03 September 2010
A simple method to produce mesoporous millimetre-sized carbon spheres that show potential for removing toxic substances from blood has been developed by scientists in China.
Part of the job of the kidney and liver in the body is to remove toxic substances from blood. But if these organs fail, patients need help to prevent toxins building up. Treatment usually involves passing blood over an adsorbent and millimetre-sized spheres of activated carbon are currently used but they suffer from sensitivity to high temperatures and an inability to absorb larger target molecules due to their small pore size.
Now, Jianlin Shi and colleagues from the Chinese Academy of Science in Shanghai have developed a simple three-step process to make millimetre-sized mesoporous carbon spheres (MMCSs) that, they claim, are more effective than commercial activated carbon spheres. Shi dissolved carbon precursor polymers and triblock copolymers in ethanol which was dispersed in hot oil. As the ethanol evaporates off, emulsion droplets of the two polymers form and self assemble to form mesostructures, which, on further heating combine into larger spherical polymer particles. Finally filtering and carbonization produces the millimeter-sized mesoporous carbon spheres.
New carbon spheres are more effective at removing toxins from blood
Shi's MMCSs have a worm-like mesoporous structure and a smooth surface. The team demonstrates that the spheres do not destroy hemoglobin or induce blood clotting - two essential elements if these MMCSs can be used in blood purification. Also, the adsorption rate is three times higher and the capacity for bilirubin - a typical toxin that is removed - is nearly twice that of commercial activated carbon spheres.
By Limin Guo, a member of the research team, explains that the key to the success of their MMCSs is the combination of the mesoporous material that is ideal for adsorbing bilirubin and the smooth, millimeter-size spheres that allow 'blood cells to conveniently and safely go through the adsorption column via the interspaces among the MMCSs'.
Freddy Kleitz, an expert in the field of mesoporous materials from Université Laval in Quebec, Canada, describes the work as 'a very important development in the field of mesoporous materials, especially carbons.' He was most impressed by the simple three-step self assembly synthesis used be the researchers, saying that it could be used to 'could synthesise the perfect morphology needed.'
Given the simple synthesis and improved properties, these MMCSs have the potential to replace commercial carbon adsorbents. Guo and colleagues are now planning to optimize the synthesis to increase MMCSs yield and test the adsorption properties of MMCSs under flowing blood.