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Article
Publication date: 20 January 2020

Li Wu, Xinxin Li, Tianmin Guan, Yong Chen and Chunwei Qi

The 3 D bioprinting technology is used to prepare the tissue engineering scaffold with precise structures for the cell proliferation and differentiation.

Abstract

Purpose

The 3 D bioprinting technology is used to prepare the tissue engineering scaffold with precise structures for the cell proliferation and differentiation.

Design/methodology/approach

According to the characteristics of the ideal tissue engineering scaffold, the microstructural design of the tissue engineering scaffold is carried out. The bioprinter is used to fabricate the tissue engineering scaffold with different structures and spacing sizes. Finally, the scaffold with good connectivity is achieved and used to cell PC12 culture.

Findings

The results show that the pore structure with the line spacing of 1 mm was the best for cell culture, and the survival rate of the inoculated cells PC12 is as high as 90%. The influence of the pore shape on the cell survival is not evidence.

Originality/value

This study shows that tissue engineering scaffolds prepared by 3 D bioprinting have graded structure for three-dimensional cell culture, which lays the foundation for the later detection of drug resistance.

Details

Rapid Prototyping Journal, vol. 26 no. 5
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 March 2006

Ker Chin Ang, Kah Fai Leong, Chee Kai Chua and Margam Chandrasekaran

The purpose of this paper is to investigate the mechanical properties and porosity relationships in fused deposition modelling (FDM) fabricated porous structures.

Abstract

Purpose

The purpose of this paper is to investigate the mechanical properties and porosity relationships in fused deposition modelling (FDM) fabricated porous structures.

Design/methodology/approach

Porous structures of numerous build architectures aimed at tissue engineering (TE) application were fabricated using the FDM. The employment of FDM to fabricate these non‐random constructs offers many advantages over conventional scaffold fabrication techniques as patient specific scaffolds with well‐defined architectures and controllable pore sizes can be fabricated accurately and rapidly. There exist several FDM parameters that one needs to specify during the scaffold fabrication process. These parameters, which can be interdependent and exhibit varying effects on scaffold properties, were identified and examined using the design of experiment (DOE) approach. Essentially, the effects of five FDM process parameters, namely air gap, raster width, build orientation, build layer and build profile, on the porosity and mechanical properties of acrylonitrile‐butadienene‐styrene (ABS) scaffold structures with three‐dimensional interconnectivity were investigated in two designed experiments. Statistical analyses of the data were performed and the respective factors that have significant influence on the porosity and mechanical properties of the scaffolds were identified. The relationship between scaffold's mechanical properties and porosity was thereafter established empirically.

Findings

Models of TE scaffolds of numerous build architectures were successfully fabricated using different parameter settings on the FDM. The DOE approach determined air gap and raster width as the most significant parameters in affecting the porosity and mechanical properties of the ABS scaffold structures. The relationship between scaffolds' mechanical properties and porosity was determined to be logarithmic, with the best mechanical properties observed in scaffolds of low porosity.

Originality/value

The paper highlights how the application FDM to tissue scaffold application can overcome most of the limitations encountered in the conventional techniques.

Details

Rapid Prototyping Journal, vol. 12 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 February 2004

F. Wang, L. Shor, A. Darling, S. Khalil, W. Sun, S. Güçeri and A. Lau

Successes in scaffold guided tissue engineering require scaffolds to have specific macroscopic geometries and internal architectures to provide the needed biological and…

Abstract

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‐ε_rm;‐caprolactone (PCL) scaffolds. Scaffolds with a controlled pore size of 250 μm and designed structural orientations were fabricated.

