Chitosan-multiwalled Carbon Nanotubes Research Articles

An efficient electrochemical disinfection of E. coli and S. aureus in drinking water using ferrocene–PAMAM–multiwalled carbon nanotubes–chitosan nanocomposite modified pyrolytic graphite electrode

This work reported an efficient electrochemical treatment for drinking water disinfection using a pyrolytic graphite electrode modified with ferrocenyl tethered poly(amidoamine) dendrimers–multiwalled carbon nanotubes–chitosan nanocomposite. The influence parameters of electrochemical disinfection of Escherichia coli and Staphylococcus aureus, such as applied potential and sterilization time, were investigated. Further investigation indicated that almost all (99.99 %) of the initial bacteria were killed after applying a low potential of 0.4 V for 10 min. During the electrochemical disinfection process, the oxidized form of ferrocene was formed on electrode, which played a key role in the disinfection towards E. coli and S. aureus. Hence, the proposed method may provide potential application for the disinfection of drinking water.

Characterization and performance study on chitosan-functionalized multi walled carbon nano tube as separator in microbial fuel cell

The influence of Multi Walled Carbon Nano Tube (MWCNT) in oxygen cross over, water absorption and performance of chitosan (CHIT) in Single Chamber Microbial Fuel Cell (SCMFC) was studied. CHIT and non covalently functionalized MWCNT with CHIT (CHIT–MWCNT) were prepared in the form of membranes and characterized using FTIR, XRD, DRS UV, CD, Raman, SEM and TEM to study the interaction of MWCNT with chitosan. CHIT–MWCNT showed lesser water absorption compared to that of CHIT. CHIT–MWCNT membrane showed oxygen mass transfer coefficient (2.66×10−4cm/s) one order less than that of CHIT (2.28×10−3cm/s). The prepared membranes were continuously tested in an in-house built Single Chamber Microbial Fuel Cell (SCMFC). The maximum power density obtained by CHIT–MWCNT composite membrane was higher compared to that of CHIT membrane obtained was 38.16mW/m2 and 46.94mW/m2 for CHIT and CHIT–MWCNT, respectively. The results of the study showed that the MWCNT incorporated chitosan composite membrane had strong influence on the properties and performance of CHIT in microbial fuel cell. Hence, CHIT–MWCNT is a promising candidate for application in microbial fuel cell.

Simultaneous determination of ascorbic acid and rutin in pharmaceutical preparations with electrochemical method based on multi-walled carbon nanotubes–chitosan composite film modified electrode

In this paper, the simultaneous voltammetric determination of ascorbic acid (AA) and rutin (Ru) has been achieved at an acetylene black paste electrode modified with multi-walled carbon nanotubes–chitosan composite film (denoted as MWCNTs–CHIT/ABPE). Compared with bare electrode, the peak currents of AA and Ru at MWCNTs–CHIT/ABPE increased greatly and the anodic peak potential difference (ΔEpa) between AA and Ru are up to 342mV, which is undoubtedly attributed to the unique characteristics of AB and MWCNTs such as excellent electric conductivity, high surface area and strong adsorptive abilities, resulting in higher accumulation efficiency to AA and Ru. The influences of some experimental conditions on the oxidation of AA and Ru were tested and the calibration plot was examined. Under the optimized condition, a good linearity was obtained in the concentration range of 1μM–0.4mM for AA in the presence of 10μM Ru and 20nM–10μM for Ru in the presence of 1mM AA. The detection limits (S/N=3) of AA and Ru are 0.8μM and 10nM, respectively. The proposed method was successfully applied to the simultaneous determination of AA and Ru in pharmaceutical samples with reliable recovery.

Effect of pH and carbon nanotube content on the corrosion behavior of electrophoretically deposited chitosan–hydroxyapatite–carbon nanotube composite coatings

In the first stage, chitosan (CH)–hydroxyapatite (HA)-multiwalled carbon nanotube (MWCNT) composite coatings were synthesized by electrophoretic deposition technique (EPD) on 316L stainless steel substrates at different levels of pH and characterized by X-ray diffraction (XRD), Raman spectroscopy, FTIR and field emission scanning electron microscopy (FESEM). A smooth distribution of HA and MWCNT particles in a chitosan matrix with strong interfacial bonding was obtained. In the next stage, effects of pH and MWCNT content of the suspension on the corrosion behavior and deposition mechanism were studied. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) curves revealed that increasing pH level of the suspension increases the corrosion protection properties of the deposited composite coating in simulated body fluid (SBF). Furthermore, Nyquist plots showed that increasing MWCNT content of the suspension resulted in higher amounts of Rp, but because of the capillary properties of MWCNTs and degradability of the chitosan matrix, corrosion protection level of the coatings containing HA–CH–MWCNT was lower than those of coatings containing solely HA–CH. Amperometric curves in different pH levels of the suspension revealed that the system is diffusion controlled at elevated pH values.

