Composite polymerized molecular imprinting membrane-based electrochemical sensor for sensitive determination of curcumin by using 4-pentenoyl-aminoacyl-chitosan oligosaccharide as functional monomer oligomer

In this work, 4-pentenoyl-alanyl-chitosan oligosaccharide (PACO), a functional oligomer of chitosan oligosaccharide with the strong affinity on curcumin (CUR), was screened from the series of 4-pentenoyl-aminoacyl-chitosan oligosaccharides through the results of computational selection. After the preparation of this oligomer, a novel molecular imprinting membrane-based electrochemical sensor was developed for sensitive detection of CUR. The molecularly imprinted membrane (MIM) of CUR was obtained by composite compensation polymerization process: bulk polymerization with good permeability on a glassy carbon electrode (GCE) surface by using CUR as the template molecule, PACO as the oligomer of functional monomer and ethylene glycol dimethacrylate as the crosslinking agent, followed by electrochemical polymerization with good sensitivity in methylene bisacrylamide solution. After removing the template molecule, the modified electrode could specifically adsorb CUR molecules. Under optimal conditions, the sensor named as CUR-MIM/GCE exhibited high sensitivity and good selectivity against some analogs of CUR such as tetrahydrocurcumin, ferulic acid, beta-carotene, and quercetin. The calibration graph of the designed sensor was linear in the range of 10 nM to 2.0 mu M with a detection limit of 5.0 nM. This sensor showed excellent selectivity and good reproducibility, and more than 90% of its original response was retained after storage in a sealed capsule at room temperature for 30 days. Moreover, the constructed sensor was successfully applied to monitor the CUR contents in turmeric extract with the relative standard deviation of less than 3.3%.