Immobilization of metallothionein as a sensitive biosensor chip for the detection of metal ions by surface plasmon resonance.
A biosensor based on mammalian metallothionein (MT) for the detection of metal ions was developed and characterized. MT was immobilized onto a carboxymethylated dextran matrix as a biosensor for the detection of metal ions by surface plasmon resonance (SPR). The optimal pH for the immobilization step was determined to be 4. The temperature for the analysis was also defined, and the highest interaction was observed at 30 degrees C. The MT sensor chip binds cadmium (Cd), zinc (Zn) or nickel (Ni), but not magnesium (Mg), manganese (Mn) and calcium (Ca). Calibration curves for the quantification of metal ions showed excellent linearity. The sensitivity for metal detection is at the micromolar level. The interaction between the metal ions and the sensor chip is influenced significantly by the presence of NaCl, Tween 20 and the pH of the reaction buffer. By decreasing the NaCl in the reaction buffer to 1 mM, the MT chip effectively differentiates cadmium from zinc and nickel. Kinetic parameters of the metal-MT interactions were also determined by using this chip. The binding affinity between the metal ions and the immobilized MT follows the order of cadmium > zinc > nickel, which is the same as that determined for MT in solution. Thus, the MT chip can be an effective biosensor for the detection and measurement of several metal ions.
Wu
Ching-Mei
CM
Department of Life Science, National Tsing Hua University, Hsinchu 350, Taiwan, Republic of China.
Lin
Lih-Yuan
LY
D000327:Adsorption; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D008668:Metallothionein / Q000737:chemistry*; D019216:Metals, Heavy / Q000032:analysis* / Q000737:chemistry*; D011485:Protein Binding; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D020349:Surface Plasmon Resonance / Q000295:instrumentation* / Q000379:methods
D020099:Coated Materials, Biocompatible; D019216:Metals, Heavy; D008668:Metallothionein