A lactate electrochemical biosensor with a titanate nanotube as direct electron transfer promoter

Abstract

Hydrogen titanate (H 2 Ti 3 O 7 ) nanotubes (TNTs) have been synthesized by a one-step hydrothermal processing. Lactate oxidase (LOx) enzyme has been immobilized on the three-dimensional porous TNT network to make an electrochemical biosensor for lactate detection. Cyclic voltammetry and amperometry tests reveal that the LOx enzyme, which is supported on TNTs, maintains their substrate-specific catalytic activity. The nanotubes offer the pathway for direct electron transfer between the electrode surface and the active redox centers of LOx, which enables the biosensor to operate at a low working potential and to avoid the influence of the presence of O 2 on the amperometric current response. The biosensor exhibits a sensitivity of 0.24 μA cm −2 mM −1 , a 90% response time of 5 s, and a linear response in the range from 0.5 to 14 mM and the redox center of enzyme obviates the need of redox mediators for electrochemical enzymatic sensors, which is attractive for the development of reagentless biosensors.

Integrated biosensors for personalized medicine

“…Huang et al deposited the obtained matrix onto glassy carbon electrode, but they still showed a sensitivity ten times lower that our results [19]. In the last example, the authors used titanate instead of carbon nanotubes [57]. The obtained sensitivity is much lower than the previous case, suggesting that carbon gives better performance not only for the nanoscale structure, but also for the material itself.…”

Quantum Dots and Wires to Improve Enzymes-Based Electrochemical Bio-sensing

“…Even in that case, the best results were obtained by using the lactate oxidase onto MWCNT alone (the present work) and embedded in a polyvinyl matrix [20] while the lactate dehydrogenase seems to be lesser efficient even when deposited onto carbon nanotubes [21]. Hydrogen titanate nanotubes have not shown performances as good as those of carbon nanotubes [22], neither the use of a bit larger carbon nanotubes with diameter equal to 15 nm [23]. Table 2.…”

Electrocatalytic Drug Metabolism by CYP2C9 Bonded to A Self-Assembled Monolayer-Modified Electrode

“…In practice, it is difficult to isolate the individual contributions of these factors because they are often interdependent. Thus, it is of interest to devise model platforms that can be used to independently control these parameters to monitor their respective effects on metabolism.P450 catalysis requires a constant supply of NADPH as the electron source and cytochrome P450 reductase (CPR) to deliver the electrons.In attempts to obviate the requirement of these redox partners/cofactors for catalysis, P450 enzymes have been immobilized on electrodes so that the electrode supplies electrons to drive the P450 catalytic cycle (Estabrook et al, 1996;Reipa et al, 1997;Gilardi et al, 2002) with effective electrical communication between the electrode and the enzyme being critical (Yang et al, 2008). Direct adsorption of enzymes on bare electrodes, such as gold, platinum, and graphite, results in diminished biocatalytic activity (Habermüller et al, 2000;Joseph et al, 2003;Shumyantseva et al, 2005).…”