“Releasing, or capturing, that is the question. Porous molecular materials”
Porous materials are one important class where the shape and distribution of “empty” space throughout the framework is a main determinant for the resulting functionality. For instance, zeolites are available with many different pore size and geometries, which is the fundament of their wide spread use in industry, e.g. as absorbents and catalysts. Drug delivery applications with porous inorganic materials are in the focus of several investigations all over the world. Following supramolecular principles, i.e., incorporating dynamically covalent bonds into a silica framework, we have reported a “break on-demand” of the silica structure. Recently we have developed disulfide-bridged organosilica nanoparticles with cage-like morphology, and assessed in detail their bioaccumulation in vivo. Interestingly their lung accumulation and their ability to escape macrophage filtering open new promises for their use as drug delivery systems.
In addition they are able to stabilize out of equilibrium species and transport them inside cells were they can be released and evolve towards the equilibrium state. But controlling the shape and the “emptiness”, of porous systems can allow the capture, and not release, of specific molecules, biomarkers. In particular a novel class of fluorescent artificial receptors (FAR) is introduced that can bind the neurotransmitters serotonin and dopamine in a bio-relevant concentration range with unprecedented affinity and selectivity. The fully synthetic receptors are based on zeolites and rapid responding and thus enable instantaneous neurotransmitter detection through cost economic and facile absorbance- and emission-based assays. Their potential for high-throughput diagnostics in urine and for monitoring of important enzymatic reactions is shown.
Finally amongst the most studied porous systems in medicine are hydrogels, which are inherently more disordered porous system than the aforementioned inorganic host materials. An example of hybrid injectable hydrogels will be given for the treatment of fistula.
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