Low fouling and ultra-sensitive electrochemical screening of ractopamine using mixed self-assembly of PEG and aptamer immobilized on the interface of poly (dopamine)/GCE: A new apta-platform towards point of care (POC) analysis

Abstract

During the twentieth century, RAC (ractopamine) as one of the important and frequently used feed additives and doping agents has attracted considerable attention in the animal breeding industry and sports competitions. Herein, we report a sensitive and easy-to fabricate electrochemical single off apta-assay for detection of RAC. To fabricate the low fouling aptasensor, the surface of GCE (glassy carbon electrode) was coated by polydopamine (PDA) to provide a suitable substrate for aptamer immobilization. Then, the diluted T95108 aptamer (sequence, 5′-AAA AAG TGC GGGC-3′) mixed with PEG (polyethylene glycol). Then, it was immobilized on the modified surface which led to efficient interaction with RAC (Target molecules). Ascorbic acid, arginine, tyrosine, L-proline, glutamic acid, cysteine, and uric acid were also used to test the selectivity of aptasensor. The modified surface was characterized by FE-SEM (field emission scanning electron microscopes) and EDS (energy-dispersive X-ray spectroscopy). Cyclic voltammetry technique was employed to evaluate the stability of designed aptasensor. DPV (differential pulse voltammetry), SWV (square wave voltammetry) and CHA (chronoamperometry) techniques were also conducted for measuring RAC concentration. Low limit of quantification (LLOQ) and linear range of aptasensor were 10 fM and 10 fM to 10 nM, respectively obtained. The applicability of the designed aptasensor was investigated in human plasma samples too.