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Keywords = optical redox ratio

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81 pages, 10454 KB  
Review
Glancing Angle Deposition in Gas Sensing: Bridging Morphological Innovations and Sensor Performances
by Shivam Singh, Kenneth Christopher Stiwinter, Jitendra Pratap Singh and Yiping Zhao
Nanomaterials 2025, 15(14), 1136; https://doi.org/10.3390/nano15141136 - 21 Jul 2025
Cited by 1 | Viewed by 999
Abstract
Glancing Angle Deposition (GLAD) has emerged as a versatile and powerful nanofabrication technique for developing next-generation gas sensors by enabling precise control over nanostructure geometry, porosity, and material composition. Through dynamic substrate tilting and rotation, GLAD facilitates the fabrication of highly porous, anisotropic [...] Read more.
Glancing Angle Deposition (GLAD) has emerged as a versatile and powerful nanofabrication technique for developing next-generation gas sensors by enabling precise control over nanostructure geometry, porosity, and material composition. Through dynamic substrate tilting and rotation, GLAD facilitates the fabrication of highly porous, anisotropic nanostructures, such as aligned, tilted, zigzag, helical, and multilayered nanorods, with tunable surface area and diffusion pathways optimized for gas detection. This review provides a comprehensive synthesis of recent advances in GLAD-based gas sensor design, focusing on how structural engineering and material integration converge to enhance sensor performance. Key materials strategies include the construction of heterojunctions and core–shell architectures, controlled doping, and nanoparticle decoration using noble metals or metal oxides to amplify charge transfer, catalytic activity, and redox responsiveness. GLAD-fabricated nanostructures have been effectively deployed across multiple gas sensing modalities, including resistive, capacitive, piezoelectric, and optical platforms, where their high aspect ratios, tailored porosity, and defect-rich surfaces facilitate enhanced gas adsorption kinetics and efficient signal transduction. These devices exhibit high sensitivity and selectivity toward a range of analytes, including NO2, CO, H2S, and volatile organic compounds (VOCs), with detection limits often reaching the parts-per-billion level. Emerging innovations, such as photo-assisted sensing and integration with artificial intelligence for data analysis and pattern recognition, further extend the capabilities of GLAD-based systems for multifunctional, real-time, and adaptive sensing. Finally, current challenges and future research directions are discussed, emphasizing the promise of GLAD as a scalable platform for next-generation gas sensing technologies. Full article
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17 pages, 1902 KB  
Article
Enhanced Mitochondrial Dynamics and Reactive Oxygen Species Levels with Reduced Antioxidant Defenses in Human Epicardial Adipose Tissue
by Ana Burgeiro, Diana Santos, Ana Catarina R. G. Fonseca, Inês Baldeiras, Ermelindo C. Leal, João Moura, João Costa-Nunes, Patrícia Monteiro Seraphim, Aryane Oliveira, António Canotilho, Gonçalo Coutinho, David Prieto, Pedro Antunes, Manuel Antunes and Eugenia Carvalho
Metabolites 2025, 15(7), 481; https://doi.org/10.3390/metabo15070481 - 16 Jul 2025
Viewed by 1048
Abstract
Background/Objectives: Epicardial adipose tissue (EAT) is metabolically active and is in dynamic crosstalk with the surrounding cardiomyocytes, modulating their function and metabolism. Oxidative stress is a key contributor to cell death and cardiac remodeling, is a hallmark of diabetes (DM) and cardiovascular [...] Read more.
