Development of Highly Sensitive Ag NPs Decorated Graphene FET Sensor for Detection of Glucose Concentration

Advancements in electrochemical glucose sensors

The development of electrochemical glucose sensors with high sensitivity, specificity, and stability, enabling real-time continuous monitoring, has posed a significant challenge. However, an opportunity exists to fabricate electrochemical glucose biosensors with optimal performance through innovative device structures and surface modification materials. This paper provides a comprehensive review of recent advances in electrochemical glucose sensors. Novel classes of nanomaterials-including metal nanoparticles, carbon-based nanomaterials, and metal-organic frameworks-with excellent electronic conductivity and high specific surface areas, have increased the availability of reactive sites to improved contact with glucose molecules. Furthermore, in line with the trend in electrochemical glucose sensor development, research progress concerning their utilisation with sweat, tears, saliva, and interstitial fluid is described. To facilitate the commercialisation of these sensors, further enhancements in biocompatibility and stability are required. Finally, the characteristics of the ideal electrochemical glucose sensor are described and the developmental trends in this field are outlines.

Flexible Bio-Electronic Hybrid Metal-Oxide Channel FET as a Glucose Sensor

A high-sensitivity flexible field-effect transistor (FET) based glucose sensor is fabricated that can surpass the conventional electrochemical glucometers in terms of sensitivity, limit of detection, and other performance parameters. The proposed biosensor is based on the FET operation with the advantage of amplification which provides a high sensitivity and a very low limit of detection. Hybrid metal oxide (ZnO and CuO) nanostructures have been synthesized in the form of hollow spheres (ZnO/CuO-NHS). The FET was fabricated by depositing ZnO/CuO-NHS on the interdigitated electrodes. Glucose oxidase (GOx) was immobilized successfully on the ZnO/CuO-NHS. Three different outputs of the sensor are examined, the FET current, the relative current change, and the drain voltage. The sensitivity of the sensor for each output type has been calculated. The readout circuit can convert the current change to the voltage change that has been used for wireless transmission. The sensor has a very low limit of detection of 30 nM with satisfactory reproducibility, good stability, and high selectivity. The electrical response of the FET biosensor towards the real human blood serum samples demonstrated that it can be offered as a potential device for glucose detection in any medical application.

Development of a portable smart Glucometer with two electrode bio-electronic test strip patch based on Cu/Au/rGO/PEDOT:PSS

Today, the importance of blood sugar monitoring in diabetic patients has created a global need to develop new glucometers. This article presents the fabrication of a portable smart glucometer for monitoring blood glucose with high sensitivity. The glucometer employs a bio-electronic test strip patch fabricated by the structure of Cu/Au/rGO/PEDOT: PSS on interdigitated electrodes. We demonstrate that this structure based on two-electrode can be superior to the three-electrode electrochemical test strips available in the market. It has good electro-catalytic properties that indicate high-performance sensing of blood glucose. The proposed bio-electronic glucometer can surpass the commercial electrochemical test strips in terms of response time, detection range, and limit of detection. Electronic modules used for the fabrication of smart glucometers, such as a power supply, analog to digital converter, OLED screen, and, wireless transmission module, are integrated onto a printed circuit board and packaged as a bio-electronics glucometer, enabling the comfortable handling of this blood glucose monitoring. The characteristics of active layers biosensors were investigated by SEM, and AFM. The glucometer can monitor glucose in the wide detection range of 0-100 mM, the limit of detection (1 µM) with a sensitivity of 5.65 mA mM^-1 and excellent sensing performance such as high selectivity, high reproducibility, and good stability of fabricated test strips. With 11 human blood and serum samples, the glucometer demonstrated high clinical accuracy with the best value of RSD of 0.012.

The design of a point of care FET biosensor to detect and screen COVID-19

Graphene field effect transistor (FET) biosensors have attracted huge attention in the point-of-care and accurate detection. With the recent spread of the new emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the need for rapid, and accurate detection & screening tools is arising. Employing these easy-to-handle sensors can offer cheap, rapid, and accurate detection. Herein, we propose the design of a reduced graphene oxide (rGO) FET biosensor for the detection of SARS-CoV-2. The main objective of this work is to detect the SARS-CoV-2 spike protein antigen on spot selectively and rapidly. The sensor consists of rGO channel, a pair of golden electrodes, and a gate underneath the channel. The channel is functionalized with COVID-19 spike protein antibodies to achieve selectivity, and with metal nanoparticles (MNPs) such as copper and silver to enhance the bio-sensing performance. The designed sensor successfully detects the SARS-CoV-2 spike protein and shows singular electrical behavior for detection. The semi-empirical modeling approach combined with none-equilibrium Green's function were used to study the electronic transport properties of the rGO-FET biosensor before and after the addition of the target molecules. The sensor's selectivity is also tested against other viruses. This study provides a promising guide for future practical fabrication.

Recent Advances in Electrochemical Sensors for the Detection of Biomolecules and Whole Cells

Electrochemical sensors are considered an auspicious tool to detect biomolecules (e.g., DNA, proteins, and lipids), which are valuable sources for the early diagnosis of diseases and disorders. Advances in electrochemical sensing platforms have enabled the development of a new type of biosensor, enabling label-free, non-destructive detection of viability, function, and the genetic signature of whole cells. Numerous studies have attempted to enhance both the sensitivity and selectivity of electrochemical sensors, which are the most critical parameters for assessing sensor performance. Various nanomaterials, including metal nanoparticles, carbon nanotubes, graphene and its derivatives, and metal oxide nanoparticles, have been used to improve the electrical conductivity and electrocatalytic properties of working electrodes, increasing sensor sensitivity. Further modifications have been implemented to advance sensor platform selectivity and biocompatibility using biomaterials such as antibodies, aptamers, extracellular matrix (ECM) proteins, and peptide composites. This paper summarizes recent electrochemical sensors designed to detect target biomolecules and animal cells (cancer cells and stem cells). We hope that this review will inspire researchers to increase their efforts to accelerate biosensor progress-enabling a prosperous future in regenerative medicine and the biomedical industry.