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Luo Y, Chen Z, Wen S, Han Q, Fu L, Yan L, Jin D, Bünzli JCG, Bao G. Magnetic regulation of the luminescence of hybrid lanthanide-doped nanoparticles. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214653] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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2
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Aspect Ratio of PEGylated Upconversion Nanocrystals Affects the Cellular Uptake In Vitro and In Vivo. Acta Biomater 2022; 147:403-413. [PMID: 35605956 DOI: 10.1016/j.actbio.2022.05.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 05/11/2022] [Accepted: 05/16/2022] [Indexed: 12/28/2022]
Abstract
The central nervous system (CNS) is protected by the blood-brain barrier (BBB), which acts as a physical barrier to regulate and prevent the uptake of endogenous metabolites and xenobiotics. However, the BBB prevents most non-lipophilic drugs from reaching the CNS following systematic administration. Therefore, there is considerable interest in identifying drug carriers that can maintain the biostability of therapeutic molecules and target their transport across the BBB. In this regard, upconversion nanoparticles (UCNPs) have become popular as a nanoparticle-based solution to this problem, with the additional benefit that they display unique properties for in vivo visualization. The majority of studies to date have explored basic spherical UCNPs for drug delivery applications. However, the biophysical properties of UCNPs, cell uptake and BBB transport have not been thoroughly investigated. In this study, we described a one-pot seed-mediated approach to precisely control longitudinal growth to produce bright UCNPs with various aspect ratios. We have systematically evaluated the effects of the physical aspect ratios and PEGylation of UCNPs on cellular uptake in different cell lines and an in vivo zebrafish model. We found that PEGylated the original UCNPs can enhance their biostability and cell uptake capacity. We identify an optimal aspect ratio for UCNP uptake into several different types of cultured cells, finding that this is generally in the ratio of 2 (length/width). This data provides a crucial clue for further optimizing UCNPs as a drug carrier to deliver therapeutic agents into the CNS. STATEMENT OF SIGNIFICANCE: The central nervous system (CNS) is protected by the blood-brain barrier (BBB), which acts as a highly selective semipermeable barrier of endothelial cells to regulate and prevent the uptake of toxins and pathogens. However, the BBB prevents most non-lipophilic drugs from reaching the CNS following systematic administration. The proposed research is significant because identifying the aspect ratio of drug carriers that maintains the biostability of therapeutic molecules and targets their transport across the blood-brain barrier (BBB) is crucial for designing an efficient drug delivery system. Therefore, this research provides a vital clue for further optimizing UCNPs as drug carriers to deliver therapeutic molecules into the brain.
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Shapoval O, Engstová H, Jirák D, Drahokoupil J, Sulková K, Berková Z, Pop-Georgievski O, Holendová B, Ježek P, Horák D. Poly(4-Styrenesulfonic Acid- co-maleic Anhydride)-Coated NaGdF 4:Yb,Tb,Nd Nanoparticles with Luminescence and Magnetic Properties for Imaging of Pancreatic Islets and β-Cells. ACS APPLIED MATERIALS & INTERFACES 2022; 14:18233-18247. [PMID: 35416039 DOI: 10.1021/acsami.2c04274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Novel Yb,Tb,Nd-doped GdF3 and NaGdF4 nanoparticles were synthesized by a coprecipitation method in ethylene glycol (EG) in the presence of the poly(4-styrenesulfonic acid-co-maleic anhydride) stabilizer. The particle size and morphology, crystal structure, and phase change were controlled by adjusting the PSSMA concentration and source of fluoride anions in the reaction. Doping of Yb3+, Tb3+, and Nd3+ ions in the NaGdF4 host nanoparticles induced luminescence under ultraviolet and near-infrared excitation and high relaxivity in magnetic resonance (MR) imaging (MRI). In vitro toxicity of the nanoparticles and their cellular uptake efficiency were determined in model rat pancreatic β-cells (INS-1E). As the NaGdF4:Yb,Tb,Nd@PSSMA-EG nanoparticles were non-toxic and possessed good luminescence and magnetic properties, they were applicable for in vitro optical and MRI of isolated pancreatic islets in phantoms. The superior contrast was achieved for in vivo T2*-weighted MR images of the islets transplanted under the kidney capsule to mice in preclinical trials.
