High Sensitivity Electrochemical Cholesterol Sensor Utilizing a Vertically Aligned Carbon Nanotube Electrode with Electropolymerized Enzyme Immobilization

Abstract

In this report, a new cholesterol sensor is developed based on a vertically aligned CNT electrode with two-step electrochemical polymerized enzyme immobilization. Vertically aligned CNTs are selectively grown on a 1 mm2 window of gold coated SiO2/Si substrate by thermal chemical vapor deposition (CVD) with gravity effect and water-assisted etching. CNTs are then simultaneously functionalized and enzyme immobilized by electrochemical polymerization of polyaniline and cholesterol enzymes. Subsequently, ineffective enzymes are removed and new enzymes are electrochemically recharged. Scanning electron microscopic characterization indicates polymer-enzyme nanoparticle coating on CNT surface. Cyclic voltammogram (CV) measurements in cholesterol solution show the oxidation and reduction peaks centered around 450 and −220 mV, respectively. An approximately linear relationship between the cholesterol concentration and the response current could be observed in the concentration range of 50–300 mg/dl with a sensitivity of approximately 0.22 μA/mg·dl−1, which is considerably higher compared to previously reported CNT bioprobe. In addition, good specificity toward glucose, uric acid acetaminophen and ascorbic acid have been obtained. Moreover, sensors have satisfactory stability, repeatability and life time. Therefore, the electropolymerized CNT bioprobe is promising for cholesterol detection in normal cholesterol concentration in human blood.

Integration of paper-based microfluidic devices with commercial electrochemical readers

“…Eqn (2) generalizes the reactions for the amperometric detection of d -glucose, cholesterol, and l -lactate 1,10,12,25. In the enzyme-catalyzed step, glucose oxidase (GOx), or another oxidase, catalyzed the oxidation of glucose (or cholesterol or lactate) to gluconic acid (or cholest-4-en-3-one or pyruvate) with concomitant reduction of Fe(III) to Fe(II) (eqn (2)); The Fe(II)(CN) 6 4− ions generated were detected amperometrically.…”

Highly Sensitive Carbon Nanotube-Based Sensing for Lactate and Glucose Monitoring in Cell Culture

“…Moreover, chemical mediators are often bounded successively to the electrode surface, with problems related to mediator concentration and chemical bounding. On the contrary, nanomaterials can be grown onto the electrode surface during microfabrication, enabling integration with VLSI chips [19].…”

Determination of Glucose and Cholesterol Using a Novel Optimized Luminol- CuO Nanoparticles-H2O2 Chemiluminescence Method by Box–Behnken Design

“…Compared with the previous methods [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55], the proposed method provided a good limit of detection and a relatively wide linear working range. Therefore, when the luminol nanocatalytic oxidation reaction by CuO NPs was coupled with the catalytic oxidation reaction by enzyme, a simple, low-cost and very sensitive CL glucose and cholesterol biosensing system was constructed.…”