Highly Sensitive and Selective Electrochemical Sensor via Cu-BTC/Au@Cu-BTC Modified Screen-Printed Electrode for the Detection of Chemical Agents

Chemical agents present significant threat to international peace, security, and human health due to their potential toxicity. Therefore, developing a sensitive, rapid, and on-site detection method is of great importance. Herein, we developed a highly sensitive and selective glove-based electrochemical sensor based on a metal–organic-framework-modified screen printed electrode (SPE) for chemical agent marker detection. Layered copper benzene-1,3,5-tricarboxylate (Cu-BTC) was successfully constructed to modify screen-printed electrodes (SPE) for detecting electrically inactive ethyl methyl phosphonate (EMPA) and isopropyl methyl phosphonate (IMPA). Additionally, gold nanoparticles (AuNPs) reduced by plasma technology have been applied to create gold nanoparticle-encapsulated copper benzene-1,3,5-tricarboxylate-modified screen-printed electrode (Au@Cu-BTC/SPE) composites for detecting thiodiglycol (TDG). The large surface area and porous structure of Cu-BTC and Au@Cu-BTC enhance the target adsorption and ion diffusion and the efficient use of catalytic materials for rapid electron transfer and zero-distance catalysis. The limit of detection (LOD) was determined to be 4.13 × 10–16 M for EMPA, 7.46 × 10–12 M for IMPA, and 4.05 × 10–12 M for TDG. Following multiple cycles and extended exposure, the sensor demonstrated exceptional repeatability and stability. The response current of Cu-BTC to EMPA and IMPA decreased by 6.75% and 4.86%, and the peak value of Au@Cu-BTC to TDG decreased by 3.3% after 4 weeks, respectively. The peak current showed a good linear relationship with the concentrations of the three target substances, with R2 values all greater than 0.99. The interaction mechanism between the modified electrode and the targets was investigated by density functional theory (DFT) with the generalized gradient approximation of the PBE functional. The results showed that compared with other metal ions, Cu2+ could coordinate tighter with organophosphates. The established MOF-modified SPE integrated with a protective glove sensor was applied for the detection of real-world samples and demonstrated a broad spectrum of practical applications.