Recent progress on field-effect transistor-based biosensors: device perspective.

Over the last few decades, field-effect transistor (FET)-based biosensors have demonstrated great potential across various industries, including medical, food, agriculture, environmental, and military sectors. These biosensors leverage the electrical properties of transistors to detect a wide range of biomolecules, such as proteins, DNA, and antibodies. This article presents a comprehensive review of advancements in the architectures of FET-based biosensors aiming to enhance device performance in terms of sensitivity, detection time, and selectivity. The review encompasses an overview of emerging FET-based biosensors and useful guidelines to reach the best device dimensions, favorable design, and realization of FET-based biosensors. Consequently, it furnishes researchers with a detailed perspective on design considerations and applications for future generations of FET-based biosensors. Finally, this article proposes intriguing avenues for further research on the topology of FET-based biosensors.

Comparative Analysis of the Hydrazine Interaction with Arylene Diimide Derivatives: Complementary Approach Using First Principles Calculation and Experimental Confirmation.

Suitable functional group-engineered π-conjugated aromatic dimides based on perylene (PDI) and naphthyl scaffolds (NDI) demonstrated excellent sensitivity toward different gaseous analytes. However, to date, no methodical analysis has been performed to rationalize molecular-level interactions in the context of optical transduction, which is essential for systematic performance optimization of NDI/PDI-based molecular sensors. Therefore, in this present work, NDI/PDI scaffolds have been designed with amino acid functional groups (alanine, ALA and glutamic acid, GLU) at the terminal positions, and we subsequently compared the efficacy of four different imide derivatives as model hosts for hydrazine adsorption. Specifically, the adsorption of hydrazine at different interaction sites has been thoroughly investigated using ab initio calculations, where the adsorption energy, charge transfer, and recovery time have been emphasized. Theoretical results exhibit that irrespective of host specification the COOH groups offer a primary interaction site for hydrazine through the hydrogen bonding interaction. The presence of more COOH groups and relatively stronger interaction with secondary edge oxygen ensure that GLU functional moieties are a superior choice over ALU for efficient hydrazine binding. The molecular energy spectrum analysis exhibits more favorable HOMO/LUMO gap variations after hydrazine interaction in the case of PDI derivatives irrespective to the nature of the amino acid residues. Therefore, by a combination of both factors, PDI-GLU has been identified as the most suitable host molecule for hydrazine among four derivatives. Finally, the key theoretical predictions has been later experimentally validated by analyzing UV-visible spectroscopy and NMR studies, wherein the mechanism of interaction has also been experimentally verified by EPR analysis and FT-IR studies.

Rags to Riches: Meliorating the Electrocatalytic Reduction of Nitrate to Ammonia over Cu-Based Nanoalloys.

The selective electrocatalytic reduction of nitrate pollutants into valuable ammonia products has gained significant momentum thanks to the emerging circular economy model. However, this technology suffers from poor selectivity, low Faradic efficiency, and a competing parallel hydrogen evolution reaction. In this regard, the use of nanoalloys offers a promising approach to fine-tune the electronic structure by shifting the position of the d-band center and modulating the interaction with nitrate and other reaction intermediates and thus enhance the selectivity of desirable products, which may not be accessible over a pristine single metallic active site. Herein, we have systematically doped Cu (d9s2) by Ni (d8s2) and Zn (d10s2) to produce Cu0.85Ni0.15/C and Cu0.85Zn0.15/C, respectively, from the corresponding bimetallic metal-organic framework materials. A thorough investigation of electrocatalytic nitrate reduction over the as-synthesized nanomaterials was done by studying the product yield, selectivity, Faradic efficiency, reaction order, rate, and activation energy. The synthesized carbon-supported nanoalloy of Cu0.85Zn0.15/C outperformed both Cu0.85Ni0.15/C and Cu/C, and the superiority was rationalized by the first-principles calculation, which unveiled the significance of the modulation of the d-bands in influencing the interaction of nitrate and other reaction intermediates with the surface, thereby enhancing the selectivity and catalytic efficacy.

