Lab News

SERS based point-of-care detection of food-borne pathogens

 Nawfal Adam Mungroo & Gustavo Oliveira & Suresh Neethirajan

Abstract

The authors have developed a microfluidic platform for improved detection of pathogenic bacteria by using silver nanoparticles and new platforms for chemometric data analysis, viz. a combination of principle component analysis and linear discriminant analysis. The method can distinguish eight key foodborne pathogens (E. coli, S. typhimirium, S. enteritis, Pseudomonas aeruginosa, L. monocytogenes, L. innocua, MRSA 35 and MRSA 86) and, hence, holds good promise for use in the food industry.

Keywords    Microfluidics . Food safety . Food analysis . Principle component analysis . Linear discriminant analysis . Silver nanoparticles . Raman spectroscopy

Mungroo, N., G. Oliveira, S. Neethirajan. 2015. SERS based point-of-care detection of food-borne pathogens. Microchimica acta.  doi: 10.1007/s00604-015-1698-y   (link

Characterization of antimicrobial efficacy of photocatalytic polymers against food-borne biofilms

Xuan Weng, Jan van Niekerk, Suresh Neethirajan, Keith Warriner

LWT Food Science and Technology (link)  doi:10.1016/j.lwt.2015.11.063

 

HIGHLIGHTS


•    TiO2 polymer coatings were tested against food-borne bacterial pathogens.
•    Antimicrobial activity strength is dependent on the length of UV irradiation.
•    H2O2 radical was generated by the polymer coating.
•    TiO2 photocatalytic polymer coatings are ideal for the development self-cleaning surfaces.

 

ABSTRACT

Biofouling of food industry equipment and other surfaces that food products contact during processing is a threat to food safety, which results in infectious outbreaks and economic losses due to corrosion, equipment impairment, and reduced heat transfer efficiency. Once firmly attached to a surface, biofilms can be almost impossible to remove using current sanitation procedures. Self-cleaning surfaces with TiO2 coatings that are activated with ultraviolet (UV) light may be effective in preventing bacterial growth or killing or removing adherent organisms but require studies to demonstrate their efficacy and determine optimum conditions for use. Therefore, we examined the efficacy of TiO2-based polymer coatings against key food-borne pathogens namely, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, and Salmonella typhimurium. Upon photo-catalytic activation of the coatings, the viability of early stage biofilms formed on each coated surface and the relative contribution of reactive oxygen species was evaluated. Results show that the relative antimicrobial activity strength was dependent on the length of UV irradiation; 5-10 minutes exposure was sufficient to inhibit/kill biofilms of each pathogenic species tested. The results of this study render contact surfaces less attractive for pathogenic biofilms while doubling as an effective mitigation strategy to remove biofilms that form despite coating.

GryphSens machine uses a drop of cow’s blood to test for diseases that can cause inflammation or reduce immunity response

The University of Guelph has developed a device that promises to make testing easier for two different dairy diseases.

The GryphSens is a device that allows diary producers to test for non-esterified fatty acid (NEFA) and beta-hydroxybutyrate (BHBA) in their animals without having to send samples to a laboratory.

“If the farmers have the opportunity to do the test by themselves rather than shipping the samples to the lab, it adds not only convenience but more of a early warning system,” said Suresh Neethirajan, the project’s principal researcher.

The device uses a droplet of cow blood, which is put onto a cartridge and inserted into the digital reading system.

The screen on the system will let the producer know if the cow has NEFA or BHBA.

The device should provide producers with an early warning system so they can adapt strategies to help, which might entail changes in feed and housing.

“So the farmers can once in a while test it on the farm, and if there are further concerns then they can call for the veterinarians,” Neethirajan said.

 

Neethirajan hopes the new device will offer a lower cost testing option for producers.

“The idea is to bring down the two disease detection to probably $2 per test for both NEFA and BHBA. Right now, the test costs $10 to $20,” Neethirajan said.

David Hobson and Andrea Weeks, from the Catalyst Centre at the University of Guelph are working on the commercialization for GryphSens.

