In-situ anchoring bimetallic nanoparticles on covalent organic framework as an ultrasensitive electrochemical sensor for levodopa detection.

Covalent organic frameworks (COFs) have been studied in many fields. However, their electrochemical properties were seldom reported. In this work, a novel high electrocatalytic material was synthesized by incorporating bimetallic nanoparticles (AgCoNPs) in a two-dimensional (2D) porous TAPB-DMTP-COF, (AgCo/TAPB-DMTP-COF, TAPB, 1,3,5-tris(4-aminophenyl)benzene; DMTP, 2,5-dimethoxyterephaldehyde). Subsequently, the resulting composite was further used to construct a novel electrochemical sensor for the ultrasensitive determination of levodopa. The analytical performance has been improved significantly due to the synergistic effect of both TAPB-DMTP-COF and AgCoNPs by increasing effective electroactive surface area and electron transfer efficiency. The linear detection range of the levodopa sensor was 0.010-100 μmol L-1. The limits of detection and quantitation were found to be 0.002 and 0.006 μmol L-1, respectively. Moreover, the sensor exhibits an excellent stability and maintains its catalytic activity after 100 scanning rounds. The applicability of the electrochemical sensor was successfully applied for the determination of levodopa content in human urine and blood serum samples. Our study not only supplies a useful tool to accurately detect levodopa in actual samples and, meanwhile, but paves a feasible way to unlock high performance 2D COF based electrode materials.