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Affiliation(s)
- Oleksandr Shapoval
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, Prague 6 162 06, Czech Republic
| | - Hana Engstová
- Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague 4 142 20, Czech Republic
| | - Daniel Jirák
- Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, Prague 4 142 21, Czech Republic
- Institute of Biophysics and Informatics, First Faculty of Medicine, Charles University, Salmovská 1, Prague 2 120 00, Czech Republic
| | - Jan Drahokoupil
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, Prague 8 182 21, Czech Republic
| | - Kateřina Sulková
- Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, Prague 4 142 21, Czech Republic
| | - Zuzana Berková
- Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, Prague 4 142 21, Czech Republic
| | - Ognen Pop-Georgievski
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, Prague 6 162 06, Czech Republic
| | - Blanka Holendová
- Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague 4 142 20, Czech Republic
| | - Petr Ježek
- Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague 4 142 20, Czech Republic
| | - Daniel Horák
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, Prague 6 162 06, Czech Republic
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Shapoval O, Brandmeier JC, Nahorniak M, Oleksa V, Makhneva E, Gorris HH, Farka Z, Horák D. PMVEMA-coated upconverting nanoparticles for upconversion-linked immunoassay of cardiac troponin. Talanta 2022; 244:123400. [PMID: 35395457 DOI: 10.1016/j.talanta.2022.123400] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 11/18/2022]
Abstract
Surface engineering of upconverting nanoparticles (UCNPs) is crucial for their bioanalytical applications. Here, an antibody specific to cardiac troponin I (cTnI), an important biomarker for acute myocardial infection, was covalently immobilized on the surface of UCNPs to prepare a label for the detection of cTnI biomarker in an upconversion-linked immunoassay (ULISA). Core-shell UCNPs (NaYF4:Yb,Tm@NaYF4) were first coated with poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) and then conjugated to antibodies. The morphology (size and uniformity), hydrodynamic diameter, chemical composition, and amount of coating on the of UCNPs, as well as their upconversion luminescence, colloidal stability, and leaching of Y3+ ions into the surrounding media, were determined. The developed ULISA allowed reaching a limit of detection (LOD) of 0.13 ng/ml and 0.25 ng/ml of cTnI in plasma and serum, respectively, which represents 12- and 2-fold improvement to conventional enzyme-linked immunosorbent based on the same immunoreagents.
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Affiliation(s)
- Oleksandr Shapoval
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, 162 06, Prague 6, Czech Republic
| | - Julian C Brandmeier
- Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Mykhailo Nahorniak
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, 162 06, Prague 6, Czech Republic
| | - Viktoriia Oleksa
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, 162 06, Prague 6, Czech Republic
| | - Ekaterina Makhneva
- Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Hans H Gorris
- Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Zdeněk Farka
- Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Daniel Horák
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, 162 06, Prague 6, Czech Republic.
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Laha SS, Thorat ND, Singh G, Sathish CI, Yi J, Dixit A, Vinu A. Rare-Earth Doped Iron Oxide Nanostructures for Cancer Theranostics: Magnetic Hyperthermia and Magnetic Resonance Imaging. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2104855. [PMID: 34874618 DOI: 10.1002/smll.202104855] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 10/11/2021] [Indexed: 05/27/2023]
Abstract
Superparamagnetic iron oxide nanoparticles (SPIONs) have been extensively investigated during the last couple of decades because of their potential applications across various disciplines ranging from spintronics to nanotheranostics. However, pure iron oxide nanoparticles cannot meet the requirement for practical applications. Doping is considered as one of the most prominent and simplest techniques to achieve optimized multifunctional properties in nanomaterials. Doped iron oxides, particularly, rare-earth (RE) doped nanostructures have shown much-improved performance for a wide range of biomedical applications, including magnetic hyperthermia and magnetic resonance imaging (MRI), compared to pure iron oxide. Extensive investigations have revealed that bigger-sized RE ions possessing high magnetic moment and strong spin-orbit coupling can serve as promising dopants to significantly regulate the properties of iron oxides for advanced biomedical applications. This review provides a detailed investigation on the role of RE ions as primary dopants for engineering the structural and magnetic properties of Fe3 O4 nanoparticles to carefully introspect and correlate their impact on cancer theranostics with a special focus on magnetic hyperthermia and MRI. In addition, prospects for achieving high-performance magnetic hyperthermia and MRI are thoroughly discussed. Finally, suggestions on future work in these two areas are also proposed.
