A Simple and Versatile Pathway for the Synthesis of Visible Light Photoreactive Nanoparticles

This work pioneers the design of visible (415 nm) and UV-B light (300 nm) reactive nanoparticles via radical polymerization in aqueous heterogeneous media based on methyl methacrylate (MMA) and unique acrylates bearing tetrazole functionalities in a simple and straightforward two step reaction. Stable colloidal nanoparticles with an average diameter of 150 nm and inherent tetrazole functionality (varying from 2.5 to 10 wt% relative to MMA) are prepared via one-pot miniemulsion polymerization. In a subsequent step, fluorescent pyrazoline moieties serving as linkage points are generated on the nanoparticles by either photoinduced nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) or nitrile imine carboxylic acid ligation (NICAL) in water, thus enabling the particles as fluorescent tracers. Through in-depth molecular surface analysis, it is demonstrated that the photoreactive nanoparticles undergo ligation to a variety of substrates bearing functionalities including maleimides, acrylates, or carboxylic acids, illustrating the versatility of the particle modification process. Critically, the unique ability of the photoreactive nanoparticles to be activated with visible light allows for their decoration with UV light-sensitive molecules. Herein, the ligation of folic acida vitamin prone to degradation under UV light-to the photoreactive nanoparticles using visible light is exemplified, demonstrating the synthetic power of our photoreactive fluorescent nanoparticle platform technology.L.D. and N.Z. contributed equally to this work. C.B.-K. acknowledges the Australian Research Council (ARC) for funding in the form of a Laureate Fellowship underpinning his photochemical research program as well as the Queensland University of Technology (QUT) for key continued support. N.Z. is grateful for the funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 665501 with the research Foundation Flanders (FWO). The XPS data of the latexes after the NICAL or NITEC reactions reported herein were obtained at the Central Analytical Research Facility (CARF) operated by the Institute for Future Environments (IFE). Access to CARF is supported by generous funding from the Science and Engineering Faculty (SEF).biomolecule tagging; miniemulsion; profluorescent particles; tetrazole-driven photochemistry; visible light ligatio