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Keywords = EPR spectroscopy and imaging

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21 pages, 5011 KB  
Article
Synthesis and Characterization of Multifunctional Mesoporous Silica Nanoparticles Containing Gold and Gadolinium as a Theranostic System
by André Felipe Oliveira, Isabela Barreto da Costa Januário Meireles, Maria Angela Barros Correia Menezes, Klaus Krambrock and Edésia Martins Barros de Sousa
J. Nanotheranostics 2025, 6(4), 26; https://doi.org/10.3390/jnt6040026 - 26 Sep 2025
Abstract
Among the many nanomaterials studied for biomedical uses, silica and gold nanoparticles have gained significant attention because of their unique physical and chemical properties and their compatibility with living tissues. Mesoporous silica nanoparticles (MSNs) have great stability and a large surface area, while [...] Read more.
Among the many nanomaterials studied for biomedical uses, silica and gold nanoparticles have gained significant attention because of their unique physical and chemical properties and their compatibility with living tissues. Mesoporous silica nanoparticles (MSNs) have great stability and a large surface area, while gold nanoparticles (AuNPs) display remarkable optical features. Both types of nanoparticles have been widely researched for their individual roles in drug delivery, imaging, biosensing, and therapy. When combined with gadolinium (Gd), a common contrast agent, these nanostructures provide improved imaging due to gadolinium’s strong paramagnetic properties. This study focuses on incorporating gold nanoparticles and gadolinium into a silica matrix to develop a theranostic system. Various analytical techniques were used to characterize the nanocomposites, including infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), nitrogen adsorption, scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray fluorescence (XRF), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), and neutron activation analysis (NAA). Techniques like XRF mapping, XANES, nitrogen adsorption, SEM, and VSM were crucial in confirming the presence of gadolinium and gold within the silica network. VSM and EPR analyses confirmed the attenuation of the saturation magnetization for all nanocomposites. This validates their potential for biomedical applications in diagnostics. Moreover, activating gold nanoparticles in a nuclear reactor generated a promising radioisotope for cancer treatment. These results indicate the potential of using a theranostic nanoplatform that employs mesoporous silica as a carrier, gold nanoparticles for radioisotopes, and gadolinium for imaging purposes. Full article
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13 pages, 6902 KB  
Article
Influence of Content and Type of Lanthanide on the Structure of Ln2O3-Covered Carbon Nanoflakes: The EPR and XPS Study
by Serguei V. Savilov, Evgeniya V. Suslova, Alexander N. Ulyanov, Konstantin I. Maslakov, Sergey V. Maximov, Denis A. Shashurin and Georgy A. Chelkov
Nanomaterials 2025, 15(13), 1016; https://doi.org/10.3390/nano15131016 - 1 Jul 2025
Viewed by 443
Abstract
Synthesized Ln2O3 (Ln = La, Nd or Gd) nanoparticles with sizes of 1–3 nm, 5–6 nm and 10–15 nm were stabilized by carbon nanoflakes (CNFs). The weight content of Ln2O3 in the Ln2O3/CNF [...] Read more.
Synthesized Ln2O3 (Ln = La, Nd or Gd) nanoparticles with sizes of 1–3 nm, 5–6 nm and 10–15 nm were stabilized by carbon nanoflakes (CNFs). The weight content of Ln2O3 in the Ln2O3/CNF composites was 20–50 wt. %, which makes these composites potentially suitable for practical use as computed tomography and magnetic resonance imaging contrast agents. The structure of CNFs and Ln2O3/CNF composites was investigated by X-ray diffraction data, X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). The EPR spectra of raw CNFs were silent. The oxidation of the CNF surface resulted in the appearance of paramagnetic centers associated with two types of unpaired electrons in the carbon support. After impregnation of the CNFs with the Ln3+ ion solution, the number of unpaired electrons was reduced, presumably due to the formation of C–O–Ln bonds. All Ln3+ ions changed the composites’ EPR spectra by reducing the number of unpaired electrons in the CNF structure. Full article
(This article belongs to the Section Synthesis, Interfaces and Nanostructures)
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28 pages, 2337 KB  
Review
Road Map for the Use of Electron Spin Resonance Spectroscopy in the Study of Functionalized Magnetic Nanoparticles
by Tomasz Kubiak and Bernadeta Dobosz
Materials 2025, 18(12), 2841; https://doi.org/10.3390/ma18122841 - 16 Jun 2025
Cited by 1 | Viewed by 840
Abstract
Electron paramagnetic resonance (EPR) spectroscopy is gaining increasing recognition in research on various nanostructures. In the case of iron oxide nanoparticles, EPR measurements offer the possibility of determining the magnetic phase and the exact type (Fe3O4, γ-Fe2O [...] Read more.
