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Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education

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Abstract and Figures

Understanding the three-dimensional morphology of a biological sample at the microscopic level is a prerequisite to a functional understanding of cell biology, tissue development and growth. Images of microscopic samples obtained by compound light microscopy are customarily recorded and represented in two dimensions from a single orientation making it difficult to extrapolate 3D context from the 2D information. The commercialisation of fast, laser-based microscope systems (e.g. confo-cal, multi-photon or lightsheet microscopy) capable of generating volume datasets of microscopic samples through optical sectioning, coupled with advances in computer technology allowing accurate volume rendering of these datasets, have facilitated significant improvement in our 3D understanding of the microscopic world in virtual space. The advent of affordable 3D printing technology now offers the prospect of generating morphologically accurate, physical models from these microscope volume datasets for use in science education, outreach and engagement. 3D printed scale replicas will provide improved sensory perception, offering tactile as well as visual interaction, leading to improved understanding of structure function relationships. Here we present a technique to reliably generate detailed, physical 3D models from Z-stacks of optical sections from confocal and lightsheet microscopes using affordable , entry-level 3D printing technology. We use the technique to generate 3D printed models of a variety of different biological samples at a range of scales including pollen grains from two species of plant; blood cells from both human and earthworm species, a section of plant root; the compound eye of an ant; and a developing Ze-brafish larva; all of which have been used in our teaching, engagement and outreach activities. Our methods can, in principle, be used to generate 3D printed models from microscope volume datasets of any small fluorescent or reflective samples.
Reconstruction of confocal volume data sets for 3D printing. A-C. 3D modelling of a human red blood cell. A. Surface-rendered model of the erythrocyte generated from a confocal Z-stack comprising 11 sections. B. The erythrocyte model was printed in two halves to convey the characteristic biconcave morphology visible in histological section planes. The support raft (sr) is still attached in this figure. C. The completed 3D print of the erythrocyte. D-F. 3D reconstruction of an eleocyte (chloragocyte) from the earthworm (Eisenia fetida). D. Maximum intensity reconstruction of the cell generated from a stack of 9 sections. Note highly autofluorescent, flavin-rich chloragosomes (ch). E. Surface rendered model showing internal structure of the chloragocyte. Grey values of cellular autofluorescence were used to segment the strong flavin signal from the chloragosomes (ch; depicted in green) from the weakly autofluorescent cytoplasm (c, depicted in red). An equatorial clipping plane was introduced into the model with an offset between red and green channels to expose the surface topography of the chloragosomes. F. The finished 3D print showing internal structure of the chloragocyte. Chloragosomes have been contrasted with green acrylic. G-I. 3D reconstruction of plant root tissue from Lilly of the Valley (Convallaria majalis). G. Maximum intensity reconstruction of the root generated from a confocal Z-stack comprising 64 sections. The vascular canals (vc) and chloroplasts (c) within associated root cells are visible. H. Surface-rendered model of the root tissue. The model has been tilted on its vertical axis to highlight sample thickness. I. The finished 3D print of the rhizome. J-L. 3D reconstruction of the compound eye of the common garden ant (Myrmica rubra). J. Maximum intensity projection of the eye generated from a confocal z-stack comprising 40 sections. Boxed area is shown in detail in K. K-L. Surface-rendered images generated from (K) autofluorescence-and (L) reflectance-based image data showing detail of the individual optical units, or ommatidia (o) making up the insect's compound eye. M. The finished 3D printed model of the compound eye (generated from the autofluorescent signal). Scale bars denote sample dimensions.
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Production of 3D Printed Scale Models from Microscope
Volume Datasets for use in STEM Education
Perry I1, Szeto J-Y1, Isaacs MD1, Gealy EC1, Rose R1, Scoeld S1,
Watson PD1, Hayes AJ1*
1Bioimaging Research Hub, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AX.
Wales, UK
EMS Engineering Science Journal
Research Article
Cite this article: Hayes AJ. Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education.
EMS Eng Sci j 2017, 1(1):002.
*Corresponding author : Dr. Anthony J.
Hayes, Bioimaging Research Hub, Cardiff
School of Biosciences, Cardiff University,
Cardiff CF10 3AX, Wales, UK,
Tel: +44(0)2920876611;
Email: hayesaj@cardiff.ac.uk
Received: 19-06-2017
Accepted: 20-06-2017
Published: 21-07-2017
Copyright: © 2017 Hayes AJ
Abstract
Understanding the three-dimensional morphology of a biological sample at the mi-
croscopic level is a prerequisite to a functional understanding of cell biology, tissue
development and growth. Images of microscopic samples obtained by compound
light microscopy are customarily recorded and represented in two dimensions from
 -
mation. The commercialisation of fast, laser-based microscope systems (e.g. confo-
cal, multi-photon or lightsheet microscopy) capable of generating volume datasets of
microscopic samples through optical sectioning, coupled with advances in computer
technology allowing accurate volume rendering of these datasets, have facilitated sig-
    