A novel protocol for ultra-trace detection of pesticides: Combined electrochemical reduction of Ellman's reagent with acetylcholinesterase inhibition

This paper proposed a novel method for ultra-trace detection of pesticides combining electrochemical reduction of Ellman's reagent with acetylcholinesterase (AChE) inhibition. The amperometric biosensor, fabricated by immobilizing AChE on multi-walled carbon nanotubes-chitosan (MWCNTs-Chi) nanocomposites modified glassy carbon electrode, enjoyed high sensitivity owing to the excellent conductivity and favourable biocompatibility of MWCNTs-Chi nanocomposites. Meanwhile, the sensitivity of the biosensor was further enhanced using the electrochemical reduction signal of DTNB for determination. Under optimum conditions, methyl parathion was detected based on its inhibition effect on AChE activity and the subsequent change in electrochemical reduction response of DTNB. Good relationship was obtained between the reduction current and pesticide concentration in the ranges of 5.0×10−7 to 1.0×10−12M with a detection limit of 7.5×10−13M (S/N=3). Moreover, the proposed protocol was successfully employed for the determination of methyl parathion in water and soil samples.

Amperometric Immunosensor Based on Gold Nanoparticles/Fe3O4-FCNTs-CS Composite Film Functionalized Interface for Carbofuran Detection

In this paper, a novel amperometric immunosensor for the determination of carbofuran based on gold nanoparticles (GNPs), magnetic Fe3O4 nanoparticles-functionalized multiwalled carbon nanotubes-chitosan (Fe3O4-FCNTs-CS), and bovine serum albumin (BSA) composite film was proposed. First, GNPs were immobilized onto the glassy carbon electrode (GCE) surface, and then the magnetic Fe3O4 nanoparticles mixed with chitosan-functionalized multiwall carbon nanotubes (CS-FCNTs) homogeneous composite (CS-FCNTs-Fe3O4) was immobilized onto the GNPs layer by electrostatic interactions between amino groups of CS and GNPs. Because chitosan (CS) contains many amino groups, it can absorb more antibodies. FCNTs have high surface area, high electrical conductivity, and it can enhance the electron transfer rate; Magnetite (Fe3O4) nanoparticles can provide a favorable microenvironment for biomolecules immobilization due to their good biocompatibility, strong superparamagnetic property, and low toxicity; and GNPs possess high surface-to-volume reaction, stability, and high conductivity. Gold Nanoparticles/Fe3O4-FCNTs-CS composite film was constructed onto the GCE surface, which had significant synergistic effects toward immunoreaction signal amplification. The stepwise assembly process was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. Under the optimal conditions, the current response was proportional to the concentration of carbofuran ranging from 1.0 ng/mL to 100.0 ng/mL and from 100.0 ng/mL to 200 µg/mL with the detection limit 0.032 ng/mL. The proposed immunosensor exhibited good accuracy, high sensitivity, and stability, and it can be used for detection of carbofuran pesticide.

Electrochemistry and electrocatalysis of a nanobiocomposite film containing hematin and carbon nanotubes–chitosan on a poly-(acridine red) modified glassy carbon electrode

A novel nanocomposite material based on poly-acridine red (PAR), multi-walled carbon nanotubes (MWCNTs) and chitosan (CS) was used to incorporate hematin onto the surface of a glassy carbon electrode for studying the electron transfer and electrocatalytic activity of hematin. A pair of well defined and quasi-reversible redox peaks, corresponding to the hematin Fe(III)/Fe(II) redox couple, appeared at about −0.272 V (vs. Ag/AgCl). The electron transfer rate constant was estimated to be 5.06 s−1. The results indicated that the MWCNT–CS and PAR composite film enhanced the electron transfer process of hematin. The hematin immobilized in the MWCNT–CS and PAR film exhibited bioelectrocatalytic activity for the reduction of H2O2. The peak current of the biosensor by cyclic voltammetry varied linearly with the concentration of H2O2 from 10.0 to 1000.0 μM and the detection limit was 1.75 μM. The amperometric response of the biosensor varied linearly with the concentration of H2O2 from 1.0 to 10.0 μM and the detection limit was 0.61 μM (S/N = 3). The results indicate that the composite film is a versatile platform for the fabrication of electrochemical biosensors.