Background/Objectives: Epicardial adipose tissue (EAT) is metabolically active and is in dynamic crosstalk with the surrounding cardiomyocytes, modulating their function and metabolism. Oxidative stress is a key contributor to cell death and cardiac remodeling, is a hallmark of diabetes (DM) and cardiovascular disease, such as coronary artery disease (CAD). However, little is known about these processes in EAT from patients undergoing cardiac surgery. This study investigates changes in mitochondrial dynamics, reactive oxygen species (ROS) production, and antioxidant defense levels in EAT compared to subcutaneous adipose tissue (SAT) in patients undergoing cardiac surgery, with a focus on the impact of DM and CAD. Methods: Adipose tissue biopsies were collected from 128 patients undergoing surgical cardiac intervention. Mitochondrial dynamics and oxidative stress markers were analyzed. Results: EAT exhibited increased expression of mitochondrial fusion markers [mitofusin 1 (p ≤ 0.001), mitofusin 2 (p = 0.038), and optic atrophy 1 (p ≤ 0.001)], as well as fission markers [fission 1 (p ≤ 0.001) and dynamin-related protein 1 (p ≤ 0.001)] relative to SAT. Additionally, ROS levels (dihydroethidium, p = 0.004) were elevated, while lipid peroxidation (malondialdehyde, p ≤ 0.001) was reduced in EAT compared to SAT. Reduced glutathione (GSH) levels (p ≤ 0.001) and the redox buffer ratio between reduced and oxidized glutathione (GSH/GSSG, p ≤ 0.001) were significantly increased in EAT. Interestingly, glutathione peroxidase activity (p ≤ 0.001) and the antioxidant defense markers catalase (p ≤ 0.001) and superoxide dismutase 2 (p = 0.001) were significantly reduced in EAT compared to SAT. Conclusions: The findings provide a unique molecular insight into the mitochondrial dynamics and oxidative stress profiles of EAT, highlighting potential avenues for a novel diagnostic method and therapeutic strategies for cardiac disease. Full article
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22 pages, 26866 KB  
Article
Facile Synthesis of Novel Conducting Copolymers Based on N-Furfuryl Pyrrole and 3,4-Ethylenedioxythiophene with Enhanced Optoelectrochemical Performances Towards Electrochromic Application
by Huixian Li, Xiaomeng Sun, Datai Liu, Xinchang Liu, Xianchao Du, Shuai Li, Xiaojing Xing, Xinfeng Cheng, Dongqin Bi and Dongfang Qiu
Molecules 2025, 30(1), 42; https://doi.org/10.3390/molecules30010042 - 26 Dec 2024
Cited by 1 | Viewed by 947
Abstract
In this article, a series of novel conducting copolymers P(FuPy-co-EDOT) are prepared via cyclic voltammetry electropolymerization method by using N-furfuryl pyrrole (FuPy) and 3,4-ethylenedioxythiophene (EDOT) as comonomers. The molecular structure, surface morphology, electrochemical, and optical properties of the resulting copolymers are [...] Read more.
In this article, a series of novel conducting copolymers P(FuPy-co-EDOT) are prepared via cyclic voltammetry electropolymerization method by using N-furfuryl pyrrole (FuPy) and 3,4-ethylenedioxythiophene (EDOT) as comonomers. The molecular structure, surface morphology, electrochemical, and optical properties of the resulting copolymers are characterized in detail upon varying the feed ratios of FuPy/EDOT in the range of 1/1 to 1/9. The results demonstrate that the prepared P(FuPy-co-EDOT) copolymers with a higher proportion of EDOT units (FuPy/EDOT: 2/8~1/9) possess good redox activity, tunable optical absorption performances, and low band gaps (1.75~1.86 eV). Spectroelectrochemistry studies indicate that the resulting copolymers with increased EDOT units show strengthened electrochromic characteristics, exhibiting a red-to-green-to-blue multicolor reversible transition, especially for the P(FuPy1-co-EDOT9) copolymer films. They also show increased optical contrast (9~34%), fast response time (0.8~2.4 s), and good coloring efficiency (110~362 cm2 C−1). Additionally, the complementary bilayer P(FuPy-co-EDOT)/PEDOT electrochromic devices (ECDs) are also assembled and evaluated to hold excellent electrochromic switching performances with relatively high optical contrast (25%), rapid response time (0.9 s), and satisfactory coloring efficiency (416 cm2 C−1). Together with the superior open circuit memory and cycling stability, they can be used as a new type of electrochromic material and have considerable prospects as promising candidates for electrochromic devices. Full article
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24 pages, 5556 KB  
Article
Differential Mitochondrial Redox Responses to the Inhibition of NAD+ Salvage Pathway of Triple Negative Breast Cancer Cells
by Jack Kollmar, Junmei Xu, Diego Gonzalves, Joseph A. Baur, Lin Z. Li, Julia Tchou and He N. Xu
Cancers 2025, 17(1), 7; https://doi.org/10.3390/cancers17010007 - 24 Dec 2024
Viewed by 1737
Abstract
Background/Objectives: Cancer cells rely on metabolic reprogramming that is supported by altered mitochondrial redox status and an increased demand for NAD+. Over expression of Nampt, the rate-limiting enzyme of the NAD+ biosynthesis salvage pathway, is common in breast cancer [...] Read more.
