Glucose sensing on screen-printed electrochemical electrodes based on porous graphene aerogel @prussian blue

Fire up Biosensor Technology to Assess the Vitality of Trees after Wildfires

The development of tools to quickly identify the fate of damaged trees after a stress event such as a wildfire is of great importance. In this context, an innovative approach to assess irreversible physiological damage in trees could help to support the planning of management decisions for disturbed sites to restore biodiversity, protect the environment and understand the adaptations of ecosystem functionality. The vitality of trees can be estimated by several physiological indicators, such as cambium activity and the amount of starch and soluble sugars, while the accumulation of ethanol in the cambial cells and phloem is considered an alarm sign of cell death. However, their determination requires time-consuming laboratory protocols, making the approach impractical in the field. Biosensors hold considerable promise for substantially advancing this field. The general objective of this review is to define a system for quantifying the plant vitality in forest areas exposed to fire. This review describes recent electrochemical biosensors that can detect plant molecules, focusing on biosensors for glucose, fructose, and ethanol as indicators of tree vitality.

Non-toxic flexible screen-printed MWCNT-based electrodes for non-invasive biomedical applications

Here, a non-toxic, flexible, low-cost, and disposable multiwalled carbon nanotube (MWCNT)-based screen-printed electrode (SPE) was developed for non-invasive health monitoring applications. A novel MWCNT-based conductive paste formulation was prepared and optimized for printing SPEs using a computer numerical control (CNC)-made stencil. The electrodes were electrochemically characterized and subjected to physical stress to investigate their mechanical durability in extreme situations such as heavy exercise. The reproducibility of the fabrication approach and the stability of the electrodes were also demonstrated. The electrochemical performance of the electrodes was tested with first dopamine (DA) and then glucose. The SPE displayed a linear response in the DA concentration range of 5-500 μM with a limit-of-detection (LOD) of 0.87 μM. Detection of glucose was carried out based on electrochemical-enzymatic redox cycling in artificial sweat; wherein the flexible SPE-based biosensor exhibited a linear response, particularly up to 1 mM with an LOD of 31.7 μM. It is likely that the high sensitivity was achieved due to the large surface-to-volume ratio of MWCNTs and micro/nanoporous network morphology of the electrode surface which was observed in scanning electron microscopy (SEM). Cytotoxicity tests confirmed that the flexible MWCNT-SPEs are non-toxic and therefore safe for non-invasive health monitoring. As a result, the electrodes displayed excellent electrochemical behavior and are expected to contribute to wearable sensor technology due to features such as high stability, sensitivity, flexibility, and non-toxicity.

The Development of Reagentless Amperometric Glucose Biosensor Based on Gold Nanostructures, Prussian Blue and Glucose Oxidase

Precise blood glucose detection plays a crucial role in diagnosing and medicating diabetes, in addition to aiding diabetic patients in effectively managing their condition. In this research, a first-generation reagentless amperometric glucose biosensor was developed by combining the graphite rod (GR) electrode modification by gold nanostructures (AuNS) and Prussian blue (PB) with glucose oxidase (GOx)-an enzyme that can oxidize glucose and produce H2O2. Firstly, AuNS was electrochemically deposited on the GR electrode (AuNS/GR), and then PB was electrochemically synthesized on the AuNS/GR electrode (PB/AuNS/GR). Finally, GOx was immobilized over the PB/AuNS nanocomposite with the assistance of Nafion (Nf) (Nf-GOx/PB/AuNS/GR). An application of PB in the design of a glucose biosensor enables an easy electrochemical reduction and, thus, the determination of the H2O2 produced during the GOx-catalyzed oxidation of glucose in the sample at a low operation potential of -0.05 V vs. Ag/AgCl/KCl3 mol L-1. In addition, AuNS increased the electrochemically active surface area, improved the GOx immobilization and ensured a higher analytical signal. The developed glucose biosensor based on the Nf-GOx/PB/AuNS/GR electrode exhibited a wide linear range, from 0.025 to 1 mmol L-1 of glucose, with a 0.0088 mmol L-1 limit of detection, good repeatability and high selectivity over electroactive interfering substances. The developed biosensor is convenient for the determination of glucose in the physiological environment.

Paper-Based Screen-Printed Ionic-Liquid/Graphene Electrode Integrated with Prussian Blue/MXene Nanocomposites Enabled Electrochemical Detection for Glucose Sensing

As glucose biosensors play an important role in glycemic control, which can prevent the diabetic complications, the development of a glucose sensing platform is still in needed. Herein, the first proposal on the in-house fabricated paper-based screen-printed ionic liquid/graphene electrode (SPIL-GE) modified with MXene (Ti₃C₂T_x), prussian blue (PB), glucose oxidase (GOx), and Nafion is reported. The concentration of PB/Ti₃C₂T_x was optimized and the optimal detection potential of PB/Ti₃C₂T_x/GOx/Nafion/SPIL-GE is -0.05 V. The performance of PB/Ti₃C₂T_x/GOx/Nafion modified SPIL-GE was characterized by cyclic voltammetry and chronoamperometry technique. This paper-based platform integrated with nanomaterial composites were realized for glucose in the range of 0.0-15.0 mM with the correlation coefficient R² = 0.9937. The limit of detection method and limit of quantification were 24.5 μM and 81.7 μM, respectively. In the method comparison, this PB/Ti₃C₂T_x/GOx/Nafion/SPIL-GE exhibits a good correlation with the reference hexokinase method. This novel glucose sensing platform can potentially be used for the good practice to enhance the sensitivity and open the opportunity to develop paper-based electroanalytical devices.