Details

Rapid Prototyping Journal, vol. 10 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Abstract

Purpose

Additive manufacturing (AM) or solid freeform fabrication (SFF) technique is extensively used to produce intrinsic 3D structures with high accuracy. Its significant contributions in the field of tissue engineering (TE) have significantly increased in the recent years. TE is used to regenerate or repair impaired tissues which are caused by trauma, disease and injury in human body. There are a number of novel materials such as polymers, ceramics and composites, which possess immense potential for production of scaffolds. However, the major challenge is in developing those bioactive and patient-specific scaffolds, which have a required controlled design like pore architecture with good interconnectivity, optimized porosity and microstructure. Such design not only supports cell proliferation but also promotes good adhesion and differentiation. However, the traditional techniques fail to fulfill all the required specific properties in tissue scaffold. The purpose of this study is to report the review on AM techniques for the fabrication of TE scaffolds.

Design/methodology/approach

The present review paper provides a detailed analysis of the widely used AM techniques to construct tissue scaffolds using stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), binder jetting (BJ) and advanced or hybrid additive manufacturing methods.

Findings

Subsequently, this study also focuses on understanding the concepts of TE scaffolds and their characteristics, working principle of scaffolds fabrication process. Besides this, mechanical properties, characteristics of microstructure, in vitro and in vivo analysis of the fabricated scaffolds have also been discussed in detail.

Originality/value

The review paper highlights the way forward in the area of additive manufacturing applications in TE field by following a systematic review methodology.

Details

Rapid Prototyping Journal, vol. 27 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

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Book part
Publication date: 26 August 2019

Janet S. Gaffney and Rebecca Jesson

Purpose – The purpose of this chapter is to understand how children expand independence within instructional interactions with their teachers. To do so, the authors…

Abstract

Purpose – The purpose of this chapter is to understand how children expand independence within instructional interactions with their teachers. To do so, the authors re-examine how scaffolding is understood and applied.

Approach – First, the authors consult websites and literature used by teachers and academics to examine how the notion of scaffolding is employed and explained. The authors analyze the roles, the intentions, the means, and the timing of scaffolding as used in popular literature to explain and support instruction. The authors then entertain a conceptual shift: What would the scaffolding process look like if learning were conceived as agentive? With this in mind, the authors interrogate descriptions of the tenets and functions of scaffolding to consider the process in relief.

Findings – The authors track the consequences of the inversion of scaffolding onto the understandings of the gradual release of responsibility (GRR) model. Scaffolding is understood as sitting within a GRR model, wherein the learner gradually releases responsibility to a teacher at the point of need. Intersubjectivity remains a basis for the model. A Window for Examining Teaching–Learning Interactions is offered as a frame with which to analyze the theories of both the child and the teacher apparent within scaffolding interactions. An accurate teacher’s theory of the child’s current and changing theories is required for teaching to be honed to invite children to efficiently access personal and contextual resources and to seek assistance when needed within engaging tasks with scope.

Practical Implications – When children are positioned as initiators of their learning, they are able to use their vast repertoire of knowledge of the world, language/s and literacies, and familial, cultural, and community ways of knowing to create, interpret, and engage in tasks. In this agentive view, children are positioned as holding full responsibility at the onset of any task and gradually releasing their responsibility to access support, when needed. Within tasks that are sufficiently wide for engagement at varied entry points, learners are the catalyst of the functions that were formerly initiated by teachers. Teachers invite children to access personal and contextual resources and to seek assistance, as needed, through additional external, contextual resources. This inverted model of scaffolding, that is child-directed rather than teacher-initiated, requires teachers to go beyond theories of teaching and learning and develop a theory of an individual child.

Details

The Gradual Release of Responsibility in Literacy Research and Practice
Type: Book
ISBN: 978-1-78769-447-7

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Article
Publication date: 1 February 2021

Rudranarayan Kandi, Pulak Mohan Pandey, Misba Majood and Sujata Mohanty

This paper aims to discuss the successful fabrication of customized tubular scaffolds for tracheal tissue engineering with a novel route using solvent-based extrusion 3D printing.

Abstract

Purpose

This paper aims to discuss the successful fabrication of customized tubular scaffolds for tracheal tissue engineering with a novel route using solvent-based extrusion 3D printing.

