Polyoxometalate-based hybrid molecular materials for antibacterial photodynamic therapy in the visible region – PolyBact

The growing resistance of bacteria to antibiotics, responsible for approximately 5 million deaths in 2019, requires the development of new antibacterial agents and/or new therapeutic strategies. Photodynamic therapy (PDT), consisting in the generation via a photosensitizer (PS) of reactive oxygen species under mild irradiation, represents a very attractive therapeutic technique. In this project, we propose to develop a new type of agents combining chemotherapy and PDT for an exalted effect. To reach this objective, inorganic polyoxomolybdates (POMos), known to exalt the antibacterial properties of organic agents, and organic entities (BODIPY, anthraquinone, benzophenone, terthiophene) will be covalently connected considering two complementary approaches. Firstly, the two entities will be connected by a bisphosphonate (BP) ligand. In these POMo/BP/BODIPY triads, the BODIPY will act as a chemo/PDT agent under visible irradiation while the POM will act as a co-factor. Secondly, POMos and organic entities chemo and photoactive under UV irradiation (anthraquinone, benzophenone, terthiophene) will be connected via an imido bond. The two fragments will thus be electronically conjugated, which will lead to a drastic bathochromic shift of the lowest energy transition of the originally UV-active organic agents, making them active in PDT under visible light irradiation. These new agents will then be shaped via a radical photopolymerization process under visible light irradiation, the biologically active molecular hybrids described above acting as photoinitiators. Moreover, the presence of these hybrid POMs must improve the mechanical properties of the obtained materials. Finally, the chemo/PDT antibacterial activity of these materials under visible irradiation will be deeply investigated.