Complexes of cobalt nanoparticles and polyfunctional curcumin as antimicrobial agents

Although antimicrobials like penicillin and tetracycline have been documented to be most popular antimicrobials, micro-organisms, especially bacteria, are becoming resistant to more and more antimicrobial agents and hence the main future research in antimicrobial therapy is to develop novel materials which could work as effective antimicrobials. In this context, using direct reduction method, 10 nm Co nanoparticles have been synthesized and further functionalized with curcumin. The characterization showed FCC structured Co nanoparticles to be electrostatically bound to curcumin using the hydroxyl linkage, retaining the magnetic moment of Co as well as the diaryl heptanoid chromophore group of curcumin with the loading percentage of~ 89%. These samples when subjected to Escherichia coli, gram negative bacterium, the antimicrobial activity of Co:curcumin was found to be much enhanced as compared to only Co and only curcumin. The results have been correlated to the mechanism in presence of moisture, which possibly suspends the Co:curcumin complex in the medium, which, due to intimate contact between the biocidal agent and the microorganism, renders the microbial agent ineffective. The synthesized system exhibited a combination of the ability of curcumin to penetrate the cell barrier and render antimicrobial action along with the chelating capacity of Co:curcumin complex. In the same way that strong metal–ligand bonds are vital for the efficiency of metal chelators of toxic metals, these strongly bound metal complexes may prove to be better antimicrobial agents, binding them to the bacterial walls.