|
A one-pot chemical reaction system based on nanoscopic capsules embedded in a polymer membrane has been devised by researchers in The Netherlands. The nanoreactor system allows cascade reactions to be carried out that would otherwise require multiple distinct reaction steps with time-consuming and wasteful separation and purification stages. Jan van Hest and Alan Rowan of the Nijmegen University, have taken their lead from biology, pointing out that living cells are the archetypal one-pot reaction system. Several multistep reactions run in parallel with high efficiency and specificity, they explain. Emulating this power in a synthetic system has been an objective in chemistry for many years. Now, with the assistance of UV-Vis spectroscopy to track their success, the Nijmegen team has adopted the cell's compartmentalisation approach to parallel reactions. The team built their nanoreactors by controlled positioning of two different enzymes in a polymer membrane composed of synthetic nanoscopic bubbles, dubbed polymersomes after their biological counterparts the liposomes, and added a third enzyme to the solution in which this system is immersed. This three-way reaction system would then allow them to run three different enzymatic reactions simultaneously, without interference, in a 'one-pot' reaction. The product from the reaction of starting material with the first enzyme would diffuse to the second enzyme for the next step and so on. In a proof of principle experiment, the researchers bound the enzyme horseradish peroxidase within the membrane and trapped glucose oxidase in the system's aqueous layer. The surrounding solution carried lipase B. The team fed the nanoreactor acetylated glucose. The lipase B removed the four acetyl groups, which allowed the resulting glucose molecules to cross the membrane and be oxidized on contact with the glucose oxidase. This reaction releases hydrogen peroxide, which is needed by the horseradish peroxidase enzyme to modify its sample substrate ABTS (2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid)) into a radical cation. Related links:
|
Cascading nanoreactors! |
