All his life, Doug Blackiston has been fascinated by metamorphosis — the way that one object changes into another. “As a kid, I loved those toys that start as one thing and transform into something else,” he recalls. He was interested in nature, too. He grew up in the country and searched nearby ponds for frog eggs, which he collected in jars. “Then I watched them change from eggs to tadpoles to frogs,” he says. “You’d never guess those creatures were the same life-forms if you didn’t know.”

Now a biologist at Tufts University in Medford, Mass., Blackiston remains fascinated by how living things transform. His specific interests have changed, but only a little. He’s tried to figure out, for example, what a caterpillar remembers after it turns into a butterfly.

More recently, though, he’s focused on coaxing cells to transform in specific ways, either on their own or through human intervention. He says that cells can become building blocks for new machines and then programmed to do useful work.

For example, he was part of a group of scientists who recently assembled cells into living robots. These tiny bots are about as big as a grain of coarse sand. “If you take a poppy seed and cut it in half twice, that’s their size,” Blackiston says.

These bots can move on their own and heal themselves after small injuries. They can also complete tasks, like working together to push objects from one place to another. In late November, his team even showed that the robots can now replicate, or make copies of themselves. The robots are made from cells of the African clawed frog, or Xenopus laevis. The scientists call their creations “computer designed organisms.” Outside of the lab, though, the devices are known as xenobots (ZEE-noh-bahtz).

Blackiston is among a growing number of scientists and engineers exploring new ways to build things with cells. Some groups combine living cells with artificial components to create “biohybrid” devices. Others have used muscle or heart tissue to create machines that walk on their own. Some of the bots can design synthetic materials for testing new drugs or medicine. Still other emerging machines mimic the actions of cells — even without using living tissue.

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A new disinfectant made from sawdust and water can knock out more than 99 percent of some disease-causing microbes. That makes the sawdust mix a potential alternative to current germ-killing chemicals. 

Many disinfectants used today can harm the environment. Take bleach and other chlorine-containing chemicals. They form toxic by-products when they get washed down the drain. Some potentially greener disinfectants exist. They rely on a chemical called “phenol” or similar compounds. But these cleaners can be costly and take a lot of energy to make.

Shicheng Zhang went searching for a better option. He’s an environmental engineer at Fudan University. It’s in Shanghai, China. Wood contains many molecules that look like phenol. They’re part of the large, branching molecules that make up plant cell walls. So Zhang wondered if microbe-killing chemicals could be extracted from sawdust through a low-cost, low-energy process.

This liquid wiped out E. coli bacteria — microbes that can cause food poisoning. The sawdust brew also killed anthrax bacteria. These microbes cause dangerous infections. What’s more, the disinfectant stopped flu viruses from being infectious.

The researchers also added different amounts of water to the sawdust soup. That let them test how concentrated it had to be to knock out germs. Depending on its concentration, the mix could zap more than 99 percent of the microbes.

Satinder Brar and Rama Pulicharla see a couple of benefits for the new disinfectant. These environmental engineers, who did not take part in the study, both work at York University in Toronto, Canada. One perk, they say, is that the sawdust mix costs little to make. Also, it has a simple recipe. No extra chemicals must be added to the sawdust and water.

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