A novel MCS-based electrochemical sensor for Pb(II) detection in the presence of nitrophenols

Due to the presence of toxic pollutants in wastewater, such as heavy metals and organic compounds, we developed a novel electrochemical sensor based on meta-chemical-surface (MCS)-based poly-methyl methacrylate-glutathione (PMMA-GSH) using the dip-pen nanolithography (DPN) technique. This sensor was specifically designed to detect Pb(II) in the presence of common organic contaminants found in wastewater, namely, p -nitrophenol (pNP) and o -nitrophenol (oNP). The MCS PMMA-GSH electrode exhibited enhanced sensitivity for Pb(II) detection across a broad concentration range of nitrophenols (3 ppb to 10 ppm), in various media with and without minerals, and both in the presence and absence of pNP and oNP. The results indicate that the sensor effectively detects Pb(II) even when water contains organic compounds soluble in aqueous media. The limit of detection (LoD) increased with higher concentrations of nitrophenols, influenced by the specific type of nitrophenol and the competitive binding interactions between Pb(II), GSH, which is part of the nanoclusters, and nitrophenols. Density Functional Theory (DFT) calculations supported these observations, indicating that Pb(II) does not bind to oNP, allowing preferential binding to GSH and thus enhancing sensitivity. In contrast, pNP tends to bind Pb(II), reducing sensor sensitivity. To the best of our knowledge, this is the first electrochemical sensor capable of detecting Pb(II) at the ppb range in the presence of organic pollutants. These findings are significant for environmental monitoring and water quality assessment, as the sensor is portable, easy to use, and requires minimal material, aligning with the principles of green engineering.