BIOSENSORS: The Future of Agro-Defence?
Professor Suresh Neethirajan, Bionano Laboratory, University of Guelph
President-Elect, Canadian Society for Bioengineering
Most countries have some sort of agriculture department working hard to protect the quality and safety of its food supplies. But early detection and management can be difficult.
One of the more recent food scares was the spread of bovine spongiform encephalophy (BSE), more commonly known as mad cow disease. Humans cannot get mad cow disease, but they can get a variant called Creutzfeldt-Jakob disease (CJD), by eating some parts of cattle infected with BSE. It is fatal, and there is currently no cure for it. At this time, it is difficult to detect in early stages, and even the cause is not clearly understood. And of course, we can’t forget about other deadly diseases: anthrax, bird flu, swine flu, etc.
Fortunately, science and engineering are providing new tools to fight diseases, both old and new. One of the more promising and exciting technologies under development are biosensors—a part of a new field of study called bionanotechnology.
Biosensor technology can improve the productivity, safety, cost and efficiency of both livestock production and crop cultivation, lessen the environmental impact of food production, and improve the safety and welfare of animals and consumers.
Biosensors, coupled with new diagnostic and detection methods, will allow the agricultural industry stay a step ahead of new and dangerous diseases.
What are Biosensors?
A biosensor is a unit that uses both biological and chemical components to detect the presence of a targeted substance, such as bacteria or toxins. The easiest way to explain this is that it’s simply a modern version of the canary in a cage, used by miners in past times to detect poisonous gases in caverns.
Another example might be using a rabbit to determine if a woman is pregnant or not. These are very simplistic examples, but they work the same way. A biological component that is known to react with a given substance is introduced to the sample material, and the reaction is measured using an electronic, visual, or chemical device that can be read by humans.
Biosensors are made up of three components:
- A bioreceptor, which is something that will react to a target substance in a known way—sort of like a piece of litmus paper changing colour to indicate the ph or acidity of a given substance.
- A biotransducer, which converts the biological reaction into something easily and quickly detectable by humans, such as an electronic signal, fluorescence, thermal, etc.
- An electronic device that can read the signal, such as a computer, monitor, oscilloscope, etc.
Bioreceptors can be of several types, depending on the types of reactions they cause, and the material used as the bioreceptor:
- Antibody/antigen – antibodies bind with the molecules they are designed to interact with, like a lock and key, making them very specific. In classic medicine, diseases are detected by the presence of the antibodies designed to bind with them. Unfortunately, by this time it may be too late to prevent the disease. Using them as biosensors greatly reduces the time it takes for early detection.
- Enzymatic – enzymes cause specific reactions with specific substances, and they do it very quickly. A good example is the way catalase breaks down hydrogen peroxide into water and oxygen. These reactions are measurable and can be quickly obtained.
- Nucleic acids/DNA – this one is difficult to explain without getting too technical. Basically, if you know which DNA sequence you are looking for, you can synthesize a similar hybrid, give it a radioactive marker, and then use it to find similar sequences in the target material, which will generate an optical signal.
- Cellular – no, I’m not talking about using a smart phone as a bioreceptor, (but that would be cool). Cells, organelles, and tissues are very sensitive to surrounding environments, and their reactions can be quickly measured.
- Other materials are currently in development.
Biotransducers convert the reactions from the bioreceptors into different signals such as electrical current; visual signals such as light, or fluorescence; or a thermal signal such as a rise or drop in temperature.
Just as a hypothetical example, let’s say we’ve introduced an enzyme that reacts with components of the anthrax bacillus shell coating into a dairy cow. We can’t see the effect with the naked eye, but a biotransducer converts the reaction into a small electrical charge through ionization that is proportional to the degree of infection. We can now measure that electrical current and not only see that there is an infection present, but how far it has progressed.
And this is all immediate, without having to wait for lab results to come back from somewhere miles and miles away. We can know within minutes what we are dealing with, and can protect the rest of the herd. Of course this is just a theoretical example, but similar biotranducers are being used right now.
The final component is the method used to read the signals. A signal is useless if it cannot be read. So, a computer, voltmeter, oscilloscope, or other appropriate device is used by the technician to both read and measure the results. These can be recorded so that progress can be tracked, and also used for future reference.
The Advantages of Biosensors
The classic method of detecting harmful biological or chemical substances is to take a sample, and either put it in a Petri dish with some auger and see what grows, or use various chemical reactions, one at a time, and observe what happens.
Taking samples from a herd of 1000 cows, labeling them, and waiting for each sample to grow something can take weeks, or even months, and be very expensive. In addition, the testing cannot be done on site, or in the field. The samples have to be sent off for testing to a lab somewhere.
