Application of Calcium-Binding Motif of E‑Cadherin for Electrochemical Detection of Pb(II)

• Published in: Analytical chemistry (Washington) 2018-06, Vol.90 (11), p.6519-6525
• Main Authors: Lotfi Zadeh Zhad, Hamid R, Lai, Rebecca Y
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino acids; Analytical chemistry; Binding Sites; Biosensing Techniques - methods; Cadherins - chemistry; Calcium; Calcium - chemistry; Carbon - chemistry; Chemistry; Cost analysis; Drinking water; E-cadherin; Electrochemical analysis; Electrochemical Techniques - methods; Electrodes; Gold; Gold - chemistry; Humans; Immobilized Proteins - chemistry; Lead - analysis; Lead - urine; Methylene blue; Methylene Blue - chemistry; Peptides; Peptides - chemistry; Pulse duration; Saliva; Saliva - chemistry; Sensors; Substrates; Urine; Voltammetry
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/acs.analchem.7b05458

We report, for the first time, the use of a 13-amino-acid peptide sequence derived from the calcium-binding site of E-cadherin in the fabrication of an electrochemical peptide-based (E-PB) Pb­(II) sensor. The sensing mechanism is analogous to that of previously developed E-PB sensors. Binding of Pb­(II) rigidifies the surface-immobilized and methylene blue (MB)-modified peptide probe, thereby limiting the accessibility of the tethered MB to the electrode surface. This change in probe flexibility results in a reduction in the MB current that is dependent on the target concentration. The sensor behaves as a “signal-off” sensor in alternating current voltammetry and cyclic voltammetry, but it can behave as a “signal-on” sensor in differential pulse voltammetry when a longer pulse width is employed. It is capable of specific detection of Pb­(II) and is selective enough to be employed in realistically complex samples such as diluted tap water, saliva, and urine samples. The detection is fast; signal saturation can be achieved in