Interconnectivity of Bioceramic Scaffolds with Different Porous Structures and Their Fluid Velocity Distribution Analyzed by Micro-CT Computer Modeling

doi:10.15541/jim20140204

Abstract

Abstract:

Pore interconnectivity is a key parameter for bone tissue engineering scaffolds, which controls penetration of body fluid with proteins and cells, and tissue ingrowth. The present study investigated the porous characteristics of hydroxyapatite (HA) scaffolds prepared via three processes (HA sphere packing, wax sphere-leaching and HA fiber aggregation) by micro-computed tomography (μCT) from following three procedures: (1) modeling of the porous structure by image reconstruction; (2) analysis of porosity along longitudinal direction; and (3) simulation of fluid flow across the scaffold by finite element analysis (FEA). Image analyses revealed that, the scaffolds prepared by the above two methods featured relatively regular porosity distributions, whereas that by HA fiber aggregation had an irregular distribution. Fluid velocity distribution by FEA suggested that scaffolds prepared by HA sphere packing and wax sphere leaching readily allowed penetration of fluid due to their favorable pore interconnectivity. The fluid velocity vector distribution predicted that circular flows dominated near the pore wall in the scaffold prepared by wax sphere leaching. These circular flows may impede the material exchange between cells attached to the pore wall and the body fluid, which may illustrate that the inferior in vivo osteogenic activity of scaffolds prepared by wax sphere leaching when compared with those produced by HA sphere packing.

Key words: tissue engineering scaffolds, structure image reconstruction, interconnectivity, computer modeling, fluid velocity distribution

CLC Number:

R318

LUO Pin-Feng, ZHI Wei, ZHANG Jing-Wei, SHI Feng, DUAN Ke, WANG Jian-xin, LU Xiong, WENG Jie. Interconnectivity of Bioceramic Scaffolds with Different Porous Structures and Their Fluid Velocity Distribution Analyzed by Micro-CT Computer Modeling[J]. Journal of Inorganic Materials, 2015, 30(1): 71-76.

Figures/Tables 8

Fig. 1 Illustration of edge detection and region filling in image analysis for scaffold structure reconstruction: original image by micro-CT (a), image after region filling (b)

Fig. 2 Reconstructed 3D models (left) revealing interconnected structures and surface morphologies (right) of scaffolds prepared by HA sphere packing (a, b), wax sphere leaching (c, d) and HA fiber aggregation (e, f)

Fig. 3 Illustration of grayscale reverseprocessing for recog- nition of pore space in a scaffold (a, b), and visualization of pore spaces in scaffolds prepared by HA sphere packing (c), wax sphere leaching (d) and HA fiber aggregation (e)

Table 1 The average macro-porosity of three different HA scaffolds

Scaffold	Average macro-porosity
HA sphere packing	40.17%
Wax sphere leaching	62.23%
HA fiber aggregation	30.34%

Fig. 4 Variation along with the height direction (longitudinal) of scaffolds prepared by HA sphere packing (a), wax sphere leaching (b), and HA fiber aggregation (c)

Fig. 5 Schematic showing model used in finite-element simu lation of fluid flow across scaffolds prepared by HA sphere packing (a) and wax sphere leaching (b)

Fig. 6 Velocity contours of fluid flow across scaffolds prepared by HA sphere packing (a) and wax sphere leaching (b) calculated by finite-element simulation

Fig. 7 Velocity vector graphs of fluid flow across scaffolds prepared by HA sphere packing (a) and wax sphere leaching (b) calculated by finite-element simulation; (b: notice circular flows near pore wall)

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