       
generating morphologically accurate, physical models from these microscope volume
           
replicas will provide improved sensory perception, offering tactile as well as visual
interaction, leading to improved understanding of structure function relationships.

Z-stacks of optical sections from confocal and lightsheet microscopes using afford-
-
ed models of a variety of different biological samples at a range of scales including
pollen grains from two species of plant; blood cells from both human and earthworm
species, a section of plant root; the compound eye of an ant; and a developing Ze-



Keywords: Confocal Microscopy; Lightsheet Microscopy;
    -
ing
Introduction
 -
cantly as a transformative technology in recent years with
dramatic improvements in printing speed, resolution and

      

resin, plastic, metal), each with their own advantages and
       
-
  -

resonance (MR) scans and to generate implants and prosthet-
-



and teaching applications. The potential of the technology to

also slowly becoming realised, with a handful of recent stud-
ies describing approaches for the creation of physical mod-

Cite this article: Hayes AJ. Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education.
EMS Eng Sci j 2017, 1(1):002.
els from volume datasets obtained by both light microscopy
       
 
-
        -
 


basis – the resolution of the print being determined by the
thickness of the printed layer.
  

volume datasets obtained by confocal and lightsheet mi-
    
-
       
samples from both plant and animal species and range in scale
from the level of cell organelle to multicellular developmen-
 
 
compatible with all imaging modalities that generate volume
-
croscopy, spinning disc microscopy, multi-photon microsco-
py etc) and thus can be applied to a variety of microscopy
platforms and image processing and analysis software. The
       
-
nology, engineering and math) activities, science education,
and outreach and engagement programmes.
Materials and Methods


Samples
To evaluate the methodology, a range of different biological
samples from single cells to multicellular organisms, includ-
ing both plant and animal species, were imaged using con-
focal or lightsheet microscopy. Images were generated from


Commercial unstained slide preparations of (a) pollen grains

latifolia); (b) erythrocytes from a human blood cell smear; (c)
a transverse section of root from the Lilly of the valley plant
-
kocytes (coelomocytes) obtained from the coelomic cavity of
 -
-



and cell nuclei (further details below). All image acquisition
-

Image Acquisition
Confocal Microscopy
  -
sheet microscopy (see below), all other samples were imaged
      
   
-
pour deposition with gold using standard scanning electron
microscopic procedures. Confocal microscopy of the samples



Cite this article: Hayes AJ. Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education.
EMS Eng Sci j 2017, 1(1):002.
   
system (Zeiss, Jena, Germany). Individual samples were vi-
  
 -
-
rived from each sample using spectral (lambda, wavelength)
   -
-
sions collected sequentially across the visible range and into


thus inform appropriate scan parameters (refer to table 1).


applying Nyquist sampling criteria and a pinhole size of 1
Airy unit (AU) to give the best signal to noise ratio. Line av-
eraging was used for electronic noise reduction throughout.

