Figure 1.
Electrochemical aptamer-based (E-AB) sensor supporting the measurement of phenylalanine. (A) E-AB sensors employ an electrode-bound (via an alkane–thiol self-assembled monolayer), redox-reporter-modified aptamer that undergoes a conformational change in the presence of its target. Specifically, binding to the phenylalanine–rhodium complex alters the kinetics with which the reporter (here methylene blue, MB) exchanges electrons with the electrode surface (ket). This produces a target-dependent change in current that can be measured via different electrochemical methods, such as square-wave voltammetry (SWV), that are sensitive to changes in electron-transfer kinetics. (B) Structure of the rhodium-based receptor [(Cp*RhCl2)2] (green) that in solution can interact with phenylalanine (red) and other nucleophilic ligands present in solution (L) forming the complex target recognized by the aptamer.18