1
Laser Engineered Graphene Paper for Mass
Spectrometry Imaging
Supplementary Information
Kun Qian,1 Liang Zhou,1 Jian Liu,1 Jie Yang,1 Hongyi Xu,2 Meihua Yu,1 Amanda
Nouwens,3 Jin Zou,2 Michael J. Monteiro1 and Chengzhong Yu1*
1
Australian Institute for Bioengineering and Nanotechnology, 2Materials Engineering
and Centre for Microscopy and Microanalysis, and 3School of Chemistry and
Molecular Biosciences, the University of Queensland, Brisbane, QLD 4072, Australia.
E-mail: c.yu@uq.edu.au; Fax: (+) 61-7-33463973
This part includes:
Supplementary Methods
Table S1
Figure S1 to S10
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Supplementary Methods:
Synthesis of the graphene paper. In the preparation of the graphene sheets, a chemical
oxidation-reduction approach was adapted, where the graphite was oxided by the
Staudenmaier method.1 5.0 g of graphite was added into a mixture solution of
concentrated sulphuric acid (87.5 mL) and fuming nitric acid (45 mL) and cooled in an
ice-water bath. Then 55 g of KClO3 was added very slowly with a period longer than 15
min into the mixture. All the operations were carried out very carefully in a fume hood
to reduce the risk of explosion due to the release of chlorine dioxide gas. After stirring
for 96 h at room temperature, the mixture was poured into 4 L of water, filtered and
washed to obtain graphite oxides. The as-made graphite oxide (0.30 g) was dispersed
into a mixed solvent (150 ml of ethylene glycol, 75 ml of water and 75 ml of PEG2000), then sonicated (SCIENTZ SB 3200DTN, 150W) for 2 hours to form a
homogeneous graphene oxide suspension. Then the whole suspension was transferred
into a Teflon-lined stainless steel autoclave and reacted to perform solvent thermal
reduction at 180 ºC for 24 hours.2,
3
Finally the graphene paper was fabricated by
vacuum filtration of 50 mL of reacted mixture.
1.
2.
3.
Hontorialucas, C., Lopezpeinado, A.J., Lopezgonzalez, J.D.D., Rojascervantes, M.L. &
Martinaranda, R.M. STUDY OF OXYGEN-CONTAINING GROUPS IN A SERIES OF
GRAPHITE OXIDES - PHYSICAL AND CHEMICAL CHARACTERIZATION. Carbon 33,
1585-1592 (1995).
Huang, X.D. et al. A magnetite nanocrystal/graphene composite as high performance anode for
lithium-ion batteries. J. Alloy. Compd. 514, 76-80 (2012).
Huang, X.D. et al. A Facile One-Step Solvothermal Synthesis of SnO2/Graphene
Nanocomposite and Its Application as an Anode Material for Lithium-Ion Batteries.
ChemPhysChem 12, 278-281 (2011).
3
Table S1 Comparison of the typical laser engineering techniques towards the
graphene film or paper
Laser
Wavelength
Laser
Operation
Spot Size
Application
Reference
Source
(nm)
Power
Model
(µm)
Field
Source
DVD
788 nm
5 mW
Continuous
Not Given
Capacitors
Ref1
Laser
Infrared
2.4 W
Continuous
~ 100 µm
Capacitors
Ref2
Printer
(CO2 laser)
Smart
337 nm
20 mW
Pulsed, 200 Hz
~ 30 µm
MS Detection
This work
Beam
(N2 laser)
Drives
1
(3 ns width)
and Imaging
El-Kady, M.F., Strong, V., Dubin, S. & Kaner, R.B. Laser Scribing of High Performance and Flexible Graphene-
Based Electrochemical Capacitors. Science 335, 1326-1330 (2012).
2
Gao, W. et al. Direct laser writing of micro-supercapacitors on hydrated graphite oxide films. Nat. Nanotechnol. 6,
496-500 (2011).
4
Figure S1. Schematics for the chemo-synthesis of graphene sheets from graphite.
The graphite was first oxidized to graphite oxide using the Staudenmaier method, which
was exfoliated to graphene oxide by sonication. The graphene sheets were obtained
through reducing the graphene oxide by a solvent thermal treatment method.
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Figure S2. X-ray photoelectron spectroscopy characterisation of the graphene
paper before and after laser engineering. (a) Untreated graphene paper. (b)
Engineered paper with 50% laser intensity.
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Figure S3. Low magnification SEM characterisation of the graphene paper
engineered at different laser intensities. (a) Untreated graphene paper. (b) 10% laser
intensity. (c) 30% laser intensity. (d) 50% laser intensity. The scale bar is 10 µm for
each image and the circled area stands for the typical area for further high resolution
SEM observations.
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Figure S4. SEM images of the engineered graphene paper after sonication. (b) is
the high resolution image of the nanospheres in (a).
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Figure S5. Matrix-free LDI MS detection of AONB on commercial NALDI™ plate
and engineered graphene paper. MS spectra of 0.85 fmol of AONB on (a)
commercial NALDI™ substrate and (b) engineered graphene paper. Asterisks indicate
the identified ions from the molecules.
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Figure S6. Matrix-assisted LDI MS detection of AONB and DOTAP lipid on the
commercial MALDI plate. MALDI MS spectra of (a) 8.5 fmol, (b) 0.85 fmol of
AONB and (c) 300 fmol, (d) 30 fmol of DOTAP on the commercial MALDI plate using
CHCA as matrix. Asterisks indicate the identified ions from the molecules.
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Figure S7. Matrix-free LDI MS detection of DOTAP lipid on engineered graphene
paper. MS spectrum of 30 fmol DOTAP lipid on engineered paper and asterisks
indicate the identified ions from the lipid molecules.
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Figure S8. Matrix-free LDI MS detection of DPPC and HSPC lipids on the
untreated and engineered graphene paper. MS spectra of (a & b) 2.7 pmol DPPC, (c
& d) 2.6 pmol HSPC on untreated and engineered graphene paper, respectively. MS
spectra of (e) 270 fmol DPPC lipid and (f) 260 fmol HSPC lipid on the engineered
graphene paper. Asterisks indicate the identified ions from the lipid molecules.
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Figure S9. The digital image of the stamped paper. The central dark black area (laser
engineered area) has been stamped with the letters. The stamp was made by laser
engraving the letters. The size of the stamp is 1 cm X 1 cm of all and the size of the
letters on the stamp is ~ 2 mm in height.
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Figure S10. MS imaging patterns of the letters. 'A' at m/z of 662 and 380 on (a, b)
untreated graphene paper and (c, d) engineered graphene paper, respectively. 'B' at m/z
of 662 and 380 on (e, f) untreated graphene paper and (g, h) engineered graphene paper,
respectively. The scale bar in a-h is 500 µm.