The bioeconomy at work: scientists make gold nanoparticles from soybeans

The nanotech revolution is going green in an amazing way. Soon, gold nanoparticles, one of the darling materials of the new science field, could be made by utilizing soybeans instead of environmentally damaging synthetic chemicals. A team of researchers at the University of Missouri-Columbia (MU) has discovered a technique with which to literally turn soybeans into gold, with nothing more than a little water and the gold salts used in traditional nanoparticle production processes.

The green discovery has created a large positive response in the scientific community. It sets up the beginning of a new knowledge frontier that interfaces plant science, chemistry and nanotechnology. Some are jubilant because the discovery will ensure that gold nanoparticles-based nanomedicine products would be made available even to the less developed regions of the world where farmers grow the renewable biomass needed to make the material.

MU researchers Kattesh Katti, Raghuraman Kannan, and Kavita Katti led a team of scientists that have discovered how to make gold nanoparticles using gold salts, the carbohydrates contained in soybeans and water. No other chemicals are used in the process, which means it could have major environmental implications for the future.

Researchers believe that gold nanoparticles are set to be used in a large number of new processes and products, from the capture of toxins and lethal microbes to solar cells, cancer therapies, next generations of computer and telecommunications tools, and in the production of 'smart' electronic devices and sensors. By making them from renewable biomass the bioeconomy receives another boost.

Kattesh Katti, professor of radiology and physics in MU's School of Medicine, senior research scientist at MURR, director of the University of Missouri Cancer Nanotechnology Platform and one of the fathers of the use of gold nanoparticles in nanomedicine comments on the advantages of the green process his team developed:

Typically, a producer must use a variety of synthetic or man-made chemicals to produce gold nanoparticles. In addition, to make the chemicals necessary for production, you need to have other artificial chemicals produced, creating an even larger, negative environmental impact. Our new process only takes what nature has made available to us and uses that to produce a technology that has already proven to have far-reaching impacts in technology and medicine.

Gold nanoparticles are tiny pieces of gold, so small that they cannot be seen by the naked eye. While the nanotechnology industry is expected to produce large quantities of the particles in the near future, researchers have been worried about the environmental impact of the global nanotechnological revolution.

To complete the formation of gold nanoparticles, harmful synthetic chemicals such as hydrazine, sodium borohydride and dimethyl formamide are needed in lengthy synthetic processes. These chemicals pose handling, storage, and transportation risks that add substantial cost and difficulty to gold nanoparticle production. These harmful chemicals also make it impractical, if not impossible, to produce gold nanoparticles in-vivo.

The MU research team turned to Mother Nature for assistance and alternatives. Amazingly, they found that by submersing gold salts in water and then adding soybeans, gold nanoparticles were generated. The water pulls a phytochemical(s) out of the soybean that is effective in reducing the gold to nanoparticles. A second phytochemical(s) from the soybean, also pulled out by the water, then interacts with the nanoparticles to stabilize them and keep them from fusing with the particles nearby. The process creates nanoparticles that are uniform in size in a 100 percent green process:
energy :: sustainability :: biomass :: bioenergy :: biotechnology :: nanotechnology :: green chemistry :: nanoparticles :: bioeconomy ::

This fits with what we need to do for the future. We are solving a pollution problem at the very beginning stages of a developing technology. We don't anticipate any waste or byproducts from this new process that would not be biodegradable. Every one of these compounds involved in the process already exists in nature. - Raghuraman Kannan, assistant professor of radiology

The new discovery has created a very large positive response in the scientific community. Researchers from as far away as Germany have been commenting on the discovery's importance and the impact it will have in the future.

Soy is grown worldwide and Dr. Katti's Nobel Prize winning discovery will ensure that gold nanoparticles-based Nanomedicine products would be made available even to the less developed regions of the world. - B. R. Barwale, 1998 winner of the world food prize and founder of Maharashtra Hybrid Seeds Company in India

Dr. Katti's discovery sets up the beginning of a new knowledge frontier that interfaces plant science, chemistry and nanotechnology. - Herbert W. Roesky, a professor and world renowned chemist from the University of Goettingen in Germany

Katti, Kannan, Henry White, MU professor of physics, and Kavita Katti, a senior research chemist, have filed a patent for the new process and developed a new company, Greennano Company, which focuses on development, commercialization and world wide supply of green nanoparticles for medical and technological applications.

Dr. Katti's novel methodology to develop gold nanoparticles with soy will have important implications as the field of nanotechnology blossoms and has greater needs for 'green' synthesis of gold based nanoparticles. It is a very important first step. - Sam Gambhir, director of the Center for Cancer Nanotechnology Excellence at Stanford University

The research team includes Kattesh and Kavita Katti, Kannan, post-doctoral scientists Satish Nune and Nripin Chanda, and Mizzou graduate student Swapna Mekapothula. The research was funded by grants from the National Cancer Institute. Katti recently presented the work at the annual National Cancer Institute Alliance for Nanotechnology in Cancer Investigator's meeting in October. He also will be presenting the research at the Fourth International Congress of Nanotechnology and the Clean Tech World Congress held in San Francisco in early November.

The discovery also could open doors for additional medical fields, as some of the chemicals used to make nanoparticles are toxic to humans. Having a 100 percent natural process could allow medical researchers to expand the use of the nanoparticles.

Dr. Katti's discovery of green and non-toxic gold nanoparticles is a significant step to help alleviate the pain and suffering of patients with Pseudoxanthoma elasticum (PXE) says Frances Bernham, president of the National Association of Pseudoxanthoma elasticum. PXE causes changes in the retina of the eye that results in significant loss of central vision.

The application of soy for the production of gold nanoparticles is amazing. It shows for the first time that chemicals within soy are capable of producing gold nanoparticles. This clearly marks the beginning of a new field of 'Phytochemical-Nanoscience' and opens up a new pathway for discoveries in nanotechnology. This invention will have far-reaching implications in nanoscience and technology research globally since nanoparticles of gold are used in almost every sensor design and are implicated in life sciences for diagnostic and therapeutic applications. - Puspendu Das, physical chemistry professor at the Indian Institute of Science Bangalore.

References:
Eurekalert: MU researchers go nano, natural and green - October 31, 2007.

United States Patent Application: 20070051202: Raghuraman Kannan et al. "Methods and articles for gold nanoparticle production" - March 8, 2007

University of Missouri: Kattesh V. Katti, Professor of Radiology & Physics Senior Research Scientist MU Research Reactor homepage.