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Biomaterials Topic #2: Surface Properties Name: 1. Aquaman has very durable skin and is able to swim at 150 mph in part due to his superhuman strength but also the surface properties of his skin.
(a) What skin ‘surface’ properties might contribute to this super swimming ability?
(b) From the diagram below, which of the following two skin samples (shown with a
drop of water on top) is likely Aquaman’s? Justify your answer.
(c) Why does water ‘bead up’ on surface B? (d) If we were to base a new biomaterial for artificial skin on Aquaman’s skin, what
surface properties of the material would we be interested in (in addition to hydrophobicity)?
(e) Now consider a material designed to interact with the tissues inside the body (i.e. muscle, blood vessels, blood, organs, etc.)? Between A and B, hypothesize which type of surface would be more biocompatible when interacting with these tissues.
(f) In fact, oftentimes scientists base new material designs on the amazing adaptations that nature has made for survival. For example, from http://www.slate.com/articles/news_and_politics/uc/2013/06/how_the_university_of_california_is_creating_real_life_superheroes.html:
“You might think twice about poking a toe in the Amazon River, but there’s one hefty fish that has no need to fear its predators. The Brazilian arapaima has evolved an impenetrable layer of armored scales that protect it from the piranha’s bite. When UC San Diego researchers took a closer look at this remarkable fish, they saw potential for an entirely new kind of military grade body armor. Professor Marc Meyers of UC San Diego’s Jacobs School of Engineering leads the team that, inspired by arapaima, is developing a class of high-‐tech ceramic materials that are hard, light and flexible. “I was fishing for arapaima and realized that they live in lakes infested with piranha,” said Meyers. Meyers began to wonder about the properties of this special fish. As he reviewed the existing literature, he was surprised to discover that no one had studied the arapaima’s resistance to the piranha’s deadly bite. “The arapaima has unique armor. It has a surface layer that is highly mineralized and therefore hard. This rides on a foundation made of collagen organized in cross-‐plied layers. Thus, the scales are both hard and flexible.” Soon, the arapaima’s superpower will be more widely applied – as Meyer’s new, flexible ceramics make possible a range of products, from bullet-‐proof body armor to puncture-‐resistant packaging.”
What techniques did Dr. Meyers likely use to analyze this unique material before trying to replicate it? 2. Biomaterials are ‘seen’ via their surface properties. Surface properties can be modified by changing the chemical or physical nature of the surface. If a certain biomaterial has an unfavorable reaction in the body (scar tissue formation, immune response, encapsulation, etc.), hypothesize what specifically might be done to change the material.
3. Match the desired experimental outcome with the appropriate technique (select the one best answer for each): If you want to… …then you use which
technique? Examine the topological patterning present on a surface
AFM
Identify the surface chemistry via the vibrational nature of the bonds
STM
Measure the electron cloud density of the surface
FTIR
Pretend to be Superman and use X-‐rays to identify atoms at the surface of a material
SIMS
Measure the mass to charge ratio to identify the chemical nature of the surface
Electron microscopy
Measure the force of interaction between a surface and a probe tip
ESCA/XPS
4. Read the attached article from The Telegraph.
(a) What inspired the design of the device developed by Dr. Steen? (b) Describe the importance of surface tension in the device design.
(c) Can you come up with any biomedical uses for this type of technology?