Water modified to absorb gases in a sponge-like way can carry 10 times as much oxygen as blood, which could help it act as an oxygen source in artificial blood substitutes or to help preserve organs and tissues.
Many gases will dissolve in water, but how much this can happen is limited because the hydrogen bonds formed between water molecules, which contain two hydrogen atoms and one oxygen atom, are difficult to break. That means they stay together rather than dissolving the gases by forming new bonds with them.
This fundamental limit can prove problematic for biological processes inside our bodies that require oxygen or other gases because we, like other mammals, are primarily made up of water.
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To get around this, at Harvard University and his colleagues have mixed water with zinc or cobalt-based nanocrystals that contain small pores in which gas molecules can be carried. Doing this increases the amount of dissolved oxygen or carbon dioxide that the water can hold by almost 100 times.
The nanocrystals are structured similarly to glass. They contain both hydrophilic (water-loving) surfaces, so they can dissolve in the water, and hydrophobic pores that water molecules can鈥檛 enter but gas molecules can.
鈥淲hat we鈥檝e done is create this empty space that can accommodate gas molecules, rather than water having to be pushed further apart for a gas molecule to fit in,鈥� says Mason.
The porous nanocrystals in the water are filled with gas simply by preparing the liquid in an atmosphere of either pure oxygen or CO2.
The high densities of gas achieved could make the water useful for many chemical processes that need to transport gas, such as in fuel cells, or in medical applications that require high levels of oxygen, such as the alleviation of decompression sickness, which can happen after ascending too fast after underwater diving.
If you can create high concentrations like this team has done and show there is more oxygen in the fluid than you would expect to see in pure oxygen gas, then that will lead to interesting applications and inspire new ideas, says at the University of Bath, UK.
Although previous studies have demonstrated porous liquids, doing this with water is an important leap forward, says at Imperial College London. 鈥淯sing water as the fluid phase could enable applications not possible with other porous liquids, due to water鈥檚 low cost, low toxicity and biocompatibility.鈥�
These uses could include working as an oxygen source within artificial blood substitutes or being used as a bath to help preserve organs and tissues.
Nature
