Consistent with theoretical assumptions, MCO fabricated sensors exhibited superior stability during 7 days of operation (~40% redox tag current loss) compared to MCH sensors (~80% redox tag current loss) with the quality of the squarewave voltammograms well preserved after multiple days of scanning (Figure ). After ~3 days, MCH sensor voltammograms showed background current contributions due to oxygen reduction at -0.5 V that exceeded the redox tag current, indicating excessive desorption of the passivation layer. Beyond day 3, the quality of MCH sensor voltammograms became progressively worse as redox tag current decreased exponentially to approximately 20% of its initial value. Such excessive loss of redox tag current is likely due to aptamer desorption, which becomes even more energetically favorable after the desorption of surrounding MCH molecules. In comparison, the MCO sensors only exhibited a slight increase in background current due to oxygen reduction, suggesting that the MCO monolayer remained largely intact.