My latest 3D printing adventure has been an opportunity to show how it can help our understanding of the structures in nature that exist at the nano-scale (and upwards).
I was commissioned by Dr Nate Adams (@nateadams), a Research Scientist at University of Sheffield, to produce a set of 3D prints that help to physically demonstrate the hierarchy and complexity of structures that produce the process of photosynthesis.
These prints form part of an exhibition called :
Hidden Worlds: Krebs and his legacy in Sheffield
This exhibition forms part of KrebsFest
KresbsFest marks the work of Sir Hans Krebs, who won a Nobel Prize in 1953 for his pioneering work at the University of Sheffield in discovering the citric acid cycle (or Krebs cycle). This cycle explains one of the most fundamental processes of life: the conversion of food into energy within a cell.
There were six prints in the set, each of which were sized to completely fill the build-plate on my Ultimaker 2 printer. So they were all around 200mm wide, though the stages of photosynthesis that they represent range from a leaf printed at normal size, down to the print representing a chlorophyll molecule which in reality occupies an incredibly tiny area of just 23 square nanometres (0.00000000000023 cm2)!
To get an idea of the sizes of these prints here are each of them pictured alongside a standardsized Ultibot (which is a very familiar 3D print to those using an Ultimaker machine).
All of these prints were produced using Faberdashery Arctic White PLA which, because of the optical brighteners within it, works really well under the display lighting at the exhibition. Interestingly PLA is itself a product of photosynthesis as it’s produced from biomass (corn starch or sugar cane).
Printing these exhibits turned out to be a very involved process and utilised all of my skills to print with minimal waste and optimum quality. Incredibly, out of all these prints, only the chlorophyll molecule was produced using support material, and none of the prints used any infill material.
The most complex, and consequently longest print to produce, was the Photosytem II protein complex taking just over 60 hours to print. The complexity of this model gives us some idea of the complexity of nature itself and the way in which it builds it’s structures.
The Cells of a Leaf and Chloroplast prints were made up of many separately printed parts which
were then assembled to produce the final high quality exhibit.
Now, whilst these 3D prints are pretty amazing it’s nothing compared to the way nature itself
builds in minute scale. The complexity of these structures, and the scales involved, are incredible
to comprehend but here is how they relate to each other :
The process starts at the smallest scale with the chlorophyll molecule :
- This molecule absorbs sunlight and hundreds of these are bound together and convert that light energy to chemical energy within proteins called photosystems. These photosystems are just 20.5 nanometres (0.0000002 cm) in size
- Thousands of photosystems sit within the thylakoid membrane along with several other proteins and additional chemicals. Here the hydrogen produced by them splitting water using the energy of sunlight combines with carbon dioxide to produce sugars, whilst the waste product, oxygen, is released to diffuse out of the cell.
- These thylakoid membranes sit within the chloroplast where they are so tightly folded that they provide a massive surface area for light absorption.
- The chloroplasts themselves are just one of the small dots on the spheres in the cells of the leaf. The structure of the leaf is nature’s version of a solar panel and the architecture in this structure ensures that water can escape and carbon dioxide can be captured.
- These cells finally make up the leaf which is such a familiar part of nature that we see around us.
Only when you are able to see each of these elements scaled up and produced as physical models do you get any kind of understanding of the how they build together into an incredibly complex hierarchy of structures.
3D printing gives us the opportunity to produce physical models with this level of complexity and accuracy of reproduction from the nano-scale data, and in the process allows us to better appreciate the unseen world of nature.
Many thanks to Nate Adams for giving me this amazing opportunity to apply 3D printing in this way, for bringing the complexity of photosynthesis to life for me (and hopefully many others), and for his contribution to this article.
Krebsfest runs from October – November 2015 at University of Sheffield. These prints will be displayed in the Western Bank Library exhibition space until February 2016.
Written by Steve Cox
CREATE Education Project – Ultimaker GB