Simultaneous Electrochemical Detection of Dopamine and Uric Acid Using Zn/Al-Layered Double Hydroxide-Modified Carbon Paste Electrodes

Here, a carbon paste modified electrode (CPME) with Zn/Al-layered double hydroxide (Zn/Al-LDH) was developed for the simultaneous electrochemical detection of dopamine (DA) and uric acid (UA). The surface morphology and structural features of the synthesized Zn/Al-LDH were analyzed using scanning electron microscopy and X-ray diffraction analysis. The LDH-modified sensor exhibited enhanced adsorptive properties, significantly improving the preconcentration and detection of the targets. Electrochemical characterization using square wave voltammetry demonstrated that the Zn/Al-LDH structure plays a crucial role in increasing sensitivity due to its high surface area and favorable electrostatic interactions by adsorptive preconcentration separate from the electrochemical cell. Under optimized conditions (preconcentration pH of 6.0 and an electrochemical cell pH of 7.0), the sensor demonstrated excellent linearity across biologically relevant concentrations, ranging from 0.2 to 20 μM, in phosphate-buffered saline (PBS), synthetic urine, and synthetic cerebrospinal fluid, with limits of detection of 68 nM for UA and 71 nM for DA. Recovery studies confirmed the sensor’s reliability in complex biological matrices, with recoveries ranging from 90% to 120%. Compared to existing electrochemical sensors, the Zn/Al LDH-modified CPE offers a promising, selective, and efficient platform for neurotransmitter and metabolite analysis in biological samples.