Amperometric immunosensor for the detection of Escherichia coli O157:H7 in food specimens

A novel, label-free amperometric immunosensor has been developed for the rapid detection of heat-killed Escherichia coli O157:H7 ( E. coli O157:H7). This immunosensor was prepared as follows. First, the long-chain, amine-terminated alkanethiol 11-amino-1-undecanethiol hydrochloride (AUT) was self-assembled onto a gold electrode surface to form an ordered, oriented, compact, and stable monolayer possessing –NH 2 functional groups that could immobilize massive gold nanoparticles (GNPs). Next, chitosan-multiwalled carbon nanotubes–SiO 2/thionine (CHIT–MWNTs–SiO 2@THI) nanocomposites and GNPs multilayer films were prepared via layer-by-layer (LBL) assembly. The surface area enhancement from the LBL assembly of the multilayer films improves the stability of the immobilized CHIT–MWNTs–SiO 2@THI. More important, the sensitivity and stability of the immunosensor can be enhanced proportionally to the quantity of the THI mediator immobilized on the electrode surface. Finally, the E. coli O157:H7 antibody (anti- E. coli O157:H7) was covalently bound to the GNP monolayer and its bioactivity was measured by enzyme-linked immunosorbent assay (ELISA). Transmission electron microscopy (TEM) was employed to characterize the morphology of the MWNTs, CHIT–MWNTs, and CHIT–MWNTs–SiO 2@THI. Under optimal conditions, the calibration curve for heat-killed E. coli O157:H7 has a working range of 4.12 × 10 2–4.12 × 10 5 colony-forming units (CFU)/ml, and the total assay time was less than 45 min.

Electrochemical imprinted sensor for determination of oleanic acid based on poly (sodium 4-styrenesulfonate-co-acrylic acid)-grafted multi-walled carbon nanotubes-chitosan and cobalt hexacyanoferrate nanoparticles

A novel sensitive and selective imprinted electrochemical sensor for the determination of oleanic acid was constructed on a carbon electrode by stepwise modification of functional multi-walled carbon nanotubes, cobalt hexacyanoferrate nanoparticles and a thin imprinted sol–gel film. The fabrication of a homogeneous porous poly (sodium 4-styrenesulfonate-co-acrylic acid)-grafted multi-walled carbon nanotubes/SiO2–chitosan nanocomposite film was conducted by controllable electrodeposition technology. The surface morphologies of the modified electrodes were characterized by scanning electron microscope. The performance of the imprinted sensor was investigated by cyclic voltammetry, square wave voltammetry and electrochemical impedance spectroscopy in detail. The imprinted sensor displayed high sensitivity and selectivity towards oleanic acid. A linear relationship between the sensor response signal and the logarithm of oleanic acid concentrations ranging from 1.0×10−8 to 1.0×10−3molL−1 was obtained with a detection limit of 2.0×10−9molL−1. It was applied to the determination of oleanic acid in real capsule samples successfully.

Selective and sensitive molecularly imprinted sol–gel film-based electrochemical sensor combining mercaptoacetic acid-modified PbS nanoparticles with Fe3O4@Au–multi-walled carbon nanotubes–chitosan

A sensitive molecularly imprinted electrochemical sensor was developed for selective detection of streptomycin by combination of mercaptoacetic acid-modified PbS nanoparticles with Au-coated Fe3O4 magnetic nanoparticles dispersed multi-walled carbon nanotubes doped chitosan film. The imprinted sensor was fabricated onto the Au electrode via stepwise modification of nanocomposites and an electrodeposited thin film of molecularly imprinted polymers via sol–gel technology. The morphologies and electrochemical behaviors of the imprinted sensor were characterized by scanning electron microscope, cyclic voltammetry, and differential pulse voltammetry, respectively. The prepared sensor showed very high recognition ability and selectivity for streptomycin. Under optimal conditions, the imprinted sensor displayed good electrocatalytic activity to the redox of streptomycin. And the differential voltammetric anodic peak current was linear to the logarithm of streptomycin concentration in the range from 1.0 × 10−6 to 1.0 × 10−3 mol L−1, and the detection limit obtained was 1.5 × 10−9 mol L−1. This proposed imprinted sensor was used successfully for streptomycin determination in different injection solution samples.