Electron paramagnetic resonance (EPR) spectroscopy is gaining increasing recognition in research on various nanostructures. In the case of iron oxide nanoparticles, EPR measurements offer the possibility of determining the magnetic phase and the exact type (Fe3O4, γ-Fe2O3, α-Fe2O3, or a combination) of the core material. Furthermore, the EPR technique enables the study of relaxation processes, estimation of the effective and surface anisotropy constants, and assessment of the influence of sample aging on the magnetic properties of nanoparticles. The scope of the information obtained can be further expanded by utilizing spin labeling of polymer-coated nanoparticles. By analyzing the signals from the attached nitroxide, one can determine certain properties of the coating and its interactions with the environment (e.g., body fluids, cells, tissues) and also perform imaging of nanoparticles in various media. In some cases, EPR can help monitor the encapsulation of active substances and their release processes. Unfortunately, despite the enormous potential, not all of the possibilities offered by EPR are routinely used in nanoscience. Therefore, the present article aims not only to present the current applications and existing trends but also to indicate directions for future EPR research, constituting a road map. Full article
(This article belongs to the Special Issue Physico-Chemical Modification of Materials for Biomedical Application)
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52 pages, 3834 KB  
Review
Nitroxides: Chemistry, Antioxidant Properties, and Biomedical Applications
by Krzysztof Gwozdzinski, Anna Pieniazek and Lukasz Gwozdzinski
Molecules 2025, 30(10), 2159; https://doi.org/10.3390/molecules30102159 - 14 May 2025
Cited by 2 | Viewed by 1579
Abstract
Nitroxides are stable organic free radicals with a wide range of applications. They have found applications in chemistry, biochemistry, biophysics, molecular biology, and biomedicine as EPR/NMR imaging techniques. As spin labels and probes, they are used in electron paramagnetic resonance (EPR) spectroscopy in [...] Read more.
Nitroxides are stable organic free radicals with a wide range of applications. They have found applications in chemistry, biochemistry, biophysics, molecular biology, and biomedicine as EPR/NMR imaging techniques. As spin labels and probes, they are used in electron paramagnetic resonance (EPR) spectroscopy in the study of proteins, lipids, nucleic acids, and enzymes, as well as for measuring oxygen concentration in cells and cellular organelles, as well as tissues and intracellular pH. Their unique redox properties have allowed them to be used as exogenous antioxidants. In this review, we have discussed the chemical properties of nitroxides and their antioxidant properties. Furthermore, we have considered their use as radioprotectors and protective agents in ischemia/reperfusion in vivo and in vitro. We also presented other applications of nitroxides in protecting cells and tissues from oxidative stress and in protein studies and discussed their use in EPR/MRI. Full article
(This article belongs to the Section Medicinal Chemistry)
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12 pages, 3486 KB  
Article
XPS Study of Grafting Paramagnetic Ions onto the Surface of Detonation Nanodiamonds
by Alexander Panich, Natalya Froumin, Aleksandr Aleksenskii and Anastasiya Chizhikova
Nanomaterials 2025, 15(4), 260; https://doi.org/10.3390/nano15040260 - 10 Feb 2025
Viewed by 1086
Abstract
Grafting of paramagnetic transition and rare earth metal ions onto the surface of detonation nanodiamonds (DNDs) was successfully implemented in the recent decade and opened new opportunities in the biomedical application of these compounds, particularly as novel contrast agents for magnetic resonance imaging. [...] Read more.
