Highly sensitive and selective detection of cancer cell with a label-free electrochemical cytosensor

► A cytosensor with high sensitivity and selectivity was developed. ► Folic acid was used to specifically recognize cancer cells. ► Surface-confined ferrocene was used as the signal indicator. ► The detection concentration range of HeLa cell was from 10 to 106 cells/mL. ► Fast DPV measurement could reduce the loss of cell viability.