I bet you didnt know Slug slime might

I bet you didn’t know… Slug slime might be the answer for medical adhesives Teacher Guide Curriculum Areas Ages Materials Animal Adaptations Chemistry 7 -11 years

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Who are the scientists? Tough adhesives for diverse wet surfaces J. Li, 1, 2, 3 A. D. Celiz, 2, 4 J. Yang, 1, 5 Q. Yang, 1, 5, 6 I. Wamala, 7 W. Whyte, 1, 2, 8 B. R. Seo, 1, 2 N. V. Vasilyev, 7 J. J. Vlassak, 1 Z. Suo, 1, 5 D. J. Mooney. 1, 2 Science 357, 378 -381 (2017) 1. John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA. 2. Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA. 3. Department of Mechanical Engineering, Mc. Gill University, Montreal, Quebec H 3 A 0 G 4, Canada. 4. Advanced Materials and Healthcare Technologies Division, School of Pharmacy, University of Nottingham, Nottingham NG 7 2 RD, UK. 5. Kavli Institute for Nanobio Science and Technology, Harvard University, Cambridge, MA 02138, USA. 6. School of Aerospace, Tsinghua University, Beijing 100084, People’s Republic of China. 7. Departments of Cardiac Surgery, Boston Children’s Hospital, Boston, MA 02115, USA. 8. Advanced Materials and Bioengineering Research Centre, Royal College of Surgeons in Ireland Trinity College Dublin, Ireland. Why are there so many different people from different universities and institutes working on this project? How did they manage to work together on this project?

What did the scientists know? There was a need for improved adhesives to use in medical applications, especially in wet conditions. Medical adhesives must satisfy a strict set of conditions to be useful. © Omegatron, licenced through Creative Commons © US Air Force photo/ Airman 1 st Class Jason J Brown Surgeons need a range of adhesives to use in different situations, both internally and externally. Various versions of Super glue have been developed for medical use. They tend to be cytotoxic though and don’t adhere well to wet surfaces.

What else did the scientists know? Nature can be an excellent source of inspiration for tackling many of our challenges. Some animals produce very strong adhesives that are effective in wet conditions. Mussels produce very strong adhesives that work well in very wet conditions. © Erik Veldhuis; modified by T Meijer, licenced through Creative Commons Slugs secrete a defensive slime that adheres very strongly to wet surfaces. What other inventions have been inspired by nature? Can you think of anything in nature that might be useful to solve a problem we encounter?

What did the scientists do? Scientists from around the world collaborated on a project to study the mucus from a species of land slug, Arion subfuscus. Why were they particularly interested in the mucus from the slug? What specialisms of scientist would have been useful on this project? In the laboratory they chemically synthesised a range of tough adhesives (TAs) based on the structure of the slug’s mucus. What do scientists mean when they talk about chemical synthesis? An example of chemical synthesis

What did the scientists find out? A species of land slug, Arion subfuscus, secretes a defensive mucus that strongly adheres to wet surfaces. The adhesive mucus adheres strongly in wet environments, is flexible and non-toxic to human cells. The resulting tough adhesives are very versatile in a range of medical situations. They can be applied as patches or injected as liquids. Researchers concluded that the adhesive secreted by slugs could be the ideal basis for a new family of medical tough adhesives.

Quick activity Which common adhesives are the strongest? Give pupils a range of common adhesives and sticky tapes and ask them to design an investigation to see which is the strongest. Pupils need to design a fair test investigation and find a way to measure how strong each adhesive is. © André Karwath, licenced through Creative Commons Resources PVA glue, glue stick, sticky tape, packing tape, masking tape, insulating tape, variety of objects to hang

Longer investigation Can you make glue from different ingredients? Make three different glues with the following ingredients. You’ll find easy-to-follow instructions online. The glues are best if they are heated while making, so you probably need to demonstrate making them rather then let the pupils do it. Flour & water with salt Milk, vinegar & bicarbonate of soda Cornflour, corn syrup & vinegar Get pupils to devise a fair test to find out which glue is the strongest or which is the quickest drying. They could hang a weight from the join and time how long it held, add increasing amounts of weight until the join breaks, or test the glues periodically and time which one hardens first. Resources Glues (see recipes above), strips of paper, stopwatch, weights

What did you find out? Which of your glue recipes was the best? How did you define the ‘best’ glue? How did you measure the ‘best’ glue? Extra challenge: Can you find different materials that your glues can stick together? Try fabric, wood, plastic and metal. What other materials can you find to try? Do some glues work better with some materials than others?

Questions for further learning What other products we use are a result of biomimicry? Can you think of other products we could adapt from nature? Children could find out about natural materials and processes that humans have copied and adapted for their own use. You may be interested in the Biomimicry Institute When was glue first used and how was it made? How has glue changed over the years? How are different commercially available glues made? Children could research and describe the evolution of the manufacture of glue over the years. What other methods of joining materials together are there? Children can explore the wide range of methods that exist for joining materials – if possible let them try out different methods and evaluate them for strength and efficiency. What else do you know about the characteristics of slugs? You may be interested in Arion subfuscus Fact file Burdock Velcro-like hook-and-loop fastener © Natural Philo licenced through Creative Commons

Maths links Area of learning Activity Measuring time/mass Testing the strength of the various glues Measure Measuring ingredients to make different glues

Writing links Area of learning Activity Instructions Write instructions for making different types of glue Non-chronological report Research and present a fact file, or timeline of glues through history

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