Carbon Nanotube-Filled Nanofibrous Membranes Electrospun from Poly(acrylonitrile-co-acrylic acid) for Glucose Biosensor

Due to its unique electrical properties, carbon nanotubes offer the exciting possibility for developing ultrasensitive electrochemical biosensors. In this work, nanofibrous membranes filled with multiwalled carbon nanotube (MWCNT) were electrospun from the mixture of poly(acrylonitrile-co-acrylic acid) (PANCAA) and MWCNT. These nanofibrous membranes were directly deposited on Pt electrodes for the fabrication of glucose biosensors. Glucose oxidase (GOx) was covalently immobilized on the membranes through the activation of carboxyl groups on the PANCAA nanofiber surface. The fluorescence spectra and circular dichroism were recorded from the mixtures of MWCNT and soluble GOx. Results show that MWCNT will disturb the secondary structure of soluble GOx but can get close to its active site. The morphologies of the nanofibrous membranes were visualized by scanning electron microscopy, illustrating that the membranes are composed of beads and nanofibers. The electrochemical properties of enzyme electrodes were characterized by chronoamperometric measurments. It is found that as MWCNT concentration increases, the current enhances correspondingly with a maximum of 50%, while the MWCNT filling delays the electrode response. Kinetic studies of the electrodes show that the secondary structure of the immobilized GOx is disturbed, while the embedded MWCNT enhances the maximum current of GOx electrode. Moreover, the enzyme electrodes can be used up to 6 times with a small decrease in current.