Disposable Smart Immunosensing Biochip Using a Novel Electrochemical signaling Method

This paper presents a smart immunosensing biochip using a novel electrochemical method for the portable clinical diagnostics system. The fluid flow of this device can be induced by capillary attraction force only and controlled by a geometrical structure. By this fluid transport mechanism, it does not require external electrical power or control circuit parts. Therefore it is suitable for disposable and portable lab-on-a-chip applications. The fabricated biochip consists of the two poly(dimethyl siloxane) (PDMS) layers and a glass substrate for immunoelectrodes. The size of the biochip is 25times20times6 mm³. The signal amplification strategy applied in this biochip is based on the back-filling immobilization of biocatalytic enzyme at immunoelectrodes, circumventing the use of enzyme-labeled antibody. For the immunosensing surface construction, a poly(amidoamine) G4-dendrimer was employed as a matrix for ligand functionalization. As a model biorecognition reaction, the dinitrophenyl (DNP) antigen-functionalized electrode was fabricated and an anti-DNP antibody was used. Glucose oxidase (GOX) was chosen to amplify electrochemical signal by enzymatic catalysis. The non-labeled native antibody was biospecfically bound to the immobilized ligand, and the activated enzyme (periodate-treated GOX) reacted and back-filled the remaining surface amine group on the dendrimer layer