Nano-yarn carbon nanotube fiber based enzymatic glucose biosensor

Abstract

A novel brush-like electrode based on carbon nanotube (CNT) nano-yarn fiber has been designed for electrochemical biosensor applications and its efficacy as an enzymatic glucose biosensor demonstrated. The CNT nano-yarn fiber was spun directly from a chemical-vapor-deposition (CVD) gas flow reaction using a mixture of ethanol and acetone as the carbon source and an iron nano-catalyst. The fiber, 28 μm in diameter, was made of bundles of double walled CNTs (DWNTs) concentrically compacted into multiple layers forming a nano-porous network structure. Cyclic voltammetry study revealed a superior electrocatalytic activity for CNT fiber compared to the traditional Pt-Ir coil electrode. The electrode end tip of the CNT fiber was freeze-fractured to obtain a unique brush-like nano-structure resembling a scale-down electrical 'flex', where glucose oxidase (GOx) enzyme was immobilized using glutaraldehyde crosslinking in the presence of bovine serum albumin (BSA). An outer epoxy-polyurethane (EPU) layer was used as semi-permeable membrane. The sensor function was tested against a standard reference electrode.The sensitivities, linear detection range and linearity for detecting glucose for the miniature CNT fiber electrode were better than that reported for a Pt-Ir coil electrode. Thermal annealing of the CNT fiber at 250 •C for 30 min prior to fabrication of the sensor resulted in a 7.5 fold increase in glucose sensitivity. The as-spun CNT fiber based glucose 2 biosensor was shown to be stable for up to 70 days. In addition, gold coating of the electrode connecting end of the CNT fiber resulted in extending the glucose detection limit to 25 μM. To conclude, superior efficiency of CNT fiber for glucose biosensing was demonstrated compared to a traditional Pt-Ir sensor.

AlN-based BAW resonators with CNT electrodes for gravimetric biosensing

“…Numerical simulations of the sensitivities of the fabricated devices to BSA were carried out by using the one dimensión Mason's model [49]. Thin layers of BSA proteins (density ~1 g cirr 3 [50]) were numerically added on top of both resonators and their responses to the additional mass loading were calculated as shown in Fig. 11.…”

“…Although there exist numerous types of biosensors such as optically based sensors [1,2], electrochemical sensors [3,4], cantilever-based detectors [5,6] or acoustic wave sensors [7,8], the acoustic wave technologies have the combined merit of all otherbiosensors: labelfree, ultra-high sensitivity, small size, electronic signal, easy to use and low-cost.…”

Polymer Composites with Carbon Nanotubes in Alignment

“…For instance, Wei et al reported that aligned nanotube/poly(vinyl acetate) arrays showed high sensitivity and good selectivity to a wide variety of chemical vapors such as tetrahydrofuran, ethanol, and cyclohexane (Wei et al, 2006). The similar improvements at sensing capabilities after the nanotube alignment had been also observed for detections of the glucose and other biosensing applications (Lin et al, 2003;Zhu, Z. et al, 2010). As previously discussed, the aligned nanotube/polymer composites show a semiconducting behavior with three-dimensional hopping conduction mechanism.…”

“…In contrast, aligned nanotubes do not need direct manipulation of individual nanotubes. Particularly, the resistance changes of individual nanotubes could be greatly amplified as millions of nanotubes were collectively addressed through a common electrode (Lin et al, 2003;Wei et al, 2006;Zhu, Z. et al, 2010). For instance, Wei et al reported that aligned nanotube/poly(vinyl acetate) arrays showed high sensitivity and good selectivity to a wide variety of chemical vapors such as tetrahydrofuran, ethanol, and cyclohexane (Wei et al, 2006).…”

Investigation of the Influence of the As-Grown ZnO Nanorods and Applied Potentials on an Electrochemical Sensor for In-Vitro Glucose Monitoring

“…The ability to monitor glucose accurately and regularly requires highly sensitive, highly selective, and reusable glucose sensors. [6][7][8][9][10]. A ZnO NR-based glucose sensor was tested by Wei et al Although ZnO NRs were grown on a thin gold film, the influence of gold was not investigated and the device was tested under 0.8 V. The obtained sensitivity was in the order of 23.1 µA·cm −2 ·mM −1 , and it was not filtered by subtracting the influences of the substrate [11].…”