Lab News

A microfluidic biosensor using graphene oxide and aptamer-functionalized quantum dots for peanut allergen detection

Xuan Weng & Suresh Neethirajan

Biosensors & Bioeelctronics   (Link)


The increasing prevalence of food allergies and the intake of packing foods in the past two decades urge the need for more rapid, accurate, and sensitive assays to detect potential allergens in food in order to control the allergen content. Most of the commercial analytical tools for allergen detection rely on immunoassays such as ELISA. As far as disadvantages, ELISA can be time-consuming and expensive. Biosensors appear as a suitable alternative for the detection of allergens because they are rapid, highly sensitive, selective, less expensive, environmentally friendly, and easy to handle. In this study, we developed a microfluidic system integrated with a quantum dots (Qdots) aptamer functionalized graphene oxide (GO) nano-biosensor for simple, rapid, and sensitive food allergen detection. The biosensor utilized Qdots-aptamer-GO complexes as probes to undergo conformational change upon interaction with the food allergens, resulting in fluorescence changes due to the fluorescence quenching and recovering properties of GO by adsorption and desorption of aptamer-conjugated Qdots. This one-step ‘turn on’ homogenous assay in a ready-to-use microfluidic chip took ~10 min to achieve a quantitative detection of Ara h 1, one of the major allergens appearing in peanuts. The results suggested this system had remarkable sensitivity and selectivity. The integration of a microfluidics platform in a homemade miniaturized optical analyzer provides a promising way for the rapid, cost-effective, and accurate on-site determination of food allergens. This biosensor can also be extended to the detection of other food allergens with a selection of corresponding aptamers.

Postdoctoral Opportunity (Point of care Diagnostics Development)

An exciting opportunity exists to join a dynamic research team at the BioNano Laboratory ( of the School of Engineering of the University Of Guelph, Canada as a Postdoctoral Research Fellow. This will be a contractual position.

The successful candidate will work on an independent project to build biosensors using electrochemical or optical based instrumentation techniques. You will work on an independent research in the development of a field deployable biosensor that will use optical or electrochemical approaches and nanomaterials for sensing chemical analytes, proteins and/or pathogens (bacteria and viruses) from blood samples and chemicals towards food safety and biomedical health applications. In addition, the candidate will also supervise undergraduate students and help other graduate students on sensor development related projects.

Specifically you will:

  • Miniaturize and automate existing lab-based assays and test them in the laboratory conditions
  • Design, develop and integrate a miniaturized biosensor module with optical or electronic detection in to an automated system
  • Evaluate and apply electrochemical, optofluidic and/or impedance based detection of a variety of analytes for the biosensors
  • Integrate reader platform for a biosensor towards development of a stand-alone portable prototype that are suitable for deployment in harsh environments

You would contribute also towards:

  • Producing high quality technical and scientific journal articles, patents, reports and presentations
  • Providing input and novel ideas and concepts for research and development

Candidate with a PhD in Analytical Chemistry, Chemical Engineering, Biomedical Nanotechnology, Electrical Engineering or Electronics or an equivalent degree or background with emphasis on sensor development is preferred. Demonstrated experience in the design, testing and prototype of mobile phone based point of care diagnostic devices and or biosensors device development is required. He/she will be expected to have excellent oral and written communication skills. Good publication records and willing to work as a team is an asset. Demonstrated work experience in biosensor development and nanomaterial characterization would be an asset.

Submit your applications along with a detailed CV, list of publications and names of 3 referees to Professor Suresh Neethirajan by email -  This email address is being protected from spambots. You need JavaScript enabled to view it.

On May 19, 2016, three of the current BioNano Lab members presented their research results at the 2016 Guelph Graduate Engineering Symposium.