Background/Objectives: Cancer cells rely on metabolic reprogramming that is supported by altered mitochondrial redox status and an increased demand for NAD+. Over expression of Nampt, the rate-limiting enzyme of the NAD+ biosynthesis salvage pathway, is common in breast cancer cells, and more so in triple negative breast cancer (TNBC) cells. Targeting the salvage pathway has been pursued for cancer therapy. However, TNBC cells have heterogeneous responses to Nampt inhibition, which contributes to the diverse outcomes. There is a lack of imaging biomarkers to differentiate among TNBC cells under metabolic stress and identify which are responsive. We aimed to characterize and differentiate among a panel of TNBC cell lines under NAD-deficient stress and identify which subtypes are more dependent on the NAD salvage pathway. Methods: Optical redox imaging (ORI), a label-free live cell imaging microscopy technique was utilized to acquire intrinsic fluorescence intensities of NADH and FAD-containing flavoproteins (Fp) thus the mitochondrial redox ratio Fp/(NADH + Fp) in a panel of TNBC cell lines. Various fluorescence probes were then added to the cultures to image the mitochondrial ROS, mitochondrial membrane potential, mitochondrial mass, and cell number. Results: Various TNBC subtypes are sensitive to Nampt inhibition in a dose- and time-dependent manner, they have differential mitochondrial redox responses; furthermore, the mitochondrial redox indices linearly correlated with mitochondrial ROS induced by various doses of a Nampt inhibitor. Moreover, the changes in the redox indices correlated with growth inhibition. Additionally, the redox state was found fully recovered after removing the Nampt inhibitor. Conclusions: This study supports the utility of ORI in rapid metabolic phenotyping of TNBC cells under NAD-deficient stress to identify responsive cells and biomarkers of treatment response, facilitating combination therapy strategies. Full article
(This article belongs to the Section Methods and Technologies Development)
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31 pages, 3833 KB  
Article
Transition Metal-Promoted LDH-Derived CoCeMgAlO Mixed Oxides as Active Catalysts for Methane Total Oxidation
by Marius C. Stoian, Cosmin Romanitan, Katja Neubauer, Hanan Atia, Constantin Cătălin Negrilă, Ionel Popescu and Ioan-Cezar Marcu
Catalysts 2024, 14(9), 625; https://doi.org/10.3390/catal14090625 - 17 Sep 2024
Cited by 3 | Viewed by 1710
Abstract
A series of M(x)CoCeMgAlO mixed oxides with different transition metals (M = Cu, Fe, Mn, and Ni) with an M content x = 3 at. %, and another series of Fe(x)CoCeMgAlO mixed oxides with Fe contents x ranging from 1 to 9 at. [...] Read more.
A series of M(x)CoCeMgAlO mixed oxides with different transition metals (M = Cu, Fe, Mn, and Ni) with an M content x = 3 at. %, and another series of Fe(x)CoCeMgAlO mixed oxides with Fe contents x ranging from 1 to 9 at. % with respect to cations, while keeping constant in both cases 40 at. % Co, 10 at. % Ce and Mg/Al atomic ratio of 3 were prepared via thermal decomposition at 750 °C in air of their corresponding layered double hydroxide (LDH) precursors obtained by coprecipitation. They were tested in a fixed bed reactor for complete methane oxidation with a gas feed of 1 vol.% methane in air to evaluate their catalytic performance. The physico-structural properties of the mixed oxide samples were investigated with several techniques, such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), elemental mappings, inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction under hydrogen (H2-TPR) and nitrogen adsorption–desorption at −196 °C. XRD analysis revealed in all the samples the presence of Co3O4 crystallites together with periclase-like and CeO2 phases, with no separate M-based oxide phase. All the cations were distributed homogeneously, as suggested by EDX measurements and elemental mappings of the samples. The metal contents, determined by EDX and ICP-OES, were in accordance with the theoretical values set for the catalysts’ preparation. The redox properties studied by H2-TPR, along with the surface composition determined by XPS, provided information to elucidate the catalytic combustion properties of the studied mixed oxide materials. The methane combustion tests showed that all the M-promoted CoCeMgAlO mixed oxides were more active than the M-free counterpart, the highest promoting effect being observed for Fe as the doping transition metal. The Fe(x)CoCeMgAlO mixed oxide sample, with x = 3 at. % Fe displayed the highest catalytic activity for methane combustion with a temperature corresponding to 50% methane conversion, T50, of 489 °C, which is ca. 40 °C lower than that of the unpromoted catalyst. This was attributed to its superior redox properties and lowest activation energy among the studied catalysts, likely due to a Fe–Co–Ce synergistic interaction. In addition, long-term tests of Fe(3)CoCeMgAlO mixed oxide were performed, showing good stability over 60 h on-stream. On the other hand, the addition of water vapors in the feed led to textural and structural changes in the Fe(3)CoCeMgAlO system, affecting its catalytic performance in methane complete oxidation. At the same time, the catalyst showed relatively good recovery of its catalytic activity as soon as the water vapors were removed from the feed. Full article
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16 pages, 2931 KB  
Article
Ageing and Polypharmacy in Mesenchymal Stromal Cells: Metabolic Impact Assessed by Hyperspectral Imaging of Autofluorescence
by Chandrasekara M. N. Chandrasekara, Gizem Gemikonakli, John Mach, Rui Sang, Ayad G. Anwer, Adnan Agha, Ewa M. Goldys, Sarah N. Hilmer and Jared M. Campbell
Int. J. Mol. Sci. 2024, 25(11), 5830; https://doi.org/10.3390/ijms25115830 - 27 May 2024
Cited by 1 | Viewed by 1712
Abstract
The impact of age on mesenchymal stromal cell (MSC) characteristics has been well researched. However, increased age is concomitant with increased prevalence of polypharmacy. This adjustable factor may have further implications for the functionality of MSCs and the effectiveness of autologous MSC procedures. [...] Read more.
