Amendment of the biocidal linkers in the metal-organic framework (MIL-68-NH₂) through post-synthetic modification to increase biological activity

Conventional antibiotics are ineffective against the growing number of multidrug-resistant bacteria that are posing a high risk to public health. Although traditional nanoparticles like metal and metal oxides have potent antibacterial properties, their excessive release of metal ions into human tissues as well as bacteria might have detrimental health effects. As a result, looking for alternative material becomes essential. Metal-organic frameworks (MOFs) are gaining interest, due to they combine two distinct areas—an organic part that exhibits intense and rapid bacterial activity and an inorganic part that contains broad-spectrum antibacterial agents. Additionally, MOFs' appropriate size enables them to either break through the bacterial membrane and degrade it or enter biofilm walls and start acting as an antibacterial agent. The ions for metal release, biocidal linkers, or even biocidal compounds enclosed in MOFs may be the source of MOFs' biological activity. MOFs are attractive prospects for biological and pharmaceutical applications because of these characteristics. Organic linkers of MOFs can be altered through solid-liquid reactions without compromising the characteristics of MOFs, the post-synthetic modification (PSM) technique is suited for bio active MOF synthesis because biocidal linkers are difficult to synthesis and can damaged before MOF formation. Here, 3-(2-hydroxyphenyl)-3-oxopropanal, methyl vinyl ketone, glyoxylic acid, and phthalaldehyde were used to synthesis and post-synthetically modify the metal organic framework based on indium ions (MIL-68-NH₂), yielding MIL-68-HP, MIL-68-VK, MIL-68-GA, and MIL-68-PA in 40, 80, 87, and 92 %, respectively. The comprehensive study, involving synthesis, characterization, and detailed biological activity testing of the modified MOFs was investigated. The findings suggest that the PSM MOFs exhibit greater biological activity than commercial antibiotics against several tested microbial species. The obtained results showed the importance of MOFs used as an alternative to conventional antibiotics, and the PSM approach to tailor their properties was a valid strategy.