Grafting of paramagnetic transition and rare earth metal ions onto the surface of detonation nanodiamonds (DNDs) was successfully implemented in the recent decade and opened new opportunities in the biomedical application of these compounds, particularly as novel contrast agents for magnetic resonance imaging. The grafting was studied mainly using EPR, NMR, and magnetic measurements. Such a highly surface-sensitive, quantitative, chemical analytic technique as X-ray photoelectron spectroscopy (XPS) was very rarely used. In this paper, we report the XPS study of grafting transition and rare-earth metal ions (Cu2+, Co2+, Mn2+, and Gd3+) onto the surface of DNDs. Binding energies for metal, carbon, oxygen, and nitrogen atoms were determined and attributed to the corresponding ion states and atomic groups. Comparing XPS and EPR findings, we showed that the developed synthesis route resulted in almost complete grafting of manganese and gadolinium atoms in the form of paramagnetic ions Mn2+ and Gd3+ to the diamond surface, while only 30% of the copper atoms on the surface are in the paramagnetic state Cu2+, and the rest 70% are in the non-magnetic Cu+ state. It was not possible to draw a similar conclusion regarding Co2+ ions due to the lack of data on the amount of these paramagnetic ions on the DND surface. Full article
(This article belongs to the Section 2D and Carbon Nanomaterials)
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24 pages, 9184 KB  
Article
Contrast Agents Based on Human Serum Albumin and Nitroxides for 1H-MRI and Overhauser-Enhanced MRI
by Dmitry Mitin, Friedemann Bullinger, Sergey Dobrynin, Jörn Engelmann, Klaus Scheffler, Mikhail Kolokolov, Olesya Krumkacheva, Kai Buckenmaier, Igor Kirilyuk and Alexey Chubarov
Int. J. Mol. Sci. 2024, 25(7), 4041; https://doi.org/10.3390/ijms25074041 - 5 Apr 2024
Cited by 8 | Viewed by 3056
Abstract
In cancer diagnostics, magnetic resonance imaging (MRI) uses contrast agents to enhance the distinction between the target tissue and background. Several promising approaches have been developed to increase MRI sensitivity, one of which is Overhauser dynamic nuclear polarization (ODNP)-enhanced MRI (OMRI). In this [...] Read more.
In cancer diagnostics, magnetic resonance imaging (MRI) uses contrast agents to enhance the distinction between the target tissue and background. Several promising approaches have been developed to increase MRI sensitivity, one of which is Overhauser dynamic nuclear polarization (ODNP)-enhanced MRI (OMRI). In this study, a macromolecular construct based on human serum albumin and nitroxyl radicals (HSA-NIT) was developed using a new synthesis method that significantly increased the modification to 21 nitroxide residues per protein. This was confirmed by electron paramagnetic resonance (EPR) spectroscopy and matrix-assisted laser desorption/ionization time-of-flight (MALDI ToF) mass spectrometry. Gel electrophoresis and circular dichroism showed no significant changes in the structure of HSA-NITs, and no oligomers were formed during modification. The cytotoxicity of HSA-NITs was comparable to that of native albumin. HSA-NITs were evaluated as potential “metal-free” organic radical relaxation-based contrast agents for 1H-MRI and as hyperpolarizing contrast agents for OMRI. Relaxivities (longitudinal and transversal relaxation rates r1 and r2) for HSA-NITs were measured at different magnetic field strengths (1.88, 3, 7, and 14 T). Phantoms were used to demonstrate the potential use of HSA-NIT as a T1- and T2-weighted relaxation-based contrast agent at 3 T and 14 T. The efficacy of 1H Overhauser dynamic nuclear polarization (ODNP) in liquids at an ultralow magnetic field (ULF, B0 = 92 ± 0.8 μT) was investigated for HSA-NIT conjugates. The HSA-NITs themselves did not show ODNP enhancement; however, under the proteolysis conditions simulating cancer tissue, HSA-NIT conjugates were cleaved into lower-molecular-weight (MW) protein fragments that activate ODNP capabilities, resulting in a maximum achievable enhancement |Emax| of 40–50 and a radiofrequency power required to achieve half of Emax, P1/2, of 21–27 W. The HSA-NIT with a higher degree of modification released increased the number of spin probes upon biodegradation, which significantly enhanced the Overhauser effect. Thus, HSA-NITs may represent a new class of MRI relaxation-based contrast agents as well as novel cleavable conjugates for use as hyperpolarizing contrast agents (HCAs) in OMRI. Full article
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14 pages, 3113 KB  
Article
The Ability of the EPR MOUSE to Study Underpaintings
by Stanley E. Liang, Olivia R. Kuzio, Matthew Pupko, Max Robbins and Joseph P. Hornak
Heritage 2023, 6(7), 5524-5537; https://doi.org/10.3390/heritage6070291 - 22 Jul 2023
Cited by 2 | Viewed by 1548
Abstract
The possibility of using the electron paramagnetic resonance (EPR) mobile universal surface explorer (MOUSE) to study underpaintings is validated. The depth sensitivity of the EPR MOUSE is measured using an EPR standard, and is verified using three paramagnetic pigments in an acrylic binder [...] Read more.
