Electrochemical detection of dopamine using negatively charged ordered mesoporous carbon (CMK-3)†

The ability to accurately detect dopamine, a crucial neurotransmitter, is essential even in the presence of interfering species. In this paper, we present a simple and effective method that uses a nanoporous conducting structure to detect dopamine. Electric double layer (EDL) overlap in a nanoporous electrode with pores only a few nanometers in size enables selective ion transport, thereby facilitating the entry of oppositely charged species into the nanopores while repelling similarly charged ones. Ordered mesoporous carbon was functionalized with carboxyl groups to create a negatively charged surface that enhances charge selectivity. Electroanalytical techniques revealed that positively charged dopamine exhibited a significantly enhanced signal, whereas that from negatively charged ascorbic acid was effectively suppressed. This negatively charged nanoporous electrode enables dopamine to be highly sensitively detected with sub-nanomolar limits, even in the presence of interfering species and without the need for molecular recognizers. These findings provide valuable insight for the development of high-performance sensors based on nanoporous electrode technology.