Researchers at MIT have published a study which confirms the ability to create self-propagating, self-repairing, living materials. This new artificial bio-material, made from the bacteria E. coli, has the potential to change everything about how humans live in our environments. The bio-material can not only self-heal, but conduct electricity, and can be used for numerous other applications. The building that fixes itself and talks to the family living within it might not be as far off as once thought.
The scientists involved in the MIT study say they were able to take advantage of a particular property of the E. coli bacterium, the ability it has to stick to the surface it is colonizing. Many bacteria attach themselves to surfaces, such as tooth enamel or the inside of an ear, and then begin to propagate, causing infections. This ability, however, can be manipulated so that industries can attach materials to the bacterium instead, and control their growth and spread.
The study, published in Nature Materials, shows how the researchers were able to in effect reprogram these bio-films which originally allowed the E. coli bacteria to attach to surfaces. These bio-films include protein chains the scientists dubbed “curli fibers.” These fibers, which contain a substance called CsgA, can be modified artificially by adding other peptide chains. Peptide chains are another kind of protein which will easily incorporate non-biological materials, which can then create living bio-materials.
Adding these secondary proteins to the curli fibers made it possible for researchers to add gold particles to the E. coli bacteria, which in turn allowed the bacteria to produce gold wires capable of conducting electricity. In other trials, the scientists were able to attach quantum dots to the bacteria. These microscopic crystals are so named because they show quantum mechanical properties. Such self-growing bio-materials could be used in the future to create very advanced computer circuits and bio-sensors for materials such as solar panels.
The experiment also allowed researchers to insure that these structures could communicate what they had “learned” to other E. coli bacteria so that the living bio-material could self-repair, and so that other bacteria could pick up the ability to incorporate these non-organic materials.
The scientists were able to do so by tagging the CsgA with another compound called histidine. Nearby bacteria were able “learn” this process from communicating with the engineered bacteria and to evolve this same ability, proving that the E. coli were able to pass on the information regarding their changes to their neighbors. What this means is that new artificial bio-materials made from these engineered E. coli bacteria could sense and communicate problems to nearby bacteria in a colony, allowing a network of these bio-materials to propagate their structures and to regenerate from any damage.
The researchers have indicated that the engineered E. coli could not, however, propagate these abilities out of control. The scientists were able to regulate the E. coli’s production of CsgA by disabling the bacteria’s ability to produce their own form of the substance. The E. coli were then engineered to produce CsgA only when another material, called the AHL molecule, was introduced. In this way, the study showed that the amount of biofilm the E. coli produced was in the control of the scientists. The presence of histidine was also regulated so that it could only appear when another molecule called Tc was introduced.
In this way, the researchers in effect created a “stop and go” signaling system. When AHL and Tc were both presented into the E. coli’s environment, the bacteria were able to produce the histidine and to incorporate the other peptides. The histidine in turn grabbed on to the other materials, such as the gold nearby, and create the living bio-wires. This ability shows one of the ways that this new artificial bio-material can change how humans live, since it can effectively grow self-healing electrical conduits and circuits.
The implications of this new living material are staggering. From self-repairing properties such as solar panels that can sense where they are damaged and produce the material to regenerate themselves, to new bio-computers with circuits such as were used in Star Trek to power intelligent living networks, this research is the basis for what could be amazing applications. One such, which could be very useful in today’s world, would be the capability to engineer self-propagating and self-maintaining bacteria to break down the cellulose from farm waste and turn it into bio-fuels in an energy-efficient manner.
With such bio-technology, used in a controlled manner, humanity may soon be able to literally grow the everyday materials needed to produce items of use. From computer circuits to solar panels to building materials for homes, the production of a stable, living material that can be adapted to so many uses would change how humans live on this Earth, and provide material that is self-propagating and renewable. Such an invention could help with the strain on resources and could be used in innumerable applications.
A few years ago, a self-healing bio-material would have been considered science fiction, but MIT’s newest research proves that at least with these new, living materials made from E. coli, science fiction is again becoming science fact. It might not be too long before humanity could produce growing materials that sense damage, self-propagate, self-repair, and even communicate with other materials nearby to form networks. Another age in human technology may be on the horizon; one wherein this new artificial bio-material can change everything about how humans live and what is made on this planet.
By Kat Turner