Utilize cSWV for Quantitative and Qualitative Determination of Cross-reactive Targets with E-AB Sensors

In this work, we investigate cross-reactive targets for tobramycin aptamer on a gold electrode surface using powerful technique continuous square wave voltammetry (cSWV). Tobramycin, gentamicin, and streptomycin are cross-reactive targets with similar structures and subtle differences, making it challenging to differentiate. However, cSWV makes it possible by offering higher resolution compared to square wave voltammetry (SWV), by continuously collecting current to maximize the information content obtainable from a single voltametric sweep, which also eliminates the need for multiple scans. After fabricating electrochemical aptamer based (EAB) sensors, each of these targets are introduced onto the sensor individually and analyzed using cSWV. cSWV provides the charge transfer rate through the critical frequency, defined as the peak of the curve between normalized peak current and the reciprocal of frequency. Notably, each cross-reactive target—tobramycin, gentamicin, and streptomycin—shows a unique critical frequency. Each of these cross-reactive targets are differentiated on the basis of their critical frequency and charge transfer rate. Moreover, quantitative analysis has also been investigated by calibration free method to detect the concentration of each of the targets. Initially, the sample is analyzed to identify the specific cross-reactive present, followed by determining the concentration of that particular cross-reactive target. The findings offer insights into differentiating various cross-reactive targets and determining their concentrations accurately. This approach holds promise for clinical diagnosis, where distinguishing between similar structure antibiotics and monitoring the concentration of antibiotics in patient is challenging.