Development of a screen-printed sensor decorated with Pt-Ni microstructures for the detection of Zn(II), ascorbic acid, and paracetamol

Abstract

Self-medication with over-the-counter (OTC) analgesics like paracetamol (PA) and its toxic byproduct, 4-aminophenol (4-AP), is on the rise. While OTC analgesics are generally safe at recommended doses, overuse can lead to liver and kidney damage. Ascorbic acid (AA) and zinc ion (Zn(II)) are often combined with PA, but excessive intake can cause gastrointestinal, kidney, and neurological issues. The unmonitored use of these substances individually or in combination raises concerns about potential overdoses and adverse reactions, highlighting the need for reliable, sensitive detection methods to ensure patient safety. Due to the electroactive nature of PA, 4-AP, AA, and Zn(II), electrochemical sensors, particularly screen-printed electrodes (SPEs), have emerged as a promising tool. SPEs, typically consisting of a working electrode, counter electrode, and reference electrode on a single substrate, have gained widespread popularity in electroanalysis over the past few decades for offering advantageous material properties, including disposability, fast response times, compact size, low cost, and ease of portability. This thesis presents the development of two electrochemical sensors based on screen-printed electrodes modified with Pt–Ni bimetallic nanoparticles for detecting paracetamol, 4-aminophenol, ascorbic acid, and zinc. The sensors, differing in their working electrodes (graphite vsgraphene), utilize Pt–Ni nanoparticles for enhanced electro-catalytic performance, enabling both individual and simultaneous detection in pharmaceutical and biological samples. The first sensor, a Pt–Ni-modified graphite-based SPE, enabled the simultaneous detection of 4-AP, PA, AA, and Zn(II). The Pt–Ni/SPE electrode was characterized by field emission scanning electron microscope (FE–SEM), transmission electron microscope (TEM), energy dispersive X–ray spectroscopy (EDX), X–ray diffractometry (XRD), and atomic force microscopy (AFM), and its electrochemical performance was assessed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimum conditions, the content of 4-AP, PA, AA and Zn(II) was quantified using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and square-wave voltammetry (SWV) techniques. The sensor demonstrated a linear DPV response for 4-AP and PA (0.5 to 200 μM) with detection limits (LODs) of 0.33 µM and 0.23 µM (S/N = 3), and sensitivities of 0.768 ±0.01 µA〖µM〗^(-1) 〖cm〗^(-2)and1.289 ±0.01 µA〖µM〗^(-1) 〖cm〗^(-2), respectively. For PA, AA, and Zn(II), the sensor exhibited linear responses ranging from 0.01 to 0.8 μM for Zn(II), 10 to 1800 μM for AA, and 0.5 to 200 μM for PA, with detection limits of 0.004 µM, 9.0 µM, and 0.15 µM for Zn(II), AA, and PA, respectively. The sensor demonstrated excellent reproducibility, stability, and anti-interference performance, successfully detecting 4-AP, PA, AA, and Zn(II) in pharmaceutical formulations and human plasma samples. The second sensor, a Pt–Ni-modified graphene-based SPE (Pt–Ni/SPGE), was developed for individual and simultaneous detection of 4-AP, AA, and PA. It showed excellent performance, exhibiting linear CV ranges from 1.0 to 1000 µM, with LOD (S/N = 3) value of 2.0 µM for both 4-AP and PA, alongside sensitivities of 2.8 ±0.01 µA〖µM〗^(-1) 〖cm〗^(-2) for 4-AP and 1.4 ±0.01 µA〖µM〗^(-1) 〖cm〗^(-2)for PA. Additionally, it demonstrated linearity from 10 µM to 2400 µM for AA and 1.0 µM to 800 µM for PA, with LODs of 30 µM and 5.0 µM, respectively. These findings demonstrate the potential of Pt–Ni-modified SPEs for sensitive, simultaneous detection of pharmaceuticals, offering a cost-effective, rapid tool for monitoring self-medication and preventing drug interactions.