A Novel Capacitive Sensor Based on Human Serum Albumin–Chelant Complex as Heavy Metal Ions Chelating Proteins

Abstract

In the present study, a capacitive sensor based on human serum albumin (HSA)–chelate complex film as dielectric layer has been fabricated. HSA film was immobilized on gold surface by adsorption method. Thioglycolic acid was used to improve insulatibity of HSA film. The sensors with HSA–chelant complex films as sensing element provide affinity to heavy metal ions. The HSA–disodium ethylenediamine tetraacetate (EDTA) capacitive sensor exhibits considerable sensitivity for heavy metal ions, whereas the HSA–nitronapthalenediazoaminobenzene‐4′‐azobenzene (Cadion 2β) capacitive sensor possessed selectivity for cadmium ion. The relative capacitance change, −ΔC _i/C ₀, vs. logarithm form of cadmium ion concentrations, log c, displayed a linear relationship. The linear range was 1 × 10⁻⁷–6.3 × 10⁻⁶ mol/L.

Keywords:

• Capacitive sensor
• Chelating protein
• Heavy metal ions
• Detection

Acknowledgment

The authors are grateful to Prof. Shouzhuo Yao (Hunan University, P.R. China) for his kindly suggestion. This work was supported by the Natural Science Foundation of education institution of Jiangsu province (No. 03KJB150003), P.R. China.