Lactate Dehydrogenase Biosensor Based on an Hybrid Carbon Nanotube‐Conducting Polymer Modified Electrode

Abstract

A lactate biosensor constructed by immobilization of the enzyme lactate dehydrogenase (LDH) on a glassy carbon electrode modified with a hybrid material composed of the conducting polymer poly (3-methylthiophene) (P3 MT), electrodeposited on the electrode surface, and multiwalled carbon nanotubes (MWCNTs), is reported. The excellent characteristics of the electrode modified with the hybrid material toward the electrochemical oxidation of NADH allowed the construction of a robust LDH electrochemical biosensor able to operate at a working potential as low as þ 300 mV without the need for redox mediator. Experimental variables affecting the performance of the biosensor: amount of LDH immobilized on the modified electrode surface, buffer composition and working pH value, MWCNTs loading in the hybrid material and NAD þ concentration were optimized. Under the optimized conditions, a linear calibration graph for lactate was obtained over the 1.0 Â10 À6 À5.0 Â10 À4 M (r ¼0.9993) concentration range, with a detection limit of 5.6 Â 10 À7 M. The biosensor design showed good repeatability of the measurements, good reproducibility in the inter-biosensor assays and a good selectivity against other organic acids, especially when the biosensor is coated with a Nafion film.

Single-walled carbon nanotubes covalently functionalized with polytyrosine: A new material for the development of NADH-based biosensors

“…The modification of electrodes with carbon nanomaterials (Gasnier et al, 2013;Sun et al, 2013;Wang et al, 2012), nanoparticles Jena and Raj, 2006;Sharifi et al, 2013) or hybrid nanomaterials (Agüí et al, 2009;Govindhan et al, 2015;Hosseini et al, 2014;Mundaca et al, 2012;Teymourian et al, 2013;Tiwari and Gupta, 2014) have demonstrated to be highly successful.…”

“…4B shows a sharp rise in the sensitivity up to 2.0x10 -3 M NAD + , with a slight decrease for higher concentrations, attributed to a slight inhibitory effect observed for higher concentrations of NAD +(Agüí et al, 2009). Therefore, 2.0x10 -3 M NAD + in solution was selected to establish the analytical characteristics of the developed biosensor.…”

Electrochemical lactate biosensor based upon chitosan/carbon nanotubes modified screen-printed graphite electrodes for the determination of lactate in embryonic cell cultures

“…carbon nanotube (Agüí et al 2009), graphene (Alwarappan et al 2009) and nanoporous carbons (You et al 2011;Zhu et al 2008) to just name a few examples since the increase in the electrode active area is reported to enhance the sensitivity, selectivity and improvement of biomolecules immobilization and electron transfer.…”

Chemical sensors based on polymer composites with carbon nanotubes and graphene: the role of the polymer

“…This P3MT- MWCNT-(Naon)/GCE electrode provides fast responses, a linear range between 5.0 Â 10 À7 and 2.0 Â 10 À5 M and a detection limit of 1.7 Â 10 À7 M. The same authors developed a lactate biosensor using a similar method. 159 Both designed biosensors 158,159 showed good repeatability of the measurements, good reproducibility in the inter-biosensor assays and a good selectivity, especially when they were coated with a Naon lm. The synergistic effect of the composite constituents towards the electrocatalytic oxidation of NADH allowed the bioelectrodes to operate at low potential values without the need for redox mediators, improving the analytical performance in comparison to similar biosensors incorporating only CNTs or conducting polymers.…”