Design/methodology/approach

The manufacturing approach involved extrusion of polymeric ink over a rotating predefined pattern to construct customized tubular structure of polycaprolactone (PCL) and polyurethane (PU). Dimensional deviation in thickness of scaffolds were calculated for various layer thicknesses of 3D printing. Physical and chemical properties of scaffolds were investigated by scanning electron microscope (SEM), contact angle measurement, Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD). Mechanical characterizations were performed, and the results were compared to the reported properties of human native trachea from previous reports. Additionally, in vitro cytotoxicity of the fabricated scaffolds was studied in terms of cell proliferation, cell adhesion and hemagglutination assay.

Findings

The developed fabrication route was flexible and accurate by printing customized tubular scaffolds of various scales. Physiochemical results showed good miscibility of PCL/PU blend, and decrease in crystalline nature of blend with the addition of PU. Preliminary mechanical assessments illustrated comparable mechanical properties with the native human trachea. Longitudinal compression test reported outstanding strength and flexibility to maintain an unobstructed lumen, necessary for the patency. Furthermore, the scaffolds were found to be biocompatible to promote cell adhesion and proliferation from the in vitro cytotoxicity results.

Practical implications

The attempt can potentially meet the demand for flexible tubular scaffolds that ease the concerns such as availability of suitable organ donors.

Originality/value

3D printing over accurate predefined templates to fabricate customized grafts gives novelty to the present method. Various customized scaffolds were compared with conventional cylindrical scaffold in terms of flexibility.

Details

Rapid Prototyping Journal, vol. 27 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 28 January 2021

Yashwant Kumar Modi and Kiran Kumar Sahu

This study aims to optimize the process parameters of ZPrinter® 450 for measured porosity (MP) and compressive strength (CS) of calcium sulfate-based porous bone scaffold

Abstract

Purpose

This study aims to optimize the process parameters of ZPrinter® 450 for measured porosity (MP) and compressive strength (CS) of calcium sulfate-based porous bone scaffold using Taguchi approach.

Design/methodology/approach

Initially, a porous scaffold with smallest pore size that can be de-powdered completely is identified through a pilot study. Five printing parameters, namely, layer thickness (LT), build orientation (BO), build position (BP), delay time (DT) and binder saturation (BS), each at three levels have been optimized for MP and CS of the fabricated scaffolds using L27 orthogonal array (OA), signal-to-noise ratio and analysis of variance (ANOVA).

Findings

The scaffolds with 600 µm pores could be de-powdered completely. Optimum levels of parameters are LT2, BO1, BP2, DT1 and BS1 for MP and LT1, BO1, BP2, DT1 and BS2 for CS. The ANOVA reveals that the BS (49.12%) is the most and BP (8.34%) is the least significant parameter for MP. LT (50.84%) is the most, BO (33.79%) is second most and DT (2.59%) is the least significant parameter for CS. Taguchi confirmation test and linear regression models indicate a good agreement between predicted and experimental values of MP and CS. The experimental values of MP and CS at the optimum levels of parameters are found 38.12% and 1.29 MPa, respectively.

Originality/value

The paper presents effect of process parameters of ZPrinter® 450 on MP and CS of calcium sulfate-based porous scaffolds. Results may be used as guideline for powder bed binder jetting three-dimensional printing of ceramic scaffolds.

Details

Rapid Prototyping Journal, vol. 27 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 13 May 2020

Peng Wang, Peng Wu, Xiangyu Wang, Xin Chen and Tao Zhou

Facility structures in liquefied natural gas (LNG) plants require tremendous amounts of scaffolding to facilitate relevant industrial operation and maintenance. As such…

Abstract

Purpose

Facility structures in liquefied natural gas (LNG) plants require tremendous amounts of scaffolding to facilitate relevant industrial operation and maintenance. As such, the productivity of scaffolding operations in turnaround maintenance (TAM) has attracted much attention in recent years. In addition, health and safety issues have been recognised as a key contributor along with productivity improvement in the LNG industry. This study aims to integrate work posture analysis into value stream mapping to achieve an optimised and balanced improvement in both productivity and health and safety.

