J-WAFS in Action: ‘Living sensors’ to detect water contamination
Tzu-Chieh Tang (Zijay) is a doctoral student in the Department of Biological Engineering at MIT, funded by the Abdul Latif Jameel Water and Food Security Lab (J-WAFS). His research is focused on developing ‘living water sensors’ that can record contaminant levels in water supplies and serve as bioremediation tools. Originally from Taiwan, Zijay joined MIT after completing a masters at the Masdar Institute in the United Arab Emirates.
J-WAFS communications and program manager Andi Sutton spoke to Zijay about his research and its aims.
What brought you to study with J-WAFS at MIT?
When I was an undergrad, synthetic biology was a relatively new field. I came across a paper that looked at how you could apply the principles of computer science and electrical engineering to do circuit design in living cells, and I thought, ‘This is really cool!’
I’ve always looked to nature for inspiration. Many living things have self-cleaning and self-healing surfaces. They’re all out there in nature. Since it’s very difficult to replicate these processes using artificial approaches, I wanted to know how I could use a living part of nature to recreate these systems. So of course, I looked to MIT, which is one of the strongest places to do research in synthetic biology. MIT also has a strong materials science community, which appealed to my interest in materials and surfaces, so it was a good combination for me.
- What problems are you trying to address with your research?
Water sensing is usually done with electronic sensors or mass spectrometers. These methods provide better results than current biological sensors can provide. Even though bio-sensing has been understood for a while, people haven’t yet found a way to deploy bio-sensors safely and cheaply. Our lab is trying to solve this problem. We want to prove how bio-sensors can have advantages over electronic sensors, like functioning without a power supply, so they can be used in remote areas that lack modern infrastructure.
- How do your biosensors work?
Our lab is engineering living materials that can sense and respond to environmental stimuli. We are using synthetic biology to engineer microbes, such as E. coli and budding yeast, to sense and record specific contaminants (heavy metals and other chemicals) by lighting up when they come in contact with them.
The major challenge of making a device out of living materials is that there is no actual structure to contain the cells. The E.coli that we use are free-floating; they don’t form a bulk material. So, we worked with Professor Xuanhe Zhao’s group in the mechanical engineering department at MIT, to use a tough hydrogel they developed to contain the microbes. This serves as a division of labor: the hydrogel provides the structural integrity, and the engineered bacteria do the sensing.
- Does this produce the self-generating living system that you were originally inspired to make?
Actually, no. What we’d really like to do is see if we can make the microbes, or other living organisms, produce their own container, as well as doing the water sensing. This is what I’m working on now. I’m collaborating with someone in the Department of Bioengineering at Imperial College London, as well as another lab in MIT’s Department of Materials Science and Engineering, that uses yeasts to do bioremediation, to create a living filter that can sense and remove chemical and biological contaminants. The work is still in its early stages, but the results are promising.
- Synthetic biology research often has a long time horizon. How will you define completion for your project?
Completion will mean that we can beat the results of the electronic water sensor counterparts in terms of specificity and sensitivity. But we are not there yet. I believe that if we can show the potential of our bio-sensors to be viable water sensing products for industry, we might get more support.
- How important has J-WAFS’ support been for your research?
One area I’m keen to do further research is in optimizing the sensors to see the true extent of their potential. This is another way that J-WAFS has been really helpful. Through J-WAFS, I was introduced to people at Xylem Inc., another J-WAFS research affiliate, about their interest in this work and possible future support. This would never have happened if I had not had this J-WAFS’ affiliation.
- Besides your current work, what other water research excites you at the moment?
Based on my experience and discussions with others in my field, it’s clear that there is already a lot of work being done in sensing and removing different contaminants from water, like heavy metal ions and chemicals. Right now, though, we don’t have very good sensors for pathogens like microbes. I think it would be really nice if we could use the fact that some microbes can detect others to build bio-sensors to detect pathogens in food and water. This is where we could beat electronic sensors in terms of sensitivity. The issue of biological contaminants is, to me, equally if not more important than chemical ones.
- What are your next steps after MIT?
I’m really excited about the research I’ve been doing, but last year I was involved in a start-up competition. So, I could see developing research for commercialization as a possible career path. But, there are so many things I still want to do, so I’m still exploring my options.
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