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Micro, Volume 3, Issue 2 (June 2023) – 17 articles

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10 pages, 5217 KiB  
Article
Selective Hydrodeoxygenation of Guaiacol to Cyclohexane over Ru-Catalysts Based on MFI Nanosheets
by Dmitry Tsaplin, Alexey Sadovnikov, Dzhamalutdin Ramazanov, Dmitry Gorbunov, Valeriya Ryleeva, Anton Maximov, Kaige Wang and Evgeny Naranov
Micro 2023, 3(2), 610-619; https://doi.org/10.3390/micro3020042 - 20 Jun 2023
Cited by 2 | Viewed by 965
Abstract
Bio-oils derived from the pyrolysis of lignin-based biomass often contain a variety of oxygenated compounds, which can compromise their usefulness as a fuel. To improve the quality of bio-oil, catalytic hydrodeoxygenation (HDO) is a crucial step that removes oxygen from the oil in [...] Read more.
Bio-oils derived from the pyrolysis of lignin-based biomass often contain a variety of oxygenated compounds, which can compromise their usefulness as a fuel. To improve the quality of bio-oil, catalytic hydrodeoxygenation (HDO) is a crucial step that removes oxygen from the oil in the form of water. In this study, we showed that MFI nanosheets are excellent supports for Ru-catalysts. We synthesized highly crystalline MFI nanosheets using a simple hydrothermal seeding procedure; the final material was obtained in 56 h of crystallization. We investigated the activity of Ru supported on different materials. Our findings indicated that Ru supported on hierarchical MFI demonstrated excellent activity in HDO of guaiacol. Our results demonstrated that Ru/ZNS-56 achieved nearly 100% selectivity towards cyclohexane under mild conditions (200 °C, 50 bar H2, 1 h). Full article
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8 pages, 1617 KiB  
Communication
F2 Laser-Induced Micro-Reticulated Structural Changes of Amorphous Carbon Thin Films
by Masayuki Okoshi
Micro 2023, 3(2), 602-609; https://doi.org/10.3390/micro3020041 - 16 Jun 2023
Viewed by 895
Abstract
Micro/nanoprocessing of materials using lasers is currently an active research topic. In that research, the choice of the laser to be used is critical, but the F2 laser, which has the shortest wavelength (157 nm) among commercially available lasers, has few research [...] Read more.
Micro/nanoprocessing of materials using lasers is currently an active research topic. In that research, the choice of the laser to be used is critical, but the F2 laser, which has the shortest wavelength (157 nm) among commercially available lasers, has few research compared to its potential. In this paper, we discovered a new photochemical processing by using an F2 laser to irradiate an amorphous carbon thin film. The short wavelength and high photon energy of the F2 laser can photoexcite the surface of the thin film at high density and generate active oxygen atoms O(1D) by photodecomposition of atmospheric oxygen molecules. As a result, the optical change of the amorphous carbon thin film was induced without thickness reduction, and a micron-sized network-like, reticulated structural change was formed in the thin film surface after one month at the latest. The formed micron-sized reticulated structure was relatively swollen, and a graphitization occurred in the structure, observed by Raman spectroscopy. However, the structure was not observed when the laser irradiated area became smaller. This work has made it possible to form a micron-sized reticulated structure including carbon nanocrystals in an amorphous carbon, which is expected to further expand the applications of carbon materials. Full article
(This article belongs to the Section Microscale Materials Science)
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11 pages, 3261 KiB  
Article
Sacrificial Doping as an Approach to Controlling the Energy Properties of Adsorption Sites in Gas-Sensitive ZnO Nanowires
by Svetlana Nalimova, Zamir Shomakhov, Anton Bobkov and Vyaсheslav Moshnikov
Micro 2023, 3(2), 591-601; https://doi.org/10.3390/micro3020040 - 01 Jun 2023
Cited by 2 | Viewed by 1011
Abstract
Currently, devices for environmental gas analyses are required in many areas of application. Among such devices, semiconductor-resistive gas sensors differ advantageously. However, their characteristics need further improvement. The development of methods for controlling the surface properties of nanostructured metal oxides for their use [...] Read more.
