Real-Time Tunable Dynamic Range for Calibration-Free Biomolecular Measurements with a Temperature-Modulated Electrochemical Aptamer-Based Sensor in an Unprocessed Actual Sample.

The sensing technologies for monitoring molecular analytes in biological fluids with high frequency and in real time could enable a broad range of applications in personalized healthcare and clinical diagnosis. However, due to the limited dynamic range (less than 81-fold), real-time analysis of biomolecular concentration varying over multiple orders of magnitude is a severe challenge faced by this class of analytical platforms. For the first time, we describe here that temperature-modulated electrochemical aptamer-based sensors with a dynamically adjustable calibration-free detection window could enable continuous, real-time, and accurate response for the several-hundredfold target concentration changes in unprocessed actual samples. Specifically, we could regulate the electrode surface temperature of sensors to obtain the corresponding dynamic range because of the temperature-dependent affinity variations. This temperature modulation method relies on an alternate hot and cold electrode reported by our group, whose surface could actively be heated and cooled without the need for altering ambient temperature, thus likewise applying for the flowing system. We then performed dual-frequency calibration-free measurements at different interface temperatures, thus achieving an extended detection window from 25 to 2500 μM for procaine in undiluted urine, 1-500 μM for adenosine triphosphate, and 5-2000 μM for adenosine in undiluted serum. The resulting sensor architecture could drastically expand the real-time response range accessible to these continuous, reagent-less biosensors.