The possibility of using the electron paramagnetic resonance (EPR) mobile universal surface explorer (MOUSE) to study underpaintings is validated. The depth sensitivity of the EPR MOUSE is measured using an EPR standard, and is verified using three paramagnetic pigments in an acrylic binder under opaque acrylic layers of titanium white and lead white. The ability to distinguish and identify two layers of EPR signal-bearing pigments is shown using pairwise sets of ultramarine, Egyptian, and Han blue pigments in an acrylic binder. And finally, the spatial imaging capability is demonstrated using a printed design of magnetite black covered with a solid second layer of the pigment. These studies demonstrate that EPR spectroscopy with the EPR MOUSE is a viable method for studying paramagnetic and ferrimagnetic underlayers of pigments. Full article
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17 pages, 10932 KB  
Article
Photoluminescence and Photocatalytic Properties of MWNTs Decorated with Fe-Doped ZnO Nanoparticles
by Adriana Popa, Maria Stefan, Sergiu Macavei, Laura Elena Muresan, Cristian Leostean, Cornelia Veronica Floare-Avram and Dana Toloman
Materials 2023, 16(7), 2858; https://doi.org/10.3390/ma16072858 - 3 Apr 2023
Cited by 6 | Viewed by 2878
Abstract
The present work reports the photoluminescence (PL) and photocatalytic properties of multi-walled carbon nanotubes (MWCNTs) decorated with Fe-doped ZnO nanoparticles. MWCNT:ZnO-Fe nanocomposite samples with weight ratios of 1:3, 1:5 and 1:10 were prepared using a facile synthesis method. The obtained crystalline phases were [...] Read more.
The present work reports the photoluminescence (PL) and photocatalytic properties of multi-walled carbon nanotubes (MWCNTs) decorated with Fe-doped ZnO nanoparticles. MWCNT:ZnO-Fe nanocomposite samples with weight ratios of 1:3, 1:5 and 1:10 were prepared using a facile synthesis method. The obtained crystalline phases were evidenced by X-ray diffraction (XRD). X-ray Photoelectron spectroscopy (XPS) revealed the presence of both 2+ and 3+ valence states of Fe ions in a ratio of approximately 0.5. The electron paramagnetic resonance EPR spectroscopy sustained the presence of Fe3+ ions in the ZnO lattice and evidenced oxygen vacancies. Transmission electron microscopy (TEM) images showed the attachment and distribution of Fe-doped ZnO nanoparticles along the nanotubes with a star-like shape. All of the samples exhibited absorption in the UV region, and the absorption edge was shifted toward a higher wavelength after the addition of MWCNT component. The photoluminescence emission spectra showed peaks in the UV and visible region. Visible emissions are a result of the presence of defects or impurity states in the material. All of the samples showed photocatalytic activity against the Rhodamine B (RhB) synthetic solution under UV irradiation. The best performance was obtained using the MWCNT:ZnO-Fe(1:5) nanocomposite samples, which exhibited a 96% degradation efficiency. The mechanism of photocatalytic activity was explained based on the reactive oxygen species generated by the nanocomposites under UV irradiation in correlation with the structural and optical information obtained in this study. Full article
(This article belongs to the Special Issue Advanced Luminescent Materials and Devices)
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12 pages, 6068 KB  
Article
A New Application of Spin and Fluorescence Double-Sensor Molecules
by Flórián Bencze, Balázs Bognár, Tamás Kálai, László Kollár, Zoltán Nagymihály and Sandor Kunsági-Máté
Molecules 2023, 28(7), 2978; https://doi.org/10.3390/molecules28072978 - 27 Mar 2023
Cited by 1 | Viewed by 1876
Abstract
EPR imaging techniques are known to be successful tools for mapping living bodies, especially because of the high transparency of tissues in the microwave range. This technique assumes the presence of radicals whose in vivo transport is also controlled by serum albumins. Accordingly, [...] Read more.
