Unit 5 Lesson 10: Using Organic Compounds
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organic compounds
class of compounds containing carbon covalently bonded to certain other atoms, especially hydrogen, oxygen, and nitrogen
Some useful materials can be developed by observing and copying nature. Spiders are so tiny, and yet in their amazing chemical-factory bodies, they produce silk that is stronger than steel and tougher than bullet-proof Kevlar fabric. Furthermore, they produce it at room temperature, with just water and amino acids, the molecules that bond together in proteins.
Spiders are able to make a variety of silks that performs various functions by altering the structure. The fiber spiders make is biodegradable and causes no environmental problems. In contrast, nylon, a human-made plastic fiber with many of the same uses as silk, is not biodegradable and is a source of pollution. If humans could figure out how to make fibers the way spiders do, it would be much better for the environment.
State two ways that spiders make their silk sticky.
In one way, spiders affect the shape of the fibers. They back-comb the silk to give it more surface area and greater intermolecular forces. In a second way, they apply water-based glue.
Scientists have been studying and trying to copy spider silk for decades. They have learned that spider silk has these amazing properties:
• strong • shock-resistant • elastic • sticky • biodegradable • tough • biocompatible with humans
People have used spider silk in fabrics and as wound coverings.
. It has antiseptic properties and vitamin K, which helps blood clot. Of particular interest is the use of spider silk as a coating for surgical implants without causing allergic or immune reactions.
Rigid spider silk fibers have a toughness factor of 180 megajoules per mete
. Kevlar, one of the toughest fabrics scientists have ever yet made, has a toughness factor of just 50 megajoules per meter. Spider silk, with a spiral structure, is also flexible and elastic. Spider silk occurs in nature, while Kevlar does not.
The variations are due to the spider silk content:
The stronger silk seems to contain more of the amino acid, an organic compound. In contrast, the more elastic silk seems to contain more of the amino acid glycine.
How large are gold nanoparticles?
5 to 400 nm
Part of what what makes Kevlar so strong is the arrangement of the molecules composing the fabric.
The molecules that compose Kevlar are long and have strong chemical bonds. The molecules stack closely together in crystal-like structures, adding to the strength of the fabric. A similar arrangement of molecules can be seen in spider silk, providing an example of how scientists make innovations by observing nature.
Using genetic engineering, however, researchers have been able to use other animals to produce spider silk proteins. So far, these molecules have been made from
the milk of goats modified Escherichia coli (E. coli) bacteria modified silkworms
Gold nanoparticles are able to partner with molecules to sense cancer cells in the body.
As cancer cells grow, the genetic material and protein in them change. These changes result in the emission of a kind of “smell” caused by volatile organic compounds that can even be sensed by specially trained cancer sniffing dogs. Sensor molecules with gold nanoparticles on them are able to sense these compounds, too. The sensor molecules give a “reading” as to whether cancer is present, as well as the type of cancer, such as prostate, colon, lung, or breast cancer. Radioactive gold nanoparticles are also expected to be used for targeted cancer treatment in the near future. So far, trials have been effective on mice and dogs.
Gold nanoparticles paired with special polymers can also stick to drug-resistant bacterial strains and tear open the cells, killing the bacteria.
As the bacteria are destroyed, the nanoparticle polymers are also destroyed and rinse away harmlessly.