Scitech | Nature knows best

Prof talks science that mimics materials found in the natural environment

A ll it takes to make the finest products is a couple of eons of evolution. The best computer? The brain: crash-free, pre-installed, plug and play, wireless. The material with the best compression strength? The femur bones in your very own legs.

The most efficient solar cell in existence comes with free installation. It’s biodegradable and not on the market. Leaves are superior at converting light into energy compared to anything that people with doctorates and research labs have been able to design.

On September 9, Christopher Barrett, a professor from McGill’s chemistry department and a member of the Centre for Self-Assembled Chemical Structures, gave a talk at the Redpath Museum entitled “Mother Nature as a Green Materials Engineer.” The lecture was part of the Cutting Edge lecture series, a program established in 2003 that grants public audiences a look at a variety of interdisciplinary scientific innovations.

Barrett’s take-home message was that nature makes an excellent collaborator when it comes to materials science. “[Nature is] offering us 3.8-billion years of research and development, at no extra charge,” said Barrett.

Many of the progressive products of evolution exist on the nanoscale, with dimensions less than the width of a human hair. DNA, for example, is both the world’s most intricate set of blueprints and the smallest.

Spider silk is another example. Spun by hundreds of tiny spinnerets, the material has a greater tensile strength than steel when compared in terms of weight. However, since a spiderweb’s strength is relative to its size, harvesting the material is impossible in its existing producible quantity.

Much of the work that Barrett discussed seeks to emulate nature, rather than collect it. “[Scientists are] not just harvesting [natural] materials, but understanding the process to make these things,” said Barrett. This venture concedes to nature’s small construction scale and bottom-up building scheme. There are no tweezers tiny enough to handle objects on the nanoscale and so the trick is to mimic not just the finished product – say, an assembled strand of DNA – but to invoke the self-assembly feature that comes built in to 100 per cent natural products.

Compounds naturally make their way through the assembly process without the help of construction workers. If it costs less energy for a protein to fold into a particular shape rather than remain as an unstructured strand, then that is what it will do; nature prefers to exert the least amount of effort and to find the lowest thermodynamic state. Engineers manipulate this concept with protein “soups,” studying, for example, what combination of genetic building blocks will assemble themselves into various DNA origami shapes like stars or squares.

Practical applications of self-assembled, nature-inspired creations include biocompatible surfaces for objects ranging from contacts and stitches to heart valves – products that need to interact with the human body without being rejected by it. There are also applications of biomimicry in light-activated therapeutics – polymers that self-assemble in water and break down under light, and are thus easy to turn on and off.

However, research in self-assembly can be difficult as it often requires an aquatic medium or environment. Computer parts need to be dry, making it difficult to integrate biological innovations, both natural and lab-made, into electronics.

Self-assembly is also a complicated process. On small scales, every hydrogen bond, every charge on every compound, matters a lot. “In order to exploit self-assembly, we have to understand self-assembly,” said Barrett.

Though he notes that self-assembly and biomimicry research is currently taking baby steps, Barrett remains enthusiastic and inspired by every development.

“We’re impressed with everything,” said Barrett. “It’s nice to feel humbled as a scientist, trying to replicate what’s already been created, what’s already evolved.”

The next lecture in the series is titled “Can we erase memories for therapeutic benefits?” and will be held on October 8 at 6 p.m. in the Redpath Museum.


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