Reproducibility of ZrO2-based freeze casting for biomaterials

Abstract

The processing technique of freeze casting has been intensely researched for its potential to create porous scaffold and infiltrated composite materials for biomedical implants and structural materials. However, in order for this technique to be employed medically or commercially, it must be able to reliably produce materials in great quantities with similar microstructures and properties. Here we investigate the reproducibility of the freeze casting process by independently fabricating three sets of eight ZrO 2 -epoxy composite scaffolds with the same processing conditions but varying solid loading (10, 15 and 20 vol.%). Statistical analyses (One-way ANOVA and Tukey's HSD tests) run upon measurements of the microstructural dimensions of these composite scaffold sets show that, while the majority of microstructures are similar, in all cases the composite scaffolds display statistically significant variability. In addition, composite scaffolds where mechanically compressed and statistically analyzed. Similar to the microstructures, almost all of their resultant properties displayed significant variability though most composite scaffolds were similar. These results suggest that additional research to improve control of the freeze casting technique is required before scaffolds and composite scaffolds can reliably be reproduced for commercial or medical applications.

Bioinspired intrinsic control of freeze cast composites: Harnessing hydrophobic hydration and clathrate hydrates

“…It was recently reported that statistically significant variability was found within samples freeze cast with the exact same processing conditions and constituents [26] (as is the case in the 0 vol.% samples here). This was proposed to be resulting from the inherent variability in the growth of ice, the fundamental templating force within the freeze casting process, which only provides control of the final porosity in one dimension [26]. In addition, at 15 vol.% each additive displays a collapsed microstructure with pore measurements similar to those at 0 vol.% (Tables 1-3).…”

“…EtOH vs. n-PrOH scaffold sets), which has recently been shown to be common amongst the microstructure and mechanics of freeze cast scaffolds [26], all mechanical data was normalized:…”

Osteogenesis ability of CAD/CAM porous zirconia scaffolds enriched with nano-hydroxyapatite particles

“…These studies either focused on optimizing the surface structure of zirconia scaffolds controlling its porosity, geometric structure, and micro-roughness, or by coating the surface with a bioactive layer to enhance the process of osteogenesis ability [10–13]. Porous zirconia scaffolds could also be used as a drug delivery vehicle to enhance bone response as well [14]. A recent study attributed enhanced cell viability to the internal structure of the scaffold rather than to the type of coating material used [15].…”

Pore structures and mechanical properties of porous titanium scaffolds by bidirectional freeze casting

“…The mechanical properties of the materials can be controlled by the porosity, pore size and pore morphology through a variety of manufacturing methods [6]. So far, many manufacturing techniques have been reported to produce porous titanium such as bubble generation [7,8], replication of polymeric sponge [9,10], rapid prototyping method [11,12], space holder method [13,14] and freeze casting [15,16].Freeze casting is a promising method to prepare porous materials with unique aligned and elongated pore structure by driving particles of the slurry to self-assemble along the ice growth direction [6,17]. The pore morphologies are mainly determined by matrix powder kinds, solvent types and frozen temperature gradient [18].…”

“…Freeze casting is a promising method to prepare porous materials with unique aligned and elongated pore structure by driving particles of the slurry to self-assemble along the ice growth direction [6,17]. The pore morphologies are mainly determined by matrix powder kinds, solvent types and frozen temperature gradient [18].…”