Colors and Critters

Like many of my classmates, I feel the pressure of a second-generation teenager trying to fulfill my parents’ aspirations. I have to admit I’m pretty “white-washed,” but my Indian culture—from the spicy satisfaction of a crispy, golden samosa to seeing my groom ride in on a horse—holds a place dear to my heart. As a dancer, I love the colorful outfits most of all. 

I know that my grandmother’s neighbor’s sister’s gardener set us up with these silk dresses, but where did they really come from? To put it bluntly, they came from bugs. Silkworms. I refuse to share a room with a spider, but thank goodness for these little guys. Silkworms are just about three inches long and—fun fact—shed their skin five times as larvae. For over 5,000 years, they have been spinning cocoons for silk production. But these fibers are creamy white, and most of us want something more interesting. The energy consuming practice of dying silk externally creates so much toxin-filled wastewater that scientists have turned to a new method: feeding caterpillars dyed leaves. The silkworms are fed just before they start spinning and can then spin colored, rather than white cocoons. Pretty cool, right? Researchers in Pune and Mysore dipped mulberry leaves (their food) in azo dyes and found that three out of seven types of dyes transferred into the caterpillars’ silk and fortunately did not affect their growth.

Why did some dyes work, and others not? Basically, certain dyes dissolve better in water than others. If you want to get technical, it has to do with the hydrophobicity of the dye as it goes from the feed to silk fiber. Scientists look at how the coloring dissolves in a hydrophobic solvent like octanol (it has a phobia of water) to how well it dissolves in water itself. The more hydrophobic, oily molecules tend to show up in the silk because they aren’t easily cleared from the silkworm’s body. Hydrophilic (water loving) coloring molecules, on the other hand, are often dissolved out when the cocoons are dipped in water. Using the right dye can produce vibrant yellows, pinks, and greens without the dangers of external dying.

The bottom line here is that these ideas are pretty great—a greener way to make beautiful clothing. If research goes well, there will definitely be perks. When I get dolled up for an Indian wedding or shindig, I won’t have to feel guilty for killing some innocent fish. (Three dead pet goldfish are all a girl can take).

But wait, it gets even better. The super silk has healing powers too. Researchers in Singapore found that the feeding process may be used to create thread with antibacterial properties. Antimicrobial drugs can be transferred into the silk just like the dye, and slowly released through an implant. To be honest, I’m up for any way to avoid choking on another white pill during flu season. The possibilities are endless, really. The same researchers are now monitoring cancer cells by feeding silkworms cancer-fighting drugs.

New methods for cultivating colored silk certainly look promising. I have a new found appreciation for the stranger who makes my grandmother’s outfits—who will help make my dream wedding dress a reality. If you’re curious, look here.
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N^2: DCDS, 2014.  I will be attending the University of Pennsylvania in the fall. I like music, travelling, and chemistry.