Abstract:A label-free sensor, based on the combination of silicon photonic bandgap (PBG) structures with immobilized molecular beacon (MB) probes, is experimentally developed. Complementary target oligonucleotides are specifically recognized through hybridization with the MB probes on the surface of the sensing structure. This combination of PBG sensing structures and MB probes demonstrates an extremely high sensitivity without the need for complex PCR-based amplification or labelling methods. correlates with morphological sub-class of acute myeloid leukaemia and the expression of its target genes in global genome-wide analysis," Leukemia 21(5), 912-916 (2007). 4. R. L. Maute, C. Schneider, P. Sumazin, A. Holmes, A. Califano, K. Basso, and R. Dalla-Favera, "tRNA-derived microRNA modulates proliferation and the DNA damage response and is down-regulated in B cell lymphoma," Proc. Natl. Acad. Sci. U.S.A. 110(4), 1404-1409 (2013). 5. L. P. Lim, N. C. Lau, P. Garrett-Engele, A. Grimson, J. M. Schelter, J. Castle, D. P. Bartel, P. S. Linsley, and J.M. Johnson, "Microarray analysis shows that some microRNAs downregulate large numbers of target mRNAs," Nature 433(7027), 769-773 (2005

An experimental study of the influence of the conformational change suffered by molecular beacon (MB) probes-upon the biorecognition of nucleic acid target oligonucleotides over evanescent wave photonic sensors-is reported. To this end, high sensitivity photonic sensors based on silicon photonic bandgap (PBG) structures were used, where the MB probes were immobilized via their 5' termination. Those MBs incorporate a biotin moiety close to their 3' termination in order to selectively bind a streptavidin molecule to them. The different photonic sensing responses obtained toward the target oligonucleotide detection, when the streptavidin molecule was bound to the MB probes or not, demonstrate the conformational change suffered by the MB upon hybridization, which promotes the displacement of the streptavidin molecule away from the surface of the photonic sensing structure.