Our laboratory is focusing on creation of new molecules by directed protein evolution (protein engineering) and artificial molecular assembly (molecular engineering) and its application to new fields.
In this web site, I introduce one of our topics:
Development of a new method to visualize asbestos.
The motivation to start this research was the “asbestos issue” that came to light in Japan 2005. Asbestos is a fibrous mineral that was used for many years in construction materials, but was later found to cause diseases such as mesothelioma and lung cancer. Asbestos diseases were found in not only workers, but also their family members living around asbestos factory; therefore, in 2006, its use was completely prohibited in Japan.
However, by that period, 40 million tons of asbestos had been used in buildings in Japan. The risk of asbestos release still remains when these asbestos-containing buildings are demolished. Therefore, possible release of asbestos fibers must bemonitored when these buildings are demolished. Current regulations require electron microscopy for identification of asbestos.
The use of electron microscopy would increase the cost and duration of asbestos analysis, making asbestos monitoring impractical at demolition sites (I can not believe it!). Thus, a rapid method is needed.
It would be easier to develop the asbestos detection method if we could use an antibody for asbestos. However, since asbestos is an inorganic substance, we could not expect that asbestos possesses the ability to elicit an immune response (generate antibody), and thus instead searched for proteins that bind specifically to asbestos in cellular protein library.
Previously we had discovered a protein that binds to silicon; we, therefore, suspected that some proteins would also bind to asbestos (asbestos is a type of silicon material). So I thought that we can screen for proteins that bind to asbestos specifically.
Since asbestos causes lung disease, we searched for asbestos-binding proteins in lung tissue and found several types of such proteins. We also discovered another asbestos-binding protein from E. coli.
Rapid asbestos visualization by asbestos-binding protein
We next considered how to use the protein-asbestos interaction to make asbestos visible. We used genetic engineering to fuse a protein that binds to asbestos with a fluorescent protein and succeeded in making asbestos visible under fluorescent microscopy. Some asbestos fibers are very thin and could only be detected under electron microscopy. Now we are able to observe these fine asbestos fibers under the conventional fluorescence microscopy by using asbestos-binding fluorescent proteins.
We named this technique “bio-fluorescence method”—a new method for detecting asbestos. This was developed by interdisciplinary research between biochemistry and mineralogy. I think that this kind of research had not previously been performed (none had applied biotechnology to mineral analysis).
It might be world’s first method created by applying biotechnology to mineral analysis.
In 2010, through an industry–university collaboration, we commercialized an asbestos detection kit based on the results of this research and introduced it to the world market. The kit is very simple to use. When a few drops of a test reagent are applied on a filter containing trapped airborne dust, the fluorescent protein binds with asbestos, which can then be observed under a fluorescence microscope. The entire process is very simple. In February 2014, we collaborated with another company to jointly develop automated fiber recognition software that can detect asbestosfibers inthe fluorescence microscopy images. Using this software, anyone can quickly check for release of asbestos fiber at demolition sites.
Moving forward, we will seek to obtain certification of this method as an “official method” approved by the Ministry of the Environment.