Development of a Highly Enantioselective Capacitive Immunosensor for the Detection of α-Amino Acids
2006; American Chemical Society; Volume: 78; Issue: 21 Linguagem: Inglês
10.1021/ac060840h
ISSN1520-6882
AutoresSong Zhang, Jingjing Ding, Ying Liu, Jilie Kong, Oliver Hofstetter,
Tópico(s)Molecular Sensors and Ion Detection
ResumoThis work describes a highly enantioselective and sensitive immunosensor for the detection of chiral amino acids based on capacitive measurement. The sensor was prepared by first binding mercaptoacetic acid to the surface of a gold electrode, followed by modification with tyramine utilizing carbodiimide activation. The hapten 4-amino-d-phenylalanine was then covalently immobilized onto the electrode by diazotization. Stereoselective binding of an anti-d-amino acid antibody to the hapten-modified sensor surface resulted in capacitance changes that were detected with high sensitivity by a potentiostatic step method. Using capacitance measurement, detection limits of 5 pg of antibody/mL were attained. The exquisite stereoselectivity of the antibody was also utilized in a competitive setup to quantitatively determine the concentration of the analyte d-phenylalanine in nonracemic samples containing both enantiomers of this amino acid. Trace impurities of d-phenylalanine as low as 0.001% could be detected.
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