Highly biocompatible multi-walled carbon nanotube–chitosan nanoparticle hybrids as protein carriers

Carbon nanotube (CNT)–organic polymer hybrids have important potential applications in the immobilization of therapeutic biomolecules. Recently developed CNT–organic polymer composites require the use of organic solvents for their preparation and have limited polymer functionalization. To address these limitations, multi-walled CNT (MWCNT)–chitosan nanoparticle (CS NP) hybrids have been synthesized in situ by an ionotropic gelation process, which is extremely mild and involves the mixture of two aqueous solutions at room temperature. The MWCNT–CS NP hybrids were characterized by atomic force microscopy and thermogravimetric analysis. Under optimal conditions the CS NP can be tethered to the MWCNT surface in high density and with relatively uniform coverage. The MWCNT–CS NP hybrids show good dispersibility and stability in aqueous solutions. In order to evaluate the potential utilization of the hybrids as protein carries the cytotoxicity to HeLa cells and protein immobilization (of bovine serum albumin (BSA), used here as a model) capacity of the hybrids were investigated in detail. The results demonstrate that the MWCNT–CS NP hybrids are biocompatible at concentrations up to 100μgmL−1 for 24h incubation. The MWCNT–CS NP hybrids improve the BSA immobilization efficiency 0.8 times and simultaneously decrease the cellular toxicity by about 50% compared with carboxylated MWCNT.

Multilayer structured amperometric immunosensor based on gold nanoparticles and Prussian blue nanoparticles/nanocomposite functionalized interface

In this paper, a novel strategy for the fabrication of sensitive reagentless amperometric immunosensor was proposed. Firstly, Prussian blue nanoparticles (PBNPs) as redox probe were immobilized on three dimensional structured membrane of the gold colloidal nanoparticles (AuNPs) doped chitosan-multiwall carbon nanotubes (CS-MWNTs) homogeneous composite (CS-MWNTs-AuNPs) by electrostatic interactions between the negatively charged PBNPs and the positively charged amino groups of CS and strong binding interaction between GNPs and nitrile group (–CN) of PBNPs. Subsequently, the gold nanoparticles (GNPs) were electrodeposited on the surface of the composite by electrochemical reduction of gold chloride tetrahydrate (HAuCl 4) to immobilize antibody biomolecules (anti-CEA) and avoid the leakage of PBNPs. The stepwise assembly process was characterized by means of cyclic voltammetry (CV) and electrochemical impendance spectroscopy (EIS). Furthermore, the morphology of the prepared nanomaterials was researched by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Under the optimized conditions, the decrease of CVs current of determination CEA was proportional to concentration ranges from 0.3 to 120 ng/mL with a detection limit of 0.1 ng/mL at a signal-to-noise of 3. Moreover, the proposed immunosensor exhibited good accuracy, high sensitivity and stability.

Adsorptive Stripping Voltammetric Detection of Tea Polyphenols at Multiwalled Carbon Nanotubes‐Chitosan Composite Electrode

AbstractThis study reports the catalytic oxidation and detection of tea polyphenols (TPs) at glassy‐carbon electrode modified with multiwalled carbon nanotubes‐chitosan (MWCNTs‐CS) film. The adsorption of TPs at the surface of the MWCNTs through π–π conjugation prevents the aggregation of nanotubes and induces a stable MWCNTs suspension in water over 30 days. Based on the adsorptive accumulation of polyphenols at MWCNTs, TPs is sensitively and selectively detected by adsorptive stripping voltammetry. The accumulation conditions and pH effect on the adsorptive stripping detection were examined. The linear range was found to be 100 to 1000 mg L−1 with a detection limit of 10 mg L−1 (S/N=3) for 2.5 min accumulation. Additionally, the MWCNTs‐CS electrode is easily renewed by applying positive potential to remove the adsorbed TPs. This method was successfully applied to determine TPs in commercially available teas with satisfied result compared with that of conventional spectrometric analysis.

