Figure 1  Reflectivity shifts observed upon injection of gold nanoparticles grafted with Split-APT sequences on various spots of the Surface Plasmon Resonance imaging (SPRi) biosensor surface without the target adenosine present in the solution. Signal increase is observed only on Split-APT8 spots through hybridization of the hairpin stems of the split‑aptamers. APT8 and APT4 spots do not present signal shift due to a folding of the complete aptamer on the surface while Split-APT4 sequences present stems (four bases) too short to hybridize with the Split-APT sequences grafted on the gold nanoparticles. Lack of non-specific signal is also confirmed on control spots with sequences CN8 and Split-APT or on pure gold.