They have filed a U.S. provisional patent and are in talks with various companies to have one of them manufacture the device and put it on the market.

They expressed hope that a milking robotic machine company would pick up the technology, so a cow could be tested every time it is milked.

“So really the game here is early detection. So that’s why we think inline monitoring. So every time a cow is coming in to get milked, if you can see that it’s trending upwards…. It provides a trigger point for people to then get in-volved,” Hobson said.

 

Depending on which company takes over commercialization, consumers could see the GryphSens on the market in about two years.

Dr. John Ayres, veterinarian at Norsask Veterinary Group in Rosthern, Sask., sees the GryphSens as promising.

“Sounds interesting. There are products like that on the market right now to one degree or another. Some of them will test blood, some of them will test milk, some of them will test urine,” Ayres said.

Ayres said a device of this kind would be more effective if it could test a whole herd of cattle instead of an individual cow.

“Usually the best results I’ve seen from whatever technology they’re using is to use it as a herd level test to indicate whether you’ve got a herd level nutritional issue kind of thing,” Ayres said.

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Three posters were presented by the BioNano Lab members of the University of Guelph at the Nano Ontario 2015 Conference held at the University of Ottawa on November 5th and 6th, 2015.

Redox Active Graphene Oxide Nanosheets: Dual-Functional Biosensor for On-Farm Monitoring of Dairy Cow Metabolic Diseases by Murugan Veerapandian and Robert Hunter

Methylene Blue Sensitized Screen Printed Immunoelectrode: Rapid Detection of Avian Influenza Virus by Rob and Murugan

SERS based Point-of-care Biosensing System for Food-Borne Pathogen Detection by Mungroo and Gustavo

Big Smile by Robert at the Ottawa Nano Ontario Annual Event

GryphSens - Equipping Farmers to Test For Severe Cattle Diseases

 IP Licensing OpportunityPDF

Up until recently, dairy farmers have been hindered in quickly detecting possible reasons for a reduction in milk production among their herd. One such reason is sub-clinical ketosis (SCK) when an affected cow appears to be well but only becomes observably under stress when SCK becomes full ketosis affecting major organs, or it could be other metabolic diseases. The only true method of detecting these abnormalities was by taking vials of the affected cow’s blood and sending samples to a lab for diagnosis. However, Bionanolab of the School of Engineering has advanced this procedure by putting the ability to diagnose a cow’s health in the hands of farmers themselves, thereby saving crucial time in detecting certain bovine metabolic irregularities, and thereby providing earlier treatment.

By detecting certain enzymes in blood, the newly developed device can pick out these biomarkers present in miniscule amounts and help identify diseases. A combination of the device’s unique composition of electrodes, a plant enzyme, and the correct amount of electric current were discovered by the bionano research team to be the winning formula used collectively in the device known as a “Gryphsens”.

A New Tool on the Farm

Through the implementation of a hand held sensor, a dairy farmer can rapidly detect whether a cow has sub-clinical ketosis or other metabolic diseases through a small amount of blood being taken and having the sample analyzed in real-time through interfacing with the Internet by a smart phone. Such technology not only allows a dairy farmer to rapidly determine a cause for a reduction in milk production, but it also allows early detection of metabolic diseases that can then be treated, facilitating a cow to return to its normal milk volume levels in a shorter period of time. The cost saving of such early detection is substantial for small and larger dairy herds.

In the case of larger dairy herds, this Canadian invention that uses a unique electrochemical measurement of samples, can be engineered for use with in-line robotic milking machines to monitor a herd individually, yet collectively, to avoid the repetitive and time-consuming method of testing each cow separately. The sensor, developed at Guelph’s Bionano laboratory of the School of Engineering by a team headed by Dr. Suresh Neethirajan is able to detect minute electrochemical activity in biological fluids that indicate biomarkers for certain irregularities and diseases. These markers flag slightly elevated levels of non-esterified fatty acids (NEFA), and a ketone prevalent in cows, β-hydroxybutyrate (BHBA), that at higher levels can both signal the early onset of ketosis and other metabolic diseases.

