Recent Advances in Food Science & Technology: Biosensors

What is a Biosensors

A biosensor is an analytical device, used for the detection of an analyte that mixes a biological component with a physicochemical detector the sensitive biological element (e.g. tissue, microorganisms, organelles, cell receptors, enzymes, antibodies, nucleic acids etc.).

Microbial Biosensors

A microbial biosensor is an analytical device that couples microorganisms with a transducer to enable rapid, accurate and sensitive detection of target analytes in fields as diverse as medicine, environmental monitoring, defense, food processing and safety. the sooner microbial biosensors used the respiratory and metabolic functions of the microorganisms to detect a substance that's either a substrate or an inhibitor of those processes. A biosensor is an analytical device that mixes a biological detector with a transducer to supply a sign proportional to the analyte concentration. biomolecules like enzymes, antibodies, receptors, organelles and microorganisms also as animal and plant cells or tissues are used as biological sensing elements.

The Biosensor system

    

The main components of a biosensor: The biocatalyst (a) converts the substrate to product. This reaction is decided by the transducer (b) which converts it to an electrical signal. The output from the transducer is (c) amplified (d) processed (e) displayed.

Basic principle of biosensor:

 Fundamentals of biosensor involved in three elements:-

• First biological reorganization element which highly specific towards the biological material analytes produces.

• Second transducers detect and transduce signal from biological target-receptor molecule to electrical signal which is thanks to reaction occur.

• Third after transduction signal from biological to electrical signal where its amplification is important and takes place and skim call at detector after processing the values are displayed for monitor and controlling the system. 

Bioreceptor

In a biosensor, the bioreceptor is meant to interact with the precise analyte of interest to supply an impact measurable by the transducer. High selectivity for te analyte among a matrix other chemical or biological components may be a key requirement of the bioreceptor. While the sort of bio molecule used can vary widely, biosensors are often classified consistent with common type’s bioreceptor interactions involving: antibody/ antigen, enzymes, nucleic acids/ DNA, cellular structures/ cells, or biomimetic materials.

Components of a Biosensor

Types of Biosensors

1. Potentiometric microbial biosensor

·     Conventional potentiometric microbial biosensors contains an ion-selective electrode (pH, ammonium, chloride then on) or a gas-sensing electrode (CO2 and NH3) coated with an immobilized microbe layer.

·     Potentiometric transducers measure the difference between a working electrode and a reference electrode, and therefore the signal is correlated to the concentration analyte.

·     The simplest potentiometric microbial biosensor is predicated on the modification ion selective electrode. Several microbial biosensors supported modification of glass pH electrode.

2. Optical microbial Biosensor

·     The modulation in optical properties like UV-vis absorption, bio- and chemi-luminescence, reflectance and fluorescence brought by the interaction of the biocatalyst with the target analyte is the idea for optical microbial biosensors.

·     Optical based biosensors offer advantages of compactness, flexibility, resistance to electrical noise, and a little probe size.

3. Bioluminescence Biosensor

·     Bioluminescence is related to the emission of sunshine by living microorganisms and it plays a really important role in realtime process monitoring.

·     The bacterial luminescence lux gene has been widely applied as a reporter either in an inducible or constitutive manner.

·     As a result, the concentration of the compound is often quantitatively analyzed by detecting the bioluminescence intensity.

 Fluorescence biosensor

·        Fluorescence spectroscopy has been widely applied in analytical chemistry. It’s a sensitive technique which will detect very low concentrations of analyte due to the instrumental principles involved. Fluorescent materials and green fluorescent protein are extensively utilized in the development of fluorescent biosensor.

Colorimetric biosensor

·     A sensitive biosensor supported color changes within the toxin sensitive colored living cells of fish was reported. Within the presence of poisons produced by microbial pathogens, the cells undergo visible color change and therefore the color changes during a dose-dependent manner.

·     The results suggest this cell-based biosensor’s potential application within the detection and identification of virulence activity related to certain air-, food-, and water-borne bacterial pathogens.

·     A colorimetric whole cell bioassay for the detection of common environmental pollutants benzene, toluene, ethyl benzene and xylene (BTEX), found at underground fuel storage tanks, using recombinant E. coli expressing toluene was reported.

4.  Amperometric microbial Biosensor

·     Amperometric microbial biosensor operates at fixed potential with reference to a reference electrode and involves the detection of the present generated by the oxidation or reduction of species at the surface of the electrode.

·     Amperometric microbial biosensors are widely developed for the determination of biochemical oxygen demand (BOD) for the measurement of biodegradable organic pollutants in aqueous samples.

·     The microbial strains used as biological detector include Torulopsis candida , Trichosporon cutaneum , Pseudomonas putida , Bacillus subtilis , Pseudomonas sp. , P. fluorescens , Thermophilic bacteria and yeast .

·     As the foremost extensively investigated microbial biosensor, the primary commercial BOD biosensor was produced by Nisshin Denki (Electric) in 1983.

·     Due to its importance in fermentation industry and clinical toxicology, microbial biosensors for ethanol have garnered the second most research attention after BOD.

APPLICATIONS OF BIOSENSORS

Ø In food industry, biosensors are wont to monitor the freshness of food.

Ø Drug discovery and evaluation of biological activity of new compounds.

Ø Potentiometric biosensors are intended primarily for monitoring levels of CO2, ammonia, and other gases dissolved in blood and other liquids.

Ø Environmental applications e.g. the detection of pesticides and river water contaminants.

Ø Determination of drug residues in food, like antibiotics and growth promoters.

Ø Analytical measurement of vitamin Bc, biotin, vitamin B12 and pantothen.

Ø Enzyme-based biosensors are used for continuous monitoring of compounds like methanol, acetonitrile, phenolics in process streams, effluents and groundwater. 

Biosensors in food analysis

Ø  There are several applications of biosensors in food analysis.

Ø  In food industry optic coated with antibodies are commonly wont to detect pathogens and food toxins. the sunshine signal system in these biosensors has been fluorescence, since this sort of optical measurement can greatly amplify the pathogens.

Ø  A range of immuno- and ligand-binding assays for the detection and measurement of small molecules like water-soluble vitamins and chemical contaminants.