Microscopic chemistry labs

ChemSci Pick of the Week

Hollow spheres, over 1000 times smaller than the width of a hair, could act as tiny microreactors, allowing reactants and products in and out whilst protecting the reaction catalyst from the outside environment.

"Life depends on the action of enzymes, natural catalysts that promote key metabolic transformations", says José Mascareñas from the Center for Research in Biological Chemistry and Molecular Materials (CiQUS) at the Universidad de Santiago de Compostela in Spain. "Scientists have worked hard to develop catalysts that could somewhat mimic the activity of enzymes in terms of efficiency and selectivity."

Metal nanoparticles are a class of catalyst that can behave a lot like an enzyme. It is also possible to retrieve them from a reaction mixture, meaning they can be reused. But most of them don’t actually work in the body – the water-based fluids found inside the body react with the nanoparticles and destroy them.

As a solution, Dr Mascareñas and his team have designed tiny porous spheres to protect the catalysts. The spheres are biocompatible – which means that their outer layers have been designed in such a way that they don’t interact negatively with the body. They are also full of tiny pores. Small molecules can enter the sphere via the pores and react in the presence of the catalyst. The newly formed molecules – the products of the reaction then exit the sphere in the same way. Larger molecules however, such as other enzymes present in the body, can’t get in, and the nanoparticle catalysts can’t leave.

"The capsules can work as selective artificial factories in biological buffers, and even in the environment of living cells", says Dr Mascareñas.

These microreactors could have huge implications for medicine. For example they could be injected into a particular part of the body to carry out a therapeutic reaction in that area only. This would reduce the risk of harmful side effects.

This article is free to read in our open access, flagship journal Chemical Science: Fernando López, Miguel A. Correa-Duarte, José L. Mascareñas et al., Chem. Sci., 2019, Accepted Manuscript. DOI: 10.1039/C8SC04390F. You can access our 2019 ChemSci Picks in this article collection.