Dr. Wahied Khawar Balwan
Increasing world population is a well-known fact and increase in food production is one of its direct consequences but even in such situations, safety of food is not to be compromised. Several conventional methods are already in existence for upholding food safety; however they might not be able to cope up with the humongous pressure on food industry. Thus modern biotechnological intervention such as biosensor technology can be used to fill the void left in food safety in detecting food-borne pathogens, drug residues and heavy metals. It can provide rapid and reliable results, but the idea of its use in food safety is in its adolescence and needs suitable troubleshooting before they can set sail in commercial markets.
Food borne pathogens pose a major threat to the welfare of people in terms of health and economy. Lapses in hygienic food habits may result in diseases ranging from mild nausea, vomiting and diarrhoea to fatal cancers. The WHO South East Asian Region, which consists of India, ranks second among WHO regions in terms of food borne disease per population. Apart from food-borne diseases, a major area of concern in food safety is presence of veterinary drug residues. Commonly encountered drug residues belong to the class of antibiotics, followed by pesticides and hormones. Another major concern is the presence of heavy metals in food which causes adverse health effects of whichMinamata and Itai-Itai diseases are good examples. Conventional methods for detection of chemical and microbial hazards in food have their own drawbacks. Though they are highly sensitive and specific, they are time consuming and may not be able cope up with the increasing demands and market size of food industry. Thus many technologies are being developed and tested to face the aforementioned shortcomings. Biosensor technology is one among them, with an aim to address various issues in food safety as one of its major objectives. A biosensor is a fabricated receptor-transducer device, capable of providing analytical information (qualitative and quantitative) using a biological recognition element. Biosensor is an interdisciplinary research venture among thefields of analytical biochemistry, biology and microelectronics.
The development of biosensors set sail in the year 1962 with the use of enzyme based electrodes for glucose estimation by Dr. Leland C. Clark Jr., who is rightfully called as “father of biosensors”. However, the term “biosensors” was coined by Karl Cammann in the year 1972 and has been scientifically defined by International Union of Pure and Applied Chemistry (IUPAC).The “biosensor” technology works on the principle of conversion of a biologically induced recognition event into a detectable signal (transduction) and readings are obtained on screen after a series of processing. The biologically induced recognition events may be in the form of enzyme substrate reaction, antigen-antibody binding, etc. Upon recognition, a physicochemical change is generated on the transducer surface, resulting in a signal which is directly measured or converted into another signal which is suitably interpreted and visualized.
As the name suggests, the word “biosensors” is an amalgamation of two essential components namely, biological component and sensing (or) physical component2 . The biological element consists of sensitive bio-element and the analyte under question, whereas the physical element consists of transducer and amplifier. Enzymes, living cells, antibodies, etc. can be used as biological elements. However, the physical elements especially transducer component is highly variable, as they include temperature, electromagnetic radiation, electric potential, electric current, mass, viscosity, etc.
SCOPE IN FOOD SAFETY
The scope of biosensors in food safety lies with the need to detect the hazards in food at a faster and cheaper rate. Since its inception, the biosensor technology has undergone fabrications and developments and they were gradually and systematically tested for its use in the field of food safety. The main advantage of biosensor technology is that it can be used to quantify non-polar molecules . Some of the developments and future prospects in food safety are:
Detection of Food borne Pathogens and Toxins
The Surface Plasmon Resonance (SPR) based biosensors (optical biosensors) have been developed by various scientists for different organisms such as E. coli with a detection time of 20 minutes, Salmonella spp. and Campylobacter. Other latest procedures under development are biosensor technology using immuno-magnetic separation technology, aptamer and Quantum Dots (QD). A less significant microbial hazard is the presence of toxins. Biosensors have also been already developed for detection of Staphylococcal Enterotoxin A (SEA) and marine shellfish toxins in food.
