Reporter-encapsulated liposomes on graphene field effect transistors for signal enhanced detection of physiological enzymes.

Abstract

A novel approach for enzymatic assay using reporter-encapsulated liposomes on graphene field effect transistors (FET) is proposed. This approach involves real time monitoring of drain current (Id) of reduced graphene oxide (rGO) upon rupture of reporter-encapsulated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) liposomes triggered by enzymes. For validation of the proposed approach, 2,4,6-trinitrophenol (TNP) is used as the reporter for specific detection of phospholipase A2 (PLA2), a key enzyme in various membrane related physiological processes. Experimental results revealed that Id increased with PLA2 concentration, which is attributed to the interaction between released TNP and rGO. The limit of detection (LOD) achieved by the proposed approach was 80 pM, which is superior to most assays reported previously and much lower than the cut-off level of circulating secretory PLA2 (2.07 nM). Besides the high accuracy of the electronic detection methodology, the signal enhancement effect realized by the excess concentration of TNP (approximately 1 mM) in liposomes is believed to be the main reason for the significantly enhanced sensitivity of the proposed assay, indicating great potential for further improvement in the sensitivity by increasing the concentration of TNP. In addition, the proposed approach is rapid (incubation time ≤ 10 min) and label-free, thus showing great potential for practical applications in the future.

• Authors: Hu Chen, Seng Koon Lim, Peng Chen, Jingfeng Huang, Yi Wang, Alagappan Palaniappan, Mark Platt, Bo Liedberg, Alfred Iing Yoong Tok
• Journal: Physical chemistry chemical physics : PCCP (Phys Chem Chem Phys) Vol. 17 Issue 5 Pg. 3451-6 (Feb 07 2015) ISSN: 1463-9084 [Electronic] England
• PMID: 25531209 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Liposomes
• Oxides
• Phosphatidylcholines
• Picrates
• Silicon Dioxide
• Graphite
• picric acid
• Phospholipases A2
• 1-palmitoyl-2-oleoylphosphatidylcholine

Topics

• Graphite (chemistry)
• Kinetics
• Liposomes (chemistry, metabolism)
• Microscopy, Electron, Scanning
• Oxides (chemistry)
• Phosphatidylcholines (chemistry)
• Phospholipases A2 (analysis)
• Picrates (chemistry)
• Silicon Dioxide (chemistry)
• Spectrophotometry
• Substrate Specificity
• Transistors, Electronic