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Affiliation(s)
- Suvra S Laha
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, 48201, USA
- Centre for Nano Science and Engineering (CeNSE), Indian Institute of Science, Bangalore, 560012, India
| | - Nanasaheb D Thorat
- Nuffield Department of Women's & Reproductive Health, Medical Sciences Division, University of Oxford, Oxford, OX3 9DU, UK
| | - Gurwinder Singh
- Global Innovative Centre for Advanced Nanomaterials, College of Engineering, Science and Environment, The University of Newcastle, Callaghan, NSW, 2308, Australia
| | - C I Sathish
- Global Innovative Centre for Advanced Nanomaterials, College of Engineering, Science and Environment, The University of Newcastle, Callaghan, NSW, 2308, Australia
| | - Jiabao Yi
- Global Innovative Centre for Advanced Nanomaterials, College of Engineering, Science and Environment, The University of Newcastle, Callaghan, NSW, 2308, Australia
| | - Ambesh Dixit
- Department of Physics, Indian Institute of Technology, Jodhpur, 342037, India
| | - Ajayan Vinu
- Global Innovative Centre for Advanced Nanomaterials, College of Engineering, Science and Environment, The University of Newcastle, Callaghan, NSW, 2308, Australia
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Polozhentsev OE, Pankin IA, Khodakova DV, Medvedev PV, Goncharova AS, Maksimov AY, Kit OI, Soldatov AV. Synthesis, Characterization and Biodistribution of GdF 3:Tb 3+@RB Nanocomposites. MATERIALS 2022; 15:ma15020569. [PMID: 35057287 PMCID: PMC8779613 DOI: 10.3390/ma15020569] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/28/2021] [Accepted: 12/31/2021] [Indexed: 01/04/2023]
Abstract
Herein we report the development of a nanocomposite for X-ray-induced photodynamic therapy (X-PDT) and computed tomography (CT) based on PEG-capped GdF3:Tb3+ scintillating nanoparticles conjugated with Rose Bengal photosensitizer via electrostatic interactions. Scintillating GdF3:Tb3+ nanoparticles were synthesized by a facile and cost-effective wet chemical precipitation method. All synthesized nanoparticles had an elongated "spindle-like" clustered morphology with an orthorhombic structure. The structure, particle size, and morphology were determined by transmission electron microscopy (TEM), X-ray diffraction (XRD), and dynamic light scattering (DLS) analysis. The presence of a polyethylene glycol (PEG) coating and Rose Bengal conjugates was proved by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and ultraviolet-visible (UV-vis) analysis. Upon X-ray irradiation of the colloidal PEG-capped GdF3:Tb3+-Rose Bengal nanocomposite solution, an efficient fluorescent resonant energy transfer between scintillating nanoparticles and Rose Bengal was detected. The biodistribution of the synthesized nanoparticles in mice after intravenous administration was studied by in vivo CT imaging.
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Affiliation(s)
- Oleg E. Polozhentsev
- The Smart Materials Research Institute, Southern Federal University, 344090 Rostov-on-Don, Russia; (I.A.P.); (P.V.M.); (A.V.S.)
