No abstract

A rapid, simple, and reliable competitive immunoassay was developed for measurement of lead ions Pb(II) in environmental samples. Avian antibodies were produced against Pb(II). Since lead ions are too small to elicit an immune response, the metal was coupled to protein carrier Bovine serum albumin (BSA) using a bifunctional chelator 1-(4-isothiocyanobenzyl) ethylenediamine N,N,N 0 , N 0 -tetra acetic acid (ITCBE). Poultry birds (layers) were immunised with this Pb(II)-ITCBE-BSA immunoconjugate and the avian antibodies (IgY) isolated from egg yolk recognised Pb(II)-ITCBE complexes as capture reagent and a Pb(II)-ITCBE conjugate of Alkaline phosphatase as an enzyme label. Antibody reaction was optimised for different concentrations of antigen and antibody dilutions. Cross reactivity with other metals were below 1% in competitive ELISA. The IC 50 value of this avian antibody was 0.19 mg mL À1 . The detection range and the detection limit were 0.02-1000 mg mL À1 and 0.2 mg mL À1 , respectively.

Among the organochlorine pesticides, DDT and HCH are the major cause for food and environmental contamination. To detect them effectively in water samples an immobilized dehydrohalogenase based potentiometric biosensor was developed. The chloride ion released as a result of dehalogenation by immobilized dehydrohalogenase during the degradation of DDT and HCH, respectively, was detected using an ion selective electrode. The voltage response had a direct linear relationship with the concentration of chloride (Cl À ) released by DDT and HCH, respectively. The immobilization was advantageous in improving the enzyme property and could be used repeatedly without losing activity.

A rapid, simple, and reliable competitive immunoassay was developed for measurement of lead ions in spiked food samples. Avian antibodies were produced against Pb(II). Since lead ions are too small to elicit an immune response, the metal was coupled to protein carrier Bovine Serum Albumin (BSA) using a bifunctional chelator 1-(4-isothiocyanobenzyl) ethylenediamine N,N,N',N'-tetraacetic acid (ITCBE). Poultry birds (layers) were immunized with this Pb(II)-ITCBE-BSA immunoconjugate and avian antibodies (IgY) were isolated from egg yolk. This avian antibody (IgY) produced recognized Pb(II)-ITCBE complexes as capture reagent. The assay depended on a competitive binding reaction between the antibody and Pb(II). Antibody reaction was optimized for different concentrations of antigen and antibody dilutions. Cross reactivity with other metals were below 1% in competitive ELISA. The detection range and the detection limit were 0.02-1000 mg · kg⁻¹ and 0.2 mg · kg⁻¹, respectively. Spike recovery studies in different food samples showed that the avian antibodies could recognize Pb(II) in food samples without much matrix effect.

A multiplex real-time isothermal amplification assay was developed using molecular beacons for the detection of Bacillus cereus and Staphylococcus aureus by targeting four important virulence genes. A correlation between targeting highly accessible DNA sequences and isothermal amplification based molecular beacon efficiency and sensitivity was demonstrated using phi(Φ)29 DNA polymerase at a constant isothermal temperature of 30°C. It was very selective and consistently detected down to 10 1 copies of DNA. The specificity and sensitivity of this assay, when tested with pure culture were high, surpassing those of currently used PCR assays for the detection of these organisms. The molecular beacon based real-time isothermal amplification (MBRTIA) assay could be carried out entirely in 96 well plates or well strips, enabling a rapid and high-throughput detection of food borne pathogens.