ORCID Profile
0000-0002-5438-2169
Current Organisation
University of Nottingham
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Publisher: SPIE
Date: 10-02-2011
DOI: 10.1117/12.873365
Publisher: Future Medicine Ltd
Date: 03-2007
Abstract: Tissue engineering is a rapidly growing field that aims to develop biological substitutes that restore, maintain or improve tissue function. The focus of research to date has been the underlying biology required for tissue-engineered therapies. However, as tissue-engineered products reach the marketplace, there is a pressing need for an improved understanding of the engineering and economic issues associated with them. This is motivated by the lack of commercial viability of many of the initial therapies that have been produced. It has been suggested in the literature that this is partly due to poor process and system design in tissue production, as well as a lack of process monitoring and control. This review argues that principles of design, measurement and process monitoring from the physical sciences are needed to move tissue engineering forward, and that much of the technology needed to realize this is already available.
Publisher: IOP Publishing
Date: 03-2008
DOI: 10.1088/1748-6041/3/1/015011
Abstract: Tissue scaffolds are integral to many regenerative medicine therapies, providing suitable environments for tissue regeneration. In order to assess their suitability, methods to routinely and reproducibly characterize scaffolds are needed. Scaffold structures are typically complex, and thus their characterization is far from trivial. The work presented in this paper is centred on the application of the principles of scaffold characterization outlined in guidelines developed by ASTM International. Specifically, this work demonstrates the capabilities of different imaging modalities and analysis techniques used to characterize scaffolds fabricated from poly(lactic-co-glycolic acid) using supercritical carbon dioxide. Three structurally different scaffolds were used. The scaffolds were imaged using: scanning electron microscopy, micro x-ray computed tomography, magnetic resonance imaging and terahertz pulsed imaging. In each case two-dimensional images were obtained from which scaffold properties were determined using image processing. The findings of this work highlight how the chosen imaging modality and image-processing technique can influence the results of scaffold characterization. It is concluded that in order to obtain useful results from image-based scaffold characterization, an imaging methodology providing sufficient contrast and resolution must be used along with robust image segmentation methods to allow intercomparison of results.
Publisher: SPIE-Intl Soc Optical Eng
Date: 2012
Publisher: Wiley
Date: 07-2009
DOI: 10.1002/BTPR.191
Abstract: This article demonstrates the application of time-lapsed imaging and image processing to inform the supercritical processing of tissue scaffolds that are integral to many regenerative therapies. The methodology presented provides online quantitative evaluation of the complex process of scaffold formation in supercritical environments. The capabilities of the developed system are demonstrated through comparison of scaffolds formed from polymers with different molecular weight and with different venting times. Visual monitoring of scaffold fabrication enabled key events in the supercritical processing of the scaffolds to be identified including the onset of polymer plasticization, supercritical points and foam formation. Image processing of images acquired during the foaming process enabled quantitative tracking of the growing scaffold boundary that provided new insight into the nature of scaffold foaming. Further, this quantitative approach assisted in the comparison of different scaffold fabrication protocols. Observed differences in scaffold formation were found to persist, post-fabrication as evidenced by micro x-ray computed tomography (micro x-ray CT) images. It is concluded that time-lapsed imaging in combination with image processing is a convenient and powerful tool to provide insight into the scaffold fabrication process.
Publisher: Springer Berlin Heidelberg
Date: 2009
Publisher: IEEE
Date: 12-2011
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.BIOMATERIALS.2009.04.035
Abstract: In order to assess the suitability of polymer tissue scaffolds for use in regenerative medicine, methods to characterise scaffolds are needed. This requires the scaffold's structure to be determined for which X-ray microscopic computed tomography (X-ray micro CT) is widely used. However, because scaffolds are generally made of materials with low X-ray attenuating properties the images produced are far from ideal, which makes distinguishing scaffold material from the pores within it a non-trivial process. This paper presents a method for generating computer-simulated scaffolds that resemble the form of foamed polymer tissue scaffolds. Virtual images of the scaffold are then produced via a simulated X-ray micro CT process enabling the effect of varying the key parameters in the imaging process to be investigated. Here this is assessed via the calculated porosity of the s le, this being a simple measure of a scaffold's properties. Results highlight the difficulties in using X-ray micro CT to characterise scaffolds constructed from materials with low X-ray attenuating properties and suggest strategies that may be adopted in order to improve the quality of the images produced.
Publisher: Wiley
Date: 24-11-2011
DOI: 10.1002/JBM.B.31957
Abstract: Although X-ray microscopic computed tomography is widely used to assess the structural properties of polymeric tissue scaffolds its validity is dependent on the quality of the images obtained. Here, the role of resolution, integration time, image averaging, and X-ray power on the accurate determination of scaffold porosity, while aiming to minimize imaging time, was investigated. This work identified key parameters for optimization and a methodology to vary them to improve results. Based on this, guidelines were developed to assist in the selection of image acquisition parameters to allow rapid and accurate scaffold imaging as required for mass manufacture.
Publisher: SPIE
Date: 10-02-2011
DOI: 10.1117/12.873302
Publisher: Springer Science and Business Media LLC
Date: 05-04-2008
DOI: 10.1007/S10856-008-3445-Y
Abstract: Polymeric tissue scaffolds are central to many regenerative medicine therapies offering a new approach to medicine. As the number of these regenerative therapies increases there is a pressing need for an improved understanding of the methods of scaffold fabrication. Of the many approaches to processing scaffolds, supercritical fluid fabrication methods have a distinct advantage over other techniques as they do not require the use of organic solvents, elevated processing temperatures or leaching processes. The work presented here is centred on the development of a new approach to monitoring supercritical scaffold fabrication based on determination of the scaffold acoustic impedance to inform protocols for scaffold fabrication. The approach taken uses an ultrasonic pulse-echo reflectometer enabling non-invasive monitoring of the supercritical environment on-line. The feasibility of this approach was investigated for two scaffolds of different molecular weight. Acoustic results demonstrate that differences in the physical properties of the two scaffolds could be resolved, particularly during the foaming process which correlated with findings from time-lapsed imaging and micro X-ray computed tomography (micro X-ray CT) images. Thus, this work demonstrates the feasibility of ultrasonic pulse-echo reflectometry to non-invasively study supercritical scaffold fabrication on-line providing a greater understanding of the scaffold fabrication process.
Publisher: SPIE
Date: 12-02-2009
DOI: 10.1117/12.812221
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for John Crowe.