- Correspondence:
| | - Ilia A. Pankin
- The Smart Materials Research Institute, Southern Federal University, 344090 Rostov-on-Don, Russia; (I.A.P.); (P.V.M.); (A.V.S.)
| | - Darya V. Khodakova
- National Medical Research Centre for Oncology of the Ministry of Health of Russia, 344037 Rostov-on-Don, Russia; (D.V.K.); (A.S.G.); (A.Y.M.); (O.I.K.)
| | - Pavel V. Medvedev
- The Smart Materials Research Institute, Southern Federal University, 344090 Rostov-on-Don, Russia; (I.A.P.); (P.V.M.); (A.V.S.)
| | - Anna S. Goncharova
- National Medical Research Centre for Oncology of the Ministry of Health of Russia, 344037 Rostov-on-Don, Russia; (D.V.K.); (A.S.G.); (A.Y.M.); (O.I.K.)
| | - Aleksey Yu. Maksimov
- National Medical Research Centre for Oncology of the Ministry of Health of Russia, 344037 Rostov-on-Don, Russia; (D.V.K.); (A.S.G.); (A.Y.M.); (O.I.K.)
| | - Oleg I. Kit
- National Medical Research Centre for Oncology of the Ministry of Health of Russia, 344037 Rostov-on-Don, Russia; (D.V.K.); (A.S.G.); (A.Y.M.); (O.I.K.)
| | - Alexander V. Soldatov
- The Smart Materials Research Institute, Southern Federal University, 344090 Rostov-on-Don, Russia; (I.A.P.); (P.V.M.); (A.V.S.)
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Slouf M, Skoupy R, Pavlova E, Krzyzanek V. High Resolution Powder Electron Diffraction in Scanning Electron Microscopy. MATERIALS 2021; 14:ma14247550. [PMID: 34947146 PMCID: PMC8708290 DOI: 10.3390/ma14247550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/03/2021] [Accepted: 12/07/2021] [Indexed: 11/16/2022]
Abstract
A modern scanning electron microscope equipped with a pixelated detector of transmitted electrons can record a four-dimensional (4D) dataset containing a two-dimensional (2D) array of 2D nanobeam electron diffraction patterns; this is known as a four-dimensional scanning transmission electron microscopy (4D-STEM). In this work, we introduce a new version of our method called 4D-STEM/PNBD (powder nanobeam diffraction), which yields high-resolution powder diffractograms, whose quality is fully comparable to standard TEM/SAED (selected-area electron diffraction) patterns. Our method converts a complex 4D-STEM dataset measured on a nanocrystalline material to a single 2D powder electron diffractogram, which is easy to process with standard software. The original version of 4D-STEM/PNBD method, which suffered from low resolution, was improved in three important areas: (i) an optimized data collection protocol enables the experimental determination of the point spread function (PSF) of the primary electron beam, (ii) an improved data processing combines an entropy-based filtering of the whole dataset with a PSF-deconvolution of the individual 2D diffractograms and (iii) completely re-written software automates all calculations and requires just a minimal user input. The new method was applied to Au, TbF3 and TiO2 nanocrystals and the resolution of the 4D-STEM/PNBD diffractograms was even slightly better than that of TEM/SAED.
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Affiliation(s)
- Miroslav Slouf
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovsky Sq. 2, 16206 Prague, Czech Republic;
- Correspondence: (M.S.); (V.K.)
| | - Radim Skoupy
- Institute of Scientific Instruments of the Czech Academy of Sciences, Kralovopolska 147, 61264 Brno, Czech Republic;
| | - Ewa Pavlova
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovsky Sq. 2, 16206 Prague, Czech Republic;
| | - Vladislav Krzyzanek
- Institute of Scientific Instruments of the Czech Academy of Sciences, Kralovopolska 147, 61264 Brno, Czech Republic;
- Correspondence: (M.S.); (V.K.)
