Development of novel nanocomposite-modified photoelectrochemical sensor based on the association of bismuth vanadate and MWCNT-grafted-molecularly imprinted poly(acrylic acid) for dopamine determination at nanomolar level.

This study proposes the development of a new photoelectrochemical (PEC) sensor for the determination of dopamine (DA) at nanomolar levels. The PEC sensor was based on a physical mixture of bismuth vanadate (BiVO) with nanocomposite molecularly imprinted poly(acrylic acid) (MIP-AA) grafted onto MWCNT by using the surface-controlled radical polymerization strategy with an INIFERTER reagent. XRD, diffuse reflectance spectroscopy (DRE), SEM, TEM, and TGA were employed to characterize the materials. Photoelectrochemical analyses were carried out with GCE/BiVO/MIP-AA sensor under visible light using a potential of 0.6 V, phosphate buffer (0.1 mol L) at pH 7.0, and modifying the GCE with a film composed of monoclinic BiVO at 3.5 mg mL and nanocomposite MIP prepared with acrylic acid (MIP-AA) at 0.1 mg mL. The proposed method using the GCE/BiVO/MIP-AA sensor presented a limit of detection (LOD) of 2.9 nmol L, a linear range from 9.7 to 150 nmol L and it was successfully applied for analysis of DA in urine samples using external calibration curve yielding recovery values of 90-105%. Additionally, the proposed PEC sensor allowed DA determination without interference from uric acid, ascorbic acid, epinephrine, norepinephrine, and other unwanted interferences.