The impact of age on mesenchymal stromal cell (MSC) characteristics has been well researched. However, increased age is concomitant with increased prevalence of polypharmacy. This adjustable factor may have further implications for the functionality of MSCs and the effectiveness of autologous MSC procedures. We applied hyperspectral microscopy of cell autofluorescence—a non-invasive imaging technique used to characterise cytometabolic heterogeneity—to identify changes in the autofluorescence signals of MSCs from (1) young mice, (2) old mice, (3) young mice randomised to receive polypharmacy (9–10 weeks of oral therapeutic doses of simvastatin, metoprolol, oxycodone, oxybutynin and citalopram), and (4) old mice randomised to receive polypharmacy. Principal Component Analysis and Logistic Regression Analysis were used to assess alterations in spectral and associated metabolic characteristics. Modelling demonstrated that cells from young mice receiving polypharmacy had less NAD(P)H and increased porphyrin relative to cells from old control mice, allowing for effective separation of the two groups (AUC of ROC curve > 0.94). Similarly, cells from old polypharmacy mice were accurately separated from those from young controls due to lower levels of NAD(P)H (p < 0.001) and higher porphyrin (p < 0.001), allowing for an extremely accurate logistic regression (AUC of ROC curve = 0.99). This polypharmacy regimen may have a more profound impact on MSCs than ageing, and can simultaneously reduce optical redox ratio (ORR) and increase porphyrin levels. This has implications for the use of autologous MSCs for older patients with chronic disease. Full article
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22 pages, 5312 KB  
Article
Use of Optical Redox Imaging to Quantify Alveolar Macrophage Redox State in Infants: Proof of Concept Experiments in a Murine Model and Human Tracheal Aspirates Samples
by He N. Xu, Diego Gonzalves, Jonathan H. Hoffman, Joseph A. Baur, Lin Z. Li and Erik A. Jensen
Antioxidants 2024, 13(5), 546; https://doi.org/10.3390/antiox13050546 - 29 Apr 2024
Cited by 2 | Viewed by 2475 | Correction
Abstract
Emerging data indicate that lung macrophages (LM) may provide a novel biomarker to classify disease endotypes in bronchopulmonary dysplasia (BPD), a form of infant chronic lung disease, and that augmentation of the LM phenotype may be a potential therapeutic target. To contribute to [...] Read more.