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Oleksa V, Macková H, Engstová H, Patsula V, Shapoval O, Velychkivska N, Ježek P, Horák D. Poly(N,N-dimethylacrylamide)-coated upconverting NaYF 4:Yb,Er@NaYF 4:Nd core-shell nanoparticles for fluorescent labeling of carcinoma cells. Sci Rep 2021; 11:21373. [PMID: 34725396 PMCID: PMC8560758 DOI: 10.1038/s41598-021-00845-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 10/19/2021] [Indexed: 01/24/2023] Open
Abstract
Upconverting luminescent lanthanide-doped nanoparticles (UCNP) belong to promising new materials that absorb infrared light able to penetrate in the deep tissue level, while emitting photons in the visible or ultraviolet region, which makes them favorable for bioimaging and cell labeling. Here, we have prepared upconverting NaYF4:Yb,Er@NaYF4:Nd core-shell nanoparticles, which were coated with copolymers of N,N-dimethylacrylamide (DMA) and 2-(acryloylamino)-2-methylpropane-1-sulfonic acid (AMPS) or tert-butyl [2-(acryloylamino)ethyl]carbamate (AEC-Boc) with negative or positive charges, respectively. The copolymers were synthesized by a reversible addition-fragmentation chain transfer (RAFT) polymerization, reaching Mn ~ 11 kDa and containing ~ 5 mol% of reactive groups. All copolymers contained bisphosphonate end-groups to be firmly anchored on the surface of NaYF4:Yb,Er@NaYF4:Nd core-shell nanoparticles. To compare properties of polymer coatings, poly(ethylene glycol)-coated and neat UCNP were used as a control. UCNP with various charges were then studied as labels of carcinoma cells, including human hepatocellular carcinoma HepG2, human cervical cancer HeLa, and rat insulinoma INS-1E cells. All the particles proved to be biocompatible (nontoxic); depending on their ξ-potential, the ability to penetrate the cells differed. This ability together with the upconversion luminescence are basic prerequisites for application of particles in photodynamic therapy (PDT) of various tumors, where emission of nanoparticles in visible light range at ~ 650 nm excites photosensitizer.
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Affiliation(s)
- Viktoriia Oleksa
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06, Prague 6, Czech Republic
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 40, Prague 2, Czech Republic
| | - Hana Macková
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06, Prague 6, Czech Republic
| | - Hana Engstová
- Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Vitalii Patsula
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06, Prague 6, Czech Republic
| | - Oleksandr Shapoval
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06, Prague 6, Czech Republic
| | - Nadiia Velychkivska
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06, Prague 6, Czech Republic
| | - Petr Ježek
- Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Daniel Horák
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06, Prague 6, Czech Republic.
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Slouf M, Skoupy R, Pavlova E, Krzyzanek V. Powder Nano-Beam Diffraction in Scanning Electron Microscope: Fast and Simple Method for Analysis of Nanoparticle Crystal Structure. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:962. [PMID: 33918700 PMCID: PMC8070269 DOI: 10.3390/nano11040962] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 03/31/2021] [Accepted: 04/06/2021] [Indexed: 02/05/2023]
Abstract
We introduce a novel scanning electron microscopy (SEM) method which yields powder electron diffraction patterns. The only requirement is that the SEM microscope must be equipped with a pixelated detector of transmitted electrons. The pixelated detectors for SEM have been commercialized recently. They can be used routinely to collect a high number of electron diffraction patterns from individual nanocrystals and/or locations (this is called four-dimensional scanning transmission electron microscopy (4D-STEM), as we obtain two-dimensional (2D) information for each pixel of the 2D scanning array). Nevertheless, the individual 4D-STEM diffractograms are difficult to analyze due to the random orientation of nanocrystalline material. In our method, all individual diffractograms (showing randomly oriented diffraction spots from a few nanocrystals) are combined into one composite diffraction pattern (showing diffraction rings typical of polycrystalline/powder materials). The final powder diffraction pattern can be analyzed by means of standard programs for TEM/SAED (Selected-Area Electron Diffraction). We called our new method 4D-STEM/PNBD (Powder NanoBeam Diffraction) and applied it to three different systems: Au nano-islands (well diffracting nanocrystals with size ~20 nm), small TbF3 nanocrystals (size < 5 nm), and large NaYF4 nanocrystals (size > 100 nm). In all three cases, the STEM/PNBD results were comparable to those obtained from TEM/SAED. Therefore, the 4D-STEM/PNBD method enables fast and simple analysis of nanocrystalline materials, which opens quite new possibilities in the field of SEM.
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Affiliation(s)
- Miroslav Slouf
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic;
| | - Radim Skoupy
- Institute of Scientific Instruments of the Czech Academy of Sciences, Kralovopolska 147, 612 64 Brno, Czech Republic;
| | - Ewa Pavlova
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic;
| | - Vladislav Krzyzanek
- Institute of Scientific Instruments of the Czech Academy of Sciences, Kralovopolska 147, 612 64 Brno, Czech Republic;
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