Fig. 4.

(a) A schematic of the relations between tDNA, pDNA, urDNA and drDNA. pDNA is immobilized on the PEPS surface using a biotin–streptavidin–biotin sandwich. The 200 nts long tDNA (green) hybridizes to pDNA (pink) in the middle, and the upstream and downstream flanking regions hybridize with upstream (yellow) and downstream (orange) rDNA which are conjugated on FRMs (dark blue spheres) and (b) relative resonance frequency shift, Δf/f, of PEPS A during various steps of pDNA immobilization and tDNA detection. The inset in (b) shows a schematic of the molecules involved in the immobilization and detection steps.