Emerging data indicate that lung macrophages (LM) may provide a novel biomarker to classify disease endotypes in bronchopulmonary dysplasia (BPD), a form of infant chronic lung disease, and that augmentation of the LM phenotype may be a potential therapeutic target. To contribute to this area of research, we first used Optical Redox Imaging (ORI) to characterize the responses to H2O2-induced oxidative stress and caffeine treatment in an in vitro model of mouse alveolar macrophages (AM). H2O2 caused a dose-dependent decrease in NADH and an increase in FAD-containing flavoproteins (Fp) and the redox ratio Fp/(NADH + Fp). Caffeine treatment did not affect Fp but significantly decreased NADH with doses of ≥50 µM, and 1000 µM caffeine treatment significantly increased the redox ratio and decreased the baseline level of mitochondrial ROS (reactive oxygen species). However, regardless of whether AM were pretreated with caffeine or not, the mitochondrial ROS levels increased to similar levels after H2O2 challenge. We then investigated the feasibility of utilizing ORI to examine macrophage redox status in tracheal aspirate (TA) samples obtained from premature infants receiving invasive ventilation. We observed significant heterogeneity in NADH, Fp, Fp/(NADH + Fp), and mitochondrial ROS of the TA macrophages. We found a possible positive correlation between gestational age and NADH and a negative correlation between mean airway pressure and NADH that provides hypotheses for future testing. Our study demonstrates that ORI is a feasible technique to characterize macrophage redox state in infant TA samples and supports further use of this method to investigate lung macrophage-mediated disease endotypes in BPD. Full article
(This article belongs to the Special Issue Oxidative Stress and Newborns)
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15 pages, 3673 KB  
Article
Quantitative Optical Redox Imaging of Melanoma Xenografts with Different Metastatic Potentials
by April Peng, He N. Xu, Lily Moon, Paul Zhang and Lin Z. Li
Cancers 2024, 16(9), 1669; https://doi.org/10.3390/cancers16091669 - 25 Apr 2024
Cited by 1 | Viewed by 1807
Abstract
To develop imaging biomarkers for tumors aggressiveness, our previous optical redox imaging (ORI) studies of the reduced nicotinamide adenine dinucleotide (NADH) and oxidized flavoproteins (Fp, containing flavin adenine dinucleotide, i.e., FAD) in tumor xenografts of human melanoma associated the high optical redox ratio [...] Read more.
To develop imaging biomarkers for tumors aggressiveness, our previous optical redox imaging (ORI) studies of the reduced nicotinamide adenine dinucleotide (NADH) and oxidized flavoproteins (Fp, containing flavin adenine dinucleotide, i.e., FAD) in tumor xenografts of human melanoma associated the high optical redox ratio (ORR = Fp/(Fp + NADH)) and its heterogeneity to the high invasive/metastatic potential, without having reported quantitative results for NADH and Fp. Here, we implemented a calibration procedure to facilitate imaging the nominal concentrations of tissue NADH and Fp in the mouse xenografts of two human melanoma lines, an indolent less metastatic A375P and a more metastatic C8161. Images of the redox indices (NADH, Fp, ORR) revealed the existence of more oxidized areas (OAs) and more reduced areas (RAs) within individual tumors. ORR was found to be higher and NADH lower in C8161 compared to that of A375P xenografts, both globally for the whole tumors and locally in OAs. The ORR in the OA can differentiate xenografts with a higher statistical significance than the global averaged ORR. H&E staining of the tumors indicated that the redox differences we identified were more likely due to intrinsically different cell metabolism, rather than variations in cell density. Full article
(This article belongs to the Special Issue Application of Fluorescence Imaging in Cancer)
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21 pages, 5552 KB  
Article
Engineering the Electronic Structure towards Visible Lights Photocatalysis of CaTiO3 Perovskites by Cation (La/Ce)-Anion (N/S) Co-Doping: A First-Principles Study
by Qiankai Zhang, Yang Wang, Yonggang Jia, Wenchao Yan, Qinghao Li, Jun Zhou and Kai Wu
Molecules 2023, 28(20), 7134; https://doi.org/10.3390/molecules28207134 - 17 Oct 2023
Cited by 14 | Viewed by 2299
Abstract
Cation-anion co-doping has proven to be an effective method of improving the photocatalytic performances of CaTiO3 perovskites. In this regard, (La/Ce-N/S) co-doped CaTiO3 models were investigated for the first time using first-principles calculations based on a supercell of 2 × 2 [...] Read more.
Cation-anion co-doping has proven to be an effective method of improving the photocatalytic performances of CaTiO3 perovskites. In this regard, (La/Ce-N/S) co-doped CaTiO3 models were investigated for the first time using first-principles calculations based on a supercell of 2 × 2 × 2 with La/Ce concentrations of 0.125, 0.25, and 0.375. The energy band structure, density of states, charge differential density, electron-hole effective masses, optical properties, and the water redox potential were calculated for various models. According to our results, (La-S)-doped CaTiO3 with a doping ratio of 0.25 (LCOS1-0.25) has superior photocatalytic hydrolysis properties due to the synergistic performances of its narrow band gap, fast carrier mobility, and superb ability to absorb visible light. Apart from the reduction of the band gap, the introduction of intermediate energy levels by La and Ce within the band gap also facilitates the transition of excited electrons from valence to the conduction band. Our calculations and findings provide theoretical insights and solid predictions for discovering CaTiO3 perovskites with excellent photocatalysis performances. Full article
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15 pages, 1867 KB  
Article
Limitations Imposed Using an Iodide/Triiodide Redox Couple in Solar-Powered Electrochromic Devices
by George Syrrokostas, Sarantis Tsamoglou and George Leftheriotis
Energies 2023, 16(20), 7084; https://doi.org/10.3390/en16207084 - 13 Oct 2023
Cited by 1 | Viewed by 2024
Abstract
In the present study, an iodide/triiodide (I/I3) redox couple is used in hybrid electrochromic devices (ECDs), and the effects of the applied bias potential and bias time on device performance are studied. An applied bias potential [...] Read more.
