Nanoscience in Nature Or “Why Don’t Water Striders Get Wet?” and Other Burning Questions • By Jeannie Nye • Lake Mills Middle School • Lake Mills, WI
So, Why Don’t Water Striders Get Wet? Water striders are able to “walk on water” for a number of reasons. Striders are assisted by five things: • surface area • gravitational forces • surface forces (van der Waals force) • a waxy (hydrophobic) surface on their legs Tell me more! (Click here.) • And most important - • The microhairs on their feet are • ‘nano-groovy’ ! Tell me more! Microhairs Nanogrooves on microhairs http://whyfiles.org/shorties/walk_on_water.html
Sticky Spider Toes These are the single hairs (setae) that make up the tuft of hair on the bottom of a jumping spider’s foot. The oval represents the approximate size of the foot magnified to 270x. Water strider toes help keep it dry, but this spider’s toes help make him sticky! This picture, magnified 8750x, shows the very dense nanosized setules on the underside of just one of those many seta (hairs) shown in the picture above. http://www.primidi.com/2004/04/26.html Tell me more!
Lots of nano-toes! • Beetles and flies also have nanostructures that help them stick to walls, ceilings and what appear to be smooth surfaces.Tell me more! • http://shasta.mpi-stuttgart.mpg.de/biomaterials.html http://shasta.mpi-stuttgart.mpg.de/research/Bio-tribology.htm
How sticky? As sticky as a … • 500,000 hairs per toe • Hundreds of nanoprojections (spatulae) per hair • Adhesive force in one foot = 100 newtons • One dime-sized spot could lift a child weighing 45 pounds. Tokay Gecko Stats: Gecko? http://pubs.acs.org/cen/critter/gecko.html http://www.cbid.gatech.edu/resources.htm If their feet are that sticky, how do they pick up their feet?
How Can a Gecko Lift Its Foot Off of a Surface? These lizards uncurl their toes like a paper party favor whistle when putting their feet down and peel the toes back up as if removing a piece of tape when they step away. http://pubs.acs.org/cen/critter/gecko1.html
How strong? As Strong as… Silk? • The nanometer-sized biodegradable threads of spider silk are stronger, by weight, than high-tensile steel. • It is also elastic enough to stretch up to 10 times its initial length.
Toucan Beaks - Strong and Light • The exterior of the toucan beak is made up of overlapping nanosized tiles of keratin, the same protein that makes up hair, fingernails, and horn. Keratin tiles glued together http://www.nuthatch.birdnature.com/jan1897/toucan.html The interior of the beak is a rigid foam made of a network of nanosized bony fibers connected by membranes. This allows the beak to absorb high-energy impacts. Foam-like interior made of bony fiber and drum-like membranes http://search.eurekalert.org/e3/query.html?qt=toucan&col=ev3rel&qc=ev3rel http://pubs.acs.org/cen/news/83/i50/8350toucan.html
What Makes Color? There are three possible reasons for color: • One reason is pigment. If color is due to pigment, the color never changes. For example, a bluejay is always blue. Though pigment isn’t based on nanoscience, the next two examples of ways to create color are based on nanoscience. http://acept.la.asu.edu/PiN/rdg/interfere/interfere.shtml
Or Could Color Be Nanoscopic? These nanostructures don’t just make me pretty. They also keep me clean by shedding water and dirt! 2. The colors of beetle and butterfly wings come from the scattering of light. Light hits the nanostructures on their scales. These nanostructures are typically smaller than the wavelengths of visible light (smaller than 400 nanometers, for example). Tell me more! (weblink) http://pubs.acs.org/cen/critter/butterfly.html
Color Can Be Iridescent, Too! 3.The third reason for color is the interference of different wavelengths of light (like oil on water). Thin films are made ofnanoparticles, smaller than 400 nanometers, that produce iridescent (rainbow-like) colors when light strikes them. Iridescent colors change when you look at the object from different angles. Tell me more! (weblink) http://acept.la.asu.edu/PiN/rdg/interfere/interfere.shtml http://www.ptfe.gatech.edu/faculty/mohan/MSLAB-research-nanobiooptics.htm
