Multiwalled Carbon Nanotubes and the Electrocatalytic Activity of Gluconobacter oxydans as the Basis of a Biosensor.

Plekhanova Plekhanova,Signore Signore,Prisyazhnaya Prisyazhnaya,Reshetilov Reshetilov,Sigaev Sigaev,Tarasov Tarasov,Bykov Bykov,Kolesov Kolesov

doi:10.3390/bios9040137

Abstract

This paper considers the effect of multiwalled carbon nanotubes (MWCNTs) on the parameters of Gluconobacter oxydans microbial biosensors. MWCNTs were shown not to affect the structural integrity of microbial cells and their respiratory activity. The positive results from using MWCNTs were due to a decrease in the impedance of the electrode. The total impedance of the system decreased significantly, from 9000 kOhm (G. oxydans/chitosan composite) to 600 kOhm (G. oxydans/MWCNTs/chitosan). Modification of the amperometric biosensor with nanotubes led to an increase in the maximal signal from 65 to 869 nA for glucose and from 181 to 1048 nA for ethanol. The biosensor sensitivity also increased 4- and 5-fold, respectively, for each of the substrates. However, the addition of MWCNTs reduced the affinity of respiratory chain enzymes to their substrates (both sugars and alcohols). Moreover, the minimal detection limits were not reduced despite a sensitivity increase. The use of MWCNTs thus improved only some microbial biosensor parameters.

Highlights

Carbon nanotubes have become the nanomaterial most frequently used to modify electrochemical devices in the past decade [1,2]
We showed the effect of an multiwalled carbon nanotubes (MWCNTs)/chitosan composite on the structure and integrity of protein complexes, as well as on the respiratory activity of bacteria and their electrochemical parameters
The impact of MWCNTs did not inhibit the activity of microorganisms and did not disturb the integrity of their cell envelopes

Summary

Introduction

Carbon nanotubes have become the nanomaterial most frequently used to modify electrochemical devices in the past decade [1,2]. Some works show the toxic effect of carbon nanotubes on living cells, including bacterial ones [4]. The use of bacterial cell–carbon nanotube composites in microbial biosensors and fuel cells is observed to improve their electrochemical properties [5]. A detailed investigation of this interaction is, of extreme importance. Such microbial biosensors can find application in the monitoring of natural and industrial water reservoirs [8] and biotechnological processes [9,10]

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Methods

Conclusion