Researchers have demonstrated that CNT have a high electrocatalytic effect, a fast electron-transfer selleck inhibitor rate, and a large working surface area [12-14]. The electrochemical sensor application of find more information the CNT was reviewed by Zhuang et al. [15] and later by Wang [16].The electrochemical Inhibitors,Modulators,Libraries oxidation of NADH or NADPH is becoming more and more interesting, especially for the purpose of analysis, because many oxidoreductases, particularly dehydrogenases, need it as cofactor Inhibitors,Modulators,Libraries to catalyze redox reaction. The ability of CNT to promote the electron transfer reactions of NADH has been used for the development of dehydrogenase-biosensors [17-21]. In addition, electrochemical biosensors based on dehydrogenases have been developed through electrocatalytic oxidation of NAD(P)H cofactors onto the modified CNT or functionalized CNT [22, 23].

Antiochia Inhibitors,Modulators,Libraries et al. [24] prepared CNT paste electrodes modified with electrodeposited film derived from Inhibitors,Modulators,Libraries 3,4-dihydroxybenzaldehyde and constructed glucose biosensors by successively coupling with glucose dehydrogenase. Zhang et al. [25] used chitosan to solubilize the CNT and to create Inhibitors,Modulators,Libraries a biocompatible environment for enzyme immobilization onto the surface of CNT.Malic acid is widely distributed in small amounts in many natural food products. It is the predominant acid in many fruits, being known as ��apple acid�� because it is found in high concentration in apples, apricots, peaches, grapes as well as various citrus fruits, berries, figs, carrots, peas, beans and tomatoes [26].

There is a need to develop selective methods based on existing biosensor technology to determine malic acid, which Inhibitors,Modulators,Libraries is a taste determining constituent of fruits and fruit juices.The enzymatic pathway exploited for the determination of malic acid is the reaction catalyzed by malate dehydrogenase:Malicacid+NAD+?MDHOxaloacetate+NADH+H+This Inhibitors,Modulators,Libraries work proposes a low potential amperometric enzyme biosensor based on a carbon nanotubes-modified glassy carbon electrode for the determination Inhibitors,Modulators,Libraries of L-malic acid. Preliminary electrochemical characterization of the electrode was performed using NADH as intermediary analyte. This allowed the analytical performances of the electrode to be examined as well as to determine the oxidation peak potential of NADH.2.

?Materials and Methods2.1. Apparatus and reagentsAll the chemical reagents were obtained from Sigma, of the highest grade available and used without Drug_discovery further Anacetrapib purification.

Single-wall carbon nanotubes (SWNT) of 0.5-100 ��m length were purchased from Aldrich. Malate dehydrogenase �C MAD-211 selleck chemicals llc (E.C.1.1.1.37) extracted from microorganism was delivered by Sorachim, France. Nafion 5% was purchased from Fluka.Cyclic voltammetry and amperometry experiments were performed using an electrochemical excellent validation analyzer ��Autolab type III connected to a PC for collecting the data.