Detection of Veterinary Drug Residues
Veterinary drug residues have emerged as a major public health concern over the last few years. Biosensor technology has been effectively applied in detection of antibiotics in poultry meat and pork. The sensitivity and specificity in detection of antibiotic residues is comparable to that of immunological assays. Biosensors have also been successfully developed to screen milk for antibiotic residues. Affinity type biosensors have been developed for monitoring of hormones. Optical, electrochemical, acoustic biosensors have been developed based onacetylcholinesterase enzyme inhibition to detect pesticides in food.
Detection of Heavy Metals
Biosensor technology also finds its application in detection of heavy metals owing to its sufficiently high sensitivity for the detection of heavy metal ions at a cheaper cost. It has been demonstrated that this technology can be used to detect cadmium, mercury and other metals such as aluminium.
DISADVANTAGES AND TROUBLESHOOTING
In spite of possessing potential to become a go-to technology in the future, it does have few disadvantages that need to be addressed to increase its chances of feasibility in the field as well as its marketability. A majority of the literature reviewed suggested the following disadvantages like Heat sterilization, Modification of biosensor by the analytes resulting in single uses, Physical and chemical changes may significantly influences the equilibrium of the components involved in the detection process, Durability issues, Portability issues and Cost of development. The methodology of troubleshooting for the disadvantages have been emphasized by various authors belonging to various disciplines. It would be wise enough if they are discussed on a common platform to arrive at an augmented solution. These efforts are to be aimed at Reducing cost of development, Multifunctional and versatile, Easy to handle, Multiple-array analysis, Portabilityand Integration.
INTEGRATION WITH CONTEMPORARY METHODS
Integrating the Biosensor technology with other methods involved in assessing the food quality have been suggested a bit more frequently in the recent years as they endorse the chances of complementing and supplementing each other. Some technologies suggested for integration are PCR (Polymerase Chain Reaction) - based detection, Nucleic acid Sequence based Amplification (NASBA), Microfluidics, Quantum dots (QD) and Nanotechnology. Though efforts to integrate microfluidics and nanotechnology are already in action, they still require further refinement. PCR based methods have long been in practice to ascertain microbiological safety of food. It has evolved over the years to very much suit the requirements in field. Some of the advancements are multiplex PCR, Real Time PCR (RT-PCR). Multiplex PCR allows for simultaneous detection of various pathogen in a single cycle. RT-PCR gives real time values and curtails the necessity for Post-PCR processing on agarose gels. Recently RT-PCR based kits are available commercially for detection of pathogens such as Escherichia coli and Campylobacter. NASBA is a sensitive method which was conceived to the world as recent as 1991 by Compton. It uses an enzyme triplet to selectively amplify RNA13. The efforts to exploit the benefits of this technology have already been initiated and methods have been developed to use this technology in the detection of some food-borne pathogens such as Campylobacter jejuni, Listeria monocytogenes, etc. Molecular based methodshave their own advantages and disadvantages in terms of their applications in food safety which needs to be assessed before venturing for chances of integration.
Quantum Dot method is another interesting fast growing technology and it has its stronghold in terms of signal detection. Quantum dots are fluorescent nanocrystals which have the properties of a semiconductor. This technology has not crossed the borders of research and development for a majority of time. However it is mooted to be a good solution for various technologies which have their drawback in terms of signal detection.
Microfluidics based method such as lab-onchip devices has been suggested to overcome the limitations of molecular methods and biosensors16. It allows for increased throughput with small amount of sample requirement and assurance of sensitivity.
Biosensor is an emerging technology with its own advantages and disadvantages over other methods used in food safety. The advantages are that its rapidity and reliability whereas its disadvantages are its cost of development. It is wise to conclude that biosensor technology still requires adequate amount of incubation period in laboratories before they set sail in commercial markets.
“Any Error in this manuscript is silent testimony of the fact that it was a Human Effort”
Dr. Wahied Khawar Balwan
Senior Assistant Professor & Head
Department of Zoology
Govt. Degree College Kilhotran, Doda
E-mail: [email protected]