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Wortmann M, Westphal M, Kaltschmidt B, Klöcker M, Layland AS, Brockhagen B, Hütten A, Frese N, Ehrmann A. Nanofibers are a matter of perspective: effects of methodology and subjectivity on diameter measurements. NANOSCALE ADVANCES 2023; 5:5900-5906. [PMID: 37881710 PMCID: PMC10597546 DOI: 10.1039/d3na00528c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 10/03/2023] [Indexed: 10/27/2023]
Abstract
Nanofibers are currently among the most researched nanomaterials in materials science. Various high-resolution microscopy techniques are used for morphological investigations, with the diameter as primary characteristic. Since methodological factors influencing the diameter distribution are usually ignored, numerical values can hardly be compared across different or even within single studies. Here, we investigate influencing factors such as microscopy technique, degree of magnification, eventual coatings, and the analysts' bias in the image selection and evaluation. We imaged a single nanofiber sample using scanning electron microscopy (SEM), helium ion microscopy (HIM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). These techniques yield significant methodological variations between the diameter distributions. We further observed a strong influence of analysts' subjectivity, with a consistent average deviation between 4 different analysts of up to 31%. The average deviation between micrographs within each category was 14%, revealing a considerable influence of micrograph selection and strong potential for cherry picking. The mean values were mostly comparable with the results using automated image analysis software, which was more reproducible, much faster, and more accurate for images with lower magnification. The results demonstrate that one of the most frequently measured characteristics of nanofibers is subject to strong systematic fluctuations that are rarely if ever addressed.
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Affiliation(s)
- Martin Wortmann
- Bielefeld University, Faculty of Physics, Universitätsstraße 25 33615 Bielefeld Germany
| | - Michael Westphal
- Bielefeld University, Faculty of Physics, Universitätsstraße 25 33615 Bielefeld Germany
| | - Bernhard Kaltschmidt
- Bielefeld University, Faculty of Physics, Universitätsstraße 25 33615 Bielefeld Germany
| | - Michaela Klöcker
- Bielefeld University of Applied Sciences and Arts, Faculty of Engineering and Mathematics Interaktion 1 33619 Bielefeld Germany
| | - Ashley S Layland
- neotem Bioanalytics, Universitätsstraße 25 33615 Bielefeld Germany
| | - Bennet Brockhagen
- Bielefeld University of Applied Sciences and Arts, Faculty of Engineering and Mathematics Interaktion 1 33619 Bielefeld Germany
| | - Andreas Hütten
- Bielefeld University, Faculty of Physics, Universitätsstraße 25 33615 Bielefeld Germany
| | - Natalie Frese
- University of Hawaii, Department of Physics and Astronomy Watanabe Hall, 2505 Correa Road Honolulu HI 96822 USA
| | - Andrea Ehrmann
- Bielefeld University of Applied Sciences and Arts, Faculty of Engineering and Mathematics Interaktion 1 33619 Bielefeld Germany
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Arrigo A, Aragona E, Battaglia Parodi M, Bandello F. Quantitative approaches in multimodal fundus imaging: State of the art and future perspectives. Prog Retin Eye Res 2023; 92:101111. [PMID: 35933313 DOI: 10.1016/j.preteyeres.2022.101111] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/16/2022] [Accepted: 07/19/2022] [Indexed: 02/01/2023]
Abstract
When it first appeared, multimodal fundus imaging revolutionized the diagnostic workup and provided extremely useful new insights into the pathogenesis of fundus diseases. The recent addition of quantitative approaches has further expanded the amount of information that can be obtained. In spite of the growing interest in advanced quantitative metrics, the scientific community has not reached a stable consensus on repeatable, standardized quantitative techniques to process and analyze the images. Furthermore, imaging artifacts may considerably affect the processing and interpretation of quantitative data, potentially affecting their reliability. The aim of this survey is to provide a comprehensive summary of the main multimodal imaging techniques, covering their limitations as well as their strengths. We also offer a thorough analysis of current quantitative imaging metrics, looking into their technical features, limitations, and interpretation. In addition, we describe the main imaging artifacts and their potential impact on imaging quality and reliability. The prospect of increasing reliance on artificial intelligence-based analyses suggests there is a need to develop more sophisticated quantitative metrics and to improve imaging technologies, incorporating clear, standardized, post-processing procedures. These measures are becoming urgent if these analyses are to cross the threshold from a research context to real-life clinical practice.
