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. Author manuscript; available in PMC: 2019 May 15.
Published in final edited form as: J Am Chem Soc. 2017 Aug 2;139(32):11207–11213. doi: 10.1021/jacs.7b05412

Figure 5.

Figure 5.

Continuous, calibration-free measurement of cocaine and doxorubicin in flowing whole blood. (A) When challenged in vitro in flowing, undiluted whole blood the absolute peak currents of cocaine-detecting E-AB sensors vary significantly from sensor to sensor and even for a single sensor over several hours (compare the zero-target baselines of individual sensors at 1 and 6 h). (B) Dual-frequency calibration-free sensing nevertheless produces reasonably accurate concentration estimations of cocaine (spiked concentrations shown as a gray dashed line) even under these demanding conditions. (C) Doxorubicin-detecting sensors exhibit similar variability when placed in flowing whole blood. (D) Dual-frequency calibration-free measurements, however, once again suppress this variability, producing concentration estimates in close agreement with the spiked concentration (gray dashed line).