In the present study, an iodide/triiodide (I/I3) redox couple is used in hybrid electrochromic devices (ECDs), and the effects of the applied bias potential and bias time on device performance are studied. An applied bias potential of ~1 V is sufficient to achieve an initial contrast ratio of 8:1 in less than 5 min. Increasing both the bias potential and bias time results in an enhancement in loss reactions at the WO3/electrolyte interface, rather than improving optical performance. Moreover, long-term performance depends on the testing procedure (regularly cycling or after storage), while the formation of iodine (I2) decreases the initial transparency of the ECDs and affects their overall performance. However, its formation cannot be avoided, even without cycling the ECDs, and the restoration of the optical performance can take place only when the electrolyte is replaced with a fresh one. Finally, a new methodology is applied for calculating the loss current, and a suggestion is made to avoid a common mistake in calculating the coloration efficiency of these hybrid ECDs. Full article
(This article belongs to the Special Issue Smart Materials and Devices for Energy Saving and Harvesting)
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11 pages, 1777 KB  
Article
An Aqueous Process for Preparing Flexible Transparent Electrodes Using Non-Oxidized Graphene/Single-Walled Carbon Nanotube Hybrid Solution
by Min Jae Oh, Gi-Cheol Son, Minkook Kim, Junyoung Jeon, Yong Hyun Kim and Myungwoo Son
Nanomaterials 2023, 13(15), 2249; https://doi.org/10.3390/nano13152249 - 3 Aug 2023
Cited by 1 | Viewed by 1626
Abstract
In this study, we prepared flexible and transparent hybrid electrodes based on an aqueous solution of non-oxidized graphene and single-walled carbon nanotubes. We used a simple halogen intercalation method to obtain high-quality graphene flakes without a redox process and prepared hybrid films using [...] Read more.
In this study, we prepared flexible and transparent hybrid electrodes based on an aqueous solution of non-oxidized graphene and single-walled carbon nanotubes. We used a simple halogen intercalation method to obtain high-quality graphene flakes without a redox process and prepared hybrid films using aqueous solutions of graphene, single-walled carbon nanotubes, and sodium dodecyl sulfate surfactant. The hybrid films showed excellent electrode properties, such as an optical transmittance of ≥90%, a sheet resistance of ~3.5 kΩ/sq., a flexibility of up to ε = 3.6% ((R) = 1.4 mm), and a high mechanical stability, even after 103 bending cycles at ε = 2.0% ((R) = 2.5 mm). Using the hybrid electrodes, thin-film transistors (TFTs) were fabricated, which exhibited an electron mobility of ~6.7 cm2 V−1 s−1, a current on-off ratio of ~1.04 × 107, and a subthreshold voltage of ~0.122 V/decade. These electrical properties are comparable with those of TFTs fabricated using Al electrodes. This suggests the possibility of customizing flexible transparent electrodes within a carbon nanomaterial system. Full article
(This article belongs to the Special Issue Carbon Nanomaterials for Electrochemical Applications)
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14 pages, 6479 KB  
Article
Enhanced Photocatalytic Activities of Ag2WO4 Modified Ag6Si2O7 through a Comprehensive p-n Heterojunction S-Scheme Process
by Navid Hussain Shah, Mengke Li, Ping Zhang, Yanyan Cui and Yaling Wang
Crystals 2023, 13(4), 633; https://doi.org/10.3390/cryst13040633 - 7 Apr 2023
Cited by 12 | Viewed by 2736
Abstract
The S-scheme photocatalyst system has become increasingly popular in recent years for its ability to efficiently degrade various pollutants, including organic dyes, pesticides, and other harmful substances. This system uses two semiconductor photocatalysts with different bandgap energies, working together in a redox reaction [...] Read more.