A Critical Time Line

Historically, the calving period is a stressful time for cows, described as a time of negative energy balance (NEB), when the onset of ketosis or other metabolic diseases are most prominent. Although the levels of NEFA and BHBA are miniscule at the beginning, early detection can reduce complications and a faster recuperation period, otherwise a later detection could lead to fatty liver, ketosis, displaced abomasum (twisted stomach), inflammation of the uterus or a retained placenta. Dairy farmers are highly cognizant that charting a cow’s NEFA and BHBA levels is the litmus test for the animal’s overall health. One of the great advantages of testing for on-farm dairy cow diseases using our developed biosensor is that it not only significantly reduces the stress on the animals due to relying on a drop of blood instead of vials sent, but also provides instant test results.

The Lab Comes to the Barn

Traditionally, these levels are determined through expensive and lengthy tests performed in laboratories. Through electrochemistry and nanotechnology the University of Guelph’s bionano team has made it possible for dairy farmers from all scales of operation to ascertain for themselves their herd’s health. Although humans have similar devices for measuring glucose levels for diabetes, the cow’s organism presents a further challenge by having 11 major blood groups versus four. The challenge was developing the sensor’s electrode that could simultaneously detect both NEFA and BHBA in variable metabolic conditions that can include a number of interfering components, which could alter the test results. Ability to detect multiple disease biomarkers from just a droplet of blood sample that could be used by untrained farmers is unique.

Disposable screen-printed carbon electrodes (SPE) were chosen for their affordability and for their compatibility with hand held and in-line robotic milking devices. From previous discoveries, the compounds used on the electrodes favoured redox active hybrid graphene oxide (GO) materials that have proven very effective in biochemical applications. In particular for this application to identify NEFA and BHBA, electrodes incorporating soybean based enzyme was layered on the GO material. This proved to be the defining chemical for detecting both NEFA and BHBA by having superior and durable redox properties of the critical biomarkers compared to untreated GO electrodes.

A Plant with the Answer

An issue the University of Guelph team had to surmount was the insulating property of GO that hindered the electrochemical function crucial for the biosensor. A particular enzyme from the soybean plant was integral in solving this problem and was incorporated into the dual electrodes. Although lipoxygenase is found in both animal and plant species, using soybean lipoxygenase-1 (SLO) was itself a first for catalyzing direct electrochemical oxidation of NEFA in conjunction with [Ru(bpy)3]2+-GO. In this situation, SLO breaks down the fatty acids found in metabolic lipids to produce fatty acid hydroperoxide. When used in conjunction with electrochemistry, NEFA became oxidized and detectable by the electrode.

On the sensor’s other electrode for detecting the ketone BHBA, it uses another enzyme (HBDH) that is produced naturally by an organism under stress and is detected through electrochemical oxidation. The isolation to enable it to be detected was engineered through the electrochemical oxidation of coenzyme NAD+ found in organisms to produce NADH. As HBDH is dependent on the coenzyme, the electrode can readily identify the enzyme through covalent bonding of atoms at the molecular level.

Using the correct micro voltage supplied by the sensor to the electrodes, it further enhances the provision of efficient and reliable readings. The result is a biosensor that has a dual function of detecting NEFA and BHBA in less than a minute on-site by the dairy farmer using a small sample of whole blood. Dairy cattle is an investment that must be kept in prime condition to maintain optimal production levels, and the Canadian biosensor is the latest tool for dairy farmers and large scale operations to monitor the health of their herds. The dual sensor can be an important part of routine screening used by farmers in the dairy barn. The ease of use and convenience will significantly enhance the management of dairy herd health.

Contact Us

Bionanotechnology Laboratory
Suresh Neethirajan

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

Office:
Room 3513 - Richards Building
50 Stone Road East

Lab: THRN 2133 BioNano Lab

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

E-mail: sneethir@uoguelph.ca

 
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