Experimental study of the evanescent-wave photonic sensors response in presence of molecular beacon conformational changes.

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.