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NUANCE and NIFTI have Article in Nature Magazine

Researchers from Department of Material Science and Engineering, Northwestern Institute for Nanotechnology and the NUANCE Center (, Northwestern University and Institute for Microbial Technology (IMTECH)-India (A Government of India National Laboratory) through ongoing global partnership in science and technology have reported a new concept in immunosensing and diagnostics called “magneto-electrochemical immunoassay” by combining carbon nanotubes and reduced graphene oxide together with electrochemical bursting of magnetic gold nanoparticles. Such novel immunoassays will open up a new class of technologies with applications in medicine, chemistry and engineering.

Graphene-based nanocomposite films have recently been used as enhanced sensing platform for the development of electrochemical sensors and biosensors because of their unique facile surface modification characteristics and high charge mobility.

The findings have been published in Nature Scientific Reports

The researchers used tiny magnetic particles encapsulated in inert coating of silicon dioxide thereby making core-shell nanostructures with favorable magnetic properties of metallic iron while preventing them from oxidation or significant degradation. It has been further coated with gold coating for its chemical inertness and biocompatibility. These particles are named as magneto-gold

The Northwestern and IMTECH work demonstrates the development of metal ion derivatized electrochemical immunoassay based on gold-iron (Au/Fe) nano-bio-probes for the detection of commonly used phenylurea herbicide diuron on reduced graphene oxide-carbon nanotubes (rGO/CNT) modified bio-sensing platform using specific diuron antibodies

The team was pleasantly surprised to see ultrahigh level of sensitivity with this new technology for new generation of herbicide diuron and its analogues up to sub-picomolar concentration given the simplicity of electrochemical immunoassay, said Vinayak Dravid, who along with his team comprising lead author Gajendra Shekhawta and Jinsong Wu. The Northwestern trio partnered with IMTECH to conduct this research as a part of NUANCE and IIN global outreach initiatives

Professor Dravid is using magnetic nanostructures for a range of biomedical applications; from Alzheimer’s disease diagnostics to cancer ”Theranostics”. He said that use of core magnetic nanostructures in this research offers rapid immunocomplex formation on magneto-microtitre plates and their further electrochemical bursting into a large number of Fe2+ ions presented ultra-high sensitivity for diuron detection on screen printed electrodes. The novel immune-detection platform demonstrated in this contribution has excellent potential applicability to rapid and sensitive screening of environmental pollutants or toxins in samples in variety of situations.

Dravid is professor of material science and engineering in the McCormick School of Engineering and Applied Science and founding member of IIN. He is also the Director of NUANCE Center and Global McCormick.

To build a working electrochemical immunosensing assay, reduced GO/CNT nanohybrid system was developed where synergistic properties of rGO and CNTs were employed for sensitive detection of the analytes of interest. The use of high aspect ratio multiwalled CNTs promoted the electrochemical conversion of GO to reduced GO.  The formation of rGO/CNT nanocomposite on the working electrode increased the surface area enabling it to capture a large amount of metal ions liberated from Au/Fe nanoparticles after electrochemical conversion in the developed magneto-electrochemical immunoassay (MEI). The assay was carried out by coating the Enzyme-linked immunosorbent assay (ELISA) plates with hapten-protein (DCPU–BSA) conjugate. Optimum dilution of synthesized Ab-Au/Fe nanobioprobes pre-mixed with different concentrations of standard samples were used and incubated on the plates.

Making massive number of such sensitive assays is viable and feasible. Tens of thousands of screen printed electrodes can be manufactured quite readily with low cost for such hybrid assay, said Dr. Gajendra Shekhawat who is Research Associate Professor at Department of Material Science and Engineering, manager of NIFTI and member of IIN.

National Science Foundation NSF-IREE and NSF-OISE grant supported this work, with partial support from NIH CCNE program at NU. The work made extensive use of NUANCE Center facilities. Jinsong Wu is research Assistance Professor with Department of Material Science and Engineering as well as the NUANCE Center.

The paper is entitled “Enhancing electrochemical detection on graphene oxide-CNT nanostructuredelectrodes using magneto-nanobioprobes”.

Scientific Reports 2, Article number: 877 doi:10.1038/srep00877

Received Accepted Published