Electrochemical detection of the antidiabetic agent metformin using nickel-cobalt layered double hydroxide (Ni–Co LDH)

Metformin is a first-line medication for treating type 2 diabetes mellitus, 70% of which remains unmetabolized in the body. As it degrades, metformin converts into guanylurea (GUU), and together these compounds have been identified as contaminants in surface waters. Their presence poses a significant threat to aquatic ecosystems, leading to reduced fecundity and increased oxidative stress in fish, which can ultimately have downstream impacts on human health. This concern highlights the need for a rapid and reliable sensor to quantify metformin, a key pharmaceutical pollutant. This study aims to develop an electrochemical sensor capable of detecting low concentrations of metformin using a nickel-cobalt layered double hydroxide-modified glassy carbon electrode (GCE). The fabricated electrode exhibits strong electrocatalytic activity toward metformin detection due to the synergistic redox mediation of the M2+/M3+ (Ni/Co) couple. Amperometric measurements show a low detection limit of 7 nM, a linear range of 5–55 nM, and a sensitivity of 0.004 µA nM−1, with a rapid response time of under 20 s. Overall, the non-enzymatic Ni-Co LDH-modified electrode provides a simple, sensitive, and effective platform for the electrochemical detection of metformin.