A piezoelectric affinity biosensor for genetically modified organisms (GMOs) detection

A piezoelectric affinity sensor, based on DNA hybridisation has been studied for applications to Genetically Modified Organisms (GMOs) detection. The thiol/dextran modified surfaces were coupled to streptavidin for immobilising 5'-biotinyltead probes (25-mer). The probes sequences were respectively internal to the amplified product of P35S and T-NOS. These target sequences were chosen on the base of their wide presence in GMOs. The system has been optimised using synthetic complementary oligonucleotides (25-mer) and the specificity of the system tested with a noncomplementary oligonucleotide (23-mer). The hybridisation study was performed also with samples of DNA isolated from CRM (Certified Reference Materials) soybean powder containing 2% of transgenic material and amplified by PCR. Non amplified genomic or plasmidic DNA was also used. The developed system was very specific, binding only the complementary DNA strand. The CV% was 20% both with synthetic oligonucleotides and PCR amplified samples. The sensor signal was independent of the sample dilution but the system is still at a semi-quantitative level.