Sensitivity Of Glucose Biosensor Research Articles

Çok Duvarlı Karbon Nanotüpler/Politiyofen Kompozit Kullanılarak Hazırlanan Amperometrik Glikoz Biyosensörü

In this study, multi-walled carbon nanotubes/polythiophene composite (MWCNTs/PTh) modified glassy carbon electrode was used for the amperometric detection of glucose. Glucose oxidase (GOx) was entrapped by a crosslinking agent on the MWCNTs/PTh composite film synthesized by electrochemical polymerization of thiophene onto MWCNTs. Characterization of composite film was achieved by cyclic voltammetry (CV), fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques. The amperometric measurements of electrode was performed at +0.70V vs. SCE, which was the electrooxidation potential of enzymatically produced H2O2. The effects of thiophene amount in the composite, pH, temperature and substrate concentration were investigated on the response of enzyme electrode. Optimum pH was 7.0 at room temperature and the response time of enzyme electrode was 25 s. The upper limit of the linear working range was 4.85 mM glucose concentration. The limit of detection of sensor was calculated as 148 µM. The sensitivity of glucose biosensor was determined as 4.39 µA mM-1 cm-2. The value of apparent Michaelis-Menten constant (KMapp) was 1.68 mM according to the Lineweaver-Burk equation. The activation energy of this immobilized enzyme system was 88.92 kJ mol-1.

(Invited) Application of High Hydrostatic Pressure and Nanofilms to the Fabrication of Enzyme Biosensors

Fabrication of enzyme biosensors has evolved since they were first conceived in the late 1950s. Increased sensitivity and reproducibility have been perhaps the two main driving forces for the development of such sensors. Increased sensitivity enables miniaturization and the development of implantable sensors for in-vivo applications. Because most oxidoreductases used in the fabrication of enzyme biosensors quickly lose their activity over time, most enzyme biosensors either are one-use disposable strips or require periodic change of membrane and frequent calibration, which makes them impractical for industrial applications. With the nanotechnology boom, several research reports have focused on increased sensitivity by creating porous nanostructures. There are also several reports on the effects of immobilization, cross-linking, and additions of solutes to stabilize enzymes and extend the operational life of enzyme biosensors. Here we summarize our research for the last 10 years on the effects of platinization conditions, including the use of high hydrostatic pressure (HHP) up to 500 MPa on the fabrication of microporous platinum black structures that maximize electrode sensitivity. In our early research we reported a 60-fold increase in sensitivity of glucose biosensors. We also report the effect of enzyme entrapment in poly-o-phenylenediamine (PoPD) nanofilms and their impact on electrode sensitivity and stability on glucose oxidase, alcohol oxidase, and galactose oxidase. High pressure and immobilization in PoPD resulted in two orders of magnitude increase in glucose oxidase biosensors. In contrast, while HHP increased the stability of AOx by a factor of ~15, immobilization only increased its stability by a factor of ~5 stability and combined HHP and immobilization only increased the stability by a factor of 6.4 relative to the enzyme in solution.

Micro additive manufacturing of glucose biosensors: A feasibility study

Flexible electrochemical sensors for measurement and quantification of biomarkers are attracting a great deal of attention in non-invasive medical applications, due to their high mechanical compatibility and conformability with the human body. Realization of the full potential of such novel systems relies heavily on their effective manufacturing. Particularly, there is a need for manufacturing techniques that can realize complex designs, consisting of multiple functional materials which are required for sensor functionality. Among emerging additive manufacturing techniques, Direct-Ink-Writing (DIW), where polymer nanocomposite inks are dispensed through nozzles and deposited with high spatial control, carries a great potential to address this need. Here, we introduce a 3D printed flexible electrochemical biosensor for glucose detection. We show that our biosensor works linearly in glucose solution with a concentration range between 100 and 1000 μM. The sensitivity of glucose biosensor is estimated to be 17.5 nA μM−1, and the calculated value of the detection limit (S/N = 3) is 6.9 μM. The demonstrated electrochemical performance and surface properties of the printed sensors show the promising advantages of using this technique over the conventional screen printing method. These advantages include higher sensitivity and specificity and, reduced material consumption.