Currently, devices for environmental gas analyses are required in many areas of application. Among such devices, semiconductor-resistive gas sensors differ advantageously. However, their characteristics need further improvement. The development of methods for controlling the surface properties of nanostructured metal oxides for their use as gas sensors is of great interest. In this paper, a method involving the sacrificial doping of ZnO nanowires to control the content of their surface defects (oxygen vacancies) was proposed. Zinc oxide nanowires were synthesized using the hydrothermal method with sodium iodide or bromide as an additional precursor. The surface composition was studied using X-ray photoelectron spectroscopy. The sensor properties of the isopropyl alcohol vapors at 150 °C were studied. It was shown that a higher concentration of oxygen vacancies/hydroxyl groups was observed on the surfaces of the samples synthesized with the addition of iodine and bromine precursors compared to the pure zinc oxide nanowires. It was also found out that these samples were more sensitive to isopropyl alcohol vapors. A model was proposed to explain the appearance of additional oxygen vacancies in the subsurface layer of the zinc oxide nanowires when sodium iodide or sodium bromide was added to the initial solution. The roles of oxygen vacancies and surface hydroxyl groups in providing the samples with an increased sensitivity were explained. Thus, a method involving the sacrificial doping of zinc oxide nanowires has been developed, which led to an improvement in their gas sensor characteristics due to an increase in the concentration of oxygen vacancies on their surface. The results are promising for percolation gas sensors equipped with additional water vapor traps that work stably in a high humidity. Full article
(This article belongs to the Special Issue Innovative Methods for Semiconductor Doping)
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13 pages, 4302 KiB  
Article
A Novel Approach of Polyethylene Glycol-4000 Hydrogels as Controlled Drug Carriers
by Muhammad Suhail, I-Hui Chiu, I-Ling Lin, Ming-Jun Tsai and Pao-Chu Wu
Micro 2023, 3(2), 578-590; https://doi.org/10.3390/micro3020039 - 01 Jun 2023
Cited by 1 | Viewed by 1400
Abstract
In this study, we developed polyethylene glycol-4000-based hydrogels for ketorolac tromethamine-controlled delivery systems through a free radical polymerization method. The developed hydrogels were subjected to FTIR, TGA, DSC, XRD, SEM, porosity analysis, dynamic swelling analysis, release studies, etc. The successful crosslinking and stability [...] Read more.
In this study, we developed polyethylene glycol-4000-based hydrogels for ketorolac tromethamine-controlled delivery systems through a free radical polymerization method. The developed hydrogels were subjected to FTIR, TGA, DSC, XRD, SEM, porosity analysis, dynamic swelling analysis, release studies, etc. The successful crosslinking and stability of the prepared hydrogels were confirmed by FTIR, DSC, and TGA analysis. The surface morphology and the reduction in the crystallinity of the polymer after grafting were shown by SEM and XRD analysis. Similarly, the soluble part of the developed hydrogels was eliminated from their insoluble part by the Soxhlet extraction process. Higher dynamic swelling and drug release were observed at high pH values compared to low pH values. High porosity was perceived with high concentrations of the monomers and polymer and decreased with the high incorporation of a crosslinker. The release mechanism of all formulations followed non-Fickian diffusion. The results demonstrate that the developed polyethylene glycol-4000 hydrogels could serve as promising controlled drug delivery carriers. Full article
(This article belongs to the Special Issue Hydrogel Nanocomposites for Biomedical Applications)
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12 pages, 2449 KiB  
Article
Pressure-Driven Sample Flow through an Electrospun Membrane Increases the Analyte Adsorption
by Aitsana Maslakova, Kirill Prusakov, Anastasia Sidorova, Elizaveta Pavlova, Alla Ramonova and Dmitry Bagrov
Micro 2023, 3(2), 566-577; https://doi.org/10.3390/micro3020038 - 26 May 2023
Cited by 1 | Viewed by 1718
Abstract
Electrospun polymer membranes are regarded as prospective biosensor components due to their large specific surface area and diverse opportunities for chemical modifications. However, their intricate porous structure can impede diffusion and render some analyte-binding sites inaccessible. To overcome these diffusion limitations and improve [...] Read more.
