We demonstrated a non-enzymatic cholesterol sensor based on a nickel oxide (NiO) and high quality graphene composite for the first time. Graphene was grown by a chemical vapor deposition technique (CVD). The nanocomposite was fabricated through the electrodeposition of nickel hydroxide onto the surface of the CVD-grown graphene, which was followed by thermal annealing. The successful formation of the NiO/graphene composite was confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. The deposition of flower-like NiO onto the graphene surface was confirmed by scanning electron microscopy. Electrochemical analyses were conducted to investigate the characteristics of the sensor during the detection of cholesterol. The sensor showed a high sensitivity of 40.6 mA mM1 cm2, a rapid response time of 5 s, and a low detection of limit of 0.13 mM. We also investigated the effects of common interfering substances on the ability of the sensor to detect cholesterol. Furthermore, we successfully determined the cholesterol in a milk sample using the developed sensor. The composite electrode exhibited excellent detection of cholesterol with good reproducibility and long-term stability owing to the combined effects of NiO and graphene.

1. Electrodeposition of flower-like nickel oxide on
CVD-grown graphene to develop an
electrochemical non-enzymatic biosensor
Arunkumar Rengaraj,‡a Yuvaraj Haldorai,‡b Cheol Hwan Kwak,a Seungbae Ahn,c
Ki-Joon Jeon,c Seok Hoon Park,d Young-Kyu Han*b and Yun Suk Huh
aDepartment of Biological Engineering, Biohybrid Systems Research Center (BSRC), Inha University, Republic of Korea
bDepartment of Energy and Materials Engineering, Dongguk University-Seoul, Republic of Korea
cDepartment of Environmental Engineering, Inha University, Republic of Korea
J. Mater. Chem. B

2. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Introduction
Cholesterol
 Lipid molecule
 Required to maintain both membrane
structural integrity and fluidity
plantcentric.wordpress.com

3. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
www.cellbiol.net
Introduction

4. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Introduction

5. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
• The only problem with the graphene is that high quality graphene is a great conductor that does not have a band gap (It cant be switched off).
• To use Graphene in the creation of future nana electronic devices ,a band gap will need to engineered.
Introduction

6. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
• A mediator is a low molecular weight redox couple which can transfer electrons from the active site of the enzyme to the surface of the electrode, thereby
establishing electrical contact between the two.
• The purpose of using metallised electrodes is to créate conditions in which the oxidation of enzymatically generated H2O2 can be achieved at a lower applied
potential, by creating a highly catalytic surface.
• In addition to reducing the effect of interferents, due to the lower applied potential, the signal-to-noise ratio is increased due to an increased electrochemically
active area.
• Nickel 's high electrical conductivity lends itself to many electronics applications.
• Nickel oxide/active carbon composites as the electrode materials for super-capacitors
NiO as a mediator
Introduction

7. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Mechanism of Cholesterol sensor
Scheme

8. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Characterization

9. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Characterization

10. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Characterization

11. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Electrochemical
Characterization

12. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Sensing of
Cholesterol

13. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Sensing of
Cholesterol

14. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Stability of the
sample

15. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Comparison

16. Inha university
Depart. Of Biological Engineering
Nano-Bio Analysis Lab, Yun's Group
Conclusion