The Macromolecular, Supramolecular and Nanochemistry (MSN) program of the NSF Division of Chemistry will support the research project of Prof. Ting Guo of the University of California at Davis. Prof. Guo and his students will investigate the effect of X-ray radiation on the surface chemistry of nanoparticles. The hypothesis to be tested is that irradiation of nanoparticles with X-rays release chemically reactive species like electrons and free radicals from the surface and these chemically reactive species could induce localized chemistry at the nanometer scale. If confirmed, this unique phenomenon will open up new research avenues in multiple traditional disciplines associated with nanochemistry. The project will have a significant impact on the fields of radiation physics and chemistry, radical chemistry, macromolecular chemistry and materials chemistry. The results of this study will also provide guidance to general studies aiming to develop X-ray contrast agents, radiation therapy, advanced 3D nanomaterial networks and architectures, and theories regarding the interactions of ionizing radiation with nanomaterials. The study will provide excellent training opportunities to undergraduate and graduate students who will acquire important skills in chemical synthesis and characterization, and biochemistry and a more holistic understanding of the emerging interdisciplinary field of nanochemistry.
The work supported by the National Science Foundation grant has helped create a new interdiscipline called X-ray Nanochemistry, which is defined as using nanomaterials to enhance the effects of X-rays. The outcomes from this work include the observation of several new processes ranging from increased chemical reaction yields to energy deposition. In one example, we discovered that nanomaterials can enhance the rate of polymerization by over 30 times when the monomers are exposed to X-rays in the presence of nanomaterials. We call this enhancement process chemical enhancement because it is caused by the catalytic nature of the nanostructures we create and employ. This discovery may lead to the making of polymer nanostructures for the semiconductor industry that can be activated by highly penetrating X-rays. In another example, we predict that it is possible to amplify the X-ray effect by over 50 times if a network of nanoparticles is used. We call this process physical enhancement because it does not rely on the chemical properties of the nanomaterials we employ. An immediate extrapolation from these two findings is that if they are combined, then it is possible to increase the effect of X-rays by over 1,000 times. This means that the amount or dose of X-rays used in a regular computed tomography (CT) may be used to treat cancer if nanomaterials or nanomachines are built and delivered to the cancer cells, or that X-rays can be used to trigger chemical reactions buried deeply in solid or opaque media such as a polymer reaction inside a computer chip. Essentially the discoveries made in this grant period have shown that X-ray Nanochemistry can be widely utilized in many important applications such as X-ray lithography, X-ray sensing, X-ray guided therapy, and X-ray nanobiology. The instrumentation created in this work is inexpensive, which will allow any universities or colleges to acquire a similar device for research and training purposes. This helps to build a more advanced national research and training infrastructure. The graduate and undergraduate students involved in this work have been well trained and they are representing the first generation of scientists to be working in this exciting new field that will contribute to the growth of our economy as well as raising our national scientific profile.
