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Abstract
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 non-complementary 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.
ACKNOWLEDGMENTS
The authors from Florence University would like to thank the Italian Ministry for Environment (Ministero dell'Ambiente) and the Italian National Research Council (CNR), in particular, their “Accordo di Progra mma” for the Research project: “Biodiversitá ed Organismi Geneticamente Modificati” for financial support. The authors are also grateful to Dr.ssa Paola De Santis, Istituto Zooprofilattico “C. Caporale”, Teramo for kindly providing some of the GMOs samples.