Screen-printed electrochemical biosensor based on a ternary Co@MoS2/rGO functionalized electrode for high-performance non-enzymatic glucose sensing

A Review on Recent Trends and Future Developments in Electrochemical Sensing

Electrochemical methods and devices have ignited prodigious interest for sensing and monitoring. The greatest challenge for science is far from meeting the expectations of consumers. Electrodes made of two-dimensional (2D) materials such as graphene, metal-organic frameworks, MXene, and transition metal dichalcogenides as well as alternative electrochemical sensing methods offer potential to improve selectivity, sensitivity, detection limit, and response time. Moreover, these advancements have accelerated the development of wearable and point-of-care electrochemical sensors, opening new possibilities and pathways for their applications. This Review presents a critical discussion of the recent developments and trends in electrochemical sensing.

Artificial enzyme innovations in electrochemical devices: advancing wearable and portable sensing technologies

With the rapid evolution of sensing technologies, the integration of nanoscale catalysts, particularly those mimicking enzymatic functions, into electrochemical devices has surfaced as a pivotal advancement. These catalysts, dubbed artificial enzymes, embody a blend of heightened sensitivity, selectivity, and durability, laying the groundwork for innovative applications in real-time health monitoring and environmental detection. This minireview penetrates into the fundamental principles of electrochemical sensing, elucidating the unique attributes that establish artificial enzymes as foundational elements in this field. We spotlight a range of innovations where these catalysts have been proficiently incorporated into wearable and portable platforms. Navigating the pathway of amalgamating these nanoscale wonders into consumer-appealing devices presents a multitude of challenges; nevertheless, the progress made thus far signals a promising trajectory. As the intersection of materials science, biochemistry, and electronics progressively intensifies, a flourishing future seems imminent for artificial enzyme-infused electrochemical devices, with the potential to redefine the landscapes of wearable health diagnostics and portable sensing solutions.

Carbon Nanomaterials-Based Screen-Printed Electrodes for Sensing Applications

Electrochemical sensors consisting of screen-printed electrodes (SPEs) are recurrent devices in the recent literature for applications in different fields of interest and contribute to the expanding electroanalytical chemistry field. This is due to inherent characteristics that can be better (or only) achieved with the use of SPEs, including miniaturization, cost reduction, lower sample consumption, compatibility with portable equipment, and disposability. SPEs are also quite versatile; they can be manufactured using different formulations of conductive inks and substrates, and are of varied designs. Naturally, the analytical performance of SPEs is directly affected by the quality of the material used for printing and modifying the electrodes. In this sense, the most varied carbon nanomaterials have been explored for the preparation and modification of SPEs, providing devices with an enhanced electrochemical response and greater sensitivity, in addition to functionalized surfaces that can immobilize biological agents for the manufacture of biosensors. Considering the relevance and timeliness of the topic, this review aimed to provide an overview of the current scenario of the use of carbonaceous nanomaterials in the context of making electrochemical SPE sensors, from which different approaches will be presented, exploring materials traditionally investigated in electrochemistry, such as graphene, carbon nanotubes, carbon black, and those more recently investigated for this (carbon quantum dots, graphitic carbon nitride, and biochar). Perspectives on the use and expansion of these devices are also considered.

Two-Dimensional Non-Carbon Materials-Based Electrochemical Printed Sensors: An Updated Review

Recently, there has been increasing interest in electrochemical printed sensors for a wide range of applications such as biomedical, pharmaceutical, food safety, and environmental fields. A major challenge is to obtain selective, sensitive, and reliable sensing platforms that can meet the stringent performance requirements of these application areas. Two-dimensional (2D) nanomaterials advances have accelerated the performance of electrochemical sensors towards more practical approaches. This review discusses the recent development of electrochemical printed sensors, with emphasis on the integration of non-carbon 2D materials as sensing platforms. A brief introduction to printed electrochemical sensors and electrochemical technique analysis are presented in the first section of this review. Subsequently, sensor surface functionalization and modification techniques including drop-casting, electrodeposition, and printing of functional ink are discussed. In the next section, we review recent insights into novel fabrication methodologies, electrochemical techniques, and sensors' performances of the most used transition metal dichalcogenides materials (such as MoS₂, MoSe₂, and WS₂), MXenes, and hexagonal boron-nitride (hBN). Finally, the challenges that are faced by electrochemical printed sensors are highlighted in the conclusion. This review is not only useful to provide insights for researchers that are currently working in the related area, but also instructive to the ones new to this field.

Chronoampermetric detection of enzymatic glucose sensor based on doped polyindole/MWCNT composites modified onto screen-printed carbon electrode as portable sensing device for diabetes

Doped-polyindole (dPIn) mixed with multi-walled carbon nanotubes (MWCNTs) were coated on a screen-printed electrode to improve the electroactive surface area and current response of the chronoamperometric enzymatic glucose sensor. Glucose oxidase mixed with chitosan (CHI-GOx) was immobilized on the electrode. (3-Aminopropyl) triethoxysilane (APTES) was used as a linker between the CHI-GOx and the dPIn. The current response of the glucose sensor increased with increasing glucose concentration according to a power law relation. The sensitivity of the CHI-GOx/APTES/dPIn was 55.7 μA mM⁻¹ cm⁻² with an LOD (limit of detection) of 0.01 mM, where the detectable glucose concentration range was 0.01–50 mM. The sensitivity of the CHI-GOx/APTES/1.5%MWCNT-dPIn was 182.9 μA mM⁻¹ cm⁻² with an LOD of 0.01 mM, where the detectable glucose concentration range was 0.01–100 mM. The detectable concentration ranges of glucose well cover the glucose concentrations in urine and blood. The fabricated enzymatic glucose sensors showed high stability during a storage period of four weeks and high selectivity relative to other interferences. Moreover, the sensor was successfully demonstrated as a continuous or step-wise glucose monitoring device. The preparation method employed here was facile and suitable for large quantity production. The glucose sensor fabricated here, consisting of the three-electrode cell of SPCE, were simple to use for glucose detection. Thus, it is promising to use as a prototype for real glucose monitoring for diabetic patients in the future.

