Single-Cu-atom anchoring on covalent organic framework as a wearable flexible electrochemical sensor for acetaminophen

In this paper, a wearable flexible patch featuring a non-enzymatic electrochemical sensor based on Cu single-atom catalysts (SACs) anchored on bipyridine-covalent organic framework (COF) electrode was proposed for specific detection of acetaminophen (AP) in human sweat. The electrode modified material is Cu single atom catalytic material (Cu-TpBpy). The bifunctional TpBpy acts as a support for binding individual Cu atoms through abundant and well-organized N-N chelating sites, while simultaneously serving as an active host for specific recognition/adsorption of AP due to its porous structure and active N sites. The resulting Cu-TpBpy with atomically dispersed Cu sites demonstrated high electrochemical activity for AP, attributed to enhanced electron transfer efficiency and reduced binding and adsorption energies. Density functional theory calculations further reveal that the Cu single-atom anchoring on TpBpy provides superior adsorption of AP than TpBpy alone, resulting in lower binding energy, and higher selectivity and sensitivity. The wearable flexible patch, based on Cu-TpBpy, enabled real-time and accurate detection of AP in human sweat and achieved a linear range of 0.3 µM-5 µM and a limit of detection of 13 nM, with satisfied stability and repeatability. This work developed a highly sensitive non-enzymatic sensing method for wearable flexible patches.