Advanced Glucose Sensors Research Articles

Co3O4 Based Non-Enzymatic Microneedle Glucose Sensor for Plant Health Monitoring

Over the last decade, various wearable sensor technologies that can monitor human health precisely in real time have extensively been developed. More recently, such wearable biosensor technologies have been employed to observe the condition of plants as well. In particular, a glucose sensor, which has been actively researched for diabetes, can also be applied to plants. A level of glucose concentration in plants indicates cellular metabolic status, biotic and abiotic stress of plants. However, unlike advanced glucose sensors for humans, early glucose sensors based on glucose oxidase are still used in plants glucose monitoring. The enzyme-based glucose sensor has several disadvantages including the stability problem due to denaturation of enzymes and difficulty of immobilizing enzymes on the electrode surface. Additionally, glucose oxidase needs a redox shuttle to transfer electrons, which complicate the sensor manufacturing process. Moreover, H2O2 is generated as a byproduct of glucose oxidase and glucose reaction, which can cause damage to plants and enzymes.In this study, non-enzymatic microneedle (MN) glucose sensor was developed using Co3O4 as a substitute for glucose oxidase. Co3O4 have electrocatalytic properties and chemical stability, showing higher sensitivity compared to glucose oxidase, and is suitable for long-term monitoring. However, it has the disadvantage of low electrical conductivity, making it difficult to transfer electrons, which are generated from the reaction with glucose, to a sensor electrode. Therefore, carbon nanomaterials were mixed to increase electron transfer efficiency and drop casted on the working electrode of a screen-printed sensor. To optimize the ratio of Co3O4 and carbon nanomaterials, the sensitivity was observed by comparing the peak current of cyclic voltammogram and saturation currents of amperogram according to each mixing ratio. Through the analysis results, it was confirmed that 17 wt% carbon nanomaterial had the highest sensitivity of 207 μA/mM cm2. Afterwards, a MN array sensor was fabricated to measure the glucose in plant leaves. MN can penetrate the epidermis of the leaf and enable to measure the glucose from near the phloem of the leaf. MN array structure was fabricated by dispensing SU-8 into a PDMS negative mold and cured by UV exposure. The working and reference electrode of MN array were coated with Co3O4/carbon composite and pseudo-Ag/AgCl ink, respectively, using a pneumatic 3D printer. Pt sputtering was conducted for forming the counter electrode. The metabolism of plants was confirmed by measuring the glucose concentration of leaves at day and night using a MN glucose sensor.

A nanoporous Cu-Ag thin film at the Cu-Ag-Zn alloy surface by spontaneous dissolution of Zn and Cu in different degrees as a highly sensitive non-enzymatic glucose sensor

In this article, we present a new dealloying way to fabricate a stable nanoporous Cu-Ag bimetallic thin film as a glucose sensor. The nanoporous Cu-Ag thin film is obtained under a mild condition simply by immersing a Cu-Ag-Zn alloy disk electrode (with minor Ag) of 2-mm diameter in 1 M KOH solution at room temperature for a short time of 3 h. The metallic Zn and Cu at the ternary alloy surface are automatically dissolved completely and partially via oxidation reactions with the solvent H2O and the dissolved O2, respectively, leaving a nanoporous structure on the disk substrate. The method is very facile, green and cost-effective. The prepared nanoporous Cu-Ag thin film consists of small nanoparticles. The presence of lesser Ag prevents the small Cu-Ag nanoparticles from agglomeration and enhances the electro-oxidation of glucose compared with the dealloyed Cu-Zn electrode. The prepared nanoporous Cu-Ag film can serve as an advanced glucose sensor with a high sensitivity of 3572 μA mM−1 cm−2, a low detection limit of 0.37 μM, a wide linear range up to 6 mM, excellent reproducibility (RSD < 5%), short response time (4 s), and long-term stability of 4 weeks. The glucose sensor has been satisfactorily applied to the determination of glucose concentration in human serum. This automatic dealloying method is expected to fabricate other stable nanoporous bimetallic films for non-enzymatic glucose sensing and other applications.