confocal software) or .czi (Carl Zeiss Image) formats.
Lightsheet Microscopy
Lightsheet microscopy, performed using a Zeiss Lightsheet
Z.1 system (Zeiss, Jena, Germany), was utilised for whole or-
    
     
-


      

agarose, drawn into a warmed capillary tube and then loaded

-
trast)
  Laser line
(nm)

bandwidth
(nm)

-
cence)



oil
 
Bulrush pollen
-
cence)
 
oil
 

-
cence)
 
oil
 
Compound
-


  -
rescence)
-
tance)

-
cence)

-
tance)
Root section
-
cence)
 
oil
 

-

nuclei)
Lightsheet
Z.1
  







   

 
to optimise the signal from these emission peaks.
into the specimen chamber of a Zeiss Lightsheet Z.1 micro-

       -
 -
tation and emission settings for simultaneous recording of
  
   

      

Cite this article: Hayes AJ. Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education.
EMS Eng Sci j 2017, 1(1):002.
Volume Reconstruction and Surface Rendering

    -
ford Instruments). Z-stacks of optical sections from each
       
       


rendered via absolute intensity thresholding with smoothing
        -
         -
Lab (), which is a free, open source
software platform that provides additional editing tools to
-
   -


also provides an advanced toolset that will allow generation
-
croscopy platforms.
3D Printing and Processing
   -
         
        -
   
        
      
-
       
       


then printed overnight. Once each print was complete, the
         
supporting scaffold carefully detached from the model using
   
models that were outside the print bed parameters (e.g. the

printed as separate halves. The complementary halves were

  
(e.g. smoothing of edges from support stubble) was per-
formed using a paint brush dipped in acetone. A water-based
acrylic paint was used to contrast features of interest in the

Results
Plant Pollen
   -
mon daisy (Bellis perennis) and Bulrush (Typha latifolia)

  -

focal Z-stacks through individual grains provided striking

     
provided volume overviews of the pollen grains and demon-
      
   
grains were spheroidal in morphology with prominent spiny
-
as Typha grains were grouped into tetrads, with reticulate
       
showed further topographic detail of the surface ornamenta-
-


-


     


Human Erythrocyte
Confocal visualisation of human blood smears revealed a
     
the green and red range of the visible spectrum. As the cells
were closely associated, we employed a circular ROI (region
of interest) to delineate a scan area around individual eryth-
rocytes. Confocal Z-stacks through the cells showed a disc
       
thickness at the centre of <1 micrometre, in agreement with
-
constructions showed the characteristic biconcave morphol-
  
process a clipping plane was introduced through the erythro-
cyte disc diameter so that the model could be printed in two
halves in order to convey the biconcave discal morphology

Earthworm Leukocyte (chloragocyte)
Chloragocytes obtained from the coelomic cavity of the earth-

       
     
-
-
-
nal from the chloragosomes, which were modelled in green,
 
        
        

surfaces and reveal topographic detail of the chloragosomes

Plant Root
Cite this article: Hayes AJ. Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education.
EMS Eng Sci j 2017, 1(1):002.


  -




I. Cut plane model showing internal surface structure of intine (dashed line indicates clipping plane).


supports are detached after printing.

Cite this article: Hayes AJ. Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education.
EMS Eng Sci j 2017, 1(1):002.
      -
    (Con-
vallaria majalis)
  

used to generate Z-stacks of optical sections through the tis-
  -
    -


internal architecture was faithfully replicated at high resolu-

Insect Compound Eye
     
through the compound eye of an ant (Myrmica rubra) re-

    -
  
   -
ple with gold provided a similar level of surface detail of the
       
-




-
        
       
      

comprising head, trunk and tail, arched around the yolk sac.
-
ial structures of the spine including neural tube, notochord,
the somites and their boundaries. The topography of these
internal structures was manifest in the surface-rendered


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      
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
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
Cite this article: Hayes AJ. Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education.
EMS Eng Sci j 2017, 1(1):002.
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B. The erythrocyte model was printed in two halves to convey the characteristic biconcave morphology visible in histological section planes. The support raft
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
associated root cells are visible.



