Single-walled carbon nanotube based coating modified with reduced graphene oxide for the design of amperometric biosensors

In this study a polycarbonate filter membrane (PcFM) with 400 nm diameter holes was covered/protruded by single walled carbon nanotubes (SWCNT) and then formed PcFM/SWCNT structure was covered by thin layer of graphene oxide (GO) or reduced graphene oxide (rGO) in order to get the multilayered PcFM/SWCNT/GO and PcFM/SWCNT/rGO coatings, respectively. It was determined that the SWCNTs filaments were able to form a layer on the polycarbonate membrane having a number of carbon nanotube arranged in different orientations. A fraction of SWCNT filaments protruded through the holes of polycarbonate membrane and in such way significantly enhanced the adhesion of SWCNT-based layer and provided electrical conductivity across the PcFM. Atomic force microscopy (AFM), scanning electron microscopy (SEM) images and Raman spectroscopy-based evaluation revealed the characteristic morphology features: wide distribution of height profile, separate GO/rGO flakes on the top of PcFM/SWCNT/GO structure and close attachment of rGO flakes on the top of multilayered PcFM/SWCNT/rGO coating. Performed contact angle measurement (CAM) enabled to determine the surface energy components and wettability data of prepared coatings. Both PcFM/SWCNT/GO and PcFM/SWCNT/rGO coatings were modified with glucose oxidase (GOx). Amperometric measurements revealed that multilayered PcFM/SWCNT/rGO/GOx coating is the most suitable structure for glucose biosensor design.