A one-step, separation-free amperometric enzyme immunosensor

• Published in: Biosensors & bioelectronics 1996, Vol.11 (4), p.409-417
• Main Authors: Ivnitski, D., Rishpon, J.
• Format: Article
• Language: English
• Subjects: amperometry; Antibodies; Biological and medical sciences; Biosensing Techniques; Biosensors; Biotechnology; Cost Control; disposable electrode; Electrochemistry; enzyme immunoassay; Fundamental and applied biological sciences. Psychology; Glucose Oxidase; Immunoenzyme Techniques - economics; immunosensor; Methods. Procedures. Technologies; Sensitivity and Specificity; signal-amplification systems; Time Factors; Various methods and equipments
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/0956-5663(96)82736-9

A new one-step, separation-free, amperometric enzyme immunosensor is described. The sensor consists of an antibody electrode that is low cost, disposable, and operates without washing or separation steps. The immunosensor combines the following signal-amplification systems: enzyme-channeling immunoassay; accumulation of the redox mediators (I 2/I −); cyclic regeneration of an enzyme (peroxidase) substrate at the (polyethylenimine) polymer/electrode interface; and control of the hydrodynamic conditions at the interface of the antibody electrode. The immunological reactions were monitored electrochemically in situ, and the binding curves were directly visualized on a computer screen. The complete immunoassay can be performed in 5–20 min depending on the complexity of the immunological reactions. Model systems using rabbit IgG and human luteinizing hormone (hLH) in a ‘sandwich’ immunoassay revealed that the immunosensor can detect concentrations of hLH in human serum as low as 1 ng ml −1.