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Affiliation(s)
- Alessandro Arrigo
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy.
| | - Emanuela Aragona
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy
| | - Maurizio Battaglia Parodi
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy
| | - Francesco Bandello
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy
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Murphy R, Turcott A, Banuelos L, Dowey E, Goodwin B, Cardinal KO. SIMPoly: A Matlab-Based Image Analysis Tool to Measure Electrospun Polymer Scaffold Fiber Diameter. Tissue Eng Part C Methods 2020; 26:628-636. [PMID: 33256558 PMCID: PMC7768983 DOI: 10.1089/ten.tec.2020.0304] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Quantifying fiber diameter is important for characterizing electrospun polymer scaffolds. Many researchers use manual measurement methods, which can be time-consuming and variable. Semi-automated tools exist, but there is room for improvement. The current work used Matlab to develop an image analysis program to quickly and consistently measure fiber diameter in scanning electron micrographs. The new Matlab method, termed “SIMPoly” (Semiautomated Image Measurements of Polymers) was validated by using synthetic images with known fiber size and was found to be accurate. The Matlab method was also applied by three different researchers to scanning electron microscopy (SEM) images of electrospun poly(lactic-co-glycolic acid) (PLGA). Results were compared with the semi-automated DiameterJ method and a manual ImageJ measurement approach, and it was found that the Matlab-based SIMPoly method provided measurements in the expected range and with the least variability between researchers. In conclusion, this work provides and describes SIMPoly, a Matlab-based image analysis method that can simply and accurately measure polymer fiber diameters in SEM images with minimal variation between users.
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Affiliation(s)
- Ryan Murphy
- Biomedical Engineering Department, Cal Poly, San Luis Obispo, California, USA
| | - Ashley Turcott
- Biomedical Engineering Department, Cal Poly, San Luis Obispo, California, USA
| | - Leo Banuelos
- Biomedical Engineering Department, Cal Poly, San Luis Obispo, California, USA
| | - Evan Dowey
- Biomedical Engineering Department, Cal Poly, San Luis Obispo, California, USA
| | - Benjamin Goodwin
- Biomedical Engineering Department, Cal Poly, San Luis Obispo, California, USA
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Ramos C, Lanno GM, Laidmäe I, Meos A, Härmas R, Kogermann K. High humidity electrospinning of porous fibers for tuning the release of drug delivery systems. INT J POLYM MATER PO 2020. [DOI: 10.1080/00914037.2020.1765361] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Celia Ramos
- Institute of Pharmacy, University of Tartu, Tartu, Estonia
| | | | - Ivo Laidmäe
- Institute of Pharmacy, University of Tartu, Tartu, Estonia
- Department of Immunology, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu, Estonia
| | - Andres Meos
- Institute of Pharmacy, University of Tartu, Tartu, Estonia
| | - Riinu Härmas
- Institute of Chemistry, University of Tartu, Tartu, Estonia
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Arrigo A, Romano F, Albertini G, Aragona E, Bandello F, Battaglia Parodi M. Vascular Patterns in Retinitis Pigmentosa on Swept-Source Optical Coherence Tomography Angiography. J Clin Med 2019; 8:jcm8091425. [PMID: 31510025 PMCID: PMC6780333 DOI: 10.3390/jcm8091425] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 08/27/2019] [Accepted: 09/04/2019] [Indexed: 12/11/2022] Open
Abstract
Background: Retinitis Pigmentosa (RP) represents a retinal dystrophy with an extremely complex pathogenesis further worsened by the impairment of the retinal vascular supply. The main goal of this study was to identify different vascular patterns in RP, by means of optical coherence tomography angiography (OCTA). Methods: A total of 32 RP patients (16 males, 50%; mean age 45.93 ± 11.4) and 32 healthy age-matched controls (16 males, 50%; age 42.8 ± 11.2). High resolution OCT and OCTA images were obtained from all participants. Several quantitative parameters were extracted both from structural OCT and OCTA images. A post-hoc analysis assessed the relationship between the quantitative OCTA parameters adopted and the following measures: best corrected visual acuity (BCVA), central macular thickness (CMT) and retinal nerve fiber layer (RNFL). Results: Mean LogMAR BCVA was 0.24 ± 0.32 for RP patients and 0.0 ± 0.0 for controls (p < 0.01). CMT, choroidal thickness and RNFL were statistically different between RP and controls (p < 0.01). OCTA parameters showed strong alterations of the retinal vascular network in RP (all p < 0.01). Several statistically significant correlations were also found. Furthermore, a vessel tortuosity cut-off of 4.80 and a vessel rarefaction cut-off of 0.62 enabled the RP cohort to be divided into two significantly different sub-groups in terms of BCVA, RNFL and CMT. Conclusions: Quantitative OCTA parameters help identify vascular abnormalities in RP, separating two different vascular patterns.
