To formulate folate receptor (FR)-specific graphene-based electrochemical electrodes, a folic acid (FA) derivative attached with two pyrene molecules on the glutamate tail of FA was synthesized. The resulting pyrene-functionalized FA (FA-Py) presented the spontaneous noncovalent binding on chemically reduced graphene oxides (rGO) through an π-π interaction. Ultrathin morphology, high water-resistance, and preservation of intact FR-specific pteroates from the rGO/FA-Py assembly allow this assembly to be exploited as robust and FR-specific electrochemical electrode materials. The limits of detecting rGO/FA-Py modified electrodes were found to be as low as 3.07 nM in FR concentrations in cyclic voltammetry analysis.

Abstract
 1. Introduction
 2. Experimental
  2.1. Materials and characterization
  2.2. Synthesis of FA-Py
  2.3. Synthesis of rGO/FA-Py assembly
  2.4. Electrochemical sensing of FRs
 3. Results and Discussion
 4. Conclusions
 References

• Binhee Kwon(Department of IT Convergence, Korea National University of Transportation)
• Jongyeap Park(Department of IT Convergence, Korea National University of Transportation)
• Woojun Jeong(Department of IT Convergence, Korea National University of Transportation)
• Guembi Jeong(Department of IT Convergence, Korea National University of Transportation)
• Hyeong Seon Ryu(Department of Organic and Nano Engineering, Hanyang University)
• Peerasak Paoprasert(Department of Chemistry, Faculty of Science and Technology, Thammasat University) Corresponding Author
• Sung Young Park(Department of IT Convergence, Korea National University of Transportation, Department of Chemical and Biological Engineering, Korea National University of Transportation) Corresponding Author
• Insik In(Department of IT Convergence, Korea National University of Transportation, Department of Polymer Science and Engineering, Korea National University of Transportation) Corresponding Author