Construction of a specific binding peptide based electrochemical approach for sensitive detection of Zn2 +

- A novel electrochemical biosensor for Zn2 + detection is fabricated.
- A specific binding peptide is employed.
- The biosensor has a detection limit of 5 nM.
- This biosensor performs satisfactorily to distinguish expected target ions.

A simple, highly sensitive, and cost-effective electrochemical method for the detection of Zn2 + is constructed employing unmodified gold nanoparticles (AuNPs) and a specific binding peptide. AuNPs are firstly modified on a glassy carbon electrode, which show excellent electrical conductivity and provide a large superficial area for subsequent attachment of peptide with cysteine residues. Acidic amino acids residues of the peptide contribute to large electron transfer resistance, which is recorded by electrochemical impedance spectroscopy. Nevertheless, in the presence of Zn2 +, the recognition sequence of the peptide (CCPGC) binds to Zn2 + with a high affinity and is therefore not able to be modified on the electrode. By analyzing the decrease in electron transfer resistance, Zn2 + level could be determined. The sensitivity of the proposed method is comparable to atomic absorption spectrometry and higher than most fluorescent, colorimetric and electrochemical sensors for Zn2 + assay. Moreover, negligible interference is observed when detecting other ions. Therefore, the developed method has great potential environmental monitoring and clinical applications.

75