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Thursday, 14 November 2013

Graphene oxide reveals the presence of pathogens

Reported in Angewandte, a novel optical biosensing system for the analysis of bacteria has been designed, fabricated, and then evaluated by ICN2 researchers.

The system consists of quantum dots–antibody microspots that are quenched by a coating of graphene oxide (GO) platelets as long as the pathogen is absent. In the presence of the pathogen, the quenching of the probes is minimum since their interaction with the coating of GO platelets is limited. This new approach exhibits a highly sensitive qualitative behaviour.

In the upcoming issue of the journal Angewandte Chemistry International Edition, a team including Dr. Eden Morales-Narvaez, Dr. Abdel-Rahim Hassan and Dr. Arben Merkoci, ICREA Professor at ICN2 and Leader of Nanobioelectronics and Biosensors Group, describes a highly sensitive pathogen-detection system that has been designed, fabricated, and then evaluated for sensing of E. coli. It employs antibody-quantum dot probes and exploits the extraordinary two-dimensional structure and fluorescence-quenching capabilities of graphene oxide (GO). The pathogen is selectively captured onto the probes, which are subsequently laser-excited to fluoresce, and then GO is added. In the presence of the pathogen (ON) the probes are barely quenched, as they scarcely interact with the GO, whereas in its absence (OFF) the fluorescent probes are quenched by electrostatic/?-? stacking interactions with the GO. The developed pathogen detection system exhibits a highly sensitive digital-like response, displaying a limit of detection around 5 colony-forming-units / mL.

As their approach offers an advantageous limit of detection when compared with conventional technologies such as ELISA or antibody microarray technology (which are around 600 times less sensitive), the researchers have also submitted an application for a European patent EP 13188693.9 for a sensitive qualitative bioassay using GO as analyte-revealing agent.

This new approach might be employed to detect bacteria and attack bacterial membrane integrity in tandem since GO bears antibacterial properties. Moreover, as a potential diagnosis tool, this novel system might be extended to different kinds of analyte such as cancer cells, perform other tasks such as molecular logic operations and be applied to other nano-biosystems.

For more information, please contact:

Dr. Arben Merkoci, ICREA Professor at ICN2 and Group Leader

Nanobioelectronics and Biosensors Group (visit www.nanobiosensors.org)

Tel: +34 937 374 604

E-mail: arben.merkoci@icn.cat

Link to the Angewandte Chemie International Edition journal article: Graphene Oxide as a Pathogen-Revealing Agent: Sensing with a Digital-Like Response