Electrospun polymer membranes are regarded as prospective biosensor components due to their large specific surface area and diverse opportunities for chemical modifications. However, their intricate porous structure can impede diffusion and render some analyte-binding sites inaccessible. To overcome these diffusion limitations and improve analyte adsorption onto the polymer, a pressure-driven sample flow through the membrane can be employed. To date, the efficiency of pressure-driven analyte delivery into these membranes has not been quantified. Here, we compare forced flow and passive sample diffusion through poly(dioxanone) electrospun membranes. We examine two model analytes, BSA and interleukin-1 beta (IL1b), to address both non-specific and specific binding. Following exposure of the membranes to the test solutions, we measured the residual concentrations of the analytes using fluorometry and enzyme-linked immunosorbent assay (ELISA) techniques. The pressure-driven sample loading was superior to passive diffusion, with a 2.8–11.5-fold change for physical adsorption and a 2.4–3.4-fold difference for specific binding. Our data can be useful for the development of immunoassays and microfluidic devices. Full article
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17 pages, 3062 KiB  
Review
Probing Italy: A Scanning Probe Microscopy Storyline
by Franco Dinelli, Marco Brucale, Francesco Valle, Cesare Ascoli, Bruno Samorì, Marco Sartore, Manuela Adami, Riccardo Galletti, Stefano Prato, Barbara Troian and Cristiano Albonetti
Micro 2023, 3(2), 549-565; https://doi.org/10.3390/micro3020037 - 18 May 2023
Viewed by 1660
Abstract
Starting from the late 1980’s, scanning probe microscopy has progressively diffused in Italy until today. In this paper, we provide a brief account of the main historical events and a current picture of the distribution of the active groups. A survey was prepared [...] Read more.
Starting from the late 1980’s, scanning probe microscopy has progressively diffused in Italy until today. In this paper, we provide a brief account of the main historical events and a current picture of the distribution of the active groups. A survey was prepared by LimeSurvey, made of six sections asking for personal and institutional data, human resources, equipment available, fields of interest, research projects, educational/dissemination activities, and two relevant publications in the last six years. It turns out that the Italian community includes more than seventy groups and two companies. It is widely diffused, although mostly concentrated near large academic and research institutions, often in locations where prominent Italian researchers have operated. This community is active in many scientific fields and can produce research of high international quality. It shows a wide competence, as proven by the list of research works published in journals ranked within the top 20% class. The diffusion of SPM microscopes in industry is still sporadic, possibly due to extensive collaborations between the research institutions and industries themselves. The authors hope that this work might be useful to the community and beyond, and that it might stimulate the formation of a more structured network. Full article
(This article belongs to the Special Issue State-of-the-Art Microscale and Nanoscale Researches in Italy)
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12 pages, 3809 KiB  
Article
Low-Cost Three-Dimensionally Printed Inverted Plug and Play Optical Instrument for Microfluidic Imaging
by Denislav Markov, Emil Grigorov, Boris Kirov, Jordan A. Denev, Vassil Galabov and Marin B. Marinov
Micro 2023, 3(2), 537-548; https://doi.org/10.3390/micro3020036 - 16 May 2023
Viewed by 1363
Abstract
Microfluidics, also known as lab-on-a-chip or micro total analysis systems, can precisely regulate and manipulate micro-sized fluids. They have great potential in biology, chemistry, and medicine, as well as other fields of science. By definition, microfluidic devices operate with small-volume samples and small [...] Read more.