                    Satvinder Panesar - Microfluidic Detection of Breast Cancer Biomarkers


            Ryan Berthelot - Analysis of Single Bacterial Cells Using Conductive Scanning Probe Microscopy and Microfluidic Platforms


                                         Cynthya Manohar - Flavonoid and Antioxidant Activity of Ontario Grown Onion Varieties


Dual immunosensor based on methylene blue-electroadsorbed graphene oxide for rapid detection of the influenza A virus antigen   

 Download Link


Rapid detection of influenza viral infections in poultry facilities is advantageous in several aspects such as environmental/personal safety, food-security, and socio-economy. Herein, we report the development of an electrochemical-based dual-sensor platform composed of methylene blue-electroadsorbed graphene oxide nanostructures modified with monoclonal antibodies against the HA proteins of H5N1 and H1N1. Bio-functional layers comprised of chitosan and protein-A molecules were implemented at the interface of the sensor element and antibodies, which synergistically enriched the bio-activity of immobilized antibodies for the immune complex formation. The differential pulse voltammetric signals resulted from the developed immunosensor platform exhibited a good correlation (R2= 0.9978 for H1N1 and R2=0.9997 for H5N1) for the wide range of target concentrations (25 to 500 pM). Chronoamperometric study also revealed the amplified current sensitivity of the immunoelectrodes even at the picomolar level. The proposed immunosensor design not only provides rapid analytical response time (<1 min) but simplicity in fabrication and instrumentation, which paves an attractive platform for on-farm monitoring of viral infections.



Soy Shows Promise as Natural Anti-Microbial Agent: Study

Soy isoflavones and peptides may inhibit the growth of microbial pathogens that cause food-borne illnesses, according to a new study from University of Guelph researchers.

Soybean derivatives are already a mainstay in food products, such as cooking oils, cheeses, ice cream, margarine, food spreads, canned foods and baked goods.

The use of soy isoflavones and peptides to reduce microbial contamination could benefit the food industry, which currently uses synthetic additives to protect foods, says engineering professor Suresh Neethirajan, director of the BioNano Laboratory.

U of G researchers used microfluidics and high-throughput screening to run millions of tests in a short period.

They found that soy can be a more effective antimicrobial agent than the current roster of synthetic chemicals.

“Heavy use of chemical antimicrobial agents has caused some strains of bacteria to become very resistant to them, rendering them ineffective for the most part,” said Neethirajan.

“Soy peptides and isoflavones are biodegradable, environmentally friendly and non-toxic. The demand for new ways to combat microbes is huge, and our study suggests soy-based isoflavones and peptides could be part of the solution.”

Neethirajan and his team found soy peptides and isoflavones limited growth of some bacteria, including Listeria and Pseudomonas pathogens.

“The really exciting thing about this study is that it shows promise in overcoming the issue of current antibiotics killing bacteria indiscriminately, whether they are pathogenic or beneficial. You need beneficial bacteria in your intestines to be able to properly process food,” he said.

Peptides are part of proteins, and can act as hormones, hormone producers or neurotransmitters. Isoflavones act as hormones and control much of the biological activity on the cellular level.

North America has one of the safest food sources in the world, said Neethirajan, but the United States Centers for Disease Control and Prevention estimates that about 48 million people in the U.S. suffer from some sort of food-borne illness every year.

“In addition, some people are worried about the potential for long-term illnesses resulting from the use of synthetic chemicals,” Neethirajan said.

“The use of soy peptides and isoflavones could combat bacteria and reduce these concerns.”

The next step is for researchers to conduct large-scale tests, Neethirajan said.

“We’ve created a recipe for this to go ahead. This could be very beneficial to food processors, as well as the farmers who grow soy beans.”

Contact Us

Bionanotechnology Laboratory
Suresh Neethirajan

School of Engineering
University of Guelph
Guelph, Ontario
Canada N1G 2W1

Room 3513 - Richards Building
50 Stone Road East

Lab: THRN 2133 BioNano Lab

Phone: (519) 824-4120 Ext 53922
Fax: (519) 836-0227


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