Cell Sensing via a Peptide/Single-Strand DNA Probe-Modified Au Screen-Printed Electrode

An electron-transfer/His-tag peptides-single-strand (ss) DNA probe is designed for the detection of cancer cells. Human myeloid leukemia cells (K562 cells) are commonly used as a model for target cancer cells. An electron-transfer peptide plays the role of a sensing moiety, and a His-tag moiety is introduced to purify the probe. A KK1B10 aptamer conjugated with the peptide sequence as an ss-DNA with target cell recognition properties is used. A probe with cysteine residue at the N-terminals is then immobilized on an Au screen-printed electrode (AuSPE). To evaluate the effect of the amino acid sequence in the probe, three types of probes are synthesized. The acetylated(Ac)-CYYCYYCH₆-amino modifier C₆(AmC₆)KK1B10 aptamer probe proves to be a superior version. The K562 cells can interact with the probe on the electrode, and the electrode responses of the probe are decreased with increases in the concentrations of the cells. The peak currents are proportional to the concentrations of the cells and ranges from 5 to 200 cells mL with a detection limit of 2 cells/mL. The recovery 99%-102% of K562 cells in human serum and bovine blood is calculated using the probe-modified AuSPE. Consequently, the proposed method can be applied to the detection of target cells.