High performance near-IR-active macro- and nano-Metal-Organic-Frameworks using organic dyes

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This research consists at designing nano-sized porous materials exhibiting multiple functions. First, these porous materials are built with an inorganic part called node and a rigid organic unit. Together, they form a 3-dimensional porous frame of various forms and cavity sizes. This material belongs to the family of coordination polymers, more specifically to metal-organic-frameworks (MOFs). Thus, the voids created by this assembly can be filled with molecules making them cargos. The word coordination means that the link between the metal and organic parts is a coordination bond, which is weaker than a covalent one. This relative fragility can be used to trigger a breakdown of the framework, therefore a release of the molecules inside the cargos (i.e. drug delivery). Second, the specificity of the proposal is that the organic units are dyes absorbing and emitting in the phototherapeutic window (650-850 nm) with an optimum position at 800 nm where light penetrates best through skin (note that the near-IR region is 780-2500 nm). In simple words, one can trigger a drug release from the outside of the patient using a radiation of 650-850 nm range. Moreover, the emission from the dye inside an organ can best escape at 800 nm and be detected outside the patient by a near-IR detector. This process is called optical imaging. Third, some dyes can absorb light and heat to up the point that the MOFs breaks down (because of the weakness of the coordination bond). Also the increase in heat by itself can also cause dammage to the living cells. It is called photothermal therapy. Fourth, oxygen is everywhere. These dyes also have the capacity to absorb light and transfer its energy to oxygen by simple contact or collision. Upon energy transfer, oxygen becomes singlet oxygen (gained energy) and is very toxic to living cell. This process is called photodynamic therapy. Interestingly, once the MOF is broken down, the dye is intact and can still be photo-active for the generation of singlet oxygen. With the appropriate dye or dyes, the construction of nano-MOFs (for medical applications as this size is appropriate to penetrate the living cells) requires only a few steps and will exhibit four target functions : imaging, drug delivery, photothermal and photodynamic therapy. This is a new concept four in one, three of them are designed to kill cancer cells. Because MOFs are easily modifyable at their surface, recognition receptors (to recognize the cancer cells) and near-IR emissive dyes can be anchored on.