Electrochemical immunosensors based on nanocaps and nanodots arrays. – ImmuNanoCaps

The immunosensors based on electrochemical transducers have gained great attention for clinical diagnostics, since they present simplified instrumentation, high sensitivity and low cost. Over time, the infection risk of vector-borne diseases in southern Europe and in particular along the Mediterranean coast should increase considerably. The project focuses on the use of innovative conductive nanocapsules for the development of sensitive label-free electrochemical immunosensors for the detection of infectious vector-borne diseases such as West Nile virus (WNV) and Dengue virus (DENV). The advantage of the nanocapsules, developed and produced at IJL in Nancy, is the possibility to tailor their size and composition to provide optimal conditions for the compounds to encapsulate or to graft. The DCM partner at Grenoble will be in charge of the electrochemical functionalization of conductive nanocapsules with functional polymer and of the development of label-free electrochemical immunosensors.

The first goal aims to enhance the sensitivity and the limit of detection for two label free impedimetric immunosensors by using a nanostructured surface device, one for the diagnostic of West Nile virus and the other for the Dengue virus. Metallic interdigitated electrodes will be fabricated by the partner IJL using microtechnology process (Ebeam lithography, photolithography, etching, thin-film deposition, …). These electrodes will be modified by coating their surface with appropriate nanostructured capsules selected in order to enhance the electron-transfer properties of the sensor but also to improve the binding properties of the bio-receptor. The immobilization of antigens will be performed by electrochemically-generated polymers, which can provide covalent binding or affinity interactions between the antigen and the functionalized polymer. Two architectures are proposed: the first proposal operates in "common" mode with a two electrodes device, the second proposal operates in "differential" mode in order to overcome the problem of the interfering signals.

The second goal aims to long-term conservation amperometric immunosensor where the enzyme labelled antibody are encapsulated in nanocapsules and are delivered at will. This immunosensor works by competition between the sample antibodies and the encapsulated labelled antibodies. Indeed, the antibodies conjugated with the enzyme will be placed in closed nanocapsules. This aims to increase significantly the lifetime of biosensors. The encapsulation of the enzyme labelled antibodies allows their long-term stability, and can be released at will with a mechanical action, for example with an ultrasonic field. On the same device, separated by a diffusion zone, are placed an area dedicated to the amperometric detection on which antigens will be grafted via a polymer electrogenerated as in the first deliverable and an area with the filled nanocapsules. Thus, our immunosensor, using lateral-flow design, can help to supplement technologies applied to point-of-care diagnosis in extremely under-resourced environments.