Microfluidics, also known as lab-on-a-chip or micro total analysis systems, can precisely regulate and manipulate micro-sized fluids. They have great potential in biology, chemistry, and medicine, as well as other fields of science. By definition, microfluidic devices operate with small-volume samples and small reactant quantities, which renders them both efficient and affordable. However, such small objects have very demanding requirements for the utilized optical detection system. Due to the specifics of those devices, monitoring the results of experiments is carried out with commercial inverted optical microscopes. Unfortunately, that type of optical device is still expensive. In this article, we present a truly functional, inexpensive, standalone, three-dimensionally printed, and inverted microscope, including the design, engineering, and manufacturing process and some of the experiments that have been conducted with it. Finally, we summarize the advantages of this three-dimensionally printed microscope (including the total fabrication costs) and the future improvements that will be introduced to it. Full article
(This article belongs to the Section Microscale Engineering)
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16 pages, 8214 KiB  
Article
Nano-Materials-Based Printed Glucose Sensor for Use in Incontinence Products for Health-Care Applications
by Moritz Hubl, Raghied M. Atta, Robin Kaufhold, Bei Wang and Ha Duong Ngo
Micro 2023, 3(2), 521-536; https://doi.org/10.3390/micro3020035 - 12 May 2023
Viewed by 1603
Abstract
Our recent development of a wireless humidity sensor system embedded in incontinence products enables new sensor applications to diagnose and supervise geriatric diseases (i.e., age-related diabetes mellitus type II). The measurement of glucose in urine, so-called glucosuria, is an early indicator for an [...] Read more.
Our recent development of a wireless humidity sensor system embedded in incontinence products enables new sensor applications to diagnose and supervise geriatric diseases (i.e., age-related diabetes mellitus type II). The measurement of glucose in urine, so-called glucosuria, is an early indicator for an incipient diabetes mellitus disease, whose symptoms are often age-related but misjudged. In this paper, an incontinence glucose sensor is printed with biocompatible ink and Prussian blue as an electron mediator on foil and functionalized with immobilized glucose oxidase. Inkjet printing of multiple layers of Nafion prevents large interference substances from diffusing into the measuring electrode and allows precise adjustment of the linear working range, which is significantly different from blood glucose measurement. Performance tests show the potential to detect minimum glucose values and store the sensor over a prolonged period at room temperature. The printed glucose sensor can be embedded into the absorber material of incontinence products, where capillary forces transport the urine analyte to the detection area. An attached readout module with an integrated potentiostat measures the glucose concentration in urine, which is transmitted wirelessly with incontinence events and stored in a cloud service for further analysis by medical staff and care workers. Full article
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11 pages, 2265 KiB  
Article
Assessment of Pharmaco-Technological Parameters of Solid Lipid Nanoparticles as Carriers for Sinapic Acid
by Stefano Russo, Giuliana Greco and Maria Grazia Sarpietro
Micro 2023, 3(2), 510-520; https://doi.org/10.3390/micro3020034 - 05 May 2023
Viewed by 1316
Abstract
Sinapic acid, 3,5-dimethoxyl-4-hydroxycinnamic acid, belonging to the class of hydroxycinnamic acids, shows antioxidant, anti-inflammatory, anticancer, hepatoprotective, cardioprotective, renoprotective, neuroprotective, antidiabetic, anxiolytic, and antibacterial activity. The aim of this work was to incorporate sinapic acid into solid lipid nanoparticles in order to improve its [...] Read more.
