The immunosensors for measurement of 2,4-dichlorophenoxyacetic acid based on electrochemical impedance spectroscopy.
Electrochemical impedance spectroscopy (EIS) was evaluated for the direct determination of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Specific antibody against 2,4-D was immobilised onto different gold electrodes. Several methods of antibody immobilisation by covalent linkage to modified surface were studied. Self-assembled monolayers formed using thiocompounds as cystamine, 4-aminothiophenol (ATPh), 3,3'-dithiopropionic acid di-(N-succinimidyl ester) (DTSP) and 11-mercaptoundecanoic acid (MUA) were chosen for the sensing surface activation. Three different sensor types were tested: screen-printed disc and finger-like structures and interdigitated array (IDA) electrodes produced by lithography. The measurements were carried out in a stationary arrangement, and the reaction between hapten and the immobilised antibody was observed online. Changes of impedance parameters were evaluated, and the best immobilisation technique (using 4-aminothiophenol) was chosen for further measurements. Impedance changes due to immunocomplex formation were evaluated, and the possibility of direct monitoring of 2,4-D binding to the antibody was demonstrated at a fixed frequency. For the strip sensor, the calibration curves were constructed in concentration range from 45 nmol l(-1) to 0.45 mmol l(-1) of 2,4-D.
Department of Biochemistry, Masaryk University, Kotlárská 2, 61137 Brno, Czech Republic. narva@chemi.muni.cz
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Navrátilová
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Skládal
D015084:2,4-Dichlorophenoxyacetic Acid / Q000032:analysis*; D015374:Biosensing Techniques; D002138:Calibration; D017097:Electric Impedance; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D005404:Fixatives; D005976:Glutaral; D006046:Gold; D007103:Immobilization; D007120:Immunochemistry; D007074:Immunoglobulin G / Q000032:analysis; D008563:Membrane Lipids; D013057:Spectrum Analysis / Q000379:methods*; D013438:Sulfhydryl Compounds / Q000737:chemistry
D005404:Fixatives; D007074:Immunoglobulin G; D008563:Membrane Lipids; D013438:Sulfhydryl Compounds; D015084:2,4-Dichlorophenoxyacetic Acid; D006046:Gold; D005976:Glutaral