Fig. 2: Plasma proteins interact with emtricitabine E-ABs.
a Dose-response curves of E-ABs functionalized with the emtricitabine (FTC) aptamer against various FTC concentrations, measured in phosphate-buffered saline (PBS, red data), human serum (blue), and human plasma (black). In these measurements, the sensors’ signal output and EC50 decrease with increasing medium complexity; with sensor signal output going from 350% in PBS down to 89% in plasma, and the EC50 decreasing from 10 µM in PBS to 80 µM in plasma. b Single point injection of 10 µM FTC into PBS (red bar) or into a solution of 600 µM (physiological) serum albumin (BSA, black) in buffered saline. The experiment of FTC into PBS addition resulted in a 53 ± 1% signal change, while the equivalent experiment in BSA solution only generated 24 ± 1%. c Experiment showing the response of FTC-binding E-ABs in the face of increasing BSA concentrations until above physiological levels (i.e., 1 mM). In the physiological range, 500–800 µM, the FTC sensor is responding to BSA with a sensor signal output = 62 ± 12%. d Plasma samples treated with 1 mg/mL proteinase K to hydrolyze albumin showed signal recovery relative to untreated plasma. In panels A and D, solid lines represent a nonlinear fit to the Hill isotherm. For all panels n = 8 sensors, and the error bars represent the standard deviation of the mean. All measurements were conducted using square wave voltammetry. % Signal is plotted as the difference between normalized measurements performed at 600 Hz and measurements performed at 8 Hz (also known as KDM), using a 25 mV square wave amplitude.
