Aptamer-embedded DNA origami cage for detecting (glycated) hemoglobin with a surface plasmon resonance sensor

Abstract DNA origami-based cages functionalized with aptamer motifs were used to detect hemoglobin and glycated hemoglobin. The binding between the cages and hemoglobin was monitored using a surface plasmon resonance (SPR) sensor. One DNA strand in the nano-cage was replaced with an aptamer that demonstrated a high affinity to hemoglobin (Hb) or glycated hemoglobin (gHb). Three types of the DNA nano-cages designed to fit the size and shape of hemoglobin were evaluated: one without an aptamer, one with the Hb-affinity aptamer (HA) and one with the gHb-affinity aptamer (GHA). Both DNA nano-cages embedded with HA and GHA showed significantly more stable binding with Hb and gHb by 5 and 9 times, respectively, than the aptamers directly immobilized on the SPR surface. HA-embedded DNA and GHA-embedded DNA improved the sensor selectivities by 9 times and 37 times between Hb and gHb.