Dynamics of BSA adsorption onto a photoablated polymer surface in a dielectric microchip

Dielectric impedance spectroscopy in a microchip was used for monitoring the adsorption of biomolecules onto a heterogeneous polymer surface obtained after the photoablation process. The sensor comprises a thin dielectric layer with two parallel carbon microband electrodes on the one side, and the photoablated surface on the other. The biomolecules need not to be labelled, as in an optical biosensor, even if they need to be attached to the polymer surface coupled with the microelectrodes when a biomolecular interaction occurs. Based on this principle, a flow sensor has been developed to record the adsorption dynamics illustrated with BSA coating on the heterogeneous surface in a linear dynamic range from 1 picomolar to 1 nanomolar at a fixed low frequency. Modeling the dielectric interface using an appropriate equivalent circuit permits extraction of the values of the interfacial impedance for ultralow protein concentrations. The promising results obtained with this methodology make it a competing method in comparison with optical or electrochemical transduction for biosensor development.