Aqueous electrodeposition of (AuNPs/MWCNT–PEDOT) composite for high-affinity acetylcholinesterase electrochemical sensors

In this work, an electrochemical transducing platform constructed from carbonaceous tubes modified with thiophene polymer and gold nanoparticles was described. The negatively charged carbon tubes attracted monomers on their surface, then migrated toward the electrode upon electrical driving force, and finally deposited on the electrode surface. Consequently, these carbon tubes were coiled and wrapped with prolonged conjugated polymer chains. Gold nanoparticles were found to be mainly nucleated and grown at highly conductive sites on carbon tubes. The combination of 2-D polymer segments, 1-D carbon tubes, and 0-D metal particles has resulted in a highly porous 3-D architecture which is crucial to increasing the electrochemical responses. Meanwhile, the charge propagation was promoted due to synergistic effect between these biocompatible and conductive materials and evidenced by a significant increase in charge transfer rate (3.5 times) and dramatic reduction in charge transfer resistance (disappearance of semicircle in Nyquist plot). The acetylcholinesterase sensor based on as-prepared hybrid film shows good attraction to acetylthiocholine (K^app_m = 0.182 mM). Thus, the developed sensor will provide a promising tool to analyze neurotransmitters and enzyme inhibitors.