Stable Leonurus cardiaca L. polysaccharide-stabilized palladium nanoparticles for sensitive colorimetric detection of acetylcholine.

Imbalances in acetylcholine levels within the human body readily precipitate neurological disorders. Hence, establishing a highly efficient and sensitive acetylcholine detection platform is of paramount importance. Palladium-based nanoparticles have high catalytic performance, which is of profoundly important in the development of nanozyme technology. Herein, we focused on extracting Leonurus cardiaca L. polysaccharide (LCLP) from Leonurus cardiaca L., which possesses an average molecular weight of 11,910 Da. Meanwhile, it has certain reducing power. Leonurus cardiaca L. polysaccharide-stabilized palladium nanoparticles (Pd-LCLP NPs) were prepared. Pd-LCLP NPs exhibited remarkable peroxidase-like properties due to their ability to decompose HO into OH. In addition, Pd-LCLP NPs were combined with the chromogenic substrate 3,3',5,5'-tetramethylbenzidine to form a colorimetric detection system for the detection of acetylcholine. The linear detection range and the limit of detection were 10 μM-200 μM and 1.02 μM (S/N = 3), respectively. This research broadened the horizon for the development of acetylcholine colorimetric biosensing systems.