EPR imaging techniques are known to be successful tools for mapping living bodies, especially because of the high transparency of tissues in the microwave range. This technique assumes the presence of radicals whose in vivo transport is also controlled by serum albumins. Accordingly, in this study, the interactions between 3-hydroxymethyl-1-oxyl-4-(pyren-1-yl)-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrole radical and the human serum albumin molecules were investigated. To clarify the adsorption processes of this radical onto the surface of human serum albumin (HSA), the interaction of the OMe derivative of the radical was also examined parallel with the studies on the radical—HSA interactions. Considering the solubility issues and also to modulate the transport, inclusion complexes of the radical with a cavitand derivative were also studied. The latter interactions were observed through fluorescence spectroscopy, fluorescence polarization, and by EPR spectroscopy. As a double-sensor molecule, we found that the fluorophore nitroxide is a good candidate as it gave further information about host-guest interactions (fluorescence, fluorescence polarization, and EPR). We also found that in the presence of a cavitand, a complex with greater stability was formed between the sensor molecule and the human serum albumin. Based on these observations, we can conclude that applying this double-sensor (spin, fluorescent) molecule is useful in cases when different interactions can affect the EPR measurements. Full article
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30 pages, 5826 KB  
Article
Solanum dulcamara L. Berries: A Convenient Model System to Study Redox Processes in Relation to Fruit Ripening
by Milica Milutinović, Đura Nakarada, Jelena Božunović, Miloš Todorović, Uroš Gašić, Suzana Živković, Marijana Skorić, Đurđa Ivković, Jelena Savić, Nina Devrnja, Neda Aničić, Tijana Banjanac, Miloš Mojović and Danijela Mišić
Antioxidants 2023, 12(2), 346; https://doi.org/10.3390/antiox12020346 - 1 Feb 2023
Cited by 11 | Viewed by 3204
Abstract
The present study provides, for the first time, a physicochemical and biochemical characterization of the redox processes associated with the ripening of Solanum dulcamara L. (bittersweet) berries. Electron Paramagnetic Resonance Spectroscopy (EPRS) and Imaging (EPRI) measurements of reactive oxygen species (ROS) were performed [...] Read more.