Design/methodology/approach

A case study approach is adopted to integrate lean and work posture analysis in a TAM site. The lean improvement is conducted through value stream mapping, and the work posture analysis is conducted through the Ovako Working Posture Analysis System method. A three-step optimisation strategy is then developed for achieving optimised performance in waste reduction and work posture improvement.

Findings

It is found that the implementation of value stream mapping can help eliminate waste in the installation process, therefore eliminating potential health and safety risks. However, health and safety of onsite workers does not always improve as lean implementation intensifies. There is an optimised erection schedule that has the lowest health and safety risk within a waste reduction target.

Originality/value

In contradiction to previous studies, which rely on qualitative assessment to identify the a positive correlation between lean and health and safety, this study reveals the distinct difference between lean attributes and health and safety attributes through a quantitative assessment and is more readily to be implemented at the site level for simultaneous improvement in lean and health and safety.

Details

Engineering, Construction and Architectural Management, vol. 27 no. 9
Type: Research Article
ISSN: 0969-9988

Keywords

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Article
Publication date: 8 January 2020

Paola Ginestra, Stefano Pandini and Elisabetta Ceretti

The purpose of this paper is to focus on the production of scaffolds with specific morphology and mechanical behavior to satisfy specific requirements regarding their…

Abstract

Purpose

The purpose of this paper is to focus on the production of scaffolds with specific morphology and mechanical behavior to satisfy specific requirements regarding their stiffness, biological interactions and surface structure that can promote cell-cell and cell-matrix interactions though proper porosity, pore size and interconnectivity.

Design/methodology/approach

This case study was focused on the production of multi-layered hybrid scaffolds made of polycaprolactone and consisting in supporting grids obtained by Material Extrusion (ME) alternated with electrospun layers. An open source 3D printer was utilized, with a grain extrusion head that allows the production and distribution of strands on the plate according to the designed geometry. Square grid samples were observed under optical microscope showing a good interconnectivity and spatial distribution of the pores, while scanning electron microscope analysis was used to study the electrospun mats morphology.

Findings

A good adhesion between the ME and electrospinning layers was achieved by compression under specific thermomechanical conditions obtaining a hybrid three-dimensional scaffold. The mechanical performances of the scaffolds have been analyzed by compression tests, and the biological characterization was carried out by seeding two different cells phenotypes on each side of the substrates.

Originality/value

The structure of the multi-layered scaffolds demonstrated to play an important role in promoting cell attachment and proliferation in a 3D culture formation. It is expected that this design will improve the performances of osteochondral scaffolds with a strong influence on the required formation of an interface tissue and structure that need to be rebuilt.

Details

Rapid Prototyping Journal, vol. 26 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 8 January 2020

Emre Özeren and Mirigul Altan

The purpose of this study was to bring a new structural hybrid design approach to improve the mechanical and biological properties of the bone scaffolds fabricated by…

Abstract

Purpose

The purpose of this study was to bring a new structural hybrid design approach to improve the mechanical and biological properties of the bone scaffolds fabricated by laser powder bed fusion, selective laser melting (SLM).

Design/methodology/approach

In designing the hybrid scaffolds, different unit cells were used such as dodecahedron (DCH), grid (G), octet-truss (OCT) with partially dense (PDsl) and fully dense (FDsl) surface layers. After fabrication of scaffolds on SLM machine, compression test and cell viability test were applied to observe the effect of hybrid design on mechanical and biological properties of the scaffolds.

Findings

It has been observed that designing the scaffold with partially dense or FDsl surfaces did not have a critical effect on the cell viability. On the contrary, the compression strength of scaffold increased from 56  to 100 MPa when the surface layer of the scaffold was designed as FDsl surface instead of partially dense surface. It has also been observed that the scaffold having the highest hybridity (PDsl+G+DCH+OCT) delivered the highest cell viability performance and had a compressive strength slightly higher than that of the scaffolds with single unit cell, PDsl+OCT.

Originality/value

This study brings a new approach to designing femur bone scaffold for fabricating with SLM. This hybrid design approach, including different unit cells in a single scaffold, covers many requirements of femur bone in terms of mechanical and biological properties.

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