The S-scheme photocatalyst system has become increasingly popular in recent years for its ability to efficiently degrade various pollutants, including organic dyes, pesticides, and other harmful substances. This system uses two semiconductor photocatalysts with different bandgap energies, working together in a redox reaction to produce a highly reactive species capable of pollutant breakdown. Here, an S-scheme Ag2WO4/Ag6Si2O7 p-n heterojunction nanocomposite was successfully developed by a coprecipitation method. By decomposing Rhodamine B (RhB) under visible-light irradiation, the photocatalytic activities of Ag6Si2O7/Ag2WO4 showed enhanced photocatalytic degradation performance of organic dyes, especially at a 4% molar ratio of the Ag2WO4-modified Ag6Si2O7 sample, whose degradation rate was 23.7 and 4.65 times those of Ag2WO4 and Ag6Si2O7, respectively. The physical and chemical properties of the samples were determined by identifying the physical structure, chemical element composition, and optical responsiveness. The optimum composite amongst the prepared materials was AgSW-4, achieving the maximum RhB degradation efficiency of 97.5%, which was higher by 60% and 20% than its counterparts Ag6Si2O7 and Ag2WO4, respectively. These results showed that in the nanocomposite structure, Ag6Si2O7 was a p-type semiconductor and Ag2WO4 was an n-type semiconductor. Based on the analysis data, a comprehensive p-n heterojunction S-scheme process was proposed to demonstrate the enhanced photocatalytic performance of the Ag6Si2O7/Ag2WO4 nanocomposite. Full article
(This article belongs to the Section Materials for Energy Applications)
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14 pages, 4165 KB  
Article
Synthesis and Characterization of Solution-Processible Donor-Acceptor Electrochromic Conjugated Copolymers Based on Quinoxalino[2′,3′:9,10]phenanthro[4,5-abc]phenazine as the Acceptor Unit
by Zhen Xu, Bozhen Wang, Lingqian Kong, Jinsheng Zhao and Yuchang Du
Polymers 2023, 15(4), 940; https://doi.org/10.3390/polym15040940 - 14 Feb 2023
Cited by 3 | Viewed by 2693
Abstract
Donor-acceptor (D-A) type conjugated polymers are of high interest in the field of electrochromism. In this study, three novel conjugated copolymers (PBPE–1, PBPE-2 and PBPE-3) based on quinoxalino[2′,3′:9,10]phenanthro[4,5-abc]phenazine (A) as the acceptor unit and 4,8-bis((2-octyldodecyl)oxy)benzo[1,2-b:4,5-b′]dithiophene (D1) and 3,3-didecyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine (ProDOT-decyl2, [...] Read more.
Donor-acceptor (D-A) type conjugated polymers are of high interest in the field of electrochromism. In this study, three novel conjugated copolymers (PBPE–1, PBPE-2 and PBPE-3) based on quinoxalino[2′,3′:9,10]phenanthro[4,5-abc]phenazine (A) as the acceptor unit and 4,8-bis((2-octyldodecyl)oxy)benzo[1,2-b:4,5-b′]dithiophene (D1) and 3,3-didecyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine (ProDOT-decyl2, D2) as the donor units with different donor-to-acceptor ratios were successfully synthesized through Stille coupling polymerization. The polymers were then characterized by cyclic voltammetry (CV), fourier transform infrared (FT-IR) spectoscopy, X-ray photoelectron spectroscopy (XPS), spectroelectrochemistry, thermogravimetry (TG), electrochromic switching and colorimetry. Optical band gap values were calculated as 1.99 eV, 2.02 eV and 2.03 eV, respectively. The three copolymers have good solubility, distinct redox peaks, wide absorption spectra, good thermal stabilities, bright color changes and significant electrochromic switching properties. Compared to the other two copolymers, the PBPE-3 film exhibited high coloration efficiency values of 513 cm2·C−1 at 504 nm and 475 cm2·C−1 at 1500 nm. The films have the advantage of exhibiting cathodic and anodic coloration. Full article
(This article belongs to the Special Issue Functional and Conductive Polymer Thin Films III)
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20 pages, 2138 KB  
Article
Two-Photon Excited Fluorescence of NADH-Alcohol Dehydrogenase Complex in a Mixture with Bacterial Enzymes
by Ioanna A. Gorbunova, Maxim E. Sasin, Dmitry V. Yachkov, Denis A. Volkov, Alexei D. Vedyaykin, Andrey A. Nikiforov and Oleg S. Vasyutinskii
Biomolecules 2023, 13(2), 256; https://doi.org/10.3390/biom13020256 - 30 Jan 2023
Cited by 6 | Viewed by 3151
Abstract
Thorough study of composition and fluorescence properties of a commercial reagent of active equine NAD-dependent alcohol dehydrogenase expressed and purified from E. coli has been carried out. Several experimental methods: spectral- and time-resolved two-photon excited fluorescence, sodium dodecyl sulfate–polyacrylamide gel electrophoresis, fast protein [...] Read more.
