mixture of strong acids (sulfuric + nitric) - few hours synthesis time - wash, filtrate , centrifugation and dry
NANOGENTOOLS Spring School May 2019- Alessandria
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5 10 15 20 25 30 35
0
10
20
30
40
50
60
70
80
90
100
Measured
GO
FLG
MLG
Inte
ns
ity
(a
.u.)
2degrees)
11.9
5
22.8
9
26.0
4
11.95 22.89 26.04
No. of layers 3 4 14
% 55 23 2221L
GO GR
GO
GR
GO d spacing = 0.75 nm (insulating; good biocompatibility with living systems) GR d spacing = 0.36 nm (highly conductive; poor biocompatibility with living systems)
NANOGENTOOLS Spring School May 2019- Alessandria
XRD spectrum of electrochemically obtained graphene
Few-layer graphene- FLG
Multi-layer graphene- MLG
n= D/d- number of layers
Bragg’s law: nλ = 2d sinϴ
Scherrer equation: D = Kλ/βcosθ
Where: d = interlayer distance D = the mean size of the crystalline domains K is the shape factor, λ is the x-ray wavelength, β is the line broadening at half the maximum intensity (FWHM) in radians, and θ is the Bragg angle
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5 10 15 20 25 30 35
0
10
20
30
40
50
Inte
nsit
y (
a.u
.)
2 (degrees)
Measured spectra
FLG
MLG
21
.28
25
.99
21.28 25.99
No. of layers 3 15
% 77 23 Gr 22a
5 10 15 20 25 30 35
0
10
20
30
40
Measured spectra
FLG
MLG
Inte
nsit
y (
a.u
.)
2 (degrees)
21.23 26.26
No. of layers 3 27
% 93 7
26
.26
21
.23
Gr 35
0.5 M- electrolyte
1 M- electrolyte
XRD spectra of electrochemically obtained graphene
Few-layer graphene- FLG
Multi-layer graphene- MLG
NANOGENTOOLS Spring School May 2019- Alessandria
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NANOGENTOOLS Spring School May 2019- Alessandria
Elextrolytes: mixture of strong acids (sulfuric; nitric); salts (ammonium sulfate ) Advantages: - Prevent the over-heating of the solution - Less graphitic material in the final product
D) Exfoliation of graphite rods via pulses of current: sensitive detection of 8-hydroxy-2’-deoxyguanosine (8-OHdG)
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EGr-A: mixture of sulfuric and nitric acid (3:1 ratio; 1 M each; 100 mL volume) EGr-S: 0.2 M ammonium sulfate
Experimental conditions Applied bias: 4-15 V Pulse duration: 0.8 s Pause: 0.2 s Time: 3 hours
NANOGENTOOLS Spring School May 2019- Alessandria
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NANOGENTOOLS Spring School May 2019- Alessandria
Scherrer equation: D = Kλ/βcosθ
Where: d = interlayer distance D = the mean size of the crystalline domains K is the shape factor, λ is the x-ray wavelength, β is the line broadening at half the maximum intensity (FWHM) in radians, and θ is the Bragg angle
XRD spectra of the synthesized materials
Bragg’s law: nλ = 2d sinϴ
EGr-S EGr-A
n= D/d- number of layers
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8-hydroxy-2’-deoxyguanosine (8-OHdG)
- 8-OHdG is an oxidative lesion of DNA induced by free radicals - its high concentration in body fluids is an indication of disease (cancer; periodontitis) - < 10-7 M – normal concentrations - 10-7 – 10-6 M – indication of a disease
NANOGENTOOLS Spring School May 2019- Alessandria
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NANOGENTOOLS Spring School May 2019- Alessandria
CVs recorded with bare GC (black) and graphene modified electrodes, GC/EGr-A (blue), GC/EGr-S (red) in pH 6 PBS solution containing 10−4 M 8-OHdG; 10 mV·s−1 scan rate
0.0 0.2 0.4 0.6 0.8
-2.0x10-4
-1.0x10-4
0.0
1.0x10-4
2.0x10-4
3.0x10-4
4.0x10-4
0.53 V
0.48 V
GC
GC/EGr-A
GC/EGr-S
E(V) vs Ag/AgCl
i
(A/c
m2)
0.47 V
Detection of 8-OHdG with graphene-modified electrodes
EGr-S : graphene in ammonium sulfate EGr-A : graphene in acidic solution
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NANOGENTOOLS Spring School May 2019- Alessandria
0.0 0.2 0.4 0.6 0.81x10
-6
2x10-6
3x10-6
4x10-6
5x10-6
6x10-6
7x10-6
8x10-6
8-OHdG in PBS pH 6 PBS 6
10-7
M
3x10-7
M
6x10-7
M
10-6
M
3x10-6
M
6x10-6
M
10-5
M
3x10-5
M
6x10-5
M
10-4
M
I (A
)
E (V) vs Ag/AgCl
GC/EGr-A
0.47 V
a.
