A bio-sensing strategy for the detection of prions in foods

An affinity based bio-sensing technique was developed using an anti-transmissible spongiform encephalopathy monoclonal antibody to detect prion in 0.1 mol/l sodium phosphate buffer. Fluoresein iso-thio-cyanate (FITC) labeled with a prion epitope (QYQRES) was used as a decoy for prions. Lowest detectable prion concentration was 8 nmol/l in phosphate buffer. The bio-sensing scheme was used to probe the presence of prions in gelatin and baby-formula. The gelatin interfered with the binding and the displacement reaction of antibody, decoy and prion. Addition of sodium dodecyl sulfate (SDS) at 0.3 mg/ml to gelatin samples facilitated prion detection in gelatin. The lowest detectable concentration of prion in gelatin was 0.5 nmol/l at 0.4 mg/ml gelatin. The baby formula samples produced light scattering and the intrinsic peak of baby formula interfered with the dye peak. Serial dilutions of baby formula were done to reduce the interference. Addition of Triton-X-100 at 0.454 mg/ml to the baby formula samples facilitated the prion detection. The lowest detectable concentration of prion was 2 nmol/l for baby formula.