Scientists create biological version of synthetic coating
The work, published in the journal Nature Communications, claims the flexible, sensitive coating is easy and cheap to manufacture in large quantities and could lead to new types of applications that can handle and process very small volumes of liquid.
Principal investigator Dr. Sanjay Kumar and his researchers, funded by an Army Research Presidential Early Career Award and a Hellman Faculty Fund Award, developed a new protein brush, made from neurofilament-derived proteins, can be controlled with protein-digesting enzymes, or proteases.
The team co-opted this protein and turned it into a polymer brush by cloning a portion of a gene that encodes one of the neurofilament bristles.
By re-engineering it, the UC Berkeley professor of bioengineering says the scientists were then able to attach the resulting protein to surfaces in a precise and oriented way, before expressing the gene in bacteria to produce the protein in large, pure quantities.
'Neurofilaments are good candidates for protein brushes'
According to Kumar, neurofilaments are good candidates for protein brushes because they are intrinsically disordered proteins, so named because they don’t have a fixed 3-D shape. The size and chemical sequence of these hair-like proteins are far easier to control when compared with their synthetic counterparts.
“Proteins are generally synthesized with the exact same sequence every time; the length and biochemical order of the protein sequence affects all of its properties, including structure and the ability to bind to other molecules and catalyze biochemical reactions," he says.
Kumar says this kind of sequence precision is difficult if not impossible, to achieve in the laboratory using the tools of chemical synthesis.
"By harnessing the precision of biology and letting the bacterial cell do all the work for us, we were able to control the exact length and sequence of the bristles of our protein brush," he adds.
The researchers showed that the protein brushes could be grafted onto surfaces, and that they dramatically expand and collapse in reaction to changes in acidity and salinity. Materials that are environmentally sensitive in this way are often referred to as “smart” materials because of their ability to adaptively respond to specific stimuli.
Other co-authors on the paper include Nithya Srinivasan, Maniraj Bhagawati, and Badriprasad Ananthanarayanan, all of whom are postdoctoral fellows in Kumar’s lab.