Amperometric indicator displacement assay for biomarker monitoring: Indirectly sensing strategy for electrochemically inactive sarcosine

Indicator displacement assay plays a fundamental role in the development of chemosensors . We explored here an ingenious yet effective strategy for amperometric assay of electrochemically inactive sarcosine based on an indicator displacement principle, in which 1,2-naphthoquinone-4-sulphonic acid sodium salt (NQS) was proposed as the receptor and the electroactive Ru(NH 3 ) 6 3+ cations used as an indicator. Due to the stronger binding affinity of the NQS toward sarcosine than toward Ru(NH 3 ) 6 3+ , the developed amperometric indicator displacement assay (A-IDA) exhibits high selectivity and excellent sensitivity toward sarcosine determination as well as with a lower detection limit (30.00   nM, S/N =3).