-


Cite this article: Hayes AJ. Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education.
EMS Eng Sci j 2017, 1(1):002.
 
-



Cite this article: Hayes AJ. Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education.
EMS Eng Sci j 2017, 1(1):002.
Discussion
This paper describes methodology for the generation of scale
       -
scope volume datasets for use in science engagement and
      
-
         
technique can be utilised with any imaging platform that gen-
erates volume datasets through optical sectioning. Using the
-

   -
rescent proteins, or by sputter coating of samples by physical


-
   
mesh. This approach would therefore be useful for intracel-
      
   -
mentation post-acquisition, either through grey value thresh-

In this study we have utilised high-end image analysis soft-
     
      
 
  -
   -
   
    
this study is therefore minimal, with a typical cost of around
 
with printing times of around 8 hours. The methodology
   


can be used as masters to generate moulds that would allow
rapid bulk casting of the models or permit the use of novel
fabrication materials.
        
        -
      -
dered in silico
presenting haptic as well as visual cues about structure and
        
      

well as providing complementary tactile information about
microscopic specimens, we have also found the models to be
     -
     


visually impaired individuals or those with other physical or
    
 
-
tance to society, as it encompasses and integrates a variety of
-
ence, technology, engineering and maths. It is therefore used
in our undergraduate teaching and training programmes and
for science outreach and engagement activities.
   
information about microscopic structure and function in sci-
ence education and research is slowly becoming realised. A
small number of recent studies have implemented additive
manufacturing techniques to generate physical models from
 -
       
skeletal muscle cells from confocal datasets; whereas both


is broadly similar to these studies, by applying a variety of
sample contrast techniques, different optical imaging modal-

-
ology.
Additive manufacturing is still an evolving technology and
whilst its advantages are considerable, it has some notable
disadvantages which include print reliability, resolution,
           
        
    

      
of the print raft to the heated print bed, and other technical
issues associated with this format. In this study we applied
     
an acceptable compromise between resolution and speed

this kept layering artefacts to an acceptable level, there was

the original microscope dataset. However, it is worthwhile
noting that greyscale thresholding, required to generate the

  
following removal of the print scaffold, which leaves minor
         
-
    -
  


then subsequently fused together.

delivering measurable improvements in additive manufac-

        

Cite this article: Hayes AJ. Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education.
EMS Eng Sci j 2017, 1(1):002.
two colours or with different printing materials (e.g. resin,

      
  
-
ther reducing costs. The cost of the printers themselves and
their printing materials has also tumbled, now making them
viable standard laboratory acquisitions. It is anticipated

printing as a transformative technology and, in the current

the microscopic world.
Author Contribution:

Acknowledgements


   

   -
 -
scan confocal microscope, Zeiss Lightsheet Z.1 microscope
       

Infrastructure fund.
References
1.        
     

        
    

 -
        

    
  -
    

5.     
production of anatomical teaching resources using three-di-
       

6.         


   -
        -
      
.
8. 
 


 Bagley JR, Galpin AJ. Three-dimensional printing of hu-
 
 


-

11. 



a new take on an old method for generating high-resolution
   







        

16.          

  

    -
-

18.         



 -
      
      -

Cite this article: Hayes AJ. Production of 3D Printed Scale Models from Microscope Volume Datasets for use in STEM Education.
EMS Eng Sci j 2017, 1(1):002.
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        

