Lab talk: Growing microflowers in the lab

Flowers aren’t only grown in greenhouses – some are grown in labs like mine.

My flowers look a bit like carnations, but with one important difference: each microscopic bloom is around the size of a single pollen grain.

We don’t make microflowers for their looks. By growing a carpet of microflowers across a material, we dramatically boost its surface area. And that could be useful in countless applications, from more efficient solar cells, to air purification systems that can filter out toxins, to super-sensitive detectors for sniffing out explosives.

Incorporating these abilities into our microflowers will be the next step in our research. Right now we’re focused on finding the perfect growing conditions.

To cultivate our microflowers, my team and I looked to nature for inspiration – and what better than our own DNA? This molecule forms its strong double helix shape thanks to powerful hydrogen bonds between neighbouring coils in the structure.

The key interaction is between nitrogen-rich groups that form the “rungs” of the DNA double helix, and phosphate groups in the DNA backbone. We mimic this interaction by making a watery solution of phosphonic acid and a nitrogen-rich molecule called melamine, then spraying this cocktail on a surface.

Even while wet, the two chemicals start to react and form sheets only a few molecules thick, bound by strong hydrogen bonds.

As the water evaporates, the growing sheets crinkle, rising up off the surface to form “petals”.

The dry flowers are only 10 microns in diameter – about half the width of the finest human hair. Their tiny petals stop water from reaching the surface, a little like the scales on butterfly wings. Droplets simply roll or bounce off.

The microflowers are non-toxic and stable if handled carefully. Next, we plan to find ways to engineer the size and shape of the microflowers, and “dope” the petals with glowing or colour-changing molecules to fine-tune them to different applications.

Who knows where they’ll spring up next?

Paper: Flower-like supramolecular self-assembly of phosphonic acid appended naphthalene diimide and melamine, Scientific Reports, 2015, vol 5, no 14609.

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