The present study provides, for the first time, a physicochemical and biochemical characterization of the redox processes associated with the ripening of Solanum dulcamara L. (bittersweet) berries. Electron Paramagnetic Resonance Spectroscopy (EPRS) and Imaging (EPRI) measurements of reactive oxygen species (ROS) were performed in parallel with the tissue-specific metabolic profiling of major antioxidants and assessment of antioxidant enzymes activity. Fruit transition from the mature green (MG) to ripe red (RR) stage involved changes in the qualitative and quantitative content of antioxidants and the associated cellular oxidation and peroxidation processes. The skin of bittersweet berries, which was the major source of antioxidants, exhibited the highest antioxidant potential against DPPH radicals and nitroxyl spin probe 3CP. The efficient enzymatic antioxidant system played a critical protective role against the deleterious effects of progressive oxidative stress during ripening. Here, we present the EPRI methodology to assess the redox status of fruits and to discriminate between the redox states of different tissues. Interestingly, the intracellular reoxidation of cell-permeable nitroxide probe 3CP was observed for the first time in fruits or any other plant tissue, and its intensity is herein proposed as a reliable indicator of oxidative stress during ripening. The described noninvasive EPRI technique has the potential to have broader application in the study of redox processes associated with the development, senescence, and postharvest storage of fruits, as well as other circumstances in which oxidative stress is implicated. Full article
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19 pages, 2225 KB  
Article
The Release of a Highly Cytotoxic Paullone Bearing a TEMPO Free Radical from the HSA Hydrogel: An EPR Spectroscopic Characterization
by Ana Vesković, Đura Nakarada, Olga Vasiljević, Anatolie Dobrov, Gabriella Spengler, Éva A. Enyedy, Vladimir B. Arion and Ana Popović Bijelić
Pharmaceutics 2022, 14(6), 1174; https://doi.org/10.3390/pharmaceutics14061174 - 30 May 2022
Cited by 2 | Viewed by 3590
Abstract
This study shows the potential of a thermally induced human serum albumin (HSA) hydrogel to serve as a drug depot for sustained release of a highly cytotoxic modified paullone ligand bearing a TEMPO free radical (HL). The binding of HL to [...] Read more.
This study shows the potential of a thermally induced human serum albumin (HSA) hydrogel to serve as a drug depot for sustained release of a highly cytotoxic modified paullone ligand bearing a TEMPO free radical (HL). The binding of HL to HSA was studied by electron paramagnetic resonance (EPR) spectroscopy and imaging. The EPR protocol was also implemented for the study of matrix degradation, and ligand diffusion rate, in two additional spin-labeled hydrogels, containing 5-doxylstearate and 3-carbamoyl-proxyl. The results showed that the hydrogel is an efficient HL reservoir as it retained 60% of the ligand during 11 days of dialysis in physiological saline. Furthermore, upon incubation with Colo 205 human colon adenocarcinoma cells for 3 days, the HL/HSA hydrogel did not exhibit cytotoxic activity, demonstrating that it is also an efficient ligand depot in the presence of living cells. It was observed that the percentage of HL release is independent of its initial concentration in the hydrogel, suggesting that HSA possesses a specific binding site for the ligand, most likely Sudlow site 2, as predicted by molecular docking. The intrinsic property of albumin to bind and transport various substances, including hydrophobic drugs, may be fine-tuned by appropriate physical/chemical hydrogel preparation procedures, providing optimal drug delivery. Full article
(This article belongs to the Special Issue Hydrogels in Drug Delivery: Progress and Challenges)
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19 pages, 1887 KB  
Article
Molecular-Level Release of Coumarin-3-Carboxylic Acid and Warfarin-Derivatives from BSA-Based Hydrogels
by Niuosha Sanaeifar, Karsten Mäder and Dariush Hinderberger
Pharmaceutics 2021, 13(10), 1661; https://doi.org/10.3390/pharmaceutics13101661 - 11 Oct 2021
Cited by 8 | Viewed by 4049
Abstract
This investigation aimed at developing BSA hydrogels as a controlled release system to study the release behavior of spin-labeled coumarin-3-carboxylic acid (SL-CCS) and warfarin (SL-WFR). The release profiles of these spin-labeled (SL-) pharmaceuticals from BSA hydrogels prepared with different procedures are compared in [...] Read more.
