Artificial life Update
Cells, enzymes, photosynthesis – soon we’ll be remaking life our own way. Not to mention making our own spare body part, and taming flu once and for all
Molecules for all occasions
Whether for a new drug or solar cell, we constantly strive to design and build intricate new molecules. Making them is one thing; making them efficiently enough for commercial production is quite another. If only we could take a leaf out of nature’s book, which uses highly specialised enzymes as catalysts to churn out vast quantities of the molecules life needs.
Increasingly, we can. We can take natural enzymes and randomly tweak their structure until a variant efficiently produces the molecule we desire. For a rather less hit-and-miss strategy, we can use computer-led “rational design” modelling processes to make artificial enzymes from scratch.
Ultimately, the aim is to trump nature. Compared with artificial catalysts, enzymes are wrapped around a relatively limited range of metals at their core. By combining the best of natural and artificial catalysis, we might be able to make enzymes – and final products – that are capable of simply anything.
Endogenous stem cells
How does my organ grow?
Stem cells are arguably the most exciting frontier in medicine right now. Most cells of the human body are irreversibly specialised or “differentiated” into roughly 200 types. Stem cells, on the other hand, are blank slates with the potential to develop in many different ways.
That means they could be used to heal a myriad of damaged or diseased tissues. Most research so far has focused on creating them from embryos or adult tissues in the laboratory, manipulating their development using chemical “growth factors” and implanting them where needed. But there could be a cleverer way: to awaken our bodies’ own “endogenous” stem cells to achieve natural regeneration.
Other animals do this. Amphibians, for example, can regrow entire lost limbs while hobbling about their daily business. Some day, the thinking goes, simply injecting the right chemicals might be enough to allow us to grow a new kidney or pancreas – or even a leg.
Energy out of thin air
A leaf is a beautiful thing. It is also a wonder of chemical engineering. Within it, photosynthetic reaction-centres collect solar energy to drive the transformation of water and carbon dioxide in the air into sugars that nourish and build the plant.
Would that we could do something similar. The sun is by far the biggest energy source we know, but sunlight can’t be everywhere all the time. If we could find a cheap way to convert solar energy into storable, transportable chemical fuels available 24/7, we would be well on our way to clean energy for all.
Some pieces of the jigsaw are already in place. Tiny light-collecting particles can be embedded on a membrane to absorb energy and split carbon dioxide and water molecules. The products are not sugars, but carbon-neutral transportation fuels: hydrogen, methanol and, in the future, high-energy-density fuels optimised for specific vehicles such as aircraft.
This year, the US Department of Energy earmarked $122 million to set up the Joint Center for Artificial Photosynthesis in California. Here and across the world the race is on to develop new absorbers, catalysts and membranes that will permit the large-scale realisation of an idea that could change the world for good. Nate Lewis
Nate Lewis is a professor of chemistry at the California Institute of Technology, Pasadena, and director of the Joint Center for Artificial Photosynthesis
A universal flu vaccine
Taming a global killer
Bird and swine flu might have receded for now, but the top candidate for a global pandemic remains: a novel strain of flu.
That is because flu mutates, so catching it one year may not stop you from catching it the next. This is why we make new flu vaccines year after year. It is also why every few decades a flu strain appears with the genetic novelty to evade our herd immunity and wreak global havoc.
How to stop that? By developing a universal vaccine effective against all strains. Various possibilities that trigger an immune response against the parts of the virus that don’t mutate are in the works. Several have reached trials in people. If they prove effective, flu could soon become just one more half-forgotten disease that we vaccinate children against