Biofuel cell and phenolic biosensor based on acid-resistant laccase–glutaraldehyde functionalized chitosan–multiwalled carbon nanotubes nanocomposite film

To immobilize laccase (Lac) from Trametes versicolor that shows its maximum enzymatic activity in acidic aqueous solutions, the biopolymer chitosan (CS) was chemically modified with glutaraldehyde (GA) to form GA functionalized CS (GAfCS), which was then allowed to react with Lac to form a Lac–GAfCS composite that is robust in weakly acidic solutions (two-step protocol), as confirmed by quartz crystal microbalance and durability tests. The Lac–GAfCS–multiwalled carbon nanotubes (MWCNTs)/glassy carbon (GC) electrode exhibited good catalytic activity towards O2 reduction in the presence of 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS), and the pH-dependent enzymatic activity of the immobilized Lac towards O2 reduction was examined. A glucose/air biofuel cell was fabricated, with the Lac–GAfCS–MWCNTs/GC electrode as the biocathode and a glucose oxidase (GOx)–GAfCS–MWCNTs/GC electrode as the bioanode in a Nafion membrane-separated acetate buffer solution (pH 5.0). The biofuel cell output a maximum power density of 9.6μW/cm2, an open-circuit cell voltage of 0.19V, and a short-circuit current density of 114μA/cm2, respectively, as measured with an electrochemical noise (ECN) apparatus. Furthermore, the Lac–GAfCS–MWCNTs/GC electrode was applied to determine catechol in Britton–Robinson buffer solution (pH 3.0), with a linear range of 0.1–50μM and a limit of detection of 20nM. In comparison with the direct use of GA for one-pot Lac–GA-CS or Lac–GA crosslinking to immobilize Lac, the use of macromolecular GAfCS in the proposed two-step protocol was proven to be less harmful to the enzymatic activity and thus more suitable for immobilizing the enzyme to construct the biofuel cell and biosensor. This work may be helpful for exploiting the popular biocompatible CS as an acid-resistant film matrix for many other biotechnology applications, and the proposed two-step crosslinking protocol is recommended for high-activity immobilization of other biomolecules.

Layer-by-layer self-assembled multilayer films of multi-walled carbon nanotubes and platinum–Prussian blue hybrid nanoparticles for the fabrication of amperometric immunosensor

A label-free amperometric immunosensor for the detection of α-fetoprotein (AFP) based on the layer-by-layer (LBL) assembly of positively charged multi-walled carbon nanotubes–chitosan (MCNTs–CS) and negatively charged platinum–Prussian blue hybrid nanoparticles (Pt–PB) on 3-mercaptopropanesulfonic, sodium salt (MPS) modified electrode is described in this paper. Transmission electron microscopy (TEM) was employed to characterize the morphologies of Pt–PB and Pt–PB–MCNTs–CS. The stepwise LBL assembly process of electroactive species on electrode surface was evaluated by cyclic voltammetry (CV). The immunosensor shows good analytical performance such as low detection limit (0.08 ng ml −1), wide linear range (from 0.1 to 15.0 and from 15.0 to 200.0 ng ml −1), good regeneration, selectivity, stability, and reproducibility for the determination of AFP. Application of the immunosensor to clinical samples demonstrated that results were in good agreement with ELISA.

Amperometric cholesterol biosensors based on carbon nanotube–chitosan–platinum–cholesterol oxidase nanobiocomposite

Abstract A highly sensitive and fast responsed biosensor was successfully fabricated in this work. Platinum nanoparticles were electrochemically deposited in multiwalled carbon nanotube (MWCNT)–chitosan matrix by a cyclic voltammetry method. A Pt(IV) complex was reduced to Pt on the surface of MWCNTs. The Pt nanoparticles in the MWCNT–chitosan film were identified with transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The doped Pt nanoparticles demonstrate the abilities to electrocatalyze the oxidation of hydrogen peroxide and substantially raise the response current. The results indicated that the Pt nanoparticles exhibited efficiently electrocatalytic activity. The influence of enzyme loading within the MWCNT–chitosan–Pt–cholesterol oxidase nanobiocomposite was explored to optimize the electroanalytical performance of the cholesterol biosensor. The optimized cholesterol biosensor shows a sensitivity of 0.044 A M−1 cm−2 and a response time of about 8 s. No response currents were observed at the MWCNT–chitosan–Pt–cholesterol oxidase nanobiocomposite modified electrode after the additions of 100 μM glucose and 1 μM ascorbic acid to 100 μM cholesterol in 0.1 M phosphate buffer solution (pH 7) in the interference study. The prepared cholesterol biosensor retained 60% of initial activity after 7 days when stored in 0.1 M phosphate buffer solution at 4 °C.