-

-


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       
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... Apesar de o foco desse estudo ter sido o público com deficiência visual, a modelagem pode ser utilizada por todos os alunos, com e sem deficiência. Perry et al. (2017) e Augusto e colaboradores (2016) utilizaram a técnica de impressão 3D para reconstruir diversas amostras biológicas, e segundo os autores, a compreensão da morfologia tridimensional de uma amostra biológica microscópica é um pré-requisito para o entendimento funcional da biologia celular, desenvolvimento e crescimento de tecidos. ...
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Os principais motivos que dificultam a aprendizagem significativa de conceitos e processos biológicos residem no ensino fragmentado e conservador, valorizando somente a reprodução do conhecimento. As práticas metodológicas que favorecem a aprendizagem levam ao entendimento e assimilação de conteúdos que por envolverem, por exemplo, a dimensão microscópica, são de difícil compreensão. Neste contexto, as metodologias ativas se apresentam como um princípio de ensino-aprendizagem de eficácia reconhecida, tendo o discente como protagonista do processo de desenvolvimento do conhecimento, com envolvimento direto, participativo e reflexivo em todas as etapas do processo. Nesse contexto, o presente trabalho objetivou usar metodologias ativas para melhorar o entendimento dos alunos de nível superior acerca de conteúdos de Embriologia, Citologia, Genética e Biologia Molecular. As docentes responsáveis pelas disciplinas propuseram a atividade nas turmas das respectivas disciplinas de Ciências Biológicas (Licenciatura) e Biomedicina. As etapas metodológicas utilizadas foram: levantamento bibliográfico; discussão e abordagem dos conhecimentos obtidos; seleção de materiais visando a conscientização ambiental; elaboração do modelo; utilização dos modelos didáticos construídos; redigir relatório e apresentação. Observou-se com esse relato de experiências a excelente interação e a participação dos alunos nas atividades desenvolvidas. Foram obtidos 14 modelos biológicos, sendo notável a predominância de modelos sobre células. Concluiu-se que o ensino de Biologia à luz das metodologias ativas contribui sobremaneira para a ressignificação do trabalho docente visando melhor desempenho dos estudantes em relação ao processo de ensino e aprendizagem. Além disso foi uma alternativa às aulas práticas que estavam inviáveis no período da pandemia.
... Lidar and photogrammetric setups for proximal sensing are likely to grow rapidly over the next few years as the image analysis techniques improve and as camera prices fall [13,14]. 3D printing of plants is an important means of providing ground truth validation to analysis models [7] and is also proving to be a great STEM (science, technology, engineering, and mathematics) teaching and outreach aid [15]. ...
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In recent years, 3D printing has become a transformative technology for the printing of custom-designed objects outside of traditional manufacturing practices. Printer technology has improved significantly with faster printing speeds, wider choice of print materials, lower machine costs, and free and open-source software. In turn, 3D printing technology is now being adopted across many scientific disciplines for rapid prototyping with emerging utility in plant science. In this article, I present survey results providing an insight into the use of 3D printing in plant science, outline a new online repository for curating plant science-related 3D printed work, and provide a perspective of future adoption for 3D printing in this field.
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The method we present here uses a scanning electron microscope programmed via macros to automatically capture dozens of images at suitable angles to generate accurate, detailed three-dimensional (3D) surface models with micron-scale resolution. We demonstrate that it is possible to use these Scanning Electron Microscope (SEM) images in conjunction with commercially available software originally developed for photogrammetry reconstructions from Digital Single Lens Reflex (DSLR) cameras and to reconstruct 3D models of the specimen. These 3D models can then be exported as polygon meshes and eventually 3D printed. This technique offers the potential to obtain data suitable to reconstruct very tiny features (e.g. diatoms, butterfly scales and mineral fabrics) at nanometre resolution. Ultimately, we foresee this as being a useful tool for better understanding spatial relationships at very high resolution. However, our motivation is also to use it to produce 3D models to be used in public outreach events and exhibitions, especially for the blind or partially sighted.
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Background Three-dimensional (3D) printing has become a useful method of fabrication for many clinical applications. It is also a technique that is becoming increasingly accessible, as the price of the necessary tools and supplies decline. One emerging, and unreported, application for 3D printing is to aid in the visualization of 3D imaging data by creating physical models of select structures of interest. Methods Presented here are three physical models that were fabricated from three different 3D microscopy datasets. Different methods of fabrication and imaging techniques were used in each case. ResultsEach model is presented in detail. This includes the imaging modality used to capture the raw data, the software used to create any computer models and the 3D printing tools used to create each model. Despite the differences in their creation, these examples follow a simple common workflow that is also detailed. Conclusions Following these approaches, one can easily make 3D printed models from 3D microscopy datasets utilizing off the shelf commercially available software and hardware.