The enzymatic glucose sensor based on a dPIn and dPIn/MWCNT modified screen-printed carbon electrode with a facile method possessed good glucose response. The detectable glucose concentration range covers well the glucose concentrations in urine and blood.

A simple unlabeled human chorionic gonadotropin biosensor based on a peptide aptamer

As an essential biochemical indicator in the fields of pregnancy and oncology, human chorionic gonadotropin (HCG) can be evaluated using colloidal gold immunochromatographic paper and quantified using a biochemical analyzer based on the principle of the antibody sandwich method. In view of the inaccuracy of the former and the complication of the latter, this study constructed an accurate, sensitive and simple unlabeled biosensor based on peptide aptamer CGGGPPLRINRHILTR for HCG detection. Molecular Operating Environment (MOE) was used to simulate the aptamer and protein docking, and western blot (WB) was used to verify the binding effect and ratio. The peptide aptamer was characterized and was then reduced with tris-(2-carboxyethyl)-phosphine hydrochloride (TCEP). After electrochemical deposition of chloroauric acid on the screen-printed electrode (SPE), the aptamer was self-assembled on the electrode surface under optimal conditions. The active site of the electrode surface was blocked with 6-mercapto-1-hexanol (MCH) and BSA. The electrochemical impedance spectrum (EIS) was used to quantify HCG in the matrix. Showing a good linear relationship in the range of 5-1500 mIU mL^-1, with a detection limit of 1 mIU mL^-1, the biosensor remained stable at room temperature for 14 days. Because of its small size, stability, sensitivity and accuracy, this biosensor has great potential to become a portable diagnostic device for HCG.

A hierarchical hollow Ni/Co-functionalized MoS2 architecture with highly sensitive non-enzymatic glucose sensing activity

A hierarchical hollow Ni/Co-codoped MoS2 architecture was successfully prepared using a Ni/Co Prussian Blue analogue as the precursor followed by the solvothermal-assisted insertion of MoS42- and extraction of [Co(CN)6]3- at 200 °C for 32 h. The obtained Ni/Co-codoped MoS2 composite exhibited a hollow microcubic structural characteristic, and the morphology, structure, and chemical compositions were carefully characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. The Ni/Co-codoped MoS2 composite used as an electrode material featured excellent glucose sensing activity and a high sensitivity of 2546 μA mM-1 cm-2 with a relatively low detection limit of 0.69 μM (S/N = 3). In addition, the Ni/Co-codoped MoS2 composite showed good anti-interference sensing performance in the presence of ascorbic acid (AA), lysine (Lys), cysteine (Cys), urea, H2O2, KCl, and other interferents. These experimental results revealed that the composite is a promising electrode material for enzyme-free glucose sensing, and the feasible synthetic strategy may provide an effective and controlled route to prepare other multi-metal substituted sulfide-based hierarchical structures with high electrochemical sensing performance.

Metal-Oxide Based Nanomaterials: Synthesis, Characterization and Their Applications in Electrical and Electrochemical Sensors

Pure, mixed and doped metal oxides (MOX) have attracted great interest for the development of electrical and electrochemical sensors since they are cheaper, faster, easier to operate and capable of online analysis and real-time identification. This review focuses on highly sensitive chemoresistive type sensors based on doped-SnO₂, RhO, ZnO-Ca, Sm_x-CoFe_2−xO₄ semiconductors used to detect toxic gases (H₂, CO, NO₂) and volatile organic compounds (VOCs) (e.g., acetone, ethanol) in monitoring of gaseous markers in the breath of patients with specific pathologies and for environmental pollution control. Interesting results about the monitoring of biochemical substances as dopamine, epinephrine, serotonin and glucose have been also reported using electrochemical sensors based on hybrid MOX nanocomposite modified glassy carbon and screen-printed carbon electrodes. The fundamental sensing mechanisms and commercial limitations of the MOX-based electrical and electrochemical sensors are discussed providing research directions to bridge the existing gap between new sensing concepts and real-world analytical applications.

Developing a versatile electrochemical platform with optimized electrode configuration through screen-printing technology toward glucose detection

Rapid on-site detection of glucose has been attracting considerable attention nowadays. Screen-printed electrodes (SPEs) were assessed as ideal detection platforms due to their advantages such as, disposability, portability, ease of miniaturization, and mass production. The topology and shape of electrodes have a crucial impact on their electrical conductivity and electrochemical properties. In this study, a versatile electrochemical platform with optimized three-electrode configuration was developed through screen-printing technology. Three types of SPEs were prepared, and their electrocatalytic properties toward glucose detection were investigated. Based on this platform, both enzyme-based (denoted as GOD/rGO) and non-enzymatic (denoted as Co@MoS2/rGO) bioactive compounds were deposited on the working electrode of the circular SPE through simply drop-casting, respectively. Their morphology was characterized through scanning electron microscopy (SEM). Cycle sweep voltammetry was used to study the electrocatalytic activity of these biosensors. The circular SPE exhibited satisfying electrochemical redox activity and much higher sensitivity towards glucose detection, which rendered it a promising candidate for point-of-care detection.