Electrochemical L-Lactic Acid Sensor Based on Immobilized ZnO Nanorods with Lactate Oxidase

Abstract

In this work, fabrication of gold coated glass substrate, growth of ZnO nanorods and potentiometric response of lactic acid are explained. The biosensor was developed by immobilizing the lactate oxidase on the ZnO nanorods in combination with glutaraldehyde as a cross linker for lactate oxidase enzyme. The potentiometric technique was applied for the measuring the output (EMF) response of l-lactic acid biosensor. We noticed that the present biosensor has wide linear detection range of concentration from 1 × 10−4–1 × 100 mM with acceptable sensitivity about 41.33 ± 1.58 mV/decade. In addition, the proposed biosensor showed fast response time less than 10 s, a good selectivity towards l-lactic acid in presence of common interfering substances such as ascorbic acid, urea, glucose, galactose, magnesium ions and calcium ions. The present biosensor based on immobilized ZnO nanorods with lactate oxidase sustained its stability for more than three weeks.

A novel OFET-based biosensor for the selective and sensitive detection of lactate levels

“…The sensitivity of the fabricated OFET sensor device is higher than that of an OFET-based device used for non-selective detection of lactate (Someya et al, 2002) and an ion-sensitive inorganic FET-based lactate biosensor (Kharitonov et al, 2001). Furthermore, the estimated sensitivity is comparable to or higher than other electrochemical approaches reported in the literature (Ibupoto et al, 2012 and the references therein). The very high level of sensitivity that was obtained allows us to control the sensitivity by shielding the active sites of the lactate oxidase (Pribil et al, 2014) for various applications.…”

An electrochemical biosensor with nanointerface for lactate detection based on lactate dehydrogenase immobilized on zinc oxide nanorods

“…This difference in isoelectric point facilitates easy binding of LDH on to ZnO nanorods through electrostatic interaction [29,30]. Recently, Ibupoto et al [20] developed a lactic acid biosensor by immobilizing lactate oxidase enzyme with a cross linker gluteraldehyde onto the ZnO nanorods. This Au/NanoZnO/LOD bio-electrode was shown to have a detection limit (LOD) of 1 Â 10 À4 mmol L À1 with a response time and sensitivity of 10 s and 41.33 ± 1.58 mV decade À1 respectively presenting linearity over 0.1-1 mmol L À1 .…”

“…Lactate dehydrogenase (LDH) [23][24][25], lactate oxidase [26][27][28] and horseradish peroxidase are the commonly used enzymes in the development of lactate sensor [20]. In the present work, LDH is used for the determination of lactic acid.…”

“…The high aspect ratio of nanoparticles in particular is promising for optoelectronics and sensor applications [16][17][18][19]. These uni-dimensional nanointerfaces, which facilitate direct electron amplification possess high sensitivity and can achieve good enzyme immobilization [20]. Recently ZnO nanorods have become more popular among researchers for biomolecule sensing due to their high surface area, biocompatibility, chemical stability and electronic amplification property [21,22].…”

ZnO nanostructures in enzyme biosensors

“…The resulting potentiometric electrochemical sensor exhibited a sensitivity of ~41 mV decade −1 , and a detection range from 0.1 μM to 1 mM [83]. A ZnO nanotetrapod network was used to adsorb LOD, because of its favorable 3D structure and electron transport properties [84].…”