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The construction of physical three-dimensional (3D) models of biomolecules can uniquely contribute to the study of the structure-function relationship. 3D structures are most often perceived using the two-dimensional and exclusively visual medium of the computer screen. Converting digital 3D molecular data into real objects enables information to be perceived through an expanded range of human senses, including direct stereoscopic vision, touch, and interaction. Such tangible models facilitate new insights, enable hypothesis testing, and serve as psychological or sensory anchors for conceptual information about the functions of biomolecules. Recent advances in consumer 3D printing technology enable, for the first time, the cost-effective fabrication of high-quality and scientifically accurate models of biomolecules in a variety of molecular representations. However, the optimization of the virtual model and its printing parameters is difficult and time consuming without detailed guidance. Here, we provide a guide on the digital design and physical fabrication of biomolecule models for research and pedagogy using open source or low-cost software and low-cost 3D printers that use fused filament fabrication technology. © 2017 Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
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Background Three-dimensional (3D) printing has numerous applications and has gained much interest in the medical world. The constantly improving quality of 3D-printing applications has contributed to their increased use on patients. This paper summarizes the literature on surgical 3D-printing applications used on patients, with a focus on reported clinical and economic outcomes. Methods Three major literature databases were screened for case series (more than three cases described in the same study) and trials of surgical applications of 3D printing in humans. Results227 surgical papers were analyzed and summarized using an evidence table. The papers described the use of 3D printing for surgical guides, anatomical models, and custom implants. 3D printing is used in multiple surgical domains, such as orthopedics, maxillofacial surgery, cranial surgery, and spinal surgery. In general, the advantages of 3D-printed parts are said to include reduced surgical time, improved medical outcome, and decreased radiation exposure. The costs of printing and additional scans generally increase the overall cost of the procedure. Conclusion3D printing is well integrated in surgical practice and research. Applications vary from anatomical models mainly intended for surgical planning to surgical guides and implants. Our research suggests that there are several advantages to 3D-printed applications, but that further research is needed to determine whether the increased intervention costs can be balanced with the observable advantages of this new technology. There is a need for a formal cost–effectiveness analysis.
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The cell biology discipline constitutes a highly dynamic field whose concepts take a long time to be incorporated into the educational system, especially in developing countries. Amongst the main obstacles to the introduction of new cell biology concepts to students is their general lack of identification with most teaching methods. The introduction of elaborated figures, movies and animations to textbooks has given a tremendous contribution to the learning process and the search for novel teaching methods has been a central goal in cell biology education. Some specialized tools, however, are usually only available in advanced research centers or in institutions that are traditionally involved with the development of novel teaching/learning processes, and are far from becoming reality in the majority of life sciences schools. When combined with the known declining interest in science among young people, a critical scenario may result. This is especially important in the field of electron microscopy and associated techniques, methods that have greatly contributed to the current knowledge on the structure and function of different cell biology models but are rarely made accessible to most students. In this work, we propose a strategy to increase the engagement of students into the world of cell and structural biology by combining 3D electron microscopy techniques and 3D prototyping technology (3D printing) to generate 3D physical models that accurately and realistically reproduce a close-to-the native structure of the cell and serve as a tool for students and teachers outside the main centers. We introduce three strategies for 3D imaging, modeling and prototyping of cells and propose the establishment of a virtual platform where different digital models can be deposited by EM groups and subsequently downloaded and printed in different schools, universities, research centers and museums, thereby modernizing teaching of cell biology and increasing the accessibility to modern approaches in basic science.
