Amperometric Glucose Biosensor Based on Glucose Oxidase Encapsulated in Carbon Nanotube–Titania–Nafion Composite Film on Platinized Glassy Carbon Electrode

Abstract

A highly sensitive and selective glucose biosensor has been developed based on immobilization of glucose oxidase within mesoporous carbon nanotube -titania -Nafion composite film coated on a platinized glassy carbon electrode. Synergistic electrocatalytic activity of carbon nanotubes and electrodeposited platinum nanoparticles on electrode surface resulted in an efficient reduction of hydrogen peroxide, allowing the sensitive and selective quantitation of glucose by the direct reduction of enzymatically-liberated hydrogen peroxide at À 0.1 V versus Ag/AgCl (3 M NaCl) without a mediator. The present biosensor responded linearly to glucose in the wide concentration range from 5.0 Â 10 À5 to 5.0 Â 10 À3 M with a good sensitivity of 154 mA M À1 cm À2. Due to the mesoporous nature of CNT -titaniaNafion composite film, the present biosensor exhibited very fast response time within 2 s. In addition, the present biosensor did not show any interference from large excess of ascorbic acid and uric acid.

Biosensors Based on Biological Nanostructures

“…However the achievement of ideal devices is not trivial and depends on factors such as biocompatibility, long-term stability, selectivity, reproducibility and miniaturization (Sadik, Aluoch et al, 2009). Nanobiosensors must exhibit dimensions of elementary biomolecules (~1000 nm) such as enzymes, proteins and DNA, and are promising in the monitoring of various physical and biochemical parameters such as body temperature, oxygen and blood glucose leves (Hiller, Kranz et al, 1996;Fiorito e De Torresi, 2001;Kros, Van Hovell et al, 2001) (Choi, Han et al, 2007). Among the applications, implantable biosensors are applied on DNA testing and pregnancy monitoring (Erdem, Karadeniz et al, 2009).…”

A Facile Preparation of H2O2 Sensors Using Layer‐by‐Layer Deposited Thin Films Composed of Poly(ethyleneimine) and Carboxymethyl Cellulose as Matrices for Immobilizing Hemin

“…It has been reported that hemin-modified electrodes exhibit redox peaks around À 0.1 to À 0.6 V, the redox potential being dependent on the type of protocol for the modification of hemin [21 -23]. Thus, the hemin-modified electrode can be easily prepared using the (PEI-CMC) 5 PEI LbL film. It is noted here that the CV response is stable and virtually no deterioration in the CV is observed upon the repeated potential cycling after overnight rinsing.…”

“…1.2 g cm À3 [28]. The (PEI-CMC) 5 PEI film-coated GC electrode was immersed in 0.05 mM hemin in 10 mM Tris-HCl buffer containing 50 mM NaCl (pH 7.4) for 60 min to impregnate the LbL film with hemin. The loading process of hemin in the LbL film was monitored for 90 min by measuring cyclic voltammetry occasionally and found that the loading was saturated after 60 min under the experimental conditions.…”

“…The repeated deposition of PEI and CMC on the surface of the quartz resonator under the same experimental conditions as above induced a negative shift in the resonance frequency, suggesting a successful preparation of the LbL film. The thickness of the 5-bilayer film (PEI-CMC) 5 PEI was estimated to be 64 AE 13 nm in dry state from the QCM data, assuming that the density of the film is ca. 1.2 g cm À3 [28].…”

Surface Modification Approaches for Electrochemical Biosensors

“…A good question is how to immobilize enzymes on nanomaterial modified electrodes, so that the biosensors have biorecognition capability while the catalytic activities of nanomaterials are preserved. Existing methods include direct absorption of enzymes by MWNTs due to the porous structure (McLamore et al, 2011;Shi et al, 2010 ), encapsulating enzymes and nanomaterials in the same polymer layer (Chen & Dong 2007;Choi et al, 2007a;Lim et al, 2005;Tsai et al, 2005), depositing multiple layers containing nanomaterials and enzymes and attaching enzymes to modified electrodes via cross-linking agents (Claussen et al, 2009;Claussen et al, 2010). Gooding et al reported a self-assembled attachment approach by incubating CNTs in microperoxidase MP-11 solution in HEPES buffer and showed that the enzymes were attached to the ends of the tubes via covalent bonds instead of being entrapped in the gaps among tubes (Gooding et al, 2003).…”