LAUSR

Electrochemical aptamer-based (E-AB) biosensor suffers from sensor-to-sensor signal variation due to the variation of total number of probes immobilized on sensor surface and heterogeneity of probe distributions, with the former attracting more attention. As such, the calibration process to correct for such variation is required for this type of sensor, causing inconvenience and inaccessibility for harsh sensing environment such as blood samples, which has dramatically limited the widespread clinical use of biosensors. In response, here we have adopted E-AB sensors to achieve calibration-free measurements of small biological/drug molecules. Specifically, we employ one probe-attached redox reporter and a second intercalated redox reporter to generate two signals, achieving good sensor-to-sensor reproducibility and thus obviate the need for calibration. We first demonstrated the capability of E-AB sensors for the accurate measurement of kanamycin, tobramycin and ATP in PBS buffer, achieving a concentration range approximate 4.7×103-fold, 2.0×103-fold and 12.7-fold, respectively. Then, we applied such calibration-free approach to the measurement of these three target molecules directly in undiluted serum, achieving concentration precision of a few micromolar.