Unbe-leaf-able: Why I don’t back this artificial photosynthesis project, yet.

by Toby McMaster

Silk Leaf, an artificial leaf made from chloroplasts and proteins extracted from silk, is the latest in a series of attempts to mimic photosynthesis. Julian Melchiorri, working with a lab at Tufts University, recently unveiled a synthetic leaf, designed to help humans colonise other worlds by providing us with much needed oxygen. Yet not everything is running as smoothly as it first seems.

The ability to recreate leaves sounds fantastic, so what’s the hitch? Well for a start it only pays up half of what it should, it duly takes in water and Carbon Dioxide, and uses light energy, but currently only reliably produces oxygen. There is no glucose and no one is really sure where the Carbon Dioxide goes. This doesn’t initially sound too bad for us: after all, assuming these things are inedible, we only need the oxygen. However if these leaves were ever to become part of a fully functional plant, these plants would need some kind of energy source. They would need glucose.

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Another obstacle lies in the physical connection of these currently isolated leaves to produce an entire plant. The xylem and phloem inside a plant’s stem, akin to the blood vessels in animals, are complex structures and at best it is naïve to think we can just stick our artificial leaves on and hope they’ll co-operate.

Finally there is currently no data (as far as I can find) on the environmental cost of producing these leaves, which is clearly a key factor in whether they are viable for a trial run on earth, before they can get anywhere near space.

However this project still has a lot of promise. It’s a step in the right direction, and the leaves actually look like leaves, which means their surface area properties are likely to be good. Moreover the fact they look like real plant bits can only help with public acceptance of them, if we ever reach that stage. This might sound like an attempt to simply come up with something nice to say, but it really is important –GM crops, vaccines and nanotechnology are examples of areas which could do a lot more for human kind if not limited by public scepticism.

Scepticism is healthy. It’s why I’m not proclaiming this project as the next big thing in science. There’s a limit though, change is scary, but sometimes it’s necessary. Scepticism without rational basis can hinder progress. Perhaps one day this leaf will help the sceptics see the light when it comes to artificial biology.

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