Development of Novel Nanomaterials for Degradation of Autoinducers of Gram-Negative Bacteria

Bacteria are able to coordinate gene expression to develop different phenotypes such as motility or biofilm formation using quorum sensing (QS) systems. To synchronise its activity, Gram-negative bacteria use N-acyl-L-homoserine lactone as QS signal molecules. Using molecularly imprinted polymers (MIP), we have attempted to synthesise polymeric catalytic nanoparticles (NPs) to hydrolyse AHL. The activity of these MIP NPs relies on the template, a transition state analogue (TSA) of the hydrolysis of AHL. The solid phase synthesis of the MIP NPs has been performed using radical polymerisation. The hydrolytic capacity of the MIP NPs was analysed by measuring the degradation of N-hexanoyl homoserine lactone (C6-AHL) by HPLC-MS and comparing the degradation degree of C6-AHL between the TSA-NPs, control-NPs and natural degradation. The first approach was accomplished using commercially available monomers, which showed a significant decrease in the concentration of the C6-AHL in the samples containing TSA-NPs. Despite being the first attempt to use MIPs as attenuating agents of the development of QS in Gram-negative bacteria, these new polymeric materials have demonstrated high efficiency. The NPs obtained using methacrylic acid (MAA) as functional monomer showed the best performance, being able to degrade 41% of C6-AHL in the sample during first 2 h, while the MAA control polymer was able to remove only 18%. Moreover, MIP NPs are more robust, cheaper and more stable than enzymes or antibodies and can be added to paints or be immobilised on the surfaces of medical devices, food containers, water tanks or as a complement for antimicrobial treatments to control resistant bacterial infections.