GC/EGr-S Linear range: 3 x 10-7 – 10-4 M Sensitivity: 0.67 A/cm2 M LOD: 9.8 x 10-8 M GC Linear range: 10-6 – 10-4 M Sensitivity: 0.22 A/cm2 M LOD: 3 x 10-7 M
Detection in standard laboratory solutions (pH 6 PBS)
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NANOGENTOOLS Spring School May 2019- Alessandria
Detection of 8-OHdG in artificial urine (pH 5.9)
GC/EGr-S Linear range: 3 x 10-7 – 10-4 M Sensitivity: 0.79 A/cm2 M LOD: 9.8 x 10-8 M GC Linear range: 10-6 – 10-4 M Sensitivity: 0.15 A/cm2 M LOD: 3 x 10-7 M
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NANOGENTOOLS Spring School May 2019- Alessandria
Reproducibility of GC/EGr-S electrodes
0.0 2.0x10-5
4.0x10-5
6.0x10-5
8.0x10-5
1.0x10-4
0.0
1.5x10-5
3.0x10-5
4.5x10-5
6.0x10-5
7.5x10-5
pH 6 PBS
C (M)
I peak (
A/c
m2)
GC/EGr-S1
GC/EGr-S2
GC/EGr-S3
a.
GC/EGr-S
0.0 2.0x10-5
4.0x10-5
6.0x10-5
8.0x10-5
1.0x10-4
0.0
2.0x10-5
4.0x10-5
6.0x10-5
8.0x10-5
b.
C (M)
I peak (
A/c
m2)
GC/EGr-S1
GC/EGr-S2
GC/EGr-S3
Artificial Urine
GC/EGr-S
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Testing saliva samples with screen-printed electrodes
SALIVA • Water: 99.5% • Electrolytes
•2-21 mM sodium •10-36 mM potassium •1.2-2.8 mM calcium •0.08-0.5 mM magnesium •25 mM bicarbonate •1.4-39 mM phosphate
•Mucus •Antibacterial compounds (hydrogen peroxide; immunoglobulin A; thiocyanate) •Epidermal growth factor •Various enzymes
The presence of 8-OHdG in saliva indicate periodontitis (gum disease)
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Screen-printed electrodes modified with graphene (EGr-S)
0.0 0.1 0.2 0.3 0.4 0.5 0.6-4.0x10
-6
-2.0x10-6
0.0
2.0x10-6
4.0x10-6
6.0x10-6
8.0x10-6
1.0x10-5
saliva
1x10-6
3x10-6
6x10-6
1x10-5
3x10-5
6x10-5
1x10-4
3x10-4
6x10-4
I (A
)
E (V) vs Ag/AgCl
0.34 V
DS SPEXF 30 III
0.0 2.0x10-4
4.0x10-4
6.0x10-4
0.0
1.0x10-6
2.0x10-6
3.0x10-6
4.0x10-6
5.0x10-6
6.0x10-6
Saliva
DS SPEXF 30
I pe
ak (
A)
C (M)
Electrolyte: saliva diluted five times with PBS pH 6 and spiked with 8-OHdG
Screen-printed electrodes Linear range: 3 x 10-6 – 10-4 M LOD: 10-6 M
50 microL
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0.0 0.1 0.2 0.3 0.4 0.5 0.6
0.0
2.0x10-6
4.0x10-6
6.0x10-6
8.0x10-6
SPEXF21
I (A
)
E (V) vs Ag/AgCl
Cx
Adaos I
Adaos II
Adaos III
0.0 5.0x10-5
1.0x10-4
1.5x10-4
2.0x10-4
2.5x10-4
5.0x10-7
1.0x10-6
1.5x10-6
2.0x10-6
2.5x10-6
3.0x10-6
x = 6.449 x 10-7/0.00974 = 6.62 x 10
-5 M
I pe
ak
(A
)
C (M)
SP EXF 21
Xadded
= 6 x 10-5
M
Xfound
= 6.62 x 10-5
M
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Conclusions Graphene can be obtained by various methods (CVD; chemical; electrochemical) The synthesis method clearly influences the electro-catalytic properties of graphene Biomarkers can be detected with such electrodes in laboratory solution More work is needed to detect the biomarkers in body fluids
Thank-you Dr. Alexandru R. Biris
Dr. Crina Socaci
Dr. Florina Pogacean
Dr. Maria Coros
Eng. Valentin Mirel
Dr. Eng. Stefan Gergely
Dr. Codruta Varodi
Dr. Marcela Rosu
Dr. Lidia Magerusan
Alex Turza, PhD student
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Acknowledgment “Program Nucleu” MEN-Romania PN-09-44 01 15 and Project PN 18 03 02 02 CNCS/CCCDI-UEFISCDI, Romania Project PN-III-P2–2.1-PED-2016-0392 (102PED/2017) Project PN-III-P2–2.1-PED-2016-0415 (103PED/2017) Project PN-III-P4-ID-PCCF2016-0006 (PCCF20/2018)