3D high spatial resolution visualisation and quantification of interconnectivity in polymer films

Fager, Cecilia; Barman, Sandra Eriksson; Röding, Magnus; Olsson, Anna; Lorén, Niklas; Corswant, Christian von; Bolin, David; Rootzén, Holger; Olsson, Eva

doi:10.1016/j.ijpharm.2020.119622

Cited by 10 publications

(8 citation statements)

References 48 publications

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“…Fig. 6a shows the zero-shear viscosity versus the ratio of HPC in the polymer blend at 6 wt% total polymer concentration in the stock solutions for the four compositions (22,30,45,60 wt% HPC). The value for the viscosity at zero-shear rate was approximated from the viscosity at the Newtonian plateau.…”

Section: Viscosity Of Ec/hpc Solutionsmentioning

confidence: 99%

“…5,8,9,[25][26][27][28][29] The 3D structure of EC/HPC films has been characterized in high resolution using focused ion beam scanning electron microscopy (FIB-SEM). [30][31][32] Porosity, pore size distribution, pore shape and connectivity have been determined from the FIB-SEM data using 3D image analysis. 32 Furthermore, confocal laser scanning microscopy (CLSM) has been used to characterize EC/ HPC film structure at the micrometer level.…”

Section: Introductionmentioning

confidence: 99%

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Structure evolution during phase separation in spin-coated ethylcellulose/hydroxypropylcellulose films

et al. 2021

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Section: Viscosity Of Ec/hpc Solutionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure evolution during phase separation in spin-coated ethylcellulose/hydroxypropylcellulose films

et al. 2021

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“…The films were denoted HPC22, HPC30 and HPC45, respectively. For a detailed description of the production process see Fager et al 22…”

Section: Data Acquisitionmentioning

confidence: 99%

“…1 shows one of the 2-D images from each stack. Again, see Fager et al 22 for a detailed description. Segmentation of the image data into solid and pore was performed in the following fashion: For each data set, manual segmentation was performed in 100 randomly selected 2-D regions of size 256 £ 256 pixels.…”

Section: Focused Ion Beam Scanning Electron Microscopy and 3-d Image Segmentationmentioning

confidence: 99%

“…Previous work detailing the 3-D microstructure of this type of EC/HPC polymers can be found in Marucci et al 16,17 and in Andersson et al, 18 where the material has been imaged using confocal microscopy and scanning electron microscopy. Transport through these coatings has been visualized using in situ environmental scanning electron microscopy in Jansson et al 19 The same type of polymer has also been characterized with respect to pore shape and branching points in H€ abel et al, 20,21 and a visualization of the interconnectivity of the three films which are used in this work can be found in Fager et al 22 In the present paper, we used our new measures, together with local porosity, pore size with respect to spheres, circles and lines, constrictivity measures, and measures based on distances through the pore structure, to extract important features of the pore geometry of 3-D images of EC/ HPC films. The images were obtained from combined focused ion beam and scanning electron microscopy (FIB-SEM) tomography of films where the aqueous soluble HPC phase had been leached, leaving the EC porous network intact.…”

Section: Introductionmentioning

confidence: 99%

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New Characterization Measures of Pore Shape and Connectivity Applied to Coatings used for Controlled Drug Release

Barman

Fager

Röding

et al. 2021

Journal of Pharmaceutical Sciences

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Pore geometry characterization-methods are important tools for understanding how pore structure influences properties such as transport through a porous material. Bottlenecks can have a large influence on transport and related properties. However, existing methods only catch certain types of bottleneck effects caused by variations in pore size. We here introduce a new measure, geodesic channel strength, which captures a different type of bottleneck effect caused by many paths coinciding in the same pore. We further develop new variants of pore size measures and propose a new way of visualizing 3-D characterization results using layered images. The new measures together with existing measures were used to characterize and visualize properties of 3-D FIB-SEM images of three leached ethyl-cellulose/hydroxypropyl-cellulose films. All films were shown to be anisotropic, and the strongest anisotropy was found in the film with lowest porosity. This film had very tortuous paths and strong geodesic channel-bottlenecks, while the paths through the other two films were relatively straight with well-connected pore networks. The geodesic channel strength was shown to give important new visual and quantitative insights about connectivity, and the new pore size measures provided useful information about anisotropies and inhomogeneities in the pore structures. The methods have been implemented in the freely available software MIST.

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Computed tomography technologies to measure key structural features of polymeric biomedical implants from bench to bedside

Pawelec,

Schoborg,

Shapiro

2024

J Biomedical Materials Res

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Implanted polymeric devices, designed to encourage tissue regeneration, require porosity. However, characterizing porosity, which affects many functional device properties, is non‐trivial. Computed tomography (CT) is a quick, versatile, and non‐destructive way to gain 3D structural information, yet various CT technologies, such as benchtop, preclinical and clinical systems, all have different capabilities. As system capabilities determine the structural information that can be obtained, seamless monitoring of key device features through all stages of clinical translation must be engineered intentionally. Therefore, in this study we tested feasibility of obtaining structural information in pre‐clinical systems and high‐resolution micro‐CT (μCT) under physiological conditions. To overcome the low CT contrast of polymers in hydrated environments, radiopaque nanoparticle contrast agent was incorporated into porous devices. The size of resolved features in porous structures is highly dependent on the resolution (voxel size) of the scan. As the voxel size of the CT scan increased (lower resolution) from 5 to 50 μm, the measured pore size was overestimated, and percentage porosity was underestimated by nearly 50%. With the homogeneous introduction of nanoparticles, changes to device structure could be quantified in the hydrated state, including at high‐resolution. Biopolymers had significant structural changes post‐hydration, including a mean increase of 130% in pore wall thickness that could potentially impact biological response. By incorporating imaging capabilities into polymeric devices, CT can be a facile way to monitor devices from initial design stages through to clinical translation.

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3D high spatial resolution visualisation and quantification of interconnectivity in polymer films

Cited by 10 publications

References 48 publications

Structure evolution during phase separation in spin-coated ethylcellulose/hydroxypropylcellulose films

Structure evolution during phase separation in spin-coated ethylcellulose/hydroxypropylcellulose films

New Characterization Measures of Pore Shape and Connectivity Applied to Coatings used for Controlled Drug Release

Computed tomography technologies to measure key structural features of polymeric biomedical implants from bench to bedside

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