The use of photoactive molecules as light-controlled antimicrobial agents has been proposed as one of the possible strategies to tackle resistance insurgence to conventional treatments in microorganisms. Antimicrobial photodynamic inactivation (PDI) relies on the combined action of an otherwise nontoxic molecule (called photosensitizer), visible light, and oxygen to produce cytotoxic effects by the photoinduced generation of reactive oxygen species, particularly singlet oxygen.
​ Since light driven toxicity of the short-lived reactive oxygen species is a short range effect (in the order of 100 nm), one of the open issues is the development of delivery systems to enhance bioavailability and drive the photoactive compounds to the microorganism. We have recently proposed supramolecular photoactive systems that exploit fully biocompatible and water soluble proteins to address the above problems. To achieve targeting, we proposed a modular approach where a photoactive protein (a modified streptavidin) is linked to a targeting protein, which is endowed with high affinity and molecular selectivity towards a molecular component located in the microorganism. Self-assembly of the building blocks is warranted by the strong streptavidin-biotin interaction. Using a variety of spectroscopic and fluorescence imaging tools, we explore the effects of assembly on photo-functional properties of the photoactive assemblies, and demonstrate the capability of the supramolecular compounds in targeting and photoinactivating the microorganism.

References
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