Nanoparticle-based 3D membrane for impedimetric biosensor applications.

This paper reports on a comparison between nano-ZnO/CuO and nano-ZnO nitrocellulose membrane biosensors, both of which were fabricated using a simple and inexpensive sonication technique. To produce the nano-ZnO/CuO membranes, the technique involved sonication of 1% (w/v) ZnO and 1% (w/v) CuO nano-crystal colloidal suspensions, with a volume ratio of 1:2. The membranes were analysed by scanning electron microscopy and energy-dispersive spectroscopy, which showed the gradated distribution of nanoparticles in the membrane. Impedance spectroscopy demonstrated that the sonication resulted in a greater than two-fold enhancement of the output signal. Changes in impedance phase values, at a frequency of 100 Hz, were used to establish dose dependent responses for C-reactive protein (CRP). Limits of detection of 27 pg/mL for the 1% (w/v) nano-ZnO and 16 pg/mL for the 1% (w/v) nano-ZnO/CuO nitrocellulose membrane biosensors were demonstrated.