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Affiliation(s)
- Alessandro Arrigo
- Department of Ophthalmology, IRCCS Ospedale San Raffaele, University Vita-Salute, via Olgettina 60, 20132 Milan, Italy.
| | - Francesco Romano
- Eye Clinic, Department of Biomedical and Clinical Science, Luigi Sacco University Hospital, 20157 Milan, Italy.
| | - Giorgia Albertini
- Department of Ophthalmology, IRCCS Ospedale San Raffaele, University Vita-Salute, via Olgettina 60, 20132 Milan, Italy.
| | - Emanuela Aragona
- Department of Ophthalmology, IRCCS Ospedale San Raffaele, University Vita-Salute, via Olgettina 60, 20132 Milan, Italy.
| | - Francesco Bandello
- Department of Ophthalmology, IRCCS Ospedale San Raffaele, University Vita-Salute, via Olgettina 60, 20132 Milan, Italy.
| | - Maurizio Battaglia Parodi
- Department of Ophthalmology, IRCCS Ospedale San Raffaele, University Vita-Salute, via Olgettina 60, 20132 Milan, Italy.
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Arrigo A, Aragona E, Capone L, Pierro L, Romano F, Bandello F, Parodi MB. Advanced Optical Coherence Tomography Angiography Analysis of Age-related Macular Degeneration Complicated by Onset of Unilateral Choroidal Neovascularization. Am J Ophthalmol 2018; 195:233-242. [PMID: 30098346 DOI: 10.1016/j.ajo.2018.08.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 07/08/2018] [Accepted: 08/01/2018] [Indexed: 11/26/2022]
Abstract
PURPOSE To analyze optical coherence tomography angiography (OCTA) quantitative features in patients affected by new-onset choroidal neovascularization (CNV) in 1 eye and early/intermediate age-related macular degeneration (AMD) in the fellow eye. DESIGN Case-control study. METHODS Setting: Clinical practice. STUDY POPULATION Thirty patients and 30 age-matched controls. OBSERVATION PROCEDURES Both cohorts underwent complete ophthalmologic examination, including best-corrected visual acuity (BCVA) measurement, biomicroscopy, fluorescein angiography (FA) and indocyanine green angiography (ICGA) examination, optical coherence tomography, and OCTA scans. The 1-way a test with Bonferroni correction was used to assess statistical significance and Tau Kendall's correlation analysis was performed. MAIN OUTCOME MEASURES BCVA, choroidal thickness, vessel density, vessel tortuosity, vessel dispersion. and vessel rarefaction. RESULTS Mean BCVA was 20/32 for CNV eyes and 20/20 for both fellow and control eyes. Choroidal thickness was 190.33 ± 63.98 μm for CNV eyes, 216.83 ± 50.31 μm for fellow eyes, and 310.52 ± 27.13 μm for controls. The quantitative analysis of retinal vessels revealed significant alterations, especially in the deep capillary plexus and radial peripapillary capillaries, both in CNV and in fellow eyes, compared with controls. In particular, decreased vessel density and tortuosity and increased dispersion and rarefaction were found. Several significant correlations were also found among the quantitative parameters adopted. CONCLUSIONS New postprocessing OCTA parameters are able to detect deep retinal vascular alterations quantitatively, in both CNV-affected and fellow eyes of patients with new-onset CNV. Further investigations are warranted in order to explore the validity of these new approaches on follow-up.
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Hotaling NA, Khristov V, Wan Q, Sharma R, Jha BS, Lotfi M, Maminishkis A, Simon CG, Bharti K. Nanofiber Scaffold-Based Tissue-Engineered Retinal Pigment Epithelium to Treat Degenerative Eye Diseases. J Ocul Pharmacol Ther 2016; 32:272-85. [PMID: 27110730 PMCID: PMC4904235 DOI: 10.1089/jop.2015.0157] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 03/24/2016] [Indexed: 12/16/2022] Open
Abstract
Clinical-grade manufacturing of a functional retinal pigment epithelium (RPE) monolayer requires reproducing, as closely as possible, the natural environment in which RPE grows. In vitro, this can be achieved by a tissue engineering approach, in which the RPE is grown on a nanofibrous biological or synthetic scaffold. Recent research has shown that nanofiber scaffolds perform better for cell growth and transplantability compared with their membrane counterparts and that the success of the scaffold in promoting cell growth/function is not heavily material dependent. With these strides, the field has advanced enough to begin to consider implementation of one, or a combination, of the tissue engineering strategies discussed herein. In this study, we review the current state of tissue engineering research for in vitro culture of RPE/scaffolds and the parameters for optimal scaffold design that have been uncovered during this research. Next, we discuss production methods and manufacturers that are capable of producing the nanofiber scaffolds in such a way that would be biologically, regulatory, clinically, and commercially viable. Then, a discussion of how the scaffolds could be characterized, both morphologically and mechanically, to develop a testing process that is viable for regulatory screening is performed. Finally, an example of a tissue-engineered RPE/scaffold construct is given to provide the reader a framework for understanding how these pieces could fit together to develop a tissue-engineered RPE/scaffold construct that could pass regulatory scrutiny and can be commercially successful.