Side-Chain Modification in Conjugated Polymer Frameworks for the Electrocatalytic Oxygen Evolution Reaction.

Conjugated polymer frameworks (CPFs) have recently sparked tremendous research interest due to their broad potentials in various frontline application areas such as photocatalysis, sensing, gas storage, energy storage, etc. These framework materials, without sidechains or functional groups on their backbone, are generally insoluble in common organic solvents and less solution processable for further device applications. There are few reports on metal-free electrocatalysis, especially oxygen evolution reaction (OER) using CPF. Herein, we have developed two triazine-based donor-acceptor conjugated polymer frameworks by coupling a 3-substituted thiophene (donor) unit with a triazine ring (acceptor) through a phenyl ring spacer. Two different sidechains, alkyl and oligoethylene glycol, were rationally introduced into the 3-position of thiophene in the polymer framework to investigate the effect of side-chain functionality on the electrocatalytic property. Both the CPFs demonstrated superior electrocatalytic OER activity and long-term durability. The electrocatalytic performance of CPF2, which achieved a current density of 10 mA/cm2 at an overpotential (η) of 328 mV, is much superior to CPF1, which reached the same current density at an overpotential of 488 mV. The porous and interconnected nanostructure of the conjugated organic building blocks, which allowed for fast charge and mass transport processes, could be attributed to the higher electrocatalytic activity of both CPFs. However, the superior activity of CPF2 compared to CPF1 may be due to the presence of a more polar oxygen-containing ethylene glycol side chain, which enhances the surface hydrophilicity, promotes better ion/charge and mass transfer, and increases the accessibility of the active sites toward adsorption through lower π-π stacking compared to hexyl side chain present in CPF1. The DFT study also supports the plausible better performance toward OER for CPF2. This study confirms the promising potentiality of metal-free CPF electrocatalysts for OER and further sidechain modification to improve their electrocatalytic property.

Site-specific ammonia adsorption and transduction on a naphthalimide derivative molecule - a complementary analysis involving ab initio calculation and experimental verification.

Naphthalene diimide derivatives (NDIs) have exhibited significant potential for sensing applications owing to their excellent photo-stability, environmental stability, reasonable electronic conductivity, and ability to form nanostructures with diverse morphologies through self-assembly. However, no systematic analysis has been performed to rationalize molecular-level interactions between ammonia (NH3) and functionalized NDI probes, which is essential for systematic performance optimizations of NDI-based NH3 sensors. Therefore, this work proposes a phenylalanine-functionalized NDI derivative (NDI-PHE) as a model host for NH3 adsorption. Subsequent molecular interactions have been comprehensively studied following a complementary approach using ab initio calculation and experimental investigation. Specifically, NH3 adsorption at different atomic positions of NDI-PHE has been investigated using ab initio calculation, where the adsorption energy, charge transfer, and recovery time have been emphasized. The environmental stability of NDI-PHE and the underlying transduction mechanism during NH3 adsorption have been experimentally demonstrated to complement the theoretical analysis. The results exhibit that the presence of phenylalanine groups acts as an anchoring moiety and augments NH3 adsorption via hydrogen bonding and proton transfer interaction. Specifically, a highly stable room temperature adsorption of NH3 near a carboxylic phenylalanine group has been observed with a suitable recovery time at higher temperatures. NH3 adsorption results in electron transfer to the host molecule leading to the formation of stable radical anion species, which significantly modulated the frontal molecular orbitals of NDI-PHE, suggesting superior transduction for both electrochemical and optical detection.

Performance Analysis of the Dielectrically Modulated Junction-Less Nanotube Field Effect Transistor for Biomolecule Detection.