Sinapic acid, 3,5-dimethoxyl-4-hydroxycinnamic acid, belonging to the class of hydroxycinnamic acids, shows antioxidant, anti-inflammatory, anticancer, hepatoprotective, cardioprotective, renoprotective, neuroprotective, antidiabetic, anxiolytic, and antibacterial activity. The aim of this work was to incorporate sinapic acid into solid lipid nanoparticles in order to improve its bioavailability. SLNs were prepared using the hot high-speed homogenization method. The pharmaco-technological properties and thermotropic profile of SLNs encapsulated with sinapic acid, as well as their interaction with biomembrane models, were evaluated. SLNs showed promising physicochemical properties and encapsulation efficiency, as well as a desirable release profile; moreover, they facilitated the interaction of sinapic acid with a biomembrane model made of multilamellar vesicles. In conclusion, this formulation can be used in further studies to assess its suitability to improve sinapic acid activity. Full article
(This article belongs to the Special Issue Microenvironment and Nanocarriers)
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14 pages, 7348 KiB  
Article
Tensile Behavior of [0/90]7 Hemp/Elium Biocomposites after Water Aging: In-Situ Micro-CT Testing and Numerical Analysis
by Quentin Drouhet, Fabienne Touchard and Laurence Chocinski-Arnault
Micro 2023, 3(2), 496-509; https://doi.org/10.3390/micro3020033 - 02 May 2023
Cited by 1 | Viewed by 1169
Abstract
This paper aims to study the tensile behavior of a woven [0/90]7 hemp/Elium composite after three different conditionings: “Ambient storage”, “Saturated at 60 °C” and “15 wet/dry cycles”. Instrumented repeated progressive tensile loading tests were carried out and showed an unexpected increase [...] Read more.
This paper aims to study the tensile behavior of a woven [0/90]7 hemp/Elium composite after three different conditionings: “Ambient storage”, “Saturated at 60 °C” and “15 wet/dry cycles”. Instrumented repeated progressive tensile loading tests were carried out and showed an unexpected increase in the secant modulus for the aged samples at the end of the test. An in-situ micro-CT tensile test was then performed on a “15 wet/dry cycles” aged sample. The analysis of the tomographic images showed the damage development with interfacial debonding and matrix cracks in the specimen volume, and also the decrease in the curvature radius of the warp yarns during tensile loading facilitated by the plasticization of the resin. Finite element calculations were thus performed and demonstrated that the increase in the modulus is directly linked to the straightening of warp yarns, showing that the evolution of the modulus on a macroscopic scale can be explained by the deformations of the yarns on a microscopic level. These results allow us to better understand the mechanical behavior and the damage mechanisms that occur in biocomposites during tensile testing after water aging. Full article
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12 pages, 2156 KiB  
Article
Machine Learning-Augmented Micro-Defect Detection on Plastic Straw
by Zhisheng Zhang, Peng Meng, Yaxin Yang and Jianxiong Zhu
Micro 2023, 3(2), 484-495; https://doi.org/10.3390/micro3020032 - 18 Apr 2023
Viewed by 1418
Abstract
Plastic straws are well-known tools to assist human beings in drinking fluid, but most of them have micro-defects including black spot defects, head problems, pressure tube defects, and sealing wrinkles. The manual detection of these defects has drawbacks such as low efficiency, a [...] Read more.
Plastic straws are well-known tools to assist human beings in drinking fluid, but most of them have micro-defects including black spot defects, head problems, pressure tube defects, and sealing wrinkles. The manual detection of these defects has drawbacks such as low efficiency, a high false detection rate, and excessive labor. This paper proposed machine vision-based detection with self-adaption and high-accuracy characteristics. A serial synthesis of algorithms including homomorphic filtering, Nobuyuki Otsu, and morphological opening operations is proposed to obtain plastic straws with binary images with good performance, and it was further found that the convolutional neural network can be designed to realize the real-time recognition of black spot defects, where the corner detection algorithm demonstrates the linear fitting of the edge point of the straw with the effective detection of sealing wrinkle defects. We also demonstrated that the multi-threshold classification algorithm is used to detect defects effectively for head problems and pressure tube defects. The detection system based on machine vision successfully overcomes shortcomings of manual inspection, which has high inspection efficiency and adaptively detects multiple defects with 96.85% accuracy. This research can effectively help straw companies achieve high-quality automated production and promotes the application of machine vision in plastic straw defects with the aid of machine learning. Full article
(This article belongs to the Section Microscale Engineering)
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13 pages, 768 KiB  
Review
Nanometals and Metal Ion Pollution from Dental Materials in Dental Environment
by Ana Carla B. C. J. Fernandes and Rodrigo França
Micro 2023, 3(2), 471-483; https://doi.org/10.3390/micro3020031 - 17 Apr 2023
Viewed by 1727
Abstract
The dental environment is being polluted with metals from dental materials in many ways, mainly due to aerosol-generating procedures; this could affect the long-term well-being of dentists, dental students, and dental personnel. The current dental pollution incorporates metallic nanoparticles, which are highly reactive [...] Read more.
