Development of a novel biosensor based on a polypyrrole–dodecylbenzene sulphonate (PPy–DBS) film for the determination of amperometric cholesterol

Abstract

Herein a novel amperometric biosensor based on a conducting polymer with anionic dopant modified electrode was successfully developed for detection of cholesterol. Polypyrrole is deposited on a platinum surface and the sodium dodecylbenzene sulphonate (DBS) ion-doped polypyrrole film was electrochemically prepared by scanning the electrode potential between -0.8 and +0.8 V at a scan rate of 20 mV/s. The present electrochemical biosensor was optimized in terms of working potential, number of cycles, concentrations of monomer, and anionic dopant. Cholesterol oxidase (ChOx) was physically entrapped in PPy-DBS to construct an amperometric cholesterol biosensor. Amperometric determination is based on the electrochemical detection of HO generated in the enzymatic reaction of cholesterol. Kinetic parameters, operational and storage stabilities, pH, and temperature dependencies were determined. Km and Imax were calculated as 0.11 μM and 0.967 nM/min, respectively. The operational stability results showed that 90.0% of the response current was retained after 30 activity assays. Morphology of electrodes was characterized by SEM and AFM. Additionally, contact angle measurements were made with 1 μL water of polymer film and enzyme electrode. As a result, the cholesterol biosensor suggested in this study is easy to prepare and is highly cost-effective. This composite (PPy-DBS) can supply a biocompatible and electrochemical microenvironment for immobilization of the enzyme, making this material a good candidate for the fabrication of highly sensitive and selective cholesterol biosensors.

Square wave voltammetric detection of cholesterol with biosensor based on poly(styrene‐‐ε‐caprolactone)/MWCNTs composite

“…In the final step, cholest‐5‐en‐3‐one, which occurs as an intermediate product, undergoes isomerization and turns into the cholest‐4‐en‐3‐one as the final product 40 . The enzymatic determination of cholesterol with biosensor can be indirectly determined by the reduction or oxidation of H 2 O 2 , which occurs as a reaction product, under the appropriate potential 41 . It should be noted that H 2 O 2 is thermodynamically unstable and its theoretical reduction potential is −0.682 V 42 .…”

“…40 The enzymatic determination of cholesterol with biosensor can be indirectly determined by the reduction or oxidation of H 2 O 2 , which occurs as a reaction product, under the appropriate potential. 41 It should be noted that H 2 O 2 is thermodynamically unstable and its theoretical reduction potential is −0.682 V. 42 It has been reported that H 2 O 2 is reduced at different potential values depending on the surface properties of the designed biosensor electrode. [43][44][45][46][47][48] For an accurate biosensor measurement, the potential value at which the reaction mechanism takes place on the electrode surface should be determined.…”

An Overview on Electrochemical Determination of Cholesterol

“…Therefore, a direct or indirect electron transfer is caused due to a redox reaction between cholesterol and enzyme. Enzymes are immobilized on functionalized electrodes with different supports based on nanomaterials [35][36][37][38][39][40][41][42][43][44], polymers [45][46][47][48][49], hydrogels and sol-gels [2,[50][51] self-assembly monolayers [52] and other matrixes. Different electrochemical methods are used to monitor electron transfer through which cholesterol can be measured, including amperometry [42,51,[53][54][55], cyclic voltammetry (CV) [56][57][58][59], differential pulse voltammetry (DPV) [60], linear sweep voltammetry (LSV) [61][62], charge transfer (CT) [63], electrochemiluminescence (ECL) [64] and electrochemical impedance spectroscopy (EIS) [65].…”

Cerium Oxide/Polypyrrole Nanocomposite as the Matrix for Cholesterol Biosensor

“…Polypyrrole (PPy), a functional conducting polymer material, is usually considered to be a p-type material with good thermal and high environmental stability, low oxidation potential, and high conductivity [24]. In recent years, PPy-based nanocomposites with different nanomaterials, such as CNT [25], metal oxide [26], dodecylbenzene sulfonate (DBS) [27], have attracted wide attention for biosensor development owing to their large specific surface areas, high conductivity, and biocompatibility. Singh et al [25] studied a biosensor by using PPy/MWCNT as the mediator for cholesterol sensing.…”

“…They also demonstrated that the developed cholesterol biosensor could be easily fabricated, had a rapid response time, and was useful in blood serum sampling. A novel amperometric biosensor based on a conducting polymer and DBS-modified electrode was successfully developed by Ozer et al [27]. ChOx was physically entrapped onto the PPy-DBS film surface; then, the cholesterol concentration was determined by performing an electrochemical detection of the H 2 O 2 generated in the enzymatic reaction of cholesterol.…”