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Interdisciplinary exploration is vital to education in the 21st century. This manuscript outlines an innovative laboratory-based teaching method that combines elements of biochemistry/molecular biology, kinesiology/health science, computer science, and manufacturing engineering to give students the ability to better conceptualize complex biological systems. Here, we utilize technology available at most universities to print three-dimensional (3D) scale models of actual human muscle cells (myofibers) out of bioplastic materials. The same methodological approach could be applied to nearly any cell type or molecular structure. This advancement is significant because historically, two-dimensional (2D) myocellular images have proven insufficient for detailed analysis of organelle organization and morphology. 3D imaging fills this void by providing accurate and quantifiable myofiber structural data. Manipulating tangible 3D models combats 2D limitation and gives students new perspectives and alternative learning experiences that may assist their understanding. This approach also exposes learners to 1) human muscle cell extraction and isolation, 2) targeted fluorescence labeling, 3) confocal microscopy, 4) image processing (via open-source software), and 5) 3D printing bioplastic scale-models (×500 larger than the actual cells). Creating these physical models may further student's interest in the invisible world of molecular and cellular biology. Furthermore, this interdisciplinary laboratory project gives instructors of all biological disciplines a new teaching tool to foster integrative thinking. © 2015 by The International Union of Biochemistry and Molecular Biology, 2015.
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Objectives: Additive manufacturing, which is more colloquially referred to as 3D printing, is quickly approaching mainstream adoption as a highly flexible processing technique that can be applied to plastic, metal, ceramic, concrete and other building materials. However, taking advantage of the tremendous versatility associated with in situ photopolymerization as well as the ability to select from a variety of preformed processible polymers, 3D printing predominantly targets the production of polymeric parts and models. The goal of this review is to connect the various additive manufacturing techniques with the monomeric and polymeric materials they use while highlighting emerging material-based developments. Methods: Modern additive manufacturing technology was introduced approximately three decades ago but this review compiles recent peer-reviewed literature reports to demonstrate the evolution underway with respect to the various building techniques that differ significantly in approach as well as the new variations in polymer-based materials being employed. Results: Recent growth of 3D printing has been dramatic and the ability of the various platform technologies to expand from rapid production prototypic models to the greater volume of readily customizable production of working parts is critical for continued high growth rates. This transition to working part production is highly dependent on adapting materials that deliver not only the requisite design accuracy but also the physical and mechanical properties necessary for the application. Significance: With the weighty distinction of being called the next industrial revolution, 3D printing technologies is already altering many industrial and academic operations including changing models for future healthcare delivery in medicine and dentistry.
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Purpose – This paper aims to discuss the use of polyvinyl alcohol (PVA) as a water-soluble support material in desktop three-dimensional (3D) printing. Using a water-soluble material as one of the printing filaments in a dual-extrusion 3D printer provides the flexibility of printing support structures and rafts in complex components and prototypes. This paper focuses on the challenges of acrylonitrile butadiene styrene (ABS)–PVA dual-extrusion printing, and optimal settings and techniques for such hybrid printing. Design/methodology/approach – Several hybrid ABS–PVA parts were printed using a commercial desktop 3D printer. An experimental study was designed to examine the solubility of the PVA support in water by varying four different parameters: length of time in water, water temperature, stirring rate and PVA surface area. The rate of PVA solubility in water was then used to examine its relationship with each parameter. Findings – Numerous problems were encountered while printing ABS–PVA printing parts, including storing the spool of PVA in a dry environment, determining optimal extrusion and build plate temperatures and ABS–PVA adherence during dual extrusion printing. There is no strong literature to address these challenges. Hence, optimal settings and techniques for effective hybrid ABS–PVA were determined. Print yields were also recorded to examine the reliability of ABS–PVA printing. Research limitations/implications – The tendency of PVA to absorb moisture resulted in a number of build fails and prevented build times longer than 40 minutes. Future work can explore how to print PVA directly from a dry environment. Practical implications – The optimal settings and techniques for dual-extrusion ABS–PVA printing that are presented in this paper can effectively be used to explore prototyping of geometrically complex parts with PVA as support material. Originality/value – In addition to the practical implications, the results from this work are a valuable addition to the literature related to printing using water-soluble polymers such as PVA. The experimental methods and techniques of this paper can be used to assess the reliability of similar 3D printing technologies.