The dental environment is being polluted with metals from dental materials in many ways, mainly due to aerosol-generating procedures; this could affect the long-term well-being of dentists, dental students, and dental personnel. The current dental pollution incorporates metallic nanoparticles, which are highly reactive and quickly become airborne, especially those particles that become unbound in the bulk composition. In addition, liquid mercury or mercury vapors may be released from dental amalgam, causing concerns in the dental community. In our study, we reviewed the behavior of metallic elements present in dental materials, their routes of exposure, and their potentially toxic effects on the dental team. This review found that skin and lung disorders are the most harmful effects of metallic exposure for dentists, dental students, and dental personnel. Therefore, chronic exposure to low concentrations of metals in the dental environment, especially in nanosized forms, should be further investigated to improve the environmental matrix, material choice, and safety protocols. Full article
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13 pages, 3000 KiB  
Article
Properties of Mechanochemically Synthesized Famatinite Cu3SbS4 Nanocrystals
by Erika Dutková, Jaroslav Kováč, Jaroslav Kováč, Jr., Jiří Hejtmánek, Petr Levinský, Adelia Kashimbetova, María Jesús Sayagués, Martin Fabián, Zdenka Lukáčová Bujňáková, Matej Baláž, Katarína Gáborová, Viktor Puchý and Ladislav Čelko
Micro 2023, 3(2), 458-470; https://doi.org/10.3390/micro3020030 - 13 Apr 2023
Viewed by 1231
Abstract
In this study, we report the optoelectric and thermoelectric properties of famatinite Cu3SbS4 that was mechanochemically synthesized in a planetary mill from powder elements for 120 min in an inert atmosphere. The tetragonal famatinite Cu3SbS4 was nanocrystalline [...] Read more.
In this study, we report the optoelectric and thermoelectric properties of famatinite Cu3SbS4 that was mechanochemically synthesized in a planetary mill from powder elements for 120 min in an inert atmosphere. The tetragonal famatinite Cu3SbS4 was nanocrystalline with a crystallite size of 14 nm, as endorsed by Rietveld refinement. High-resolution transmission electron microscopy showed several crystallites in the range of 20–50 nm. Raman spectroscopy proved the purity of the synthesized famatinite Cu3SbS4 and chemical-state characterization performed by X-ray photoelectron spectroscopy confirmed that the prepared sample was pure. The Cu1+, Sb5+, and S2− oxidation states in Cu3SbS4 sample were approved. The morphology characterization showed homogeneity of the prepared sample. The photoresponse of Cu3SbS4 was confirmed from I–V measurements in the dark and under illumination. The photocurrent increase reached 20% compared to the current in the dark at a voltage of 5 V. The achieved results confirm that synthesized famatinite Cu3SbS4 can be applied as a suitable absorbent material in solar cells. The performed thermoelectric measurements revealed a figure of merit ZT of 0.05 at 600 K. Full article
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24 pages, 9201 KiB  
Article
Designing Viscoelastic Gelatin-PEG Macroporous Hybrid Hydrogel with Anisotropic Morphology and Mechanical Properties for Tissue Engineering Application
by Kamol Dey, Silvia Agnelli and Luciana Sartore
Micro 2023, 3(2), 434-457; https://doi.org/10.3390/micro3020029 - 11 Apr 2023
Cited by 3 | Viewed by 2068
Abstract
The mechanical properties of scaffolds play a vital role in regulating key cellular processes in tissue development and regeneration in the field of tissue engineering. Recently, scaffolding material design strategies leverage viscoelasticity to guide stem cells toward specific tissue regeneration. Herein, we designed [...] Read more.