Thorough study of composition and fluorescence properties of a commercial reagent of active equine NAD-dependent alcohol dehydrogenase expressed and purified from E. coli has been carried out. Several experimental methods: spectral- and time-resolved two-photon excited fluorescence, sodium dodecyl sulfate–polyacrylamide gel electrophoresis, fast protein liquid chromatography, and mass spectrometry were used for analysis. The reagent under study was found to contain also a number of natural fluorophores: free NAD(P)H, NADH-alcohol dehydrogenase, NADPH-isocitrate dehydrogenase, and pyridoxal 5-phosphate—serine hydroxymethyltransferase complexes. The results obtained demonstrated the potential and limitations of popular optical methods as FLIM for separation of fluorescence signals from free and protein-bound forms of NADH, NADPH, and FAD that are essential coenzymes in redox reactions in all living cells. In particular, NADH-alcohol dehydrogenase and NADPH-isocitrate dehydrogenase complexes could not be optically separated in our experimental conditions although fast protein liquid chromatography and mass spectrometry analysis undoubtedly indicated the presence of both enzymes in the molecular sample used. Also, the results of fluorescence, fast protein liquid chromatography, and mass spectrometry analysis revealed a significant contribution of the enzyme-bound coenzyme pyridoxal 5-phosphate to the fluorescence signal that could be separated from enzyme-bound NADH by using bandpass filters, but could effectively mask contribution from enzyme-bound FAD because the fluorescence spectra of the species practically overlapped. It was shown that enzyme-bound pyridoxal 5-phosphate fluorescence can be separated from enzyme-bound NAD(P)H and FAD through analysis of short fluorescence decay times of about tens of picoseconds. However, this analysis was found to be effective only at relatively high number of peak photon counts in recorded fluorescence signals. The results obtained in this study can be used for interpretation of fluorescence signals from a mixture of enzyme-bound fluorophores and should be taken into consideration when determining the intracellular NADH/FAD ratio using FLIM. Full article
(This article belongs to the Collection Feature Papers in Enzymology)
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Article
Highly Sensitive ZnO/Au Nanosquare Arrays Electrode for Glucose Biosensing by Electrochemical and Optical Detection
by Vinda Zakiyatuz Zulfa, Nasori Nasori, Ulya Farahdina, Miftakhul Firdhaus, Ihwanul Aziz, Hari Suprihatin, Muslikha Nourma Rhomadhoni and Agus Rubiyanto
Molecules 2023, 28(2), 617; https://doi.org/10.3390/molecules28020617 - 7 Jan 2023
Cited by 11 | Viewed by 3215
Abstract
The fabrication of a ZnO/Au nanosquare-array electrode was successfully carried out for the detection of glucose concentration in biomedical applications. The fabrication of the ZnO/Au nanosquare array using an ultra-thin alumina mask (UTAM) based on the imprinted anodic aluminum oxide (AAO) template and [...] Read more.
The fabrication of a ZnO/Au nanosquare-array electrode was successfully carried out for the detection of glucose concentration in biomedical applications. The fabrication of the ZnO/Au nanosquare array using an ultra-thin alumina mask (UTAM) based on the imprinted anodic aluminum oxide (AAO) template and the direct current (DC) sputtering method was able to produce a very well-ordered nanosquare arrangement with a side size of 300 nm and a thickness of 100 nm. Tests were done to evaluate the performance of the electrode by means of cyclic voltammetry (CV) which showed that the addition of glucose oxidase (GOx) increased the sensitivity of the electrode up to 1180 ± 116 μA mM−1cm−2, compared with its sensitivity prior to the addition of GOx of 188.34 ± 18.70 mA mM−1 cm−2. A iox/ired ratio equal to ~1 between the peaks of redox reactions was obtained for high (hyperglycemia), normal, and low (hypoglycemia) levels of glucose. The ZnO/Au nanosquare-array electrode was 7.54% more sensitive than the ZnO/Au thin-film electrode. Furthermore, finite-difference time-domain (FDTD) simulations and theoretical calculations of the energy density of the electric and magnetic fields produced by the ZnO/Au electrode were carried out and compared to the results of CV. From the results of CV, FDTD simulation, and theoretical calculations, it was confirmed that the ZnO/Au nanosquare array possessed a significant optical absorption and that the quantum effect from the nanosquare array resulted in a higher sensitivity than the thin film. Full article
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