2014 Uncategorized

MIT Scientists Produce Hybrid Material

According to a paper published in Nature Materials, Massachusetts Institute of Technology (MIT) scientists recently have incorporated inorganic matter with living cells to develop a material that has properties of living and non-living things using E.coli bacteria.

Led by Timothy Lu, a professor of electrical engineering and biological engineering, MIT researchers used E.coli bacteria to produce biofilms (group of microorganisms where cells stick on a surface through adhesion) that have “curli fibers” which are comprised of protein peptides called CsgA. CsgA help bacteria attach to surfaces, allowing them to grip non-living materials.

(E.coli bacteria, the substance used to produce the biofilms that have the curli fibers. Wikipedia)

MIT News revealed that the researchers manipulated these E.coli cells to create various curli fibers. Since CsgA can only be produced under specific conditions, the researchers had to create a certain genetically engineered strain that contains a molecule called AHL. With AHL, the cells secreted CsgA and by controlling the amount of AHL present, researchers were able to control production of curli fibers. In addition, the researchers wanted to create curli fibers that can specifically grab onto gold nanoparticles, and thus produced CsgA with peptides that contain clusters of the amino acid histidine. This particular CsgA can only be produced with a molecule called aTc. The researchers manipulated amounts of AHL and aTc so that sufficient amount of curli fibers could grab onto the gold nanoparticles.

In the end, the scientists were able to produce a network of gold nanowires, which can conduct electricity.

The scientists also produced another type of curli fiber that attached to a substance coined the name SpyCatcher. The researchers put quantum dots, which are semiconductor nanocrystals, and the curli fibers were able to grab onto the quantum dots. The scientists grew the different strains of E.coli (which contained the slightly different curli fibers) and were able to create a material of both gold nanoparticles and quantum dots.

“It’s a really simple system but what happens over time is you get curli that’s increasingly labeled by gold particles. It shows that indeed you can make cells that talk to each other and they can change the composition of the material over time. Ultimately, we hope to emulate how natural systems, like bone, form. No one tells bone what to do, but it generates a material in response to environmental signals,” Lu says according to MIT news.

The recent discover of synthesizing hybrid materials that integrate living material with everyday applications gives hope for future developments such as future computers, biosensors, and biomedical devises. This research shows that perhaps a system, maybe a smartphone one day, can recognize its own defects and respond by repairing itself. Solar cells, which can converts light into electricity, may also potentially use the self healing quality of living cells to develop solar panels that can repair themselves by self command.

Now the researchers want to further explore this mechanism by coating the biofilms with enzymes, which catalyze the breakdown of cellulose and see if it could convert agricultural wastes to biofuels. Who knows what else is in store for these hybrid materials!