This investigation aimed at developing BSA hydrogels as a controlled release system to study the release behavior of spin-labeled coumarin-3-carboxylic acid (SL-CCS) and warfarin (SL-WFR). The release profiles of these spin-labeled (SL-) pharmaceuticals from BSA hydrogels prepared with different procedures are compared in detail. The mechanical properties of the gels during formation and release were studied via rheology, while a nanoscopic view on the release behavior was achieved by analyzing SL-drugs–BSA interaction using continuous wave electron paramagnetic resonance (CW EPR) spectroscopy. The influence of type of drug, drug concentration, duration of gel formation, and gelation methods on release behavior were characterized by CW EPR spectroscopy, EPR imaging (EPRI), and dynamic light scattering (DLS), which provide information on the interaction of BSA with SL-drugs, the percentage of drug inside the hydrogel and the nature and size of the released structures, respectively. We found that the release rate of SL-CCS and SL-WFR from BSA hydrogels is tunable through drug ratios, hydrogel incubation time and gelation procedures. All of the results indicate that BSA hydrogels can be potentially exploited in controlled drug delivery applications. Full article
(This article belongs to the Special Issue Albumin-Based Drug Delivery Systems)
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21 pages, 4121 KB  
Article
Uptake of Cell-Penetrating Peptide RL2 by Human Lung Cancer Cells: Monitoring by Electron Paramagnetic Resonance and Confocal Laser Scanning Microscopy
by Sergey S. Ovcherenko, Olga A. Chinak, Anton V. Chechushkov, Sergey A. Dobrynin, Igor A. Kirilyuk, Olesya A. Krumkacheva, Vladimir A. Richter and Elena G. Bagryanskaya
Molecules 2021, 26(18), 5442; https://doi.org/10.3390/molecules26185442 - 7 Sep 2021
Cited by 17 | Viewed by 3768
Abstract
RL2 is a recombinant analogue of a human κ-casein fragment, capable of penetrating cells and inducing apoptosis of cancer cells with no toxicity to normal cells. The exact mechanism of RL2 penetration into cells remains unknown. In this study, we investigated the mechanism [...] Read more.
RL2 is a recombinant analogue of a human κ-casein fragment, capable of penetrating cells and inducing apoptosis of cancer cells with no toxicity to normal cells. The exact mechanism of RL2 penetration into cells remains unknown. In this study, we investigated the mechanism of RL2 penetration into human lung cancer A549 cells by a combination of electron paramagnetic resonance (EPR) spectroscopy and confocal laser scanning microscopy. EPR spectra of A549 cells incubated with RL2 (sRL2) spin-labeled by a highly stable 3-carboxy-2,2,5,5-tetraethylpyrrolidine-1-oxyl radical were found to contain three components, with their contributions changing with time. The combined EPR and confocal-microscopy data allowed us to assign these three forms of sRL2 to the spin-labeled protein sticking to the membrane of the cell and endosomes, to the spin-labeled protein in the cell interior, and to spin labeled short peptides formed in the cell because of protein digestion. EPR spectroscopy enabled us to follow the kinetics of transformations between different forms of the spin-labeled protein at a minimal spin concentration (3–16 μM) in the cell. The prospects of applications of spin-labeled cell-penetrating peptides to EPR imaging, DNP, and magnetic resonance imaging are discussed, as is possible research on an intrinsically disordered protein in the cell by pulsed dipolar EPR spectroscopy. Full article
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16 pages, 4317 KB  
Article
Synthesis, Biomacromolecular Interactions, Photodynamic NO Releasing and Cellular Imaging of Two [RuCl(qn)(Lbpy)(NO)]X Complexes
by Luna Song, Hehe Bai, Chenyang Liu, Wenjun Gong, Ai Wang, Li Wang, Yi Zhao, Xuan Zhao and Hongfei Wang
Molecules 2021, 26(9), 2545; https://doi.org/10.3390/molecules26092545 - 27 Apr 2021
Cited by 5 | Viewed by 2551
Abstract
Two light-activated NO donors [RuCl(qn)(Lbpy)(NO)]X with 8-hydroxyquinoline (qn) and 2,2′-bipyridine derivatives (Lbpy) as co-ligands were synthesized (Lbpy1 = 4,4′-dicarboxyl-2,2′-dipyridine, X = Cl and Lbpy2 = 4,4′-dimethoxycarbonyl-2,2′-dipyridine, X = NO3), and characterized using ultraviolet–visible (UV-vis) spectroscopy, Fourier transform [...] Read more.
