APPLICATION OF BIOSENSORS IN VETERINARY, FOOD AND AGRICULTURAL FIELDS

Biosensors in Veterinary

Detection of Pathogens in Meat

An immune competitive assay which detected pathogens in spiked meat extracts at 104CFU/mL after a 3hr enrichment was developed. The application of techniques like this will help reduce or eliminate contamination of pathogens and toxicants in foods.

Detection of Drugs (Ractopamine Residues) in Swine

Ractopamine (RCT) is a beta-adrenergic agonist licensed for growth promotion in pigs in the USA but illegal in Europe. Due to its molecular structure many of the existing screening and confirmatory tests for betaagonist compounds fail to detect RCT and its metabolites. A screening assay based on optical biosensor detection of RCT and its metabolites following sample extraction was developed. Detection limits well below 1ng/ml or g were achieved in urine and tissue samples.

The Determination of Immunoglobulin G in Bovine Colostrum and Milk

An automated biosensor-based assay has been developed for the determination of IgG in bovine milk and colostrum using either goat or rabbit anti-bovine IgG or protein G as ligand. The method is configured as a direct and non-labelled immunoassay, with quantitation against an authentic IgG calibrant. Whole colostrum or milk is prepared for analysis by dilution into buffer. Analysis conditions including ligand immobilization, flow-rate, contact time and regeneration were optimised and non-specific binding considerations evaluated.

Biosensors in Food

Vitamin Analysis in Food Products

Biosensor-based analysis is becoming more and more important in the food industry and one of the fields of application is in vitamins analysis. The method for vitamin analysis is a label-free, inhibition assay. The SPR biosensor monitors interactions of a specific binding protein with the vitamin immobilized on a CM5 sensor chip. The prepared samples are mixed with a fixed concentration of the vitamin binding protein by the autosampler and injected over the chip surface. The vitamin present in the sample binds to the protein and subsequently inhibits it from binding to the surface of the sensor chip. The higher the concentration of the vitamin is in the sample, the higher the level of inhibition and hence the lower the response of the biosensor. A regeneration step prepares the chip surface for the next sample. Quantification is performed by multi-level calibration with the vitamin standards.

Detecting Antibiotics in Food; Regulatory and Quality Control

The presence of banned antibiotics in honey is one recent example why food consumer groups are insistent on better quality assurances and increased testing. Methods for detecting chemical contaminants, e.g. streptomycin and chloramphenicol, that combine reliability and throughput at the required sensitivity are in demand. Biosensors will can analyse the presence of antibiotics reliably, effectively and in a short time.

Amperometric Biosensor in Food Analysis

Histamine could accumulate in seafood when bacteria spoilage commenced and caused histamine poisoning without altering the fish normal appearance and odor. Therefore, a histamine biosensor using immobilized enzyme diamine oxidase (DAO) has been developed for the rapid monitoring of the histamine levels in tiger prawn (Penaeus monodon). The histamine biosensor has a response time of less than 1 minute and optimum pH operation was 7.4. the reusable biosensor is simple and can be used for direct histamine determination without further pretreatment, and is suitable for routine analysis of tiger Prawns to monitor spoilage.

Potentiometric Biosensor in Food Analysis

A potentiometric biosensor for the analysis of isocitrate was developed by using a CO₃²⁻-selective electrode and enzyme immobilization in flow injection analysis (FIA). The interference effect of major sugars and organic acids on the sensor system was less than 5%. Isocitrate concentrations of some fruit juices analyzed by the isocitrate sensor system were compared with those analyzed by gas chromatography (GC). No significant difference was found between the two analytical methods in any of the fruit juices. This suggests that the isocitrate sensor system is reliable in determining the isocitrate concentrations of foods.

Immunobiosensors Biosensor in Food Analysis

Immunobiosensors were developed for detection of Escherichia coli O157:H7 based on the surface immobilization of monoclone antibodies onto indium tin oxide (ITO) electrodes. The immobilization of antibodies onto ITO chips was carried out by silanization (Silanization is the process of adding Organo functional Silane groups to the suppourt. The functional groups of the Silane can then be used/modified to bind a specific molecule to it). The biosensor could detect the target bacteria with a detection limit of 4times10³ CFU/mL. This biosensor was characterized with high sensitivity, excellent selectivity, short detection time and easy operation. It has a promising application in clinical laboratory diagnoses, environmental detection and food safety.

Biosensors in Agriculture

Concentrations of herbicides, pesticides and heavy metals in agricultural lands is increasing and this is a matter of concern. Biosensors can be used to measure the levels of pesticides, herbicide and heavy metals in the soil and ground water. (details in Biosensors for Environmental Monitoring concept)

Biosensors can also be used to forecast the possible occurrence of soil disease, which has not been feasible with the existing technology. The biological diagnosis of soil using biosensor means opening the way to reliable prevention and decontamination of soil disease at an earlier stage.