US scientists have produced metal organic frameworks (MOFS) that release NO in a controlled manner, which could have many uses in biomedical applications. 

Metal-organic frameworks (MOFs) are a relatively new class of hybrid inorganic-organic porous materials that have gained immense interest for gas adsorption, separations and catalysis applications due to their chemical tunability, high porosity and thermal stability. But their use in biotechnology has been slow to progress because traditional synthetic methods have not been able to produce suitable stability and functionality. 

Now Seth Cohen and co-workers at the University of California San Diego, La Jolla, have transformed two pre-synthesised MOFs into new frameworks that could offer controlled delivery of nitric oxide, which could be useful for many anti-bacterial, anti-thrombic and wound healing applications.

Cohen treated MOFs containing pendant amine with NO under high pressure to produce diazeniumdiolate (NONOate) functional groups within the MOF. Significantly, by Cohen's method only covalent interactions between the incorporated NONOates are produced which allow controlled release of large amounts of NO. Previously synthetic NO-releasing porous materials used non-covalent interactions which made the NO release less manageable. Also, Cohen's materials are a lot cheaper and less toxic than other systems.  

'The biological activity of NO makes these materials very attractive for a wide range of biological and medical applications' says Russell Morris, an expert in MOFs at University of St Andrews, UK. 'Given that the chemical composition of many MOFs is toxicologically acceptable, this approach may be an interesting new method to prepare medically active MOFs.' 

Cohen says, 'using post-synthetic modification we should be able to control the way these materials degrade and therefore, we will be able to modulate any possible toxicity. Out of the inorganic materials currently being looked at for biomedical applications, these post-synthetic modified MOFs have a lot of potential.' 

Lorena Tomas Laudo 

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