Apr 9 2019
The materials science domain has become pulsating with “metal-organic frameworks” (MOFs), versatile compounds composed of metal ions linked to organic ligands, thereby forming one-, two-, or three-dimensional structures. There is currently a constantly expanding list of applications for MOF, including detoxing water from heavy metals and fluoride anions, separating petrochemicals, and extracting hydrogen or even gold from it.
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But recently, researchers have started making MOFs, composed of building blocks that usually make up biomolecules, for example, nucleic acids for DNA or amino acids for proteins. Besides the traditional MOF use in chemical catalysis, these biologically derived MOFs can be also employed as models for complex biomolecules that are hard to isolate and examine using other means.
Currently, a team of chemical engineers at EPFL Valais Wallis have synthesized a novel biologically-derived MOF that can be used as a “nanoreactor” – a place where miniature, otherwise-inaccessible reactions can occur. Guided by Kyriakos Stylianou, researchers from the labs of Berend Smit and Lyndon Emsley built and examined the new MOF with adenine molecules – one of the four nucleobases that constitute DNA and RNA.
The reason for this was to imitate the workings of DNA, one of which includes hydrogen-bonding interactions between adenine and another nucleobase, thymine. This is an important step in the development of the DNA double helix, but it also adds to the overall folding of both DNA and RNA within the cell.
Examining their new MOF, the scientists learned that thymine molecules diffuse inside its pores. Mimicking this diffusion, they found that thymine molecules were hydrogen-bonded with adenine molecules on the MOF’s cavities, meaning that it was effective in imitating what occurs in DNA.
“The adenine molecules act as structure-directing agents and ‘lock’ thymine molecules in specific positions within the cavities of our MOF,” says Kyriakos Stylianou. So the scientists exploited this locking and illuminated the thymine-loaded MOF – a method to catalyze a chemical reaction.
Consequently, the thymine molecules could be dimerized into a di-thymine product, which the researchers successfully isolated – a major advantage, provided that di-thymine is connected to skin cancer and can, at present, be easily isolated and explored.
“Overall, our study highlights the utility of biologically derived MOFs as nanoreactors for capturing biological molecules through specific interactions, and for transforming them into other molecules,” says Stylianou.