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December 5, 2005 | A version of this story appeared in Volume 83, Issue 49


Sight for sore eyes

I am a chemist working in an engineering environment. I recently saw something through an optical microscope that I did not expect to see. In fact, it sent my heart racing. Molecules of hyaluronan, a biomacromolecule, appeared to self-assemble before my very eyes. I repeated the experiment several times and found that the results were reproducible. The highly ordered and crystalline structures showed a periodicity and a long-range order that I never thought was possible.

As a good scientist, I captured all these images and searched for a scientific answer. It appears that heat generated from the light source used during optical microscopy of hyaluronan fragments triggers self-assembly. Perhaps the light sources removed water from the hydrated oligomers and caused them to crystallize into incredible structures that already existed in solution. I am not sure about all the details, but I thought I would let the readers get a peek at the diversity of the spontaneous structures I found.

The crystalline matrices seen in these images open the mind to a number of possibilities. Hyaluronan, a versatile biopolymer and chief architect of the extracellular matrix and the human eye vitreous, never ceases to amaze me. Its properties outside of human tissue have far-reaching implications for biomaterials research. I envision the first biocompatible integrated programmable device. I suspect this technology will blossom, and I recommend that such devices resulting from this technology be called Nano-BITS, for Nanoscale Biocompatible Information Transfer Systems.

I can't wait to tell more.

Raymond E. Turner
Cambridge, Mass.

Nuclear fuel retrieval

The controversy over Yucca Mountain and safely storing waste for millions of years ignores the reality of our world's long-term energy needs. Over a time frame going beyond 100 years, fossil fuels will be largely depleted and the world will be forced to rely on reprocessed nuclear fuel and breeder reactors for energy. Our current policy utilizes a small portion of mined uranium and buries the remainder for eternity.

Reprocessed nuclear fuel and breeder reactors would permit total utilization of actinides. Quite likely, hydrogen transportation fuel would be made by electrolysis of water using nuclear-generated electricity. I rather doubt that renewable sources of power, such as solar, wind, hydroelectric, geothermal, wave, and tidal power, can be utilized to such an extent that nuclear-generated electricity could be ignored.

One of the design considerations of a reactor-fuel-storage facility should include the retrieval of that fuel at some future time for reprocessing and reuse. Over a very long time, spent nuclear fuel rods will be too valuable a resource to leave buried in a place like Yucca Mountain.

James Ingemanson
Crystal Lake, Ill.


The letter by Raymond E. Turner was updated on Oct. 19, 2022, to clarify that the heat from the light source is the part of the light source that seemed to trigger hyaluronan fragments’ self-assembly.



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