Gold nanoparticles anchored onto covalent poly deep eutectic solvent functionalized graphene: An electrochemical aptasensor for the detection of C-reactive protein

An electrochemical aptasensor for specific recognition of CRP biomarker was designed and synthesized with a novel porous and planar structure based on poly deep eutectic solvent modified graphene oxide coated by gold nanoparticles. Different steps of the synthesis of sponge-like aptasensor were characterized by SEM, mapping, EDX, FTIR, XRD, HRTEM, and BET. The designed DNA aptamers were prepared on the Au NPs-modified electrode surface through the gold-sulfur affinity. The presence of the high amount of the AuNPs as a signal amplifier on the surface of the composite afforded a label-free electrochemical aptasensor for the selective and sensitive detection of CRP via electrochemical impedance spectroscopy (EIS). To achieve an efficient sensitivity, optimization of the variables affecting this method was carried out. Under the optimized conditions, the proposed technique provided good linearity in the range of 0.001-50 ng mL-1 as well as a low detection limit of 0.0003 ng mL-1. The sensor moreover was used for the determination of CRP in human serum in which recoveries are between 96.0 and 102.2%, and the relative standard deviations are within 2.09-5.47%. The designed platform provides an efficient pathway for the sensitive detection of various biomolecules in a label-free manner by changing the corresponding particular aptamer recognition strands.