Disposable electrochemical immunosensor for carcinoembryonic antigen using ferrocene liposomes and MWCNT screen-printed electrode

Disposable electrochemical immunosensor for the detection of carcinoembryonic antigen (CEA) in saliva and serum was developed. Monoclonal anti-CEA antibodies (alpha CEA) were covalently immobilized on polyethyleneimine wrapped multiwalled carbon nanotubes screen-printed electrode. A sandwich immunoassay was performed with CEA and alpha CEA tagged ferrocene carboxylic acid encapsulated liposomes (alpha CEA-FCL). The square wave voltammetry (SWV) was employed to analyze faradic redox responses of the released ferrocene carboxylic acid from the immunoconjugated liposomes on the electrode surface. The magnitude of the SWV peak current was directly related to the concentration of CEA. The calibration curve for CEA concentration was in the range of 5 x 10(-12) to 5 x 10(-7) g mL(-1) with a detection limit of 1 x 10(-12) g mL(-1) (S/N = 3). This method provides a high precise and sensitive determination of CEA in human blood serum and saliva samples. (C) 2008 Elsevier B.V. All rights reserved.