A gold nanoparticle labeling strategy for the sensitive kinetic assay of the carbamate–acetylcholinesterase interaction by surface plasmon resonance

The article presents a novel strategy for a sensitive investigation of the interaction between acetylcholinesterase (AChE) and its small molecular carbamate inhibitors. Two carbamate inhibitors with different ether linkages and the terminal lipoate were synthesized and labeled with gold nanoparticles (AuNPs). With the signal amplification of AuNPs, the specific interactions between the AuNPs labeled carbamate inhibitors (ALC1 and ALC2) and the immobilized AChE on sensor chip surface were readily examined. The detection sensitivities of ALC1 and ALC2 were 176 and 121 m°/nM, respectively, with the detection limits of 7.0 and 12 pM at a signal-to-noise ratio of 3. The association/dissociation constants for the binding interaction between carbamate inhibitors and AChE were reported for the first time. The affinity constants were estimated to be 3.13 × 106 and 6.39 × 105 M−1 for ALC1 and ALC2 respectively. This AuNPs labeling strategy is versatile and may be applicable for the direct or competitive SPR kinetic assay of the interaction between small molecule inhibitors and their target proteins with a high sensitivity.