A new multi-identification system based on a poly(l-cysteine) sensor for simultaneous detection of multiple steroid hormones in serum

•A P(l-Cys)/GCE sensor was prepared as a synthetic receptor for multiple hormones.•The recognition site of this sensor for the steroid parent nucleus is Δ4-3-ketone.•The reduction potential of steroids varies with their parent nucleus.•The reduction signal of steroids does not interfere with other coexisting steroids.•Hormones in serum can be detected simultaneously with the P(l-Cys)/GCE sensor.