The mechanical properties of scaffolds play a vital role in regulating key cellular processes in tissue development and regeneration in the field of tissue engineering. Recently, scaffolding material design strategies leverage viscoelasticity to guide stem cells toward specific tissue regeneration. Herein, we designed and developed a viscoelastic Gel-PEG hybrid hydrogel with anisotropic morphology and mechanical properties using a gelatin and functionalized PEG (as a crosslinker) under a benign condition for tissue engineering application. The chemical crosslinking/grafting reaction was mainly involved between epoxide groups of PEG and available functional groups of gelatin. FTIR spectra revealed the hybrid nature of Gel-PEG hydrogel. The hybrid hydrogel showed good swelling behavior (water content > 600%), high porosity and pore interconnectivity suitable for tissue engineering application. Simple unidirectional freezing followed by a freeze-drying technique allowed the creation of structurally stable 3D anisotropic macroporous architecture that showed tissue-like elasticity and was capable of withstanding high deformation (50% strain) without being damaged. The tensile and compressive modulus of Gel-PEG hybrid hydrogel were found to be 0.863 MPa and 0.330 MPa, respectively, which are within the range of normal human articular cartilage. In-depth mechanical characterizations showed that the Gel-PEG hybrid hydrogel possessed natural-tissue-like mechanics such as non-linear and J-shaped stress-strain curves, stress softening effect, high fatigue resistance and stress relaxation response. A month-long hydrolytic degradation test revealed that the hydrogel gradually degraded in a homogeneous manner over time but maintained its structural stability and anisotropic mechanics. Overall, all these interesting features provide a potential opportunity for Gel-PEG hybrid hydrogel as a scaffold in a wide range of tissue engineering applications. Full article
(This article belongs to the Special Issue Hydrogel Nanocomposites for Biomedical Applications)
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30 pages, 29775 KiB  
Article
Digitally Based Precision Time-Domain Spectrometer for NMR Relaxation and NMR Cryoporometry
by John Beausire Wyatt Webber and Pavel Demin
Micro 2023, 3(2), 404-433; https://doi.org/10.3390/micro3020028 - 03 Apr 2023
Viewed by 1704
Abstract
NMR Relaxation (NMRR) is an extremely useful quantitative technique for material science, particularly for studying polymers and porous materials. NMR Cryoporometry (NMRC) is a powerful technique for the measurement of pore-size distributions and total porosities. This paper discusses the use, capabilities and application [...] Read more.
NMR Relaxation (NMRR) is an extremely useful quantitative technique for material science, particularly for studying polymers and porous materials. NMR Cryoporometry (NMRC) is a powerful technique for the measurement of pore-size distributions and total porosities. This paper discusses the use, capabilities and application of a newly developed compact NMR time-domain relaxation spectrometer suitable for studying both solid and liquid samples (Mk3 NMR Relaxation spectrometer & Cryoporometer, Lab-Tools (nano-science), Ramsgate, Kent, UK. (2019)). This highly compact precision NMR Spectrometer is based on a Field Programmable Gate array (FPGA) module and custom surface mount low-noise NMR receiver and NMR linear transmitter. A high proportion of the RF circuitry is in a digital form, implemented as firmware in the FPGA, which gives the instrument an excellent long-term stability. It also includes an on-chip Linux computer. The FPGA module is credit-card sized, and both the NMR receiver and NMR transmitter are even smaller. The software, including the top-level NMR pulse sequence definitions, are written in an array processing language, Apl. The spectrometer comes complete with a Graphical User Interface (GUI) for control and on- and offline curve fitting and data analysis. The recent development of the Lab-Tools Peltier thermo-electrically cooled NMR variable-temperature (V-T) probe that cools the sample below −60 °C is also discussed. This Peltier cooling gives the precision temperature control and smoothness needed by NMR Cryoporometry (10 mK near the probe liquid bulk melting point). This enables the NMRC measurement of pore-size distributions in porous materials, for the unusually wide pore-size range of sub-nano to over 1 micron-sized pores. The NMR Spectrometer’s unusually small size, ability to measure solids, low noise and high performance make it particularly suitable for material science studies both in the field and in university, research institute, company and even school laboratories. A human portable version now exists. Use of the controlling GUI is described, and results from example NMR Relaxation and NMR Cryoporometric measurements are given. Full article
(This article belongs to the Section Analysis Methods and Instruments)
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13 pages, 6321 KiB  
Article
Effect of Functionalized CdSSe Quantum Dots in the CYP450 Activity of HEPG2 Cells
by Luis Alamo-Nole and Jury Cruz-Hernandez
Micro 2023, 3(2), 391-403; https://doi.org/10.3390/micro3020027 - 03 Apr 2023
Viewed by 1004
Abstract
Quantum dots (QDs) have different properties: high electron density, magnetic moment, phosphorescence, photoluminescence (fluorescence), and strong optical absorption. The layer or ligands on the QDs surface has a vital role because they allow the stabilization and practical uses on different matrixes. Ligand exchange [...] Read more.
