3D Printed Hierarchical Porous Poly(ε-caprolactone) Scaffolds from Pickering High Internal Phase Emulsion Templating

Abstract

In the realm of biomaterials, particularly bone tissue engineering, there has been a great increase in interest in scaffolds with hierarchical porosity and customizable multifunctionality. Recently, the three-dimensional (3D) printing of biopolymer-based inks (solutions or emulsions) has gained high popularity for fabricating tissue engineering scaffolds, which optimally satisfies the desired properties and performances. Herein, therefore, we explore the fabrication of 3D printed hierarchical porous scaffolds of poly(ε-caprolactone) (PCL) using the water-in-oil (w/o) Pickering PCL high internal phase emulsions (HIPEs) as the ink in 3D printer. The Pickering PCL HIPEs stabilized using hydrophobically modified nanoclay comprised of aqueous poly(vinyl alcohol) (PVA) as the dispersed phase. Rheological measurements suggested the shear thinning behavior of Pickering HIPEs having a dispersed droplet diameter of 3–25 μm. The pore morphology resembling the natural extracellular matrix and the mechanical properties of scaffolds were customized by tuning the emulsion composition and 3D printing parameters. In vitro biomineralization and drug release studies proved the scaffolds’ potential in developing the apatite-rich bioactive interphase and controlled drug delivery, respectively. During in vitro osteoblast (MG63) growth experiments for up to 7 days, good adhesion and proliferation on PCL scaffolds confirmed their cytocompatibility, assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) analysis. This study suggests that the assembly of HIPE templates and 3D printing is a promising approach to creating hierarchical porous scaffolds potentially suitable for bone tissue engineering and can be stretched to other biopolymers as well.

Improving physio-mechanical and biological properties of 3D-printed PLA scaffolds via in-situ argon cold plasma treatment

“…Conventional techniques, however, present some limitations, such as the high cytotoxicity of organic solvents as well as the difficulty in controlling scaffold microstructure and accuracy 10 – 12 . On the other hand, additive manufacturing techniques do not require cytotoxic organic solvents and are capable of precisely controlling pore size and neat geometry 13 , 14 . Among different AM methods, stereolithography (SLA), fused deposition molding (FDM) or extrusion based printing processes, selective laser sintering (SLS), and 3D bioprinting have been successfully used to make 3D scaffolds.…”

Synthesis and Applications of Elastomeric Polymerized High Internal Phase Emulsions (PolyHIPEs)

“…Alternatively, an extrusion-based 3D-printing method of water-in-oil emulsions was recently used to prepare micro- and macroporous PCL tissue scaffolds using a solvent casting approach. Srivastava and co-workers 103 prepared water-in-oil Pickering emulsions using hydrophobically modified nanoclay (Cloisite 30B) as the emulsifier and PCL ( M n = 43000 g/mol) in the continues phase, and the emulsions could be extruded and then dried, without the loss of the desired pore structure due to the highly stable nature of the emulsion. The 3D-printed PCL-polyHIPEs were elastic and could be compressed to 60% without fracture, and the polyHIPEs with the highest loading content of Cloisite 30B obtained the highest Young’s modulus of ∼1.1 MPa at 2 wt % compared to ∼0.2 MPa at 1 wt %.…”

Unique Crystallization Characteristics of Pickering High Internal Phase Emulsion Templated Porous Constructs

“…The introduction of oil-in-oil nonaqueous HIPEs overcame these major restrains of conventional systems. − Over the years, polyHIPEs have been fabricated using a wide range of polymers and various polymerization techniques including free radical polymerization, atom transfer radical polymerization, reversible addition–fragmentation chain transfer, and ring-opening polymerization (ROP), etc . Further, various studies indicating the influence of polyHIPE composition on material properties like mechanical strength, liquid uptake capacity, thermal behavior, biodegradation, etc., have been reported. However, despite the crucial role of crystallization kinetics in regulating these diverse structural properties, − the crystallization behavior of the polyHIPE structures has scantly been explored.…”