Biosensors can speed up the process exponentially, be more accurate, cheaper, and some can even be used on site. Biosensors can measure substances that are not able to be estimated by other more conventional methods. The ultimate goal is to combine and miniaturize the units so that, eventually, they will have one unit that samples, analyzes, and measures, all on one small electronic chip that can be taken anywhere.
Imagine how fast and efficient it would be if you could take a sample from a cow or chicken in mere minutes, get the results while you are standing there, and immediately share those results with other livestock producers, food inspectors, processing plants, or anyone else with a need to know.
Biosensors and Agricultural Safety
According to the World Health Organization (WHO), over 600 million people suffer from food-borne illnesses every year, resulting in over 200,000 deaths annually, many of them children (WHO Fact sheet N°399 December 2015)
Food-borne illnesses cost over 152 billion dollars annually, just in the United States, in the form of healthcare, workplace, and other economic losses. Food-borne illnesses place a huge burden on already stressed healthcare systems, and cost farmers and food producers dearly. Another area of concern is the increased incidences of food allergies, such as to peanuts and gluten.
Biosensors can detect the presence of allergens just as easily as they can other food contaminants. Bionanotechnology is a major step towards addressing all of these problems.
The ability to sample, test, and evaluate possible sources, in the field, before they become a problem, would greatly reduce risks to consumers and producers alike. Being able to get results instantly would also provide enhanced national security, since food-borne disease-causing microbes can also be used as bio-weapons.
Biosensors can be used along with technologies such as smart phones, iPads, and other mobile devices, in conjunction with the internet, to provide instantaneous transmission of information and results, as well as things like remote and continuous testing. Biosensor technology can provide information that can be shared immediately with farmers, livestock producers, distributors, agricultural inspectors, law enforcement and national security agencies, etc.
There are three main areas of concern; dairy, poultry, and pork. Development is underway on biosensor systems for things like early detection and management of melamine contamination in dairy products, food allergens in processing facilities, metabolic diseases in dairy cows, avian flu in poultry, infections in animal wounds, 3D Imaging for biological systems, biosensor systems for continuous monitoring of food quality that can be deployed in food storage facilities, and grain bins etc., screening for genetic disorders, and much more. It won’t be long before we are able to continuously monitor the status of our food supplies in real time.
The Future of Biosensor Tech
The world population is growing, and every year it creates more demand on the world’s food supplies. This puts added strain on the environment, and it is becoming increasingly important to develop better, more sustainable methods of providing food along the entire supply chain, from the crop and livestock cultivators, to processing, transportation, storage, and ultimately, the consumer.
Biosensor technology can provide complete control over every step of the supply chain. Bionanotechnology can analyze the food quality and safety while allowing for less CO2 emissions, less greenhouse gasses, reduced pesticide, antibiotic and steroid use, and also monitor the quality of the soil and general environment the food is produced in.
Bionanotechnology is on the cutting edge, and the market for it has grown from 98.2 billion dollars (US) in 2006, to over 180 billion (US) in 2016. A very large part of this market is for creating safe, sustainable food supplies for the world.
Biosensors are being developed, or in some cases, already deployed, to monitor crops, soil analysis, pesticides and other contaminants, and even the very composition of the food itself, such as vitamin content, and quality of sugars, etc.
Other uses are monitoring the use of water for better management, managing excesses and waste, creating smart packaging that continuously monitors food quality, robotic analytical tools, etc.
Coupled with new advances in microtechnology and microfluidics, it will be possible to develop new low-cost, ready-to-use systems, sort of like a complete lab on a single computer chip.
Wearable biosensors are in development for continuously monitoring the health and status of livestock. Wearable sensors can allow a livestock producer to be alerted as soon as an animal becomes infected, allowing it to be culled from the herd before it can infect other animals.
Electronic leg bands are also being tested which monitor cattle feeding and milking behaviors and patterns. These are just some of the new and exciting things that are currently under development.
The future looks bright for the establishment of technologies using biosensors to be able to have a significant effect on the safety, efficiency, and productivity of agricultural and veterinary concerns, as well as going a long way towards helping to protect the environment, reducing the evolution of resistant strains of harmful microbes, and allowing for much more rapid response to the emergence of new and deadly diseases.
Dr. Suresh Neethirajan
Dr. Suresh Neethirajan is an assistant professor in the School of Engineering at the University of Guelph. He received his BSc from Tamil Nadu Agricultural University, India (2002), and PhD from the University of Manitoba (2009). Dr. Neethirajan’s research interests are in bio-instrumentation, bioimaging and bionanotechnology. His research involves the study of biological systems using nano-scale imaging techniques, and microfluidics for energy, health and agricultural applications.