Fluorescent Nanobiosensors for Sensing Glucose

Glucose sensing in diabetes diagnosis and therapy is of great importance due to the prevalence of diabetes in the world. Furthermore, glucose sensing is also critical in the food and drug industries. Sensing glucose has been accomplished through various strategies, such as electrochemical or optical methods. Novel transducers made with nanomaterials that integrate fluorescent techniques have allowed for the development of advanced glucose sensors with superior sensitivity and convenience. In this review, glucose sensing by fluorescent nanobiosensor systems is discussed. Firstly, typical fluorescence emitting/interacting nanomaterials utilized in various glucose assays are discussed. Secondly, strategies for integrating fluorescent nanomaterials and biological sensing elements are reviewed and discussed. In summary, this review highlights the applicability of fluorescent nanomaterials, which makes them ideal for glucose sensing. Insight on the future direction of fluorescent nanobiosensor systems is also provided.

Rapid electrochemical conversion of smooth Cu surfaces to urchin-like Cu nanowire arrays via flower-like Cu2Se nanosheets as an advanced nonenzymatic glucose sensor

A novel surface conversion of smooth copper electrodes into flower-like Cu2Se nanosheets is realized in 5∼150 s by a cathodic polarization at −2.1 V vs. saturated mercurous sulfate electrode in a solution of 0.5 M Na2SO4 containing 20 mM Na2SeSO3. It involves continuous autooxidation of Cu to Cu2Se and its electroreduction. The flower-like Cu2Se nanosheets can be further transformed in situ into urchin-like Cu nanowire arrays by cyclic voltammetry for 5∼20 cycles in a solution of 0.1 M NaOH. It undergoes repeated anodization/dissolution and deposition of Cu. The mechanisms for these fast anomalous conversions have been elucidated in detail. The in situ formed urchin-like Cu nanowire arrays from the flower-like Cu2Se can serve as an advanced glucose sensor, which possesses these merits of high sensitivity (3745 μA mM−1 cm−2), low detection limit (0.51 μM), wide linear range (up to 6.11 mM), long-term stability (remaining 90.5% of its initial current response for a 12-week storage), excellent reproducibility (RSD < 5%), and reliable accuracy (with a recovery of 101%).

Stem Cell Derived Beta Cells: The State of the Science.

Stem Cell Derived Beta Cells: The State of the Science.

Fluorescence Glucose Detection: Advances Toward the Ideal In Vivo Biosensor

The importance of glucose monitoring for in vivo as well as for ex vivo applications has driven a vast number of scientific groups to pursue the development of an advanced glucose sensor. Such a sensor must be robust, versatile, and capable of the long-term, accurate and reproducible detection of glucose levels in various testing media. Among the different configurations and signal transduction mechanisms used, fluorescence-based glucose sensors constitute a growing class of glucose sensors represented by an increasing number of significant contributions to the field over the last few years. This manuscript reviews the progress in the development of fluorescence based glucose sensors resulting from the advances in the design of new receptor systems for glucose recognition and the utilization of new fluorescence transduction schemes.

Continuous in vivo monitoring in diabetes: the subcutaneous glucose concentration.

The most advanced glucose sensors are measuring amperometrically the hydrogen peroxide generated in a stoichiometric relation to the prevailing glucose concentration during glucose oxidase-mediated glucose oxidation. They proved useful in commercially available glucose analysers and in experimental subcutaneous (sc) monitoring. Here it is shown (a) that under steady state conditions the s.c glucose concentration is nearly identical to that in blood, (b) that sc. inserted glucose electrodes do mirror the intracorporal glucose concentration both under hypo-, normo-, and hyperglycaemic conditions with a clinically relevant accuracy, (c) that automated feedback control of intracorporal glucose concentration is possible applying the output of sc. glucose sensor as an input to the computer that controls the insulin pump, and (d) that stable function of sc. sensor may be accomplished over intervals up to one day; in some cases applications over up to ten days have been reported. The underlying problem consists in an insufficient functional biostability which is a function of biocompatibility and size of the sensor, of its sterility, and of the permanent skin penetration. The latter is still required to get the device in place, to keep it in function, and to make use of the data under any condition. At this time, sc. glucose electrodes to be employed as hypoglycaemia-warning systems over one day are considered clinically important and technically achievable.

The Characteristics of a New Glucose Sensor for Use in an Artificial Pancreatic Beta Cell

A new glucose sensor has been developed for the continuous extracorporeal monitoring of blood glucose concentrations in conjunction with an artificial pancreatic beta cell simulator. This sensor has a rapid ninety percent response time (less than 1 min), is stable for periods of up to 140 hours of accumulated use and can be calibrated without the use of a reference glucose analyzer. Its reliability has been confirmed in over 100 clinical studies. A comparison of this sensor to other glucose sensors designed for artificial pancreatic beta cell devices is made and the sensor is shown to be the most advanced glucose sensor presently available for extracorporeal continuous glucose monitoring in man.