Highly selective SERS detection of acetylcholinesterase in human blood based on catalytic reaction

Acetylcholinesterase (AChE) is a key hydrolase in the cholinergic system, which directly determines the degradation of neurotransmitters. Therefore, it is a significant challenge to detect AChE in human blood with high sensitivity and selectivity in physiological and pathological processes. A novel nanoprobe by decorating the surface of gold nanoparticles with neostigmine (NE) AuNPs/NE was constructed for the AChE assay in serum. The principle is based on the specific recognition and cleavage of carbamate bonds in AuNPs/NE by AChE to form hydroxyl groups, resulting in changes of SERS spectra. The results show that 10 nm AuNPs/NE exhibit excellent catalytic activity for this reaction and the reaction rate is six times higher than that of 70 nm AuNPs/NE. Benefiting from the combined advantages of catalytic reaction specificity and molecular finger printing provided by SERS technology, AuNPs/NE exhibit high selectivity for AChE. The limit of detection (LOD) of this method for AChE activity was low to 0.02 U/mL. In addition, the spiked recovery of AChE in serum samples was 75.0%-119.2%. The proposed sensor also exhibits long-term stability and high biocompatibility with the increasing incubation time. More importantly, this work provides a new perspective for elucidating the role of AChE regulated by oxidative stress in the pathology of depression.