Study of carbon nanotubes–HRP modified electrode and its application for novel on-line biosensors

Abstract

In this paper, multi-walled carbon nanotubes (MWCNTs) were successfully immobilized on the surface of a glassy carbon electrode by mixing with horse-radish peroxidase (HRP). The electrochemical behavior of H2O2 was also studied with the MWCNTs-HRP modified electrode as a working electrode. The MWCNTs-HRP modified electrode showed excellent response of reduction current for the determination of H2O2 at the potential of -300 mV (vs. Ag/AgCl). We assembled the MWCNTs-HRP modified electrode in a thin-layer flow cell and the H2O2 solution was continuously introduced into the cell with a syringe pump. We optimized the sensitivity of the H2O2 sensor by adjusting the working potential and the pH of the buffer solution. The peak current increased linearly with the concentration of H2O2 in the range 3.0 x 10(-7) to approximately 2.0 x 10(-4) mol L(-1). The detection limit is 1.0 x 10(-7) mol L(-1) (S/N = 3). The interferences from ascorbic acid, uric acid and other electroactive substances can be greatly excluded since the sensor can be operated at -300 mV. Stability and reproducibility of the MWCNTs-HRP chemically modified electrode were also studied in this paper. Fabricated with glucose and lactate oxidase, the MWCNTs-HRP electrode was also applied to prepare the on-line glucose and lactate biosensors because of the high sensitivity for the determination of H2O2.

Carbon nanotube-based transducers for immunoassays

“…Good electrochemical communication between multi-walled carbon nanotubes (MWNTs) and redox proteins have been observed both at the protein surface in the case of horse radish peroxidase (HRP) [5,6], cytochrome C [7] and azurin [8], and deep within the protein macrostructure e.g. glucose oxidase [9].…”

Electrochemical sensors based on carbon nanotubes and their use in biomedical research

“…Предел обнаружения соответствовал концентрации 1´10 -7 моль/л. Так как определение выполнялось при электрическом потенциале -300 мВ, то присутствие в пробе аскорбиновой и мочевой кислоты не влияло на результат измерений [50].…”

“…При этом сенсоры на основе абразивного нанесения углеродных нанотрубок, а также их жидкостного нанесения с помощью N,N-диметилформамида, поверхностно-активных веществ и Нафиона характеризуются чрезвычайно широкими аналитическими возможностями. Они позволяют определять аскорбиновую [45] и мочевую [39] кислоту, пероксид водорода [35,37,38,50,62,[70][71][72], гемоглобин [47], цистеин [30,34],…”

Purification, Functionalization, and Bioconjugation of Carbon Nanotubes

“…CNTs are difficult to disperse and cannot be wetted by liquids with surface tensions higher than 100-200 mN/m. Thus, only ~0.1 mg of MWCNTs can be solubilized (with the aid of sonication) in 1 mL of DMF -one of the most effective solvents for CNT solubilization (50). Furthermore, CNTs tend to agglomerate as bundles in solvents, and if dispersed can reagglomerate quickly thereafter due to electrostatic attraction.…”