Optical projection tomography as a tool for 3D imaging of hydrogels

Figueiras, Edite; Soto, Ana M.; Jesus, Danilo Andrade De; Lehti, M.; Koivisto, Janne T.; Párraga, Jenny E.; Silva‐Correia, Joana; Oliveira, Joaquím M.; Reis, Rui L.; Kellomäki, Minna; Hyttinen, Jari

doi:10.1364/boe.5.003443

Cited by 26 publications

(40 citation statements)

References 10 publications

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“…From day 1 to day 7, hydrogels presented a homogeneous intensities distribution characteristic of transparent hydrogels (random coil main conformation). From day 10 until day 14, an increase in entropy was observed, which is related with a random intensity distribution in high density hydrogels (β-sheet main conformation) [ 40 , 41 ].…”

Section: Resultsmentioning

confidence: 99%

Rapidly responsive silk fibroin hydrogels as an artificial matrix for the programmed tumor cells death

et al. 2018

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Timely and spatially-regulated injectable hydrogels, able to suppress growing tumors in response to conformational transitions of proteins, are of great interest in cancer research and treatment. Herein, we report rapidly responsive silk fibroin (SF) hydrogels formed by a horseradish peroxidase (HRP) crosslinking reaction at physiological conditions, and demonstrate their use as an artificial biomimetic three-dimensional (3D) matrix. The proposed SF hydrogels presented a viscoelastic nature of injectable hydrogels and spontaneous conformational changes from random coil to β-sheet conformation under physiological conditions. A human neuronal glioblastoma (U251) cell line was used for screening cell encapsulation and in vitro evaluation within the SF hydrogels. The transparent random coil SF hydrogels promoted cell viability and proliferation up to 10 days of culturing, while the crystalline SF hydrogels converted into β-sheet structure induced the formation of TUNEL-positive apoptotic cells. Therefore, this work provides a powerful tool for the investigation of the microenvironment on the programed tumor cells death, by using rapidly responsive SF hydrogels as 3D in vitro tumor models.

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Section: Resultsmentioning

confidence: 99%

Rapidly responsive silk fibroin hydrogels as an artificial matrix for the programmed tumor cells death

et al. 2018

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“…Filtered back projection (FBP) algorithms are the most commonly used algorithm for OPT reconstruction . However, FBP algorithm cannot be fully applied to OPT reconstructions .…”

Section: Introductionmentioning

confidence: 99%

Dual‐modality optical projection tomography reconstruction method from fewer views

Dou

Liu

Yang

2018

Journal of Biophotonics

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In optical projection tomography (OPT), for longitudinal living model studies, multiple measurements of the same sample are required at different time points. It is important to decrease both the total acquisition time and the light dose to the sample. We improved the ordered subsets expectation maximization reconstruction algorithm for OPT, which reduces the acquisition time and number of projections greatly compared with filtered back projection (FBP), and obtained satisfactory reconstructed images. Using zebrafish, in transmission and fluorescence mode, we demonstrate the capability of the method to reconstruct image from downsampled projection subsets. The result shows that the reconstruction image quality of the proposed method using 30 projections is comparable to that of FBP using 720 projections. The total acquisition procedure can be finished in a few seconds. The method also provides OPT with the remarkable capability to resist noises and artifacts. Projection image and fused image of zebrafish.

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“…On the other hand, due to the transparency of most hydrogels, clearing protocols are not required for OPT imaging. 26 In the present work, we aim to show for the first time how OPT can offer methods to characterize hydrogel structure and its properties, expanding the preliminary results by Figueiras et al 27 and Soto and co-workers. 26,28 Here we demonstrate the characterization of gellan-gum-based hydrogels by analyzing image microtextures and mass transport properties.…”

Section: Introductionmentioning

confidence: 84%

Optical Projection Tomography Technique for Image Texture and Mass Transport Studies in Hydrogels Based on Gellan Gum

et al. 2016

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The microstructure and permeability are crucial factors for the development of hydrogels for tissue engineering, since they influence cell nutrition, penetration, and proliferation. The currently available imaging methods able to characterize hydrogels have many limitations. They often require sample drying and other destructive processing, which can change hydrogel structure, or they have limited imaging penetration depth. In this work, we show for the first time an alternative nondestructive method, based on optical projection tomography (OPT) imaging, to characterize hydrated hydrogels without the need of sample processing. As proof of concept, we used gellan gum (GG) hydrogels obtained by several cross-linking methods. Transmission mode OPT was used to analyze image microtextures, and emission mode OPT to study mass transport. Differences in hydrogel structure related to different types of cross-linking and between modified and native GG were found through the acquired Haralick's image texture features followed by multiple discriminant analysis (MDA). In mass transport studies, the mobility of FITC-dextran (MW 20, 150, 2000 kDa) was analyzed through the macroscopic hydrogel. The FITC-dextran velocities were found to be inversely proportional to the size of the dextran as expected. Furthermore, the threshold size in which the transport is affected by the hydrogel mesh was found to be 150 kDa (Stokes' radii between 69 and 95 Å). On the other hand, the mass transport study allowed us to define an index of homogeneity to assess the cross-linking distribution, structure inside the hydrogel, and repeatability of hydrogel production. As a conclusion, we showed that the set of OPT imaging based material characterization methods presented here are useful for screening many characteristics of hydrogel compositions in relatively short time in an inexpensive manner, providing tools for improving the process of designing hydrogels for tissue engineering and drugs/cells delivery applications.

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Optical projection tomography as a tool for 3D imaging of hydrogels

Cited by 26 publications

References 10 publications

Rapidly responsive silk fibroin hydrogels as an artificial matrix for the programmed tumor cells death

Rapidly responsive silk fibroin hydrogels as an artificial matrix for the programmed tumor cells death

Dual‐modality optical projection tomography reconstruction method from fewer views

Optical Projection Tomography Technique for Image Texture and Mass Transport Studies in Hydrogels Based on Gellan Gum

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