Two light-activated NO donors [RuCl(qn)(Lbpy)(NO)]X with 8-hydroxyquinoline (qn) and 2,2′-bipyridine derivatives (Lbpy) as co-ligands were synthesized (Lbpy1 = 4,4′-dicarboxyl-2,2′-dipyridine, X = Cl and Lbpy2 = 4,4′-dimethoxycarbonyl-2,2′-dipyridine, X = NO3), and characterized using ultraviolet–visible (UV-vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (1H NMR), elemental analysis and electrospray ionization mass spectrometry (ESI-MS) spectra. The [RuCl(qn)(Lbpy2)(NO)]NO3 complex was crystallized and exhibited distorted octahedral geometry, in which the Ru–N(O) bond length was 1.752(6) Å and the Ru–N–O angle was 177.6(6)°. Time-resolved FT-IR and electron paramagnetic resonance (EPR) spectra were used to confirm the photoactivated NO release of the complexes. The binding constant (Kb) of two complexes with human serum albumin (HSA) and DNA were quantitatively evaluated using fluorescence spectroscopy, Ru-Lbpy1 (Kb~106 with HSA and ~104 with DNA) had higher affinity than Ru-Lbpy2. The interactions between the complexes and HSA were investigated using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) and EPR spectra. HSA can be used as a carrier to facilitate the release of NO from the complexes upon photoirradiation. The confocal imaging of photo-induced NO release in living cells was successfully observed with a fluorescent NO probe. Moreover, the photocleavage of pBR322 DNA for the complexes and the effect of different Lbpy substituted groups in the complexes on their reactivity were analyzed. Full article
(This article belongs to the Special Issue Anticancer Compounds with Different Biological Targets)
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20 pages, 5144 KB  
Article
Biotransformation of Food-Grade and Nanometric TiO2 in the Oral–Gastro–Intestinal Tract: Driving Forces and Effect on the Toxicity toward Intestinal Epithelial Cells
by Arianna Marucco, Marion Prono, David Beal, Enrica Alasonati, Paola Fisicaro, Enrico Bergamaschi, Marie Carriere and Ivana Fenoglio
Nanomaterials 2020, 10(11), 2132; https://doi.org/10.3390/nano10112132 - 27 Oct 2020
Cited by 24 | Viewed by 4003
Abstract
Background: Oral exposure to titanium dioxide (TiO2) is common since it is widely used in food and pharmaceutical products. Concern on the safety of this substance has been recently raised, due to the presence of an ultrafine fraction in food-grade TiO [...] Read more.
Background: Oral exposure to titanium dioxide (TiO2) is common since it is widely used in food and pharmaceutical products. Concern on the safety of this substance has been recently raised, due to the presence of an ultrafine fraction in food-grade TiO2. Discrepancy exists among data reported in in vitro and in vivo studies on intestinal acute/chronic toxicity of TiO2. This might be due to the different biological identity of TiO2 in traditional in vitro test by respect in vivo conditions. Methods: One food-grade TiO2 and two nanometric TiO2 samples were treated with a simulated human digestive dystem (SHDS) in order to investigate the bio-transformation occurring to the particles once ingested in term of size distribution (Dynamic Light Scattering—DLS-, Flow Particle Imaging, Asymmetric Flow Field Flow Fractionation-AF4-) and surface modification (Electrophoretic Light Scattering—ELS-, Electron Paramagnetic Resonance Spectroscopy—EPR-). The effect of SHDS on the cyto-, genotoxicity and potential to induce oxidative stress towards human colorectal carcinoma HCT116 cells was also assessed. Results: Aggregation as a consequence of the high ionic strength of the gastric and intestinal simulated fluids was observed, together with the formation of a partially irreversible bio-corona containing phosphate ions and proteins. Such bio-corona led to a partial masking of the TiO2 particles surface and reactivity. Pristine and treated TiO2 nanoparticles showed comparable acute toxicity and genotoxicity toward HCT116 cells, whereas a small decrease of the induction of oxidative stress after treatment was observed. Conclusions: Overall the results underline the importance of SHDS as a tool to improve the predictive power of in vitro tests towards intestinal nanomaterial toxicity. Full article
(This article belongs to the Section Biology and Medicines)
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