Squid Lightson a Nanoscale Would somebody turn on the lights, please? First, it has a light-producing organ on its underside. How does it produce light? Why, it contains bacteria that produce luminescent light on the nanoscale. • Secondly, the squid has stacks of silvery nanoplatelets made of proteins behind the tissue to reflect the light downward from the squid. • The light prevents it from casting a shadow when seen from above or forming a silhouette when seen from below. The Hawaiian bobtail squid uses a two part process to hide from predators at night. http://pubs.acs.org/cen/topstory/8202/8202notw3.html
“You Light Up My Life” orBioluminescence Basics • Bioluminescence in fireflies is nanoscale. The glow is caused by the exciting of electrons by a firefly’s enzyme. • When the electrons quiet down and go back to their stable state, they give off light. • They glow to attract mates and communicate. What’s an enzyme? • Angler fish use bioluminescent lures to attract fish. http://pubs.acs.org/cen/science/84/8414biolum.html http://www.anglerfish.info/
A “Blue Light Special” • Tiny crustaceans, Ostracods, also known as "seed shrimp" or "sea fireflies," also use this enzyme to produce bioluminescence in courtship. The males produce blue dots in the water, which are used to attract mates. A close-up using a scanning electron microscope http://www.pisces-conservation.com/index.html?softost.html$softebookmenu.html http://pubs.acs.org/cen/science/84/8414biolum.html
Jellyfish Lights A jellyfish-type invertebrate, called a siphonophore, uses red bioluminescent lures created at the nanoscale to attract prey. Doesn’t it seem odd that it would use red light since red isn’t easily visible underwater? Click here for a weblink to a video and lesson on bioluminescent deep sea organisms. http://www.coml.org/medres/high2005/highlightimages.htm
Hippo Sweat is Nanoscience? Hippo sweat contains compounds that absorb light in the range of 200 – 600 nanometers. This compound protects the hippo’s skin like sunscreen. http://www.pbs.org/kratts/world/africa/hippo/index.html One of the compounds in hippo sweat, hipposudoric acid, inhibits bacterial growth and is hydrophilic, too. Can you think of ways the hippo benefits from these properties? http://pubs.acs.org/cen/news/8222/8222notw9.html
Get Ready, Get Set, Drink! • Imagine you’re a very thirsty tiny beetle in a desert. How can you get a drink? • The Namib desert beetle in the deserts of southwest Africa has a novel idea. • First it must collect drinking water using its wings, which are waxed and covered with raised unwaxed nanobumps. The bumps attract water (hydrophilic). When enough water collects it rolls down the waxy areas, which repel water (hydrophobic), into the beetle’s mouth. Click here for more information! http://www.newscientist.com/article.ns?id=dn1508 A closeup of the nanobumps on a beetle’s back. http://biomechanics.bio.uci.edu/_html/nh_biomech/namib/beetle.htm
Speaking of Water…Let’s Look at Snowflakes! Have you ever looked closely at a snowflake and wondered why they’re all different?
It’s Because They’re Nano-Flakes! They build up on the nanoscale, one molecules at a time. Their size and shape is determined by the altitude and air pressure where they are formed. Use the same bottom up construction to make your own snowflakes by clicking on this web link: http://profhorn.meteor.wisc.edu/wxwise/snowflake/makesnow.html For more information click on the following link: http://www.its.caltech.edu/~atomic/snowcrystals/primer/primer.htm
Nanoscience Is Everywhere in Nature • Living cells have been using their own nanoscale devices to create structures one atom or molecule at a time for millions of years. • To be specific, DNA is copied, proteins are formed, and complex hormones are manufactured by cellular devices far more complex than the most advanced manufacturing processes we have today. Click here for an example! http://dallas.bizjournals.com/dallas/stories/2001/09/10/focus2.html?page=3
Mother Nature Mankind has always found inspiration in Mother Nature. Today developingtechnologies allow us to probe and better understand the nanoscience of Mother Nature.