Direct Electrochemistry of Hemoglobin Entrapped in Composite Electrodeposited Chitosan‐Multiwall Carbon Nanotubes and Nanogold Particles Membrane and Its Electrocatalytic Application

AbstractHemoglobin was entrapped in composite electrodeposited chitosan‐multiwall carbon nanotubes (MCNTs) film by assembling gold nanoparticles and hemoglobin step by step. In phosphate buffer solution (pH 7), a pair of well‐defined and quasireversible redox peaks appeared with formal potential at −0.289 V and peak separation of 100 mV. The redox peaks respected for the direct electrochemistry of hemoglobin at the surface of chitosan‐MCNTs‐gold nanoparticles modified electrode. The parameters of experiments have also been optimized. The composite electrode showed excellent electrocatalysis to peroxide hydrogen and oxygen, the peak current was linearly proportional to H2O2 concentration in the range from 1×10−6 mol/L to 4.7×10−4 mol/L with a detection limit of 5.0×10−7 mol/L, and this biosensor exhibited high stability, good reproducibility and better selectivity. The biosensor showed a Michaelis–Menten kinetic response as H2O2 concentration is larger than 5.0×10−4 mol/L, the apparent Michaelis–Menten constant for hydrogen peroxide was calculated to be 1.61 μmol/L.

Sensitive immunoassay of human chorionic gonadotrophin based on multi-walled carbon nanotube–chitosan matrix

A novel amperometric immunosensor for human chorionic gonadotropin (HCG) assay has been fabricated through incorporating toluidine blue (TB) and hemoglobin (Hb) on the multiwall carbon nanotube (MWNT)-chitosan (CS) modified glassy carbon electrode, followed by electrostatic adsorption of a conducting gold nanoparticles (nanogold) film as sensing interface. The MWNT-CS matrix provided a congenial microenvironment for the immobilization of biomolecules and promoted the electron transfer to enhance the sensitivity of the immunosensor. Due to the strong electrocatalytic properties of Hb and MWNT toward H(2)O(2), the Hb and MWNT significantly amplified the current signal of the antigen-antibody reaction. The immobilized toluidine blue as an electron transfer mediator exhibited excellent electrochemical redox property. After the immunosensor was incubated with HCG solution, the access of activity center of the Hb to toluidine blue was partly inhibited, which leaded to a linear decrease in the catalytic efficiency of the Hb to the oxidation of immobilized toluidine blue by H(2)O(2) over HCG concentration ranges from 0.8 to 500 mIU/mL. Under optimal condition, the detection limit for the HCG immunoassay was 0.3 mIU/mL estimated at a signal-to-noise ratio of 3. Moreover, the proposed immunosensor displayed a satisfactory stability and reproducibility.

Immobilization of lactate dehydrogenase within multiwalled carbon nanotube-chitosan nanocomposite for application to lactate biosensors

A composite of multiwalled carbon nanotubes-chitosan (MWCNT-CHIT) was used as a matrix for entrapment of lactate dehydrogenase (LDH) onto a glassy carbon electrode in order to fabricate amperometric biosensor. The homogeneity of the resulting multiwalled carbon nanotubes-chitosan-lactate dehydrogenase (MWCNT-CHIT-LDH) nanobiocomposite film was investigated by atomic force microscopy (AFM). It shows that the enzyme is homogeneously immobilized within MWCNT-CHIT-LDH. The inclusion of MWCNT within MWCNT-CHIT-LDH exhibits the abilities to raise the current responses, to decrease the electrooxidation potential of β-nicotinamide adenine dinucleotide, reduced form (NADH), and to prevent the electrode surface fouling. The influence of several experimental parameters such as applied potential, solution pH value, NAD+ concentration, and enzyme loading was explored to optimize the electroanalytical performance of the biosensor. The optimized biosensor for the determination of lactate shows a sensitivity of 0.0083AM−1cm−2 and a response time of about 3s. The proposed biosensor retained 65% of its original response after 7 days.