Development Of Non-enzymatic Sensor Research Articles

Supported Pt Nanoclusters on Single-Layer MoS2 for the Detection of Cortisol: From Atomistic Scale to Device Modeling

The development of nonenzymatic sensors is a challenge which requires, on the one hand, careful design of the sensing materials with respect to the chosen analyte, and on the other hand, suitable device architectures. In this work, we propose single-layer molybdenum disulfide (MoS2) decorated with subnanometer Pt clusters as the sensing platform for the detection of cortisol. The aim is to assess the suitability of such a sensing platform for the development of wearable and portable cortisol sensors. For this study, we performed multiscale computer simulations at the materials level up to device scale. First, ab initio simulations within the framework of density functional theory (DFT) allowed us to gain insights into the interaction, at the atomic level, between the analyte (cortisol) and the sensing platform (MoS2/Pt). Then, by carrying out technology computer-aided design (TCAD) simulations, we were able to consider a device architecture and investigate its performance as cortisol sensor. Following our multiscale simulation strategy, we were able to assess the proposed field-effect transistor (FET) sensor, whose channel is made of Pt-decorated MoS2. The sensing mechanism relies on the chemiresistive response of the device to the adsorption of cortisol on the channel, which leads to a sizable charge transfer from the analyte to the substrate and, consequently, to the measurable shift in the gate voltage threshold of the FET. Our findings suggest that both the choice of the sensing materials and the proposed FET architecture are suitable for detecting cortisol by non-enzymatic means. In the best case scenario, we predict theoretical gate voltage shifts between 76 and 780 mV with respect to the cluster concentration and between 27 and 780 mV when varying the cluster occupancy by cortisol. We may expect our results to provide the necessary basis to develop highly sensitive nonenzymatic cortisol sensors based on 2D materials decorated with Pt nanoclusters.

Three-Phases Interface Induced Local Alkalinity Generation Enables Electrocatalytic Glucose Oxidation in Neutral Electrolyte.

Electrocatalytic glucose oxidation is crucial to the development of non-enzymatic sensors, an attractive alternative for enzymatic biosensors. However, due to OH− consumption during the catalytic process, non-enzymatic detection generally requires electrolytes having an alkaline pH value, limiting its practical application since biofluids are neutral. Herein, via interfacial microenvironment design, we addressed this limitation by developing a non-enzymatic sensor with an air–solid–liquid triphase interface electrodes that synergistically integrates the functions of local alkalinity generation and electrocatalytic glucose oxidation. A sufficiently high local pH value was achieved via oxygen reduction reaction at the triphase interface, which consequently enabled the electrochemical oxidation (detection) of glucose in neutral solution. Moreover, we found that the linear detection range and sensitivity of triphase non-enzymatic sensor can be tuned by changing the electrocatalysts of the detection electrode. The triphase electrode architecture provides a new platform for further exploration and promotes practical application of non-enzymatic sensors.

In-situ single-step electrochemical AgO modified graphite pencil electrode for trace determination of DL-methionine in human serum sample

A proficient and cost-effective electrochemical method for the determination of DL-methionine (DLM) has been successfully developed. The in-situ single-step AgO modification of the graphite pencil electrode (GPE) was characterized by Field Emission Scanning Electron Microscope (FE-SEM), Energy Dispersed X-ray (EDX), X-ray Photoelectron Spectroscopy (XPS), and cyclic voltammetry. The electrocatalytic activity of the silver ions in 0.10 M NaOH (pH 13.7 ± 0.2) initiated the oxidation reaction of DLM on the GPE surface via Ag2+ metal-induced reaction of hydroxyl radical (OH·). Electrode linearity dependence obtained is given as iμA= 68.1CDLM + 2.99 for a linear range concentration of 60 μM - 500 μM with a correlation coefficient (R2) of 0.986 and limit of detection of 0.42 μM. Effects of potential interferences such as ascorbic acid (AA), l-alanine (Aln) and cysteine was found to be insignificant. The developed detection method was found to be suitable for both voltammetric and amperometric techniques for the development of non enzymatic sensor of DLM, and its real life application in human serum sample by standard addition method with a correlation coefficient (R2) of 0.999.

Flexible Non-Enzymatic Glucose Sensor Obtained Via Wet Metallization Coupled with Inkjet Printing

Flexible sensors and electronic devices constitute one of the great frontiers of research in the third millennium. The advantages of these technologies are obvious: the possibility to wrap or fold the devices (with space saving benefits), the opportunity to manufacture wearable accessories and the weight reduction of the final product [1]. Many vital sectors of the modern manufacturing industry are interested by the general evolution towards flexible electronics: displays, solar cells, batteries and sensors. In the case of biosensors in particular the development of flexible devices is particularly attractive due to their ability to adapt to human body, making possible the realization of wearable medical equipment. Example of biosensors include devices for the detection of glucose, organophosphates, proteins, antibiotics and many others. Their working principle may vary, but one of the most promising is the electrochemical one. Most of the electrochemical sensors are based on an enzyme mediated catalysis that produces or uses electrons. The resulting flux of current can be quantified and used for the sensing of the target specie. These sensors, called enzymatic, present however some disadvantages. Firstly, the enzyme loses activity over time. Moreover, the enzyme is typically not completely stable when immobilized on a substrate. For these reasons, a primary goal of modern research on biosensing is the development of non-enzymatic sensors. In the present work, a flexible non-enzymatic electrochemical glucose biosensor is presented. The functioning of the device is based on CuO, a common p-type semiconductor already used for the manufacturing of non-enzymatic glucose sensors [2, 3]. CuO nanoparticles are synthesized via a hydrothermal reaction and inkjet printed on a flexible substrate. Such flexible substrate is obtained by electroless plating with NiP a polymer sheet and by subsequently applying a platinum layer via electrolytic deposition. Sensitivity and selectivity of the obtained devices are finally tested with electrochemical techniques and their operative range is determined. The obtained single use bendable sensors may result of great interest for the control of patients affected by diabetes mellitus, a pathology that constitute one of the primary health risks in the world. [1] M. A. Alam, and S. Kumar; ed. B. Bhushan; “Flexible Electronics" chapter in Encyclopedia of Nanotechnology, Springer Netherlands, Dordrecht (2012) 860-865 [2] R. Ahmad, N. Tripathy, Y. B. Hahn, A. Umar, A. A. Ibrahim and S. H. Kim, Dalt. Trans. 44 (2015) 12488-12492 [3] R. Ahmad, M. Vaseem, N. Tripathy and Y. B. Hahn, Anal. Chem. 85 (2013) 10448-10454

Synthesis of Highly Dispersed Ag Nanoparticles under Microwave Irradiation with PAMAM Dendrimer as Reductant and Stabilizer for Nonenzymatic Detecting Hydrogen Peroxide

A simple and sensitive electrochemical method for the nonenzymatic detection of hydrogen peroxide (H2O2) has been proposed. Highly dispersed Ag nanoparticles (NPs) were synthesized under microwave irradiation with PAMAM dendrimer as reductant and stabilizer. The formation of Ag NPs decorated with PAMAM dendrimer (Ag-G3.5-PAMAM) was confirmed by ultraviolet visible spectrophotometer (UV-vis). The as-prepared Ag-G3.5-PAMAM was used to modify the glassy carbon electrode (GCE) for nonenzymatic detection of hydrogen peroxide. It is showed that the fabricated electrochemical sensor based on Ag-G3.5-PAMAM exhibits fast response to hydrogen peroxide.The result indicates that Ag-G3.5-PAMAM may have promising applications in the development of nonenzymatic sensor for hydrogen peroxide in the future.