Lauren Shor

Precision extruding deposition and characterization of cellular poly‐ε‐caprolactone tissue scaffolds

Successes in scaffold guided tissue engineering require scaffolds to have specific macroscopic geometries and internal architectures to provide the needed biological and biophysical functions. Freeform fabrication provides an effective process tool to manufacture many advanced scaffolds with designed properties. This paper reports our recent study on using a novel precision extruding deposition (PED) process technique to directly fabricate cellular poly‐e_rm;‐caprolactone (PCL) scaffolds. Scaffolds with a controlled pore size of 250 μm and designed structural orientations were fabricated.

Precision extruding deposition (PED) fabrication of polycaprolactone (PCL) scaffolds for bone tissue engineering

Bone tissue engineering is an emerging field providing viable substitutes for bone regeneration. Recent advances have allowed scientists and engineers to develop scaffolds for guided bone growth. However, success requires scaffolds to have specific macroscopic geometries and internal architectures conducive to biological and biophysical functions. Freeform fabrication provides an effective process tool to manufacture three-dimensional porous scaffolds with complex shapes and designed properties. A novel precision extruding deposition (PED) technique was developed to fabricate polycaprolactone (PCL) scaffolds. It was possible to manufacture scaffolds with a controlled pore size of 350 microm with designed structural orientations using this method. The scaffold morphology, internal micro-architecture and mechanical properties were evaluated using scanning electron microscopy (SEM), micro-computed tomography (micro-CT) and mechanical testing, respectively. An in vitro cell-scaffold interaction study was carried out using primary fetal bovine osteoblasts. Specifically, the cell proliferation and differentiation was evaluated by Alamar Blue assay for cell metabolic activity, alkaline phosphatase activity and osteoblast production of calcium. An in vivo study was performed on nude mice to determine the capability of osteoblast-seeded PCL to induce osteogenesis. Each scaffold was implanted subcutaneously in nude mice and, following sacrifice, was explanted at one of a series of time intervals. The explants were then evaluated histologically for possible areas of osseointegration. Microscopy and radiological examination showed multiple areas of osseous ingrowth suggesting that the osteoblast-seeded PCL scaffolds evoke osteogenesis in vivo. These studies demonstrated the viability of the PED process to fabricate PCL scaffolds having the necessary mechanical properties, structural integrity, and controlled pore size and interconnectivity desired for bone tissue engineering.

New developments in fused deposition modeling of ceramics

Purpose – To shift from rapid prototyping (RP) to agile fabrication by broadening the material selection, e.g. using ceramics, hence improving the properties (e.g. mechanical properties) of fused deposition modeling (FDM) products.Design/methodology/approach – This paper presents the development of a novel extrusion system, based on the FDM technology. The new set‐up, consisting of a mini‐extruder mounted on a high‐precision positioning system, is fed with bulk material in granulated form, instead that with the more common filament.Findings – Previous research showed that the applications of new materials with specific characteristics in a commercial FDM system are limited by the use of intermediate precursors, i.e. a filament. The new design described in this paper overcomes the problem thanks to the new feeding system.Research limitations/implications – The work presented in this paper is only the starting point for further development. The new system design was tested and encouraging improvements of th...

Solid Freeform Fabrication of Polycaprolactone∕Hydroxyapatite Tissue Scaffolds

Bone tissue engineering is an emerging field providing viable substitutes for bone regeneration. Freeform fabrication provides an effective process tool to manufacture scaffolds with complex shapes and designed properties. We developed a novel precision extruding deposition (PED) technique to fabricate composite polycaprolactone/hydroxyapatite (PCL/HA) scaffolds. 25% concentration by weight of HA was used to reinforce 3D scaffolds. Two groups of scaffolds having 60% and 70% porosities and with pore sizes of 450 μm and 750 μm respectively, were evaluated for their morphology and compressive properties using scanning electron microscopy and the mechanical testing. In vitro cell-scaffold interaction study was carried out using primary fetal bovine osteoblasts. The cell proliferation and differentiation were evaluated by Alamar Blue assay and alkaline phosphatase activity. Our results suggested that compressive modulus of PCL/HA scaffold was 84 MPa for 60% porous scaffolds and was 76 MPa for 70% porous scaffolds. The osteoblasts were able to migrate and proliferate for the cultured time over the scaffolds. Our study demonstrated the viability of the PED process to fabricate PCL scaffolds having necessary mechanical property, structural integrity, controlled pore size, and pore interconnectivity desired for bone tissue engineering.