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Affiliation(s)
- Nathan A. Hotaling
- Biosystems and Biomaterials Division, National Institute of Standards and Technology, Gaithersburg, Maryland
- Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Vladimir Khristov
- Section of Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Qin Wan
- Section of Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Ruchi Sharma
- Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Balendu Shekhar Jha
- Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Mostafa Lotfi
- Section of Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Arvydas Maminishkis
- Section of Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Carl G. Simon
- Biosystems and Biomaterials Division, National Institute of Standards and Technology, Gaithersburg, Maryland
| | - Kapil Bharti
- Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland
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DiameterJ: A validated open source nanofiber diameter measurement tool. Biomaterials 2015; 61:327-38. [PMID: 26043061 DOI: 10.1016/j.biomaterials.2015.05.015] [Citation(s) in RCA: 292] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 05/04/2015] [Accepted: 05/14/2015] [Indexed: 01/10/2023]
Abstract
Despite the growing use of nanofiber scaffolds for tissue engineering applications, there is not a validated, readily available, free solution for rapid, automated analysis of nanofiber diameter from scanning electron microscope (SEM) micrographs. Thus, the goal of this study was to create a user friendly ImageJ/FIJI plugin that would analyze SEM micrographs of nanofibers to determine nanofiber diameter on a desktop computer within 60 s. Additional design goals included 1) compatibility with a variety of existing segmentation algorithms, and 2) an open source code to enable further improvement of the plugin. Using existing algorithms for centerline determination, Euclidean distance transforms and a novel pixel transformation technique, a plugin called "DiameterJ" was created for ImageJ/FIJI. The plugin was validated using 1) digital synthetic images of white lines on a black background and 2) SEM images of nominally monodispersed steel wires of known diameters. DiameterJ analyzed SEM micrographs in 20 s, produced diameters not statistically different from known values, was over 10-times closer to known diameter values than other open source software, provided hundreds of times the sampling of manual measurement, and was hundreds of times faster than manual assessment of nanofiber diameter. DiameterJ enables users to rapidly and thoroughly determine the structural features of nanofiber scaffolds and could potentially allow new insights to be formed into fiber diameter distribution and cell response.
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Ottavian M, Barolo M, García-Muñoz S. Maintenance of Machine Vision Systems for Product Quality Assessment. Part I. Addressing Changes in Lighting Conditions. Ind Eng Chem Res 2013. [DOI: 10.1021/ie303295t] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matteo Ottavian
- CAPE-Lab − Computer-Aided
Process Engineering Laboratory, Department of Industrial Engineering, University of Padova, via Marzolo, 9 −
35131 Padova PD, Italy
| | - Massimiliano Barolo
- CAPE-Lab − Computer-Aided
Process Engineering Laboratory, Department of Industrial Engineering, University of Padova, via Marzolo, 9 −
35131 Padova PD, Italy
| | - Salvador García-Muñoz
- Pfizer Worldwide Research & Development, 445 Eastern Point Road, Groton, Connecticut 06340, United States
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Szentivanyi A, Chakradeo T, Zernetsch H, Glasmacher B. Electrospun cellular microenvironments: Understanding controlled release and scaffold structure. Adv Drug Deliv Rev 2011; 63:209-20. [PMID: 21145932 DOI: 10.1016/j.addr.2010.12.002] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 11/12/2010] [Accepted: 12/01/2010] [Indexed: 12/11/2022]
Abstract
Electrospinning is a versatile technique in tissue engineering for the production of scaffolds. To guide tissue development, scaffolds must provide specific biochemical, structural and mechanical cues to cells and deliver them in a controlled fashion over time. Electrospun scaffold design thus includes aspects of both controlled release and structural cues. Controlled multicomponent and multiphasic drug delivery can be achieved by the careful application and combination of novel electrospinning techniques, i.e., emulsion and co-axial electrospinning. Drug distribution and polymer properties influence the resulting release kinetics. Pore size is far more relevant as a structural parameter than previously recognized. It enables cell proliferation and ingrowth, whereas fiber diameter predominantly influences cell fate. Both parameters can be exploited by combining multiple fiber types in the form of multifiber and multilayer scaffolds. Such scaffolds are required to reproduce more complex tissue structures.
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Affiliation(s)
- Andreas Szentivanyi
- Institute for Multiphase Processes, Gottfried Wilhelm Leibniz Universitaet, Callinstrasse 36, Hannover, Germany.
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Simon LL, Abbou Oucherif K, Nagy ZK, Hungerbuhler K. Bulk video imaging based multivariate image analysis, process control chart and acoustic signal assisted nucleation detection. Chem Eng Sci 2010. [DOI: 10.1016/j.ces.2010.05.045] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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