Figure 1.

Conceptual illustration of the label-free biosensors working principle and drug screening assay design. (A) Schematics of the electrochemical sensor based on carbon screen-printed electrodes (EPS). (B) Randles equivalent circuit for an electrode in electrolyte contact. (C) Illustrative representation of electrochemical impedance spectroscopy (EIS) signals, before and after interaction of the DA-BSA conjugate with D3R for the case of APD or control drug interactions. (D) Schematics of the nanoplasmonic sensor based on nanohole arrays. (E) Illustrative representation of extraordinary optical transmission (EOT) spectroscopy signal, before and after analyte capture. (F) Illustrative representation of the real-time sensorgram extracted from spectroscopic displacements during the analyte capture. (G) Schematics of the APD screening assay based on indirect competitive detection: (i) Standard: dopamine binds to D3R in solution and impedes its binding to the DA-BSA conjugate; (ii) A good antipsychotic drug (APD) will also bind to D3R and hamper its binding to the DA-BSA conjugate; and (iii) a non-specific drug will not bind to D3R and it will bind to the DA-BSA conjugate.