Immunosensors analytical process

There are mainly three types of transducers used in immunosensors electrochemical, optical, and microgravimetric transducers. The immunosensors may operate either as direct immunosensors or as indirect ones. For direct immunosensors, the transducers directly detect the physical or chemical effects resulting from the immunocomplex formation at the interfaces, with no additional labels used. The direct immunosensors detect the analytes in real time. For indirect immunosensors, one or multiple labeled bio-reagents are commonly used during the detection processes, and the transducers should detect the signals from the labels. These indirect detections used to need several washing and separation steps and are sometimes called immunoassays. Compared with the direct immunosensors, the indirect immunosensors may have higher sensitivity and better ability to defend interference from non-specific adsorption. 

Number of antibodies that can be produced is practically unlimited, hence wide development of immunoassays not only for determination of macromolecules, which induce immunoreactions, but also for small molecule analytes inducing such reaction after binding into suitable conjugates. Besides immunoassays carried out in various formats and immunoaffinity liquid chromatography, since many years very broad studies are carried out on design of integrated immunosensors.127129 In principle their construction should simplify the immunochemical determination by elimination various steps necessary in conventional immunoassays based on the use of labels to monitor the immunochemical reaction. In immunochemical process, the... 

The schematic of the flow-injection immunofiltration assay system is shown in Fig. l.b. The system has the following main components the immunosensor assembly (locked components as shown in Fig. l.a), a peristaltic pump, a five-way valve with flow injector and a mixing chamber, reagents and waste vessels, analyte supplier and an electrochemical interface which consists of a dedicated calibrated potentiostat, an LC display and analog data output. The electrochemical interface is used to provide the working potential for the immunosensor and to process the output signal. A manual jack is used for moving the holder to lock with the immunocolumn and the adapter (motion shown by arrows in Fig. l.a). 

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