2023-10-16 19:45:56
Organometallic scaffolds could one day release nitric oxide with antibacterial properties.
Because metal-organic frameworks (MOFs), highly porous metal structures, are so structurally and chemically diverse, they could be used for many applications, such as drug delivery and environmental cleanup. But we need to know better how they work, especially when they are embedded in polymers. Now, researchers have developed and characterized nitric oxide (NO)-storing MOFs embedded in a thin film with novel antibacterial potential.
Studying the interactions between MOFs and polymers within membranes can be complicated, requiring complex analytical methods and considerable resources. In previous studies, Russell E. Morris of the University of St. Andrews in the United Kingdom and his colleagues studied the interaction between a nickel-containing MOF and polyurethane. But the focused ion beam scanning electron microscopy (FIB-SEM) method they used can alter or damage both polymers and MOFs. Thus, the same researchers, together with Zeiss Microscopy, used a new FIB-SEM technique using cryogenics to increase the stability of the MOF composites.
To test it, they created three membranes in collaboration with researchers at Colorado State University (United States) that contained a nickel MOF called CPO-27-Ni, a copper MOF called CuBTTri, or both. Next, using their cryogenic FIB-SEM technique, they observed the particles in each MOF in greater detail than with other imaging methods. The images also showed that the metal complexes were evenly distributed across the membranes and did not overlap. Next, the research team, led by Romy Ettlinger of the University of St. Andrews in the United Kingdom, examined the films’ ability to release nitric oxide, a molecule with antibacterial properties that could have biomedical applications. In the experiments, MOF-embedded membranes had different triggers and responses:
CPO-27-Ni released nitric oxide rapidly, in a short burst, in response to humidity.
CuBTTri acted as a catalyst when exposed to a tripeptide, S-nitrosoglutathione (GSNO), a natural source of nitric oxide in the human body, and produced a sustained release of nitric oxide in response.
Together, CPO-27-Ni and CuBTTri produced a membrane that releases nitric oxide rapidly and sustainably when sequentially exposed to moisture and GSNO.
Nickel and copper MOFs were combined to create a composite material that achieved an optimal two-stage nitric oxide delivery system. The researchers suggest that this two-step administration could be useful in medical devices, both to achieve immediate antibacterial effects and to offer long-term prevention of microbial fouling.
Membrane films containing MOFs, such as those shown here, which produce nitric oxide, could provide antibacterial properties in medical devices. (Image: adapted from ACS Applied Materials & Interfaces 2023, DOI: 10.1021/acsami.3c11283)
Ettlinger, Morris and their colleagues present the technical details of their MOFs in the academic journal ACS Applied Materials & Interfaces, under the title “Mixed Metal-Organic Framework Mixed-Matrix Membranes: Insights into Simultaneous Moisture-Triggered and Catalytic Delivery of Nitric Oxide using Cryo-scanning Electron Microscopy”. (Source: American Chemical Society)
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