3-D printed adjustable microelectrode arrays for electrochemical sensing and biosensing

Printed electronics has emerged as an important fabrication technique that overcomes several shortcomings of conventional lithography and provides custom rapid prototyping for various sensor applications. In this work, silver microelectrode arrays (MEA) with three different electrode spacing were fabricated using 3-D printing by the aerosol jet technology. The microelectrodes were printed at a length scale of about 15μm, with the space between the electrodes accurately controlled to about 2 times (30μm, MEA30), 6.6 times (100μm, MEA100) and 12 times (180μm, MEA180) the trace width, respectively. Hydrogen peroxide and glucose were chosen as model analytes to demonstrate the performance of the MEA for sensor applications. The electrodes are shown to reduce hydrogen peroxide with a reduction current proportional to the concentration of hydrogen peroxide for certain concentration ranges. Further, the sensitivity of the current for the three electrode configurations was shown to decrease with an increase in the microelectrode spacing (sensitivity of MEA30:MEA100:MEA180 was in the ratio of 3.7:2.8:1), demonstrating optimal MEA geometry for such applications. The noise of the different electrode configurations is also characterized and shows a dramatic reduction from MEA30 to MEA100 and MEA180 electrodes. Further, it is shown that the response current is proportional to MEA100 and MEA180 electrode areas, but not for the area of MEA30 electrode (the current density of MEA30:MEA100:MEA180 is 0.25:1:1), indicating that the MEA30 electrodes suffer from diffusion overlap from neighboring electrodes. The work thus establishes the lower limit of microelectrode spacing for our geometry. The lowest detection limit of the MEAs was calculated (with S/N=3) to be 0.45μM. Glucose oxidase was immobilized on MEA100 microelectrodes to demonstrate a glucose biosensor application. The sensitivity of glucose biosensor was 1.73μAmM−1 and the calculated value of detection limit (S/N=3) was 1.7μM. The electrochemical response characteristics of the MEAs were in agreement with the predictions of existing models. The current work opens up the possibility of additive manufacturing as a fabrication technique for low cost custom-shaped MEA structures that can be used as electrochemical platforms for a wide range of sensor applications.

The Morphologies of Pt Decorated on PANI Membrane and Effects on Glucose Biosensor

This paper mainly studies on the morphologies of Platinum(Pt) nanoparticles decorated on polyanilene(PANI)and their influence on the sensitivity of glucose biosensor. Seldom researches were carried on the morphologies of Pt nanoparticles and the optimization of parameters. Compared by scanning electron microscopy(SEM), cyclic voltammetry(CV) and glucose current response, Pt completely wrapped PANI nanofibers shows better electrochemical stability, sensitivity and larger catalytic area than different kinds of Pt decorated PANI membranes. Pt completely wrapped PANI nanofibers are provided by electrochemical deposition Pt nanoparticles on PANI nanofibers under a special voltage. The average diameter of nanofibers which form porous Pt/PANI membrane is 100 nm. CVs of this membrane become stable in seven circles and provide a higher current peak which indicates larger catalytic area. The sensitivity indicated by current-time glucose response is several times of the other membranes.

Потенциометрическое определение глюкозы в сыворотке крови человека с помощью биосенсора на основе глюкозооксидазы и йодидного электрода

Glucose potentiometric biosensor was prepared by immobilizing glucose oxidase on iodide-selective electrode. The hydrogen peroxide formed after the oxidation of glucose catalysed by glucose oxidase (GOD) was oxidized by sodium molybdate (SMo) at iodide electrode in the presence ofdichlorometane. The glucose concentration was calculated from the decrease of iodide concentration determined by iodide-selective sensor. The sensitivity of glucose biosensor towards iodide ions and glucose was in the concentration ranges of 1.0 x 10(-1) - 1.0 x 10(-6) M and 1.0 x 10(-2) - 1.0 x 10(-4) M, respectively. The characterization of proposed glucose biosensor and glucose assay in human serum were also investigated.