Optimized Technologies for Cointegration of MOS Transistor and Glucose Oxidase Enzyme on a Si-Wafer

The biosensors that work with field effect transistors as transducers and enzymes as bio-receptors are called ENFET devices. In the actual paper, a traditional MOS-FET transistor is cointegrated with a glucose oxidase enzyme, offering a glucose biosensor. The manufacturing process of the proposed ENFET is optimized in the second iteration. Above the MOS gate oxide, the enzymatic bioreceptor as the glucose oxidase is entrapped onto the nano-structured TiO2 compound. This paper proposes multiple details for cointegration between MOS devices with enzymatic biosensors. The Ti conversion into a nanostructured layer occurs by anodization. Two cross-linkers are experimentally studied for a better enzyme immobilization. The final part of the paper combines experimental data with analytical models and extracts the calibration curve of this ENFET transistor, prescribing at the same time a design methodology

Influence of Random Plasmonic Metasurfaces on Fluorescence Enhancement

One of the strategies employed to increase the sensitivity of the fluorescence-based biosensors is to deposit chromophores on plasmonic metasurfaces which are periodic arrays of resonating nano-antennas that allow the control of the electromagnetic field leading to fluorescence enhancement. While artificially engineered metasurfaces realized by micro/nano-fabrication techniques lead to a precise tailoring of the excitation field and resonant cavity properties, the technological overhead, small areas, and high manufacturing cost renders them unsuitable for mass production. A method to circumvent these challenges is to use random distribution of metallic nanoparticles sustaining plasmonic resonances, which present the properties required to significantly enhance the fluorescence. We investigate metasurfaces composed of random aggregates of metal nanoparticles deposited on a silicon and glass substrates. The finite difference time domain simulations of the interaction of the incident electromagnetic wave with the structures reveals a significant enhancement of the excitation field, which is due to the resonant plasmonic modes sustained by the nanoparticles aggregates. We experimentally investigated the role of these structures in the fluorescent behaviour of Rhodamine 6G dispersed in polymethylmethacrylate finding an enhancement that is 423-fold. This suggests that nanoparticle aggregates have the potential to constitute a suitable platform for low-cost, mass-produced fluorescent biosensors

Integrated nanozyme electrochemical sensor for the detection of tannic acid: An advanced approach to rapid and efficient environmental monitoring

This study presents a novel methodology for the rapid on-site detection of tannic acid (TA), a prevalent organic contaminant in various natural environments, notably in plant-derived sources. The proposed approach involves the development of a compact integrated electrochemical sensor incorporating a nanozyme system. Specifically, this system comprises Fe2O3 nanoparticles (NPs) embedded within a chitosan (CS) matrix, immobilized onto a sulfur-doped graphene (S-Gr) substrate deposited on a gold electrode (AuE). The Fe2O3NPs exhibit peroxidase-like artificial enzyme activity, contributing to exceptional stability and catalytic efficiency in TA oxidation processes. Additionally, the CS matrix acts as a stabilizing agent, enhancing the performance and recyclability of the nanozyme. Furthermore, the S-Gr nanomaterial facilitates rapid electron transfer, leading to heightened sensitivity and prompt response times. The integration of these advanced nanomaterials with a microfabricated electrode presents an economically feasible, reliable, and effective solution for TA detection, with promising prospects for large-scale deployment and environmental monitoring. The Fe2O3CS-S-Gr/AuE sensing system demonstrates a calculated limit of detection (LOD) of 3.6 × 10−3 µM and an increased sensitivity of 0.2 µA×µM−1, with a wide linear concentration range spanning from 0.01 to 1000 µM for TA detection. Notably, the recovery values obtained for surface water samples fall within the range of 97.7 % to 99.5 %, indicating strong agreement with results derived from the standard method, UHPLC-MS/MS

Investigation of wet etching technique for selective patterning of ferroelectric zirconium-doped hafnium oxide thin films for high-frequency electronic applications

This paper presents the area-selective wet etching (ASWE) method as a novel approach to have a selective patterning of a 6.8 nm-thick zirconium-doped hafnium oxide (HZO) thin film, to improve the performance of a metal ferroelectric metal (MFM)-like structure. According to the electromagnetic simulations of microwave phase shifters with patterned HZO thin films, it is underlined the importance to have selectively targeted areas covered with HZO instead of full-coverage wafers, to gain a further increase in the microwave performance of low-voltage tunable high-frequency components. The impact of the ASWE method on the morpho-structural properties was studied using various investigation tools in a non-destructive manner. X-ray reflectivity (XRR) has been employed at different immersion times, up to 120 s. Based on the extended Fast Fourier Transform (FFT) analysis, as well as from the simulation of the experimental curves in the framework of parallel-tempering algorithm, the determination of the etching rate became possible. X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) clearly indicated the complete removal of HZO after etching processes at 180 s. The method is fast, reliable, and low-cost, thus filling the actual gap in providing the necessary ferroelectric thin films exclusively in selected areas of interest

New Zn(II) Coordination Polymers Constructed from Amino-Alcohols and Aromatic Dicarboxylic Acids: Synthesis, Structure, Photocatalytic Properties, and Solid-State Conversion to ZnO

Four new coordination polymers have been obtained solvothermally from the reactions of Zn­(NO₃)₂·6H₂O with 1,2-, 1,3-, or 1,4-benzedicarboxylic acids in the presence of various amino-alcohols: ₁^∞[Zn₂(Htea)₂(1,2-bdc)] (<b>1</b>), ₁^∞[Zn­(H₃tris)­(1,3-bdc)­(CH₃OH)] (<b>2</b>), ₃^∞[Zn₅(Htea)₂(1,3-bdc)₃(H₂O)]·2.6H₂O (<b>3</b>), and ₃^∞[Zn₃(H₂dea)₂(1,4-bdc)₃] (<b>4</b>) (H₃tea = triethanolamine, H₃tris = tris­(hydroxymethyl)­aminomethane, H₂dea = diethanolamine, 1,2-H₂bdc =1,2-benzenedicarboxylic acid, 1,3-H₂bdc =1,3-benzenedicarboxylic acid, and 1,4-H₂bdc =1,4-benzenedicarboxylic acid). Their crystal structures, thermogravimetric analyses, solid-state transformation to ZnO and characterization of the resultant zinc oxide particles are reported. Compounds <b>1</b> and <b>2</b> show three-dimensional (3D) supramolecular architectures, generated from the interconnection of the zigzag (in <b>1</b>) and respectively the linear (in <b>2</b>) chains through hydrogen bonding interactions. The crystal structure of <b>3</b> revealed the presence of five different types of zinc atoms that are successively linked through carboxilato or alkoxo bridges in a helicoidal chain running along the crystallographic <i>a</i> axis. Both right-handed (<i>P</i>) and left-handed (<i>M</i>) helices are present in the crystal, and they are alternately interconnected by pairs of isophthalato bridges, resulting in channels of hexagonal shape, filled with water molecules. Compound <b>4</b> has a 3D structure in which linear centrosymmetric {Zn₃(H₂dea)₂}⁶⁺ nodes are joined by terephthalate bridges. Owing to its porous network, compound <b>3</b> was tested in two selective reactions: photooxidation of phenol to hydroquinone and aerobic photooxidative condensation of benzylamine to <i>N</i>-benzylidenebenzylamine