Precision Extruding Deposition for Freeform Fabrication of PCL and PCL-HA Tissue Scaffolds

Computer-aided tissue engineering approach was used to develop a novel Precision Extrusion Deposition (PED) process to directly fabricate Polycaprolactone (PCL) and composite PCL/Hydroxyapatite (PCL-HA) tissue scaffolds. The process optimization was carried out to fabricate both PCL and PCL-HA (25% concentration by weight of HA) with a controlled pore size and internal pore structure of the 0°/90° pattern. Two groups of scaffolds having 60 and 70% porosity and with pore sizes of 450 and 750 microns, respectively, were evaluated for their morphology and compressive properties using Scanning Electron Microscopy (SEM) and mechanical testing. The surface modification with plasma was conducted on PCL scaffold to increase the cellular attachment and proliferation. Our results suggested that inclusion of HA significantly increased the compressive modulus from 59 to 84 MPa for 60% porous scaffolds and from 30 to 76 MPa for 70% porous scaffolds. In vitro cell–scaffolds interaction study was carried out using primary fetal bovine osteoblasts to assess the feasibility of scaffolds for bone tissue engineering application. In addition, the results in surface hydrophilicity and roughness show that plasma surface modification can increase the hydrophilicity while introducing the nano-scale surface roughness on PCL surface. The cell proliferation and differentiation were calculated by Alamar Blue assay and by determining alkaline phosphatase activity. The osteoblasts were able to migrate and proliferate over the cultured time for both PCL as well as PCL-HA scaffolds. Our study demonstrated the viability of the PED process to the fabricate PCL and PCL-HA composite scaffolds having necessary mechanical property, structural integrity, controlled pore size and pore interconnectivity desired for bone tissue engineering.

Precision Extruding Deposition of Polycaprolactone and Composite Polycaprolactone/Hydroxyapatite Scaffolds for Tissue Engineering

Precision Extruding Deposition (PED) process wasused to directly fabricate Polycaprolactone (PCL) and PCL/Hydroxyapatite (HA) composite tissue scaffolds. HA powder wasmelt blended with PCL, a biodegradable polymer. Scaffolds with controlled pore size porosity were fabricated. The scaffold morphology and the mechanical properties were evaluated using SEM and mechanical testing. In vivo biological studies were conducted to investigate the cellular responses of the PCLscaffolds. Results and characterizations demonstrate the viabilityof the PED process as well as the good mechanical property, structural integrity, controlled pore size, pore interconnectivity, and the biological compatibility of the fabricated scaffolds.

Precision extruding deposition of composite polycaprolactone/hydroxyapatite scaffolds for bone tissue engineering

Precision extruding deposition (PED) process was used to directly fabricate Polycaprolactone (PCL)/hydroxyapatite (HA) composite tissue scaffolds. HA powder was melt blended with PCL, a biodegradable polymer. Scaffolds with a controlled pore size of 400 /spl mu/m and a 64% porosity were fabricated. The scaffold morphology and the mechanical properties were evaluated using SEM and mechanical testing. Preliminary biological study was conducted to investigate the cellular responses of the composite scaffolds. Results and characterizations demonstrate the viability of the PED process as well as the good mechanical property, structural integrity, controlled pore size, pore interconnectivity, and the biological compatibility of the fabricated PCL/HA scaffolds.

Fabrication of cellular poly-/spl isin/-caprolactone (PCL) scaffolds by precision extruding deposition process

Many applications in tissue engineering require scaffolds with specific micro- and macroscopic geometries and internal architectures in order to provide desirable biological and biophysical functions for intended tissue. Freeform fabrication has often been used as an effective process to produce such required scaffolds with designed structures and properties. This paper reports our study on exploring a novel precision extruding deposition (PED) method to directly fabricate cellular-like poly-/spl isin/-caprolactone (PCL) scaffolds. Scaffolds with designed pore size at about 250 /spl mu/m and at different strut orientations were fabricated. Results of the fabrication and the SEM optical micrographics evaluation for the structural formability and process-ability of as-fabricated scaffolds are presented.

Design and freeform fabrication of load bearing tissue scaffolds

Scaffolds with designed interior pore architecture, predefined porosity and a well interconnected predetermined network has been the most favored design approach for tissue engineering applications. This paper will present the details of our development in the design and fabrication of biomimetic tissue scaffolds based on tissue requirements. This includes the 3D reconstruction of patient-specific medical imaging data (CT/MRI), the evaluation of tissue properties, the incorporation of intended biophysical and biological requirements into the design model, and the characterization of designed scaffold mechanical properties. The paper also presents a novel design approach to generate the designed scaffolds using layered freeform fabrication without forming complicated 3D CAD scaffold models. Feasibility studies applying the algorithm to example models and the generation of fabrication planning instructions involving heterogeneous structures will also be presented.

Space Filling Curves: Its Design and Fabrication for Extrusion Based SFF Systems

Scaffolds with designed interior pore architecture, predefined porosity and a well interconnected predetermined network has been the most favored design approach for tissue engineering applications. Solid freeform fabrication technologies have provided the capability of fabricating tissue scaffolds with desired characteristics due to its integration with CAD enabled tools. However, currently the interior macro pore design of scaffolds have been limited to simple regular shapes of either squares or circles due to limited CAD capability. In this paper we seek to enhance the design of the scaffold architecture by using space filling curves within its interior space. The process involves: definition and characterization of space filling curves such as the Hilbert Curve and Sierpinski Curves, applying the principle of layered manufacturing to determine the scaffold individual layered process planes and layered contours; Feasibility studies applying the curve generators to sample models and the generation of fabrication planning instructions for extrusion based SFF systems is presented.Copyright