Quantum dots (QDs) have different properties: high electron density, magnetic moment, phosphorescence, photoluminescence (fluorescence), and strong optical absorption. The layer or ligands on the QDs surface has a vital role because they allow the stabilization and practical uses on different matrixes. Ligand exchange is a commonly carried out methodology to incorporate functional groups that alter the solubility, introduce electron transfer partners, integrate biological receptors, or improve the properties of the QDs surface. CdSSe QDs were synthesized using a microwave system using thioglycolic acid (TGA) as a sulfur source and cover agent. The TGA ligand was interchanged with cysteine (Cys), glutamic acid (GA), glutathione (GTO), glutaraldehyde (GLT), and lysine (Lys). The viability and response of the CYP1A1, CYP1A2, and CYP3A4 isoenzymes were directly measured in HEP-G2 cells after exposure to CdSSe-TGA, CdSSe-Cys, CdSSe-GA, CdSSe-GTO, CdSSe-GLT, and CdSSe-Lys. CdSSe and CdSSe-GTO (10 mg/L) decrease viability by around 65%. The response of the cytochrome isoenzymes is based on the organic ligand on the surface of the CdSSe QDs. Changes in CYP 1A1 could be related to carcinogenic xenobiotics. Fluorescence microscopy shows CdSSe QDs on and inside HEPG2 cells. The results confirm that apoptosis and necrosis are the principal mechanisms of decreased viability. Full article
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9 pages, 3051 KiB  
Article
Methodic Approach of Atomic-Force Microscopy (AFM) to Study Morphological Changes of Cells and Model Systems
by Vladimir Binyukov, Elena Mil, Ludmila Matienko, Anastasia Albantova and Alexander Goloshchapov
Micro 2023, 3(2), 382-390; https://doi.org/10.3390/micro3020026 - 28 Mar 2023
Cited by 1 | Viewed by 1181
Abstract
For the first time AFM (atomic-force microscopy) was used to record significant changes in the geometric parameters of the image of erythrocytes in vitro under conditions of glycolytic starvation (ATP (Adenosine triphosphate) deficiency). The difference in the action of antioxidants, phenosan K, and [...] Read more.
For the first time AFM (atomic-force microscopy) was used to record significant changes in the geometric parameters of the image of erythrocytes in vitro under conditions of glycolytic starvation (ATP (Adenosine triphosphate) deficiency). The difference in the action of antioxidants, phenosan K, and Ihfan-10 on erythrocytes that we detected with AFM seems to be mainly due to their difference in hydrophobicity. We used the AFM method to research the self-organization of the components of the active center of P450 (Porphyrin-450) metalloenzymes that are part of a class of hemoproteins with functions of affinity to molecular oxygen O2. Stable supramolecular nanostructures in the form of triangular prisms based on the iron porphyrin complex with amino acids due to self-assembly involving intermolecular hydrogen bonds were received. A possible scheme for the formation of such structures is proposed. Full article
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