The design of a high-performance Dielectrically Modulated Field Effect Transistor (DMFET) with smaller device dimension (channel length ≤ 100nm) has recently drawn significant research attention for point-of-care (POC) diagenesis applications. Driven by this paradigm, a Hetero-Gate Metal Dielectrically Modulated Junction-Less Nanotube Field Effect Transistor (DM-JLNFET) architecture is introduced and systematically investigated for label-free electrochemical biosensing application with the help of extensive numerical device simulations. The DM-JLNFET is carefully designed to exploit the advantages of superior gate control over channel electrostatics and electron injection component as well as strong immunity towards the short channel effects that lead to a notably high sensing performance compared to its conventional counterparts. In this context, the underlying physics of the transduction mechanism is analyzed in detail based on the device electrostatics and the carrier transport mechanism. The sensing performance of the proposed biosensor is quantified in terms of the drain current and threshold voltage sensitivities, which represents the relative modulations in these parameters with biomolecule conjugation. Typically, the DM-JLNFET exhibits a drain current and threshold voltage sensitivities as high as 1×10 12 and 0.70, respectively, for biomolecule dielectric constant above 2. Furthermore, the sensing performance demonstrates strong immunities towards non-uniform cavity occupancy. Finally, extensive comparative performance analysis with Dielectrically Modulated Nanowire Field Effect Transistor (DM-NWFET) is performed. The results exhibit that the proposed DM-JLNFET can offer more than 100% and eight orders of magnitude improvements in the threshold voltage and drain current sensitivities, respectively, for a range of small biomolecule dielectric constants.

Comparative Analysis of LiMPO4 (M = Fe, Co, Cr, Mn, V) as Cathode Materials for Lithium-Ion Battery Applications-A First-Principle-Based Theoretical Approach.

The rapidly increasing demand for energy storage has been consistently driving the exploration of different materials for Li-ion batteries, where the olivine lithium-metal phosphates (LiMPO4) are considered one of the most potential candidates for cathode-electrode design. In this context, the work presents an extensive comparative theoretical study of the electrochemical and electrical properties of iron (Fe)-, cobalt (Co)-, manganese (Mn)-, chromium (Cr)-, and vanadium (V)-based LiMPO4 materials for cathode design in lithium (Li)-ion battery applications, using the density-functional-theory (DFT)-based first-principle-calculation approach. The work emphasized different material and performance aspects of the cathode design, including the cohesive energy of the material, Li-intercalation energy in olivine structure, and intrinsic diffusion coefficient across the Li channel, as well as equilibrium potential and open-circuit potential at different charge-states of Li-ion batteries. The results indicate the specification of the metal atom significantly influences the Li diffusion across the olivine structure and the overall energetics of different LiMPO4. In this context, a clear correlation between the structural and electrochemical properties has been demonstrated in different LiMPO4. The key findings offer significant theoretical and design-level insight for estimating the performance of studied LiMPO4-based Li-ion batteries while interfacing with different application areas.

Controlling C-C coupling in electrocatalytic reduction of CO2 over Cu1-xZnx/C.

From the perspective of sustainable environment and economic value, the electroreduction of CO2 to higher order multicarbon products is more coveted than that of C1 products, owing to their higher energy densities and a wider applicability. However, the reduction process remains extremely challenging due to the bottleneck of C-C coupling over the catalyst surfaces, and therefore designing a suitable catalyst for efficient and selective electrocatalytic reduction of CO2 is a need of the hour. With the target of producing C3+ products with higher selectivity, in this study we explored the nano-alloys of Cu1-xZnx as electrocatalysts for CO2 reduction. The nano-alloy Cu1-xZnx synthesized from the corresponding bimetallic metal organic framework materials demonstrated a gradual enhancement in the selectivity of acetone upon CO2 electroreduction with higher doping of Zn. The Cu1-xZnx alloy opened up a wide possibility of fine-tuning the electronic structure by shifting the position of the d-band centre and modulating the interaction with intermediate CO and thus enhanced the selectivity of desirable products, which might not have been accessible otherwise. The postulated molecular mechanism of CO2 electroreduction involving the desorption of the poorly adsorbed intermediate CO due to the presence of Zn and spilling over of free CO to Cu sites in the nano-